DC Systems, Energy Conversion & Storage Matchmaking Event de... · high-power converter. Methodology: After initial literature review into the topologies used for high power and low

DC Systems, Energy Conversion & Storage

Matchmaking Event 13th November 2019

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Master’s Thesis Proposal

Efficient Energy Conversion DC systems, Energy conversion & Storage

INTEGRATING OFFSHORE WIND ENERGY IN THE GRID

Type of project: MSc thesis

Problem definition:

The converters in the wind turbines create some harmonic distortion that gets amplified through the network. Especially in the case of offshore wind farms, by the time this distortion reaches the PCC with the grid, it has been significantly amplified and there is a high risk of violating the grid code. Real wind farms have seen themselves forced to install very expensive – and inflexible – passive filters.

The scientific community has the challenge to try to devise new mitigation measures to reduce this amplification. However, this is not possible yet because nowadays we cannot even properly estimate the expected distortion at the PCC. Basically, nowadays the harmonic distortion at the PCC is estimated by using one technique called “Summation Law” but there is extensive proof in the literature (based on measurements on actual wind farms) that this summation law is not accurate.

The objective of this Master Thesis would be to check if another method (based on probability theory) delivers more accurate results than the Summation Law.

Methodology:

- Model a wind farm in the software PowerFactory. - Automate the simulation of the wind farm with different harmonic profiles injected by the

wind turbine converters based on a probabilistic profile. - Extract conclusions at the PCC. - Compare with Summation Law results.

This Master Thesis involves extensive simulations but no laboratory work.

Possibility of writing a conference paper (depending on the student ambitions).

Skills the student will learn with this MSc Thesis:

Application of statistics to a practical problem in Industry

Using a very common software used in industry (PowerFactory)

Knowledge on a topic that is – and will be for the years to come – fundamental for the development of renewable sources: integration in the grid.

Contact details:

PhD student: Lucia Beloqui Larumbe, [email protected]

Supervisor: Dr. Zian Qin, [email protected]

mailto:[email protected]


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AC/AC MATRIX CONVERTER FOR AN 11KW WIRELESS CHARGER


Scope: To design an AC/AC matrix converter for an 11kW wireless charger for electric vehicles.

Problem definition: A high-frequency inverter needs to be placed at the transmitter side of the wireless charger, such that a magnetic field can be transferred to the receiver side. Since the AC 50 Hz grid is generally the power source, proper conversion stages need to be designed to feed that inverter. Intuitively, it is preferable to have the minimum possible number of stages to have higher efficiency. Using two conversion stages could be a possibility: a standard AC/DC converter followed by a DC/DC voltage regulator stage. Another option could be using only one conversion stage: either a buck or boost-type AC/DC converter (see the picture), which directly includes the voltage regulation. On the other hand, the conversion stages can be reduced even more by using an AC/AC matrix converter that transforms the low-frequency grid voltage into high-frequency voltage directly (See the picture). Methodology: First, a literature research must be executed on the characteristic of EVs wireless charging, focusing on the transmitter’s power electronics. A comparison needs to be made between different arrangements. An investigation is going to be carried out on AC/AC converters already used in wireless charging, and their pitfalls are going to be highlighted. An AC/AC converter is going to be designed for an 11kW wireless charger.

Research Objectives:

Understand and identify the challenges of an AC/AC converter for EVs wireless charging for what concerns the operation, control, and components.

Design an AC/AC matrix converter for an 11kW wireless charger for electric vehicles.

Contact details:

PhD student: Francesca Grazian ([email protected])

Supervisor: Dr. Thiago Batista Soeiro ([email protected]) Prof. Pavol Bauer ([email protected])




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LOW-PROFILE PCB FOR AN 11KW WIRELESS CHARGING CONVERTER


Scope: Design a low-profile PCB for an 11kW wireless charging converter, such that it uses as heatsink the aluminum shield of the receiver coil.

Problem definition: An important constraint in wireless charging for electric vehicles is the physical. The receiver coil needs to be within the dimensions of the vehicle's chassis, and the power electronics onboard has also a limited space in which it can be placed. As a consequence, the power density is a challenge, especially because the automotive manufacturers are not willing to give up on much space. This problem can be mitigated by placing the power electronics in an at arrangement on the backside of the coil, such that the magnetic field shielding aluminum plate can also be used for heat-spreading.

Methodology: First, a literature research must be executed on the general characteristics of EVs wireless charging. After this, the focus is on power electronics used and their implementation. Since the final objective is to design a PCB with a high power density and high efficiency, a detailed thermal analysis needs to be carried out by simulations. In this way, the dimensions of the PCB can be found. As an example, important results are the thickness of both the thermal pad (X1) and aluminum shield (X2), and the minimum distance between the components (d). Finally, to verify these results, the designed PCB is going to be prototyped, and its heat-spreading capability is going to be tested.


Understand and identify the challenges of a low-profile PCB for a wireless charging converter with high power density.

Find out the minimum dimensions of the system, based on detailed thermal analysis.

Contact details:






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WIFI COMMUNICATION FOR EV WIRELESS CHARGING

Type of project: Extra Project/ SIP 2

Scope:

To evaluate the feasibility of the Wi-Fi as a communication method for EV wireless charging in terms of communication speed, energy consumption, accuracy and interaction with multiple devices.

Problem definition:

The communication between transmitter and receiver in EVs wireless charging can allow different features such as supporting to the user in the coils’ alignment, the compatibility check of the systems, and requesting either the start, stop or pause of the charging process. Moreover, through the communication, the receiver can ask the transmitter for specific voltage levels while the charging process is running. In this project, the use of Wi-Fi (Sub-1 GHz) is evaluated for EVs wireless charging.

Methodology:

The (short) first phase is understanding the different wireless communication protocols (Bluetooth, Wi-Fi, ZigBee etc.). Then, the project is dedicated to familiarizing with TI Launchpad development Kits and programming them such that they can communicate through Wi-Fi (Sub-1 GHz). Therefore, the project is mainly taking place in the laboratory.


Understanding the operation of TI Launchpad development Kits for Wi-Fi communication.

Characterize this communication in terms of speed, energy consumption, accuracy and space range.

Evaluate the scenario in which multiple devices are interacting together. What would happen to the charging process?

Contact details:






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LOW VOLTAGE HIGH POWER CONVERTER FOR NOVEL CO2 ELECTROLYSER


Scope:

To design an efficient high power converter for CO2 electrolysis which enables the development of “power-to-fuel” technologies, accelerating the shift of the fossil-based liquid fuel industry towards renewable sources.

Problem definition:

Current liquid fuel production technologies have high carbon footprint and contribute to the global warming effect, a new alternative under development is liquid fuel production based on electrical energy which has gained momentum lately with the introduction of carbon capture and new catalyst materials for CO2 electrolysis. Research into medium-to-large scale CO2 electrolysers is scarce and TU Delft’s e-refinery project aims at developing 100kW range prototypes in the next years, which requires the study and development of a highly-efficient power conditioning system, enabling more research into up-scaling CO2 electrolyser technology. The restrictions imposed by the electrolyser’s chemical processes call for a low-voltage converter, and the scale of the intended prototype call for a high-power converter.

Methodology:

After initial literature review into the topologies used for high power and low voltage, a good understanding of the load is necessary, so there will be an open communication line with our chemistry colleagues. With a known load, the converter can be designed and built.


Understand the operation of high power low-voltage topologies

Select a suitable topology for the CO2 electrolyser

Design, construct and test a converter prototype

Contact details:

PhD student: Cristian Pașcalău ( [email protected])





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SOLAR CONVERTER FOR NOVEL CO2 ELECTROLYSER


Scope:

To design an efficient solar converter with MPPT for CO2 electrolysis which enables the development of “power-to-X” technologies, accelerating the shift of the fossil-based chemical industry towards renewable sources.

Problem definition:

A new alternative of liquid fuel production based on electrical energy is under development and has gained momentum lately with the introduction of carbon capture and new catalyst materials for CO2 electrolysis. Research into medium-to-large scale CO2 electrolysers is scarce and TU Delft’s e-refinery project aims at developing 100kW range prototypes in the next years, which requires the study and development of a highly-efficient power conditioning system, enabling more research into up-scaling CO2 electrolyser technology. Integration of solar power is a necessary step for making carbon-neutral chemicals and the efficient adaptation of solar energy to a usable form of electrical energy for electrolysis is a crucial link in the future e-refinery.

Methodology:

After initial literature review into the topologies used for solar dc-dc converters, the optimum voltage range for interface with the CO2 electrolyser must be found together with a suitable MPPT strategy.


Understand the operation of solar MPPT converters

Select a suitable topology for the solar converter

Design, construct and test a converter prototype

Contact details:

PhD student: Cristian Pașcalău ( [email protected])





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SOLID-STATE CIRCUIT BREAKER – AUXILIARY POWER SUPPLY DESIGN


Scope:

The two main challenges of meshed low voltage DC grids today are the flexible control of power flow and short-circuit protection. The conventional approach to deal with both problems is to incorporate galvanically isolated DC-DC converters with integrated short-circuit protection, which are rated for the full power rating of the grid. In the previous research, partially rated power flow control converter was proposed in combination with a solid-state short circuit breaker (sscb). This thesis builds on these results.

Problem definition:

The sscb is required to operate during all abnormal states of the grid reliably. The crucial part is supplying the auxiliary power to the sscb during faults. The aux. power supply for sscb poses an exciting design challenge. Besides the extreme operational conditions, the power supply needs to be very efficient across a wide input voltage range.

Methodology:

In the first phase, the student will get familiar with the design requirements of the sscb for lvdc system. Based on the literature review of the available solutions for the auxiliary power the student selects the best fit for the application. Then proceeds with the design of the prototype power supply.


Choose appropriate topology for the sscb aux. power supply

Design the pcb and integration with the existing sscb

Experimental verification

Contact details:

PhD student: P.Purgat ([email protected] )

Supervisor: dr. Z. Qin([email protected]) prof. P. Bauer ([email protected])




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SOLID-STATE CIRCUIT BREAKER – CURRENT LIMITING


Scope:

One of the main challenges of low voltage DC systems is the protection against short-circuits. The difficulty arises due to the fast fault current rise. The solid-state circuit breakers (SSCBs) can interrupt fault within hundreds of nanoseconds. The SSCB can, however, be designed to limit the rise of the fault current via operation of the semiconductors in the linear region. The new SiC JFETs appear as the ideal candidate to integrate this functionality.

Problem definition:

In the previous project, an SSCB with MOSFETs was designed and tested in the laboratory. The solution achieves satisfactory results in short-circuit interruption. However, it is not capable of limiting the rise of the short-circuit current. In this project, the thermal capability of the SiC JFETs will be checked, and appropriate driving circuits will be designed.

Methodology:

In the first phase, the student will get familiar with the design requirements of the SSCB for the LVDC system via literature review, and from the previous work done at our laboratory. In the second stage, the thermal capabilities of SiC JFETs will be evaluated in simulation. In the third stage of the project, a highly efficient gate driving circuit will be designed that will be able to drive the JFETs in the linear region. In the last phase, the designed circuits will be experimentally validated.


Thermal modelling of SiC JFETs and estimation of the current limiting capabilities of SSCB.

Design of intelligent high-efficiency gate driver circuits

Experimental validation of the designed solutions in the laboratory.

Contact details:


Supervisor: dr. Z. Qin([email protected]) dr. T. Batista Soeiro ([email protected])

prof. P. Bauer ([email protected])





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SOLID-STATE CIRCUIT BREAKER – CURRENT LIMITING


Scope:

One of the main challenges of low voltage DC systems is the protection against short-circuits. The difficulty arises due to the fast fault current rise. The solid-state circuit breakers (SSCBs) can interrupt fault within hundreds of nanoseconds. Thus the fault detection time is a significant time of the entire fault interruption process and requires special attention.

Problem definition:

In the previous project, a short-circuit detection system was designed and tested in the laboratory. The solution achieves satisfactory results under nominal conditions. However, the robustness of the solution to the thermal and other variations is the weak point. In the project, the existing solution will be improved, and the robustness of the new solution will be tested.

Methodology:

In the first phase, the student will get familiar with the design requirements of the SSCB and short circuit detection. The knowledge gained from the literature and the previous work done at our laboratory will be the base for the redesign of the existing solution. In the last stage, a robustness test will be developed, and the new solution will be tested.


Testing of existing solutions against thermal and other variations in operating conditions.

Improve the existing circuits and design improved circuits based on the results from the first stage.

Experimentally validate the improved circuits in the robustness tests.

Contact details:






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TRIPLE ACTIVE BRIDGE CONVERTER – MODEL PREDICTIVE CONTROL


Scope:

Multi-port converters~(MPC) have gained research attention as a potential solution for versatile energy management systems able to integrate diverse renewable energy sources or conventional energy sources, storage systems, and loads. The main advantages of MPCs include lower component count compared to standalone converters, higher efficiency, the possibility of centralized control, and potentially higher power density. Therefore, potential applications for the MPCs range from electric vehicles, more-electric aircrafts to smart grids.

Problem definition:

A key challenge of TAB converter design and control is the inherent cross-coupling of the power flows between the ports due to the multi-winding transformer. Therefore, the TAB converter behaves as a multi-input multi-output~(MIMO) system with coupled control loops which is difficult to control. One of the main limitations of the currently existing approaches is the controller complexity. Predictive control is often considered for several advantages it can provide, such as fast dynamics, easy inclusion of constraints, and simple digital implementation.

Methodology:

In the first phase, the student will get familiar with the triple active bridge converter operation. Based on the literature review of the predictive controllers for phase-shifted topology a suitable candidate will be chosen for the triple active bridge converter. The controller will be first tested using Simulink/PLECS and in the last stage tested experimentally with hardware-in-the-loop or laboratory prototype.


Choose predictive controller structure for triple active bridge

Design model predictive controller for triple active bridge

Experimental verification

Contact details:






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RAPID MODULE SOLUTIONS FOR SIC MOSFETS

Type of project: <MSc thesis>

IMS PCB for thermal conduction SMD SiC Mosfets

SMD SiC Mosfets based half bridge module Thermal picture in COMSOL

Scope:

The scope of the project is providing design practices with SiC MOSFETs and comparison of different thermal management solutions of rapid module solution with SMD packages.

Problem definition:

SiC MOSFETs are widely available as discrete packages in terms of voltage class and current rating, however the modules solution is relatively limited. In this project the goal is to identify the pros and cons of a rapid module solution with SMD device on IMS compare to a real power module solution.

Methodology:

Simulation tools will be used to clarify different thermal management solutions and a solution will be built and test in the lab to compare with simulation


How to drive and utilize the SiC MOSFET

Thermal management

Simulation and lab comparison

Contact details:

Supervisor: Zian Qin, [email protected]


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Extra Project Proposal


DERIVING LOSS AND THERMAL ANALYTICAL MODELS FOR MAGNETIC DEVICES

Type of project: Extra Project / SIP 2 /MSc thesis

Scope:

Studying and deriving loss and thermal analytical models for accurate design of magnetic components.

Problem definition:

For high power converters, weight reduction and thermal management of the passive components are of great importance. The optimum design of such components has to be done case-by-case according to the application needs and typically constitutes a multi-objective problem where trade-off between weight, power density, efficiency, cost, form factor, etc have to be met. The design is not only dependent on the commercial available material properties but also the application requirements and operational particularities of the power electronics, such as pulse-width modulation (PWM) method used, the required control bandwidth, fault handling requirements, EMC standards, semiconductor power losses, and cooling conditions. The comprehensive design procedure and analytical physical limits for the component must be obtained in order to obtain a good technical insight during the design phase of economic sensible power electronic-based products. Methodology:

To study, model, design and simulate magnetic components. All to be implemented in MATLAB and finite element method solver software, such as FEMM or Comsol.


Literature review of magnetic component design methodologies;

To derive analytical models to design and evaluate magnetic components in MATLAB and FEMM or Comsol;

Contact details:

Supervisor:

Dr. Ir. Thiago Batista Soeiro, [email protected]

Prof. Dr. Eng. Pavol Bauer, [email protected]



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STUDY AND DEVELOPMENT OF A POWER REDISTRIBUTOR FOR DISTRIBUTION GRIDS


Scope:

Study, design and implementation of an active filter based power redistributor for improving the phase load of distribution transformers.

Problem definition:

In energy distribution systems power electronic based devices such as STATCOMs (Static Synchronous Compensators), DVRs (Dynamic Voltage Restorers) and UPQC (Unified Power Quality Conditioners) can be used in order to improve the energy power quality with focus on the Medium-Voltage (MV) grid. In the future energy scenario where the power consumption of houses and major city infrastructures will dramatically rise, especially by the increasing adoption of electric vehicles and electric heaters, the balance of power supplied by each distribution phase will become more and more complicated at the Low-Voltage (LV) grid. In this work the concept of shunt active filter is used in the LV grid or the secondary-side of the distribution transformer in order to compensate the loads reactive power, current harmonics and above all to balance the power absorbed in all three distribution phases and neutral wires. The latter functionality enabled by the operation of the circuitry as a power redistributor is of paramount importance because this will improve the power utilization of the distribution transformer, thus, enhancing the capacity of the energy distribution system.

Methodology:

To study, simulate and implement in an existing 2-level voltage source converter the functioning of an active filter based power redistributor.


Literature review for power electronic based power redistributor;

Develop mathematical analytical models for the power and control of the circuitry;

Implementation of the studied concepts in an existing prototype.

Contact details:

Supervisor:



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DIMENSIONING ULTRA COMPACT AND EFFICIENCY POWER ELECTRONICS FEATURING SOFT-SWITCHING FOR ELECTRIC VEHICLE CHARGERS


Scope:

Study, design and implementation of a grid interface circuit or AC-DC converter featuring Triangular Current Modulation (TCM) for two power stage charging of Electric Vehicles (EV).

Problem definition:

The Electric Vehicle (EV) charging market is very dynamic. The so called AC-type chargers can be found confined within the vehicle or on-board. This must be able to withstand the harsh environment with ambient temperature of above 75 oC. Therefore, compact and high-efficiency power electronics (and implementing electrolytic-less capacitors) in the power range of 6 kW .. 12 kW is desired. The operation of the grid-connected power stage with triangular current modulation and phase-shift interleaving has become standard in high compact and high efficiency systems. The required large current ripples across the magnetics allows the operation of the bridge-legs of the circuit with Zero-Voltage Switching (ZVS), leading to the utilization of smaller passives and cooling systems. Unfortunately, variable switching frequency operation is required and means to limit the frequency range are necessary in a digital implementation with the latest microcontrollers available in the market. The addition of passive networks and/or the use of modified TCM algorithms have shown promising results.

Methodology:

To study, simulate, implement a narrow frequency range triangular current modulation in a TI DSP. The functionality of the developed software will be tested in an existing AC-DC power converter.


Literature review in high efficiency and ultra-compact power AC-DC conversion systems;

Investigation and proposal of TCM techniques narrowing switching frequency range;

Implementation of a developed TCM modulation in an existing TI DSP control board;

Test the developed software in an existing prototype.

Contact details:

Supervisor:





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FUTURE DC TRANSMISSION GRIDS: STUDY AND IMPLEMENTATION OF OPTIMUM PULSE PATTERN (OPP) MODULATION AND PREDICTIVE CONTROL


Scope:

Study and implementation of MMC for future DC-type Transmission using intelligent control algorithms based on predictive control and optimum pulse pattern modulation.

Problem definition:

The modular multilevel converter or MMC is one of the favourable circuits for implementing DC-type medium or high voltage distribution/transmission. The high number of serial circuit cells brings advantages in terms of harmonic performance but complexity for capacitor voltage control. Optimum Pulse Pattern modulation has shown superior performance than PWM techniques when the switching frequency is only few times higher than the fundamental. Predictive control technique is also a powerful tool to enhance system performance specially when the allowed processing time is large enough. The combination of both techniques can bring many operational advantages for the MMC.

Methodology:

To study, simulate, design and test the usage of OPPs and predictive control in a MMC using computational tools and TU Delft’s laboratory facilities.


Literature review of usage of predictive control and optimum pulse pattern in MMCs;

Derive analytical models for MMC verifying operational performance merits such as harmonic injection, capacitor cell voltage balance, circulating currents, component losses, etc;

Benchmark the developed OPPs against conventional modulations, e.g. nearst level, PWM phase-shift/disposition, Space Vector, etc;

Implement the developed study in the MMC hardware demonstrator.

Contact details:

Supervisor:





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MICRO-INVERTER USING MODULAR MULTILEVEL CONVERTER IN SOLAR APPLICATION


Scope:

To investigate the benefits of modular multilevel converter employing low voltage SMD Si-Mosfets.

Problem definition:

Up to 5 kW PV installations micro-inverters are common alternatives for the typical string solar inverters. The main drawback of the technology is the slight higher initial cost, however a more efficient energy generation can be achieved because each one of the PV modules are operated optimally at the maximum power point. The modular multilevel converter can be used employing low voltage rated Si Mosfets which displays excellent loss performance. Power efficiency above 97% is possible yielding to much lower total cost of ownership than string inverters. Additionally, the system can be designed with redundancy for improved reliability (no single point of failure). Conductive electromagnetic interference which is a typical problem in solar applications can be dealt within the modular cell.

Methodology:

To study, simulate, design, construct and test a power electronics inverter using computational tools and TU Delft’s laboratory facilities.


Literature review of transformer-less PV inverters: String and Micro-inverter technologies

Propose innovative solutions to conductive EMI

Benchmark suitable inverter solutions using multi-objective design approach

Design and construct a single-phase PV inverter solution using modular power electronics

Test the constructed prototype

Contact details:

Supervisor:



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DEVELOPPING INTELLIGENT GATE DRIVERS WITH ULTRA-FAST SHORT-CIRCUIT DETECTION FOR HIGH PERFORMANCE SEMICONDUCTOR TECHNOLOGY

Type of project: Extra Project / SIP2 / MSc thesis

Scope:

To design and construct a high-side gate driver for Silicon Carbide (SiC) MOSFETS with high voltage isolation and common-mode noise rejection featuring ultra-fast short-circuit detection.

Problem definition:

Silicon Carbide (SiC) based Metal-Oxide Semiconductor-Field-Effect Transistors (MOSFETS) are widely praised as the future of high-end power converters due to their improved performance over conventional Silicon (Si)- based devices. To unlock the full potential of the SiC technology high-speed gate driver circuitry are necessary to reduce the time of the commutation dynamics of the MOSFET and thus reduce the energy dissipated during each switching action. This operational benefit results in an increment of the Electromagnetic Interference (EMI) caused by the consequent high dV/dt and di/dt of the switching mechanism. More importantly, EMI issues can degrade the breakdown capability of the insulation materials and cause instability and unexpected behaviour of the control circuitry. Finally, ultra-fast short-circuit detection and the respective corrective action must be implemented in order to protect both the power converter and their connected sensitive loads. In today’s commercial available SiC MOSFETS a short-circuit action can lead to over-current in the excess of 10x the rated value within 10µs, which implied that the detection circuitry + the reaction time to a short-circuit event must be ideally within < 1 µs.

Methodology:

To study, simulate, design, construct and test an intelligent gate driver using computational tools.


Literature review of high-voltage gate drivers and fast short-circuit detection

Design and construct an intelligent gate driver

Test the constructed prototype

Contact details:

Supervisor:



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PLANNING ENERGY STORAGE IN MV DISTRIBUTION GRIDS: IMPLEMENTATION OF MODULAR CASCADED H-BRIDGE CONVERTERS AND ANCILLARY SERVICE PROVSION


Scope:

Study and implementation of modular power electronics and intelligent control algorithms to integrate energy storage into medium voltage (MV) power grids and provision of ancillary grid support.

Problem definition:

The penetration of intermittent renewable energy sources like wind and solar is dramatically increasing. At the same time introduction of new types of loads like electric vehicles is resulting in an increased and unpredicted demand of electricity. This has brought about severe impacts on electrical distribution networks, which currently offer very little operational flexibility. In the future, it is expected a substantial increase in the number of Battery Energy Storage Systems (BESSs) connected to the low voltage or medium voltage distribution networks. For the medium voltage grid modular power electronics based on the cascaded H-bridge converter (CHB) constitutes a good choice. Therein, the required isolation can be shifted to the modular cells where a high frequency AC-link is created. This circuit is not only well suited for congestion management but it can also work as a STATCOM providing harmonic compensation and other ancillary grid services.

Methodology:

To study and design a power converter implementing the CHB converter and LLC resonant circuit. Evaluate the benefit of using the energy storage system for several grid ancillary service provision.


Literature review of BESSs in medium voltage grids and grid ancillary service provision market;

Benchmark the proposed BESSs against state of art solutions;

Implement the developed study in a hardware demonstrator.

Contact details:

PhD student: Marco Stecca <[email protected]>

Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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OPTIMIZING A TWO LEVEL CONVERTER FOR GRID CONNECTED ENERGY STORAGE

Type of project: Extra Project / SIP2

Scope:

Study and optimize a two level converter for grid connected energy storage systems.

Problem definition:

The penetration of intermittent renewable energy sources like wind and solar is dramatically increasing. At the same time introduction of new types of loads like electric vehicles is resulting in an increased and unpredicted demand of electricity. This has brought about severe impacts on electrical distribution networks, which currently offer very little operational flexibility. In the future, it is expected a substantial increase in the number of Battery Energy Storage Systems (BESSs) connected to the low voltage or medium voltage distribution networks. The interface between storage systems and the grid available in the market are several, however the most common solution for the connection to MV grids, where it is required to step up the voltage, is through a two level converter.

Methodology:

To study and optimally design a power converter implementing the two level converter. Evaluate the benefit of using the energy storage system for several grid ancillary service provision. The optimization of the converter will be linked on the ancillary services which the storage will provide.


Literature review of BESSs, ancillary service market and two level converters;

Optimize the selected topology for ancillary service provision;

Implement the developed study in a hardware demonstrator.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

20

D C E & S




SUPER CAP / LI-ION HYBRID STORAGE SYSTEM FOR BATTERY LIFETIME IMPROVEMENT


Figure 1: Possible hybrid topologies Figure 2: PV output power

Scope:

Investigate whether a hybrid super capacitor / li-ion storage system can be used to increase battery lifetime

Problem definition:

Li-ion batteries are often used in PV systems in order to mitigate the intermittency of PV. However, the stochastic nature of PV can impose heavy stress on the battery when large power surges arise due to clouding (see Figure 2). The goal of this thesis is to investigate whether it is possible to improve the lifetime of the li-ion battery by using a hybrid super capacitor / li-ion based storage system. Here the goal of the super capacitors is to absorb the large power surges and release them at a more constant lower power to the battery. Another goal of the system could be to prevent grid cut-off when a large power surge causes the inverter to trip. As for example could happen after a sudden power increase after a period of shading. The first part of this thesis will consists of modelling the components, after which the control should be developed in simulations. Finally, a prototype can be built in the lab.

Methodology:

Investigate li-ion aging

Determine best topology based on simulations and develop the control scheme

Develop a lab setup Research Objectives:

Develop a hybrid energy storage system and control scheme

Investigate the effect of the proposed system on li-ion aging

Contact details:

PhD student: Wiljan Vermeer, [email protected]

Supervisor: Gautham Ram Chandra Mouli, [email protected]

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D C E & S




INVESTIGATION OF PULSE CHARGING ON A BATTERY PACK LEVEL


(a) (b)

Fig 1: Different cell balancing techniques: (a): passive balancing, (b): active balancing

Scope: Quantify the benefits of pulse charging on a pack level

Problem definition:

In literature the effects of pulse charging on a single cell have been studied. If operated under the right conditions (duty cycle and frequency), it has shown to have various benefits for batteries such as improved efficiency, reduced charging time and increased lifetime. However, on a module/pack level components such as the BMS (cell balancing) and protection circuitry affect the possible benefits of pulse charging. Furthermore, these effects have not been investigated yet in literature. Therefore, the goal of this thesis is to quantify to effects of pulse charging on a module/pack level. To do this, the effect of pulse charging of all relative components inside the pack will be analysed.

Methodology:

Perform a literature study on pulse charging and battery packs

Simulate the effect of pulsed charging on all relative components

Perform lab tests to verify the results Research Objectives:

Literature review

Develop simulations of batteries cells and BMS circuitry.

Develop a testing setup

Contact details:

PhD students: Wiljan Vermeer, [email protected]

Supervisors: Dr. Ir. Gautham Ram Chandra Mouli [email protected]



22

D C E & S




HIGH TEMPERATURE SUPERCONDUCTIVITY FOR DEGAUSSING


Scope:

Due to their permeability, naval ships distort Earth’s magnetic field. These anomalies in the magnetic field can be detected by sensors attached to airplanes or, even worse, magnetic mines. Luckily, there are methods to prevent detection by making ships “magnetically invisible”. One of these methods is to install a degaussing system, a set of coils designed to induce a magnetic field which compensates for the distortion.

Problem definition:

Nowadays, degaussing coils are made out of copper. Due to energy losses and weight issues, however, it might be better to use a superconductive material. Moreover, the developments in high temperature superconductivity (HTS), makes the use of superconductors a serious option.

In superconductive coils, the current density can be much higher than in copper coils. Therefore, a superconductive degaussing coil can have a higher amount of Ampere turns and a lower amount of turns than a copper degaussing coils. This will cause an increase in the power supply, however. The aim of this thesis is to find a suitable power electronic topology to supply the higher degaussing current without too much losses.

Methodology:

In this project a model should be built to simulate the differences of superconductive coils and degaussing coils. A test setup can be built to test the power supply topology.


To conduct a literature review

To obtain a model of superconductive coils and a power system

To define and test an experimental test set-up

Contact details:

PhD student: Djurre Wikkerink, [email protected]

Supervisors: Prof. Rob Ross, [email protected] Dr. Armando Rodrigo Mor, [email protected]

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D C E & S



DC Grids and Storage for Smart Cities DC systems, Energy conversion & Storage

INVESTIGATION OF FUEL CELL TECHNOLOGY FOR SEASONAL STORAGE IN BUILDING APPLICATIONS


Figure 1: Fuel cell have a high specific energy Figure 1: FC schematic representation

Scope: Investigate the feasibility of using fuel cell technology as (seasonal) storage for buildings

Problem definition:

Currently lithium based battery storage systems are the most common for building applications because these provide the best trade-off between energy & power density and costs. However the energy density is still not high enough to act as seasonal storage, where excess PV energy stored in summer is used in winter. This leads to very poor battery utilization if not controlled properly (see Figure 1). Because of its extremely high energy density, fuel cell technology is a candidate for a seasonal storage system. However, at the moment is still underdeveloped. The goal of this thesis is to investigate the feasibility of a fuel cell based storage system, possibly in combination with a Li-ion battery, for building applications.

Methodology:

Study fuel cell & li-ion based storage systems

Provide a case study

Optimize the (hybrid) storage system for the case study


To investigate the feasibility of fuel cell technology for seasonal storage in buildings

To optimize the hybrid system for the case study

Contact details:



24

D C E & S




OPTIMAL BUILDING LOAD SCHEDULING UNDER UNCERTAINTY OF FORECASTING


Fig 1: ideal scheduling Fig 2: Uncertainty of PV forecast

Scope: Develop an optimal scheduling algorithm which ensures optimality under uncertainty of load & PV forecast

Problem definition:

In order for scheduling algorithms (e.g. EV smart charging) to work, accurate forecasting of PV power supply and load power demand are needed. However, both of these forecasts will always have errors which will result in non-optimal results. The goal of this thesis is to tackle these problems by extending an existing scheduling problem, where ideal forecasting is assumed, such that it is able to handle this uncertainty. This can be done using various techniques. Some examples are: robust optimization techniques, time series forecasting techniques in combination with moving horizon principles, neural networks, etc.

Methodology:

Find the best suited method to deal with forecasting/stochasticity.

Implement the proposed method in simulations.

Verify the method compared to ideal forecasting.


A literature review on forecasting method & optimization.

An accurate forecasting method of both load & supply.

An integration of forecasting and scheduling.

Contact details:



25

D C E & S




DEVELOPMENT OF AN OPERATIONAL BATTERY MODEL INCLUDING THERMAL & AGING BEHAVIOUR


Fig 1: Battery Model

Scope: Develop a battery model which takes into account electrical, thermal & aging aspects

Problem definition:

Storage systems play a key role in modern society, in the form of grid applications, electric transport or handheld devices. In order to properly design a system which includes batteries, a detailed model is needed which can accurately describe its behaviour. For li-ion batteries, this behaviour is very complex and varies all the time over operating conditions such as power, SoC, temperature and age.

Therefore, the goal of this thesis is to develop an operational model which takes into account all stress factors. The model will be a combination of theoretical equations and empirical models, therefore some lab testing is required.

Methodology:

Perform a literature study

Provide a testing methodology for all empirical tests

Develop the model based on theoretical and empirical results


Literature review about battery modelling

Develop a general testing methodology (also for other lithium technologies)

Develop the operational model

Contact details:

PhD students: Wiljan Vermeer, [email protected] Marco Stecca, [email protected]




26

D C E & S




EXPERIMENTAL DESIGN AND VALIDATION OF DC DISTRIBUTION GRIDS


Scope: It is essential for the broad adoption of DC distribution grids to design an experimental set-up and verify the research done on the modelling, stability, control and protection of DC distribution grids. Different projects are available to design converters, protection devices or do experiments. Problem definition: DC distribution grids are foreseen to have several advantages over ac in terms of efficiency, distribution lines, and converters. However, more theoretical and experimental work is required to research and prove these advantages. A dc microgrid set-up is available in the lab to do the verification and validation of dc distribution system research. Furthermore, new or improved components for this microgrid need to be designed and built for future research. Methodology: These topics either mainly involve the design of converters, solid-state protection devices and/or the execution of experiments. Moreover these projects might entail literature research, simulations and (microcontroller) programming. Examples of Research Objectives:

Design of an isolated DC/DC converter

Design of a solid-state circuit breaker

Design and implementation of the communication between power electronic converters

Conduct experiments regarding the control of DC distribution grids

Conduct experiments with respect to the protection of DC distribution grids

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Thiago Batista Soeiro ([email protected]) Laura Ramirez-Elizondo ([email protected])

Prof. Dr. Eng. Pavol Bauer ([email protected]

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D C E & S



DC Grids and Storage for Smart Cities

DC systems, Energy conversion & Storage

MODELLING, STABILITY, CONTROL AND PROTECTION OF DC GRIDS


Fuse

~

Macrogrid Zone 1

Zone 0

Zone 3

Zone 2

Zone 3

Circuit Breaker

Scope: To aid the broad adoption of DC distribution grids more research is required on the modelling, stability, control and protection of dc distribution grids. Many topics within these categories are available for master students. Problem definition: Distribution grids are subjected to changes such as the increasing participation of distributed energy resources (DER), segmentation of the grid (for example into microgrids), and increasing participation of prosumers. This poses significant challenges with respect to stability, control and protection. DC distribution grids are foreseen to have several advantages over ac in terms of efficiency, distribution lines, and converters. Furthermore, they do not require the synchronization or reactive power governance. Therefore, the interconnection of dc (micro)grids is significantly simpler. Methodology: These topics mainly involve literature research, analytical derivations, simulations and/or programming. However, design/experimental topics are also available. Examples of available topics are:

Power flow control in DC distribution grids

Transient analysis of DC distribution grids

Small-signal stability of DC distribution grids

Centralized/decentralized/distributed control of DC distribution grids

Optimal sizing and allocation of storage in DC distribution grids

Protection of DC distribution grids

Contact details:

PhD student: Nils H. van der Blij ([email protected])

Supervisor: Thiago Batista Soeiro ([email protected]) Laura Ramirez-Elizondo ([email protected])

Prof. Dr. Eng. Pavol Bauer ([email protected]

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D C E & S




POWER ELECTRONICS FOR GRID CONNECTED ENERGY STORAGE SYSTEMS

Type of project: Extra Project / SIP2

Scope:

Study the most common AC/DC converter topologies for grid connected storage systems.

Problem definition:

Battery energy storage system are becoming an effective option for grid operators to face the technical issues deriving from an increase of non-predictable renewable generation. When connected to distribution grids storage systems can be used for performing several ancillary services, voltage control, frequency control, congestion management, etc… . The requirements in term of response speed or system availability might differ according to the functionality provided.

Since storage systems are interfaced with the grid through power electronic converters, these difference in the requirements can be reflected in the design of the conversion unit.

Methodology:

The research consists firstly on a survey on the main AC/DC converter topology and on the grid ancillary services. Later the student will evaluate the best fitting converter according to the functionality that the storage unit will provide. Through this project the student will get familiar with the most common AC/DC converters and with storage systems.


Literature review of BESSs converter topologies and grid ancillary service provision market.

Evaluate the advantages of each topology on the others.

Simulate the behaviour of the different topologies in the provision of ancillary services.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

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D C E & S




POWER ELECTRONICS CONTROL FOR SEAMLESS ISLANDING TRANSITION


Scope:

Develop and test control strategies for power electronic converters to allow a seamless transition of distribution grids during unintentional islanding.

Problem definition:

Islanding operation is a situation in which a portion of electric grids continues to operate even if disconnected from the main network. Islanding can be intentional or unintentional, the second condition it is not yet allowed due to difficulties of grid operators in ensuring an acceptable level of security and power quality to the customers.

However with an increasing penetration of distribution generators (DG) and storage systems (ESS) it might be possible to operate distribution grids in islanding operation safely. The main challenges are first in detecting the fault, then in controlling the transient that arises accordingly and, if these two steps are completed successfully, in keeping the system stable balancing loads and generation.

Methodology:

The research consists on first studying the islanding operation of distribution grids, the load/generation requirements and the role of storage in this. Second the student will develop a control strategy for the power electronic converters in order to manage the transient during the island formation.


Study the grid requirements for sustaining islanding operation.

Evaluate the role of the power electronics device in the dynamic behaviour of the grid during the transition.

Design a control strategy for achieving a seamless transition after the disconnection from the main grid.

Contact details:


Supervisors: Dr. Ir. Thiago Batista Soeiro <[email protected]> Dr. Ir. Laura Ramirez Elizondo <[email protected]> Prof. Dr. Ir. Pavol Bauer <[email protected]>

30

D C E & S




BATTERY MODELLING AND TESTING FOR GRID CONNECTED AND RESIDENTIAL APPLICATIONS


Scope:

Estimating the effect of calendar and cycling ageing in residential / grid connected battery modules

Problem definition:

In the future storage systems might play a key role in the distribution grid planning. For a proper integration and planning of the storage device it is necessary to have an extended knowledge about their performances and lifetime. However external conditions and the battery cycling pattern has strong influence especially in the lifetime. For this reason it is interesting to study the battery behaviour in the utilization different cases (voltage control, losses minimization, congestion management, primary frequency control). The expected result of the project is to extract detailed information about the battery performances and lifetime, when performing several grid services, to be used in grid expansion studies or for the designing of home energy management systems.

Methodology:

The research consists on first developing several battery cycling patterns compatibles to the different functionalities and then testing them on the battery banks. The main electrochemical, electrical and thermal parameters will be extracted and models will be built accordingly.


Literature review about battery performances and modelling techniques.

Create battery cycling patterns for the different applications.

Test the batteries for evaluating calendar and cycling ageing.

Build detailed models to be used for project feasibility studies and verify their fitness with the selected application.

Contact details:

PhD student: Marco Stecca [email protected] Wiljan Vermeer [email protected]

Supervisors: Dr. Ir. Laura Ramirez Elizondo [email protected] Prof. Dr. Ir. Pavol Bauer [email protected]





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FAULT TOLERANCE AND RIDE THROUGH OF SOLID STATE TRANSFORMERS


H Bridge DAB

H Bridge DAB

H Bridge DAB

10 kV AC

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

H Bridge DAB

±375 VDC

DC/DC

DC/DC

±750 VDC

SSCB

SSCB

DC/AC380 V

AC

Scope: The scope of the project is fault tolerance and ride through of solid state transformers Problem definition: Power electronics based solid state transformer is an emerging technology to bridge the dc grid and the ac utility grid. To handle medium or high voltage, solid state transformers usually have a modular topology. Such a topology also brings potential of fault tolerance to solid state transformers. However, the fault tolerant control or ride through of solid state transformers has not been thoroughly studied. Methodology: Simulation tools will be used to investigate the influence of different faults of the grid as well as the solid state transformers. Fault tolerance and ride through strategies will be verified in simulation tools.


Investigation of fault scenarios confronted by solid state transformers

Fault tolerant control strategies

Fault ride through strategies

Contact details:

Supervisor: Dr. Zian Qin, [email protected]


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D C E & S



DC Grids and Storage for Smart Cities


COMPARISON OF BUILDING BLOCKS FOR LVDC GRIDS


Microgrid

MicrogridNanogrid

Energy Storage System

Renewable Energy Sources

Electrical Loads

Fault Isolation Device

Microgrid

MV Grid

~

Scope: Generally, future distribution grids lack the robustness and inertia of current AC systems. Therefore, additional control is necessary to ensure appropriate operation. For example, the power flow in multi-terminal dc grids needs to be controlled to achieve efficient operation. For this end different solutions were proposed in the previous research, including the partially rated power flow control converter with integrated short circuit protection. Problem definition: The primary goal of the thesis is to compare different building blocks i.e. different power electronic solutions for the control of the LVDC grids. At TU Delft integrated cost efficient building block for LVDC grids was proposed recently. The goal is to benchmark the proposed solutions against the other existing concepts. Methodology: In the first stage of the project the student will be acquainted with the state of the art research in the LVDC systems. In the second phase using existing simulation tools different power electronic concepts for the control of LVDC grid will be compared. In the last stage, chosen scenarios will be verified in a laboratory-scale microgrid. Research Objectives:

Review of power electronic concepts for control of LVDC systems.

Simulations and comparison of the power electronic concepts.

Experimental verification of the chosen scenarios in the laboratory.

Contact details:

PhD student: Pavel Purgat ([email protected]) Nils van der Blij ([email protected])

Supervisor: Zian Qin ([email protected]) Pavol Bauer ([email protected])





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D C E & S




DEVELOPPING DISTRIBUTED CONROL SCHEME FOR POWER MANGMENT IN DC MICRO GRID


Scope: Improvement of DC network system in large scale mainly depends on the new controlling techniques. Recently, decentralized and distributed strategies have received a great deal of attention, However, these strategies are still immature and need more development to address critical issues such as voltage deviation and power error tracking.

Problem definition: Traditionally, the clustered and interconnected Micro Girds in the tertiary level are controlled via the central controlling strategy. This approach is sufficient for the small scale MGs with less complexity. However; it is not competent in the complex systems. Distributed controlling approach seems the best option in the complex system with a suitable algorithm.

Methodology:

Literature review of decentralized and distributed controlling techniques and adaptability of

their algorithm for different controlling levels in DC network

Identification of the issues in central controlling

Power flow analysis in DC network


Develop and recognition of the most adaptable distributed controlling algorithm for power

flow analysis in the tertiary level

Simulation of small scale DCMG to validate the controlling algorithm

Contact details:

PhD student: Farshid Norouzi, [email protected]

Supervisor: Laura M. Ramirez-Elizondo ([email protected]) Prof. Dr. Eng. Pavol Bauer ([email protected])



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D C E & S



Electromechanics and Electric Mobility DC systems, Energy conversion & Storage

STATIONARY STORAGE FOR IMPROVING THE ENERGY RECOVERY IN DC TROLLEY GRIDS


Scope:

A trolleybus is an electric bus that draws power from overhead wires, in the way a tram does. One of the distinctive features of such electric vehicles is their ability to send the braking power back to the overhead lines to be used by another bus on the same section.

Problem definition:

In reality, a lot of energy is wasted when the bus brakes, as it is not often the case that another bus is on the same section and in need of power. The energy is then wasted into breaking resistors, but it has the potential, however, to be recovered using properly sized, positioned and operated stationary storage on the sections.


Determine the energy to be recovered, and consequently the proper size, control algorithm, and costs of the stationary storage. Show that the designed system can simultaneously improve the energy efficiency and the voltage profile of the supply lines.

Methodology:

Model (MATLAB) of the energy consumption of an fleet of trolleybuses to include the different charging infrastructure and bus traffic

Determine the power/energy consumption of the buses under different traffic scenarios.

Estimate the proper (shared) grid integrated storage to recover the braking energy.

Simulate the impact of the storage addition on the voltage profile and the consumed energy for different storage sizes, types, and locations. Deduce the best scenario, including costs.

Motivated student can also look into PV-integration (remember that trolley grid has unidirectional power flow, so excess solar energy cannot be sunk to the main grid).

o This project is part of the Trolley2.0 European Project Objectives

Contact details:

PhD student: <Ibrahim Diab, [email protected] >

Supervisor: <Dr. Gautham Ram Chandra Mouli; A. Shekhar; Prof. P Bauer>


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D C E & S




DESIGNING THE TRANSITION TO IN-MOTION-CHARGING OF ELECTRIC BUSES


Charging CorridorNo overhead lines

Scope:

A suggestion that is gaining research momentum for charging electric buses is the In-Motion-Charging method or IMC. IMC combines the advantages of both electric buses and of trolleybuses: the supply source is batteries, yet the bus is charged in motion, without the need to stop.

Problem definition:

Despite progress in battery technologies, an electric bus still cannot operate the whole day without the need to stop and charge. This brings inflexibility in routes and timetables, as well as significant weight addition to the bus, which consequently increases its traction demands. IMC offers the possibility of smaller batteries, charged on-the-go, as long as there are sufficient charging corridors (length and spacing between corridors).


Extend the models (MATLAB) of the energy consumption of an fleet of electric buses to include the IMC scenarios, and determine the minimal layout of catenary operations needed in different city topologies, bus fleet sizes, and traffic scenarios. Compare the costs of IMC scenarios to those of a catenary-less operation with overnight charging and those of a full-catenary operation.

Methodology:

Determine the power/energy consumption pattern of different traffic scenarios based on the data from some European cities (Arnhem, Gdynia, Szeged,..)

Estimate the length and placement of the charging corridors for different scenarios.

Compare the cost of IMC to other charging possibilities.

Motivated student can also look into stationary storage for voltage stability and/or EV charging, and/or into the costs of transitioning from a trolleybus infrastructure to IMC.

This project is part of the Trolley2.0 European Project Objectives

Contact details:




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D C E & S




COMPARISON OF CHARGING INFRASTRUCTURES FOR ELECTRIFIED BUSES


Overnight charging

Trolley bus or IMC

Opportunity charging

Scope:

A main objective of current Electric Mobility research is to achieve reliable transportation while minimizing both the catenary-dependent operation and the costs. Buses can receive the needed electrical energy in a variety of ways. One method is from overhead trolley lines or In-Motion-Charging. Another possibility is “opportunity charging” of the on-board batteries at the bus stops or at the end-of-the-line. Finally, there is the “overnight charging” at the dedicated depots.

Problem definition:

Trolley buses and IMC require relatively smaller battery designs, but with a need for overhead lines. Opportunity charging takes away from the route and timetable flexibility and can incur serious schedule delays. Overnight charging methods work only with significantly large storage.


Estimate the energy consumption of an fleet of electric buses in presence of different charging infrastructures, locations, and bus types and determine the proper capacity of the five proposed infrastructures. Then, quantifying operational and installation costs and its trade-offs with the driving range extension.

Methodology:

Compare the technical implications of different methods such as overnight charging, opportunity charging, in-motion charging and trolley systems.

Model the driving range of an electric bus based on the specification, velocity profile, on-board storage and charging infrastructure.

Minimize the storage requirement using different charging solutions while maximizing the driving range of the bus.

Determine the economic viability of the chosen charging scheme for a case-study with a fleet of electric buses in a city route (for example: Arnhem, Gdynia, or Szeged)

Contact details:




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D C E & S




SUSTAINABLE TRANSPORTATION: POWERING TROLLEYBUS DC GRIDS USING PV


Scope:

A trolleybus is an electric bus that draws power from overhead wires, in the way a tram does. Today’s DC trolley grids only serve the purpose of powering these buses, although they have the potential to be a more active grid with integrated storage and distributed generation.

Problem definition:

Trolley grids are DC grids with indirect CO2 emissions (depending on the electricity source). Stationary storage is already implemented in some grids to recuperate the braking energy of the buses and help the voltage profile as well as reducing the energy demand, and thereby the CO2 footprint. PV is a good way to reduce this footprint, especially that both PV and the grid are DC, and that the storage is already available.


Estimate the PV generation needed to (partially) cover the trolley loads, as well as the sizing and placement of the stationary storage to cover the load demand of the buses.

Methodology:

Determine the power/energy consumption of the buses during different traffic scenarios.

Size the PV generation based on the load demand (with and without grid exchange) and investigate both its placement on the AC or the DC side

Determine the proper storage size for a variety of objectives (minimum cost, minimum grid exchange, In-Motion-Charging systems, etc.) and suggest power management algorithms.

Simulate the impact of the various PV and storage additions on the voltage profile.

Motivated student can also look into integrating EV charging stations. This project is part of the Trolley2.0 European Project Objectives

Contact details:




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D C E & S




ACTIVE ACOUSTIC NOISE REDUCTION OF PERMANENT MAGNET SYNCHRONOUS MACHINE


Scope: Reduce electromagnetic excited noise emitted from permanent magnet synchronous machine using active control method.

Problem definition: Comfortable user experience requires electric machine to be quiet in a wide speed range for different applications, e.g. electric vehicle and home appliances. Currently unpleasant vibration and noise from the electric motor is reduced by auxiliary approaches such as attenuation or absorbance. If the vibration and noise problem could be solved by active control of electrical machines, it will save the overall cost and reduce the system size.

Methodology: Existing modelling technique will be improved and applied to investigate methods for electromagnetic excited acoustic noise reduction. Different modulation techniques, and LCL filters will be investigated. Based on the selected methods, simulations will be carried out to compare the performance. Selected control methods will be implemented on an existing motor drive.


Acoustic noise modelling of electric machines.

Investigate and compare different approaches for noise reduction through control.

Implement active noise reduction control algorithm in an existing setup.

Collaboration with Industry: No

Contact details:

Daily Supervisor: Dr. Jianning Dong ([email protected])

Dr. Thiago Batista Soeiro ([email protected])

Supervisor: Prof. Pavol Bauer ([email protected])




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D C E & S




MULTI-OBJECTIVE ELECTRICAL MACHINE OPTIMIZATION DESIGN FRAMEWORK BASED ON OPEN SOURCE PLATFORMS


Photo courtesy: pyleecan project (http://www.pyleecan.org/)

Scope: This project aims at developing an electrical machine design and optimization framework based on open source platforms.

Problem definition: Emerging applications including transportation electrification, robotics and renewable electricity generation require customized design of electrical machines, so that the designed machines meet multi-physical constraints and have the most optimal performance. Therefore the design process should be a multi-physical approach and requires effective optimization methods. There are numerous open source packages available to model different aspects of electrical machines and optimize the design. However, in order to use them for the electrical machine design, they should be synthesized to work effectively.

Methodology: Electrical machine design methodology and criteria should be studied first. Then suited open source software packages will be reviewed and chosen based on the design methods and criteria. Interface codes will be developed and tested. Developed codes will be made open source to the community after the project finishes.


Review of available open source packages can be used for electrical machine design.

Development of interfaces and glue code to deliver a complete electrical machine design

framework.

Use the developed framework to optimize electrical machines for transportation

electrification applications.

Contact details:



http://www.pyleecan.org/



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D C E & S




ONLINE PARAMETER IDENTIFICATION OF PERMANENT MAGNET SYNCHRONOUS MACHINES


Scope: Identify the inductance, flux linkage and resistance of permanent magnet synchronous machines for faster and more accurate control.

Problem definition: Permanent magnet synchronous machines are used extensively in renewable energy, transportation and industry process. The performance of the permanent magnet machine based drive system is highly dependent on how accurate the machine parameters are, because not only maximum torque per ampere (MPTA) control , flux weakening control, but also the position sensor-less control are dependent on those parameters. However, these parameters are heavily dependent on the temperature and saturation of the machine. In order to achieve highly dynamic performance, online parameter identifications should be implemented.

Methodology: The research will start with a literature study on all available online parameters identifications. The most suitable method for the machine in the lab will be proposed based on the investigation. Then simulation models will be used to develop and compare the identification methods. In the end, the simulated methods should be implemented in hardware and tested in the lab setup.


A review of all available parameter identification methods.

Implementation and comparison of different methods in simulation.

Development and deployment the parameter identification methods in hardware.

Collaboration with Industry: No

Contact details:


Dr. Thiago Batista Soeiro ([email protected])





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D C E & S




VIRTUAL MACHINE – POWER HARDWARE-IN-LOOP EMULATION OF ELECTRICAL MACHINES


Scope: This project aims at development of a power hardware-in-loop (HIL) emulation system of electrical machines.

Problem definition: Power-HIL simulations are essential for cost-effect and time-effective developments of modern powertrains in electric vehicles and electric aircrafts. Control algorithms can be tested through mathematical dynamic models of electrical machines without building real prototypes. To fully represent the dynamic performance of the electrical machine, magnetic saturation, losses and temperature rise of motors should be considered in the model. Comprehensive models should be built and integrated in the real time simulation platform. A power converter will be used to mimic the dynamic behaviour of the emulated electrical machine. High bandwidth current controller and filters should be designed to ensure fast and precise response of phase currents.

Methodology: HIL simulation platform has been developed in MATLAB/Simulink and OPAL-RT. Filtering and sensing circuits, and current controllers should be designed to achieve fast and accurate response so that the currents of the virtual machine follows the predicted values from the HIL models.


Design and implementation of filtering and sensing circuits

Design and implementation of a high bandwidth, high precision current control loop

Power HIL emulation of a permanent magnet synchronous machine

Contact details:





42

D C E & S




WIRELESS POWERED ULTRA-HIGH SPEED VACTRAIN


ACDC

StationStation Station

3ph Charging rail Cruising rail

Battery Train

Scope: This project aims at feasibility study and preliminary design of a wireless powered ultra-high speed train using evacuated tubes (vactrain).

Problem definition: Research on vactrain has been focused on propulsion or magnetic levitation of the train. The power supply of the train, although is equally or even more important from the system point of view, is often neglected. At such high speeds, it is not possible to use the conventional pantograph-based system to power the train because of friction and arcing. This project proposes to apply dynamic wireless charging technology in vactrains, and integrate the wireless power transfer system with the propulsion system, based on the principle of doubly fed induction machine. The charging rail is laid close to and at the stations, which is equipped with coils. When the train stops at, approaches or leaves the stations, the train side coils and the charging rail from a doubly fed induction machine, which is used for both propulsion/braking and battery charging. During cruising, the train side coils can form an induction machine or a reluctance machine together with low-cost passive rails to provide minimal power required for cruising and after failure restart.

Methodology: A mission profile of the vactrain is first defined. Power and energy required of the system will be calculated based on analytical models. Size and weight of key components will be calculated based on both analytical results and simulations. Finite element method may be needed to validate the design.


Feasibility study of wireless powered vactrain, with integrated propulsion system.

Preliminary design of the wireless charging system.

Analytical design and numerical validation of the integrated propulsion charging system.

Contact details:





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ANALYSIS OF THE ELECTROMAGNETIC FIELD RADIATION OF WIRELESS CHARGING SYSTEMS


Scope: As an approach to mitigate the range anxiety and bulky battery packages of EVs, dynamic inductive power transfer (DIPT) for EVs charging attracts lots of attention. As a loosely-coupled power transfer system, leakage field cannot be avoided. For the safety of users, the magnetic radiation has to be considered.

Problem definition: When the DIPT system is energized, a certain amount of magnetic field may be exposed to pedestrians and pose a threat to their health. On one hand, the radiation of a DIPT system should be identified according to the international standards. On the other hand, proper measures should be taken to decrease the radiation, including shielding and coupler design.

Methodology:

Study of the basic principles of inductive power transfer technology

Review of relevent EMC internation standards

Analysis of the radiation of DIPT systems

Key factors determining the radiation of a DIPT system


Methodology to simulate the radiation of a certain DIPT system

Possible solutions to decrease the radiation of DIPT systems

Contact details:

PhD student: Wenli Shi [email protected], LB 03.850

Supervisor: Dr. Jianning Dong [email protected], LB 03.630 Prof. Pavol Bauer [email protected] , LB 03.600


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ANALYSIS OF THE IMPERFECT COUPLING OF DYNAMIC WIRELESS CHARGING SYSTEMS


DCAC

DCAC

DC Power

Road

Receiver

Transmitter Transmitter

Road

Transmitter

Scope: As an approach to mitigate the range anxiety and bulky battery packages of EVs, dynamic inductive power transfer (DIPT) for EVs charging attracts lots of attention. Compared with stationary charging, DIPT systems are faced with more critical operation conditions because of the displacement between the transmitter and the receiver.

Problem definition: In DIPT systems, transmitters are discretely deployed in a string along the lane. If transmitters are placed too close, cross coupling of transmits can be introduced to the system and leads to extra reactive power. Besides, one receiver can be coupled with multiple transmitters, which complicates the design of DIPT system.

Methodology:


Modeling and analysis of the primary cross coupling

Modeling and analysis of the one-receiver-multiple-transmitters coupling


Modeling approach of the imperfact coupling of DIPT systems

Guidelines to mitigate the adverse effect of the imperfect coupling

Contact details:




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FOREIGN CONDUCTIVE OBJECTS DETECTION FOR DYNAMIC WIRELESS CHARGING SYSTEMS


Scope: As an approach to mitigate the range anxiety and bulky battery packages of EVs, dynamic inductive power transfer (DIPT) for EVs charging attracts lots of attention. Conductive objects like coins and cans may exist on the road, and performances of dynamic IPT system can be affected if these objects are placed on top of transmitters under roads.

Problem definition: When conductive objects are placed near or in the magnetic field produced by DIPT systems, eddy current will be generated. This eddy current could lead to power loss, change in magnetic field and electrical waveforms. Foreign object detection methods should be proposed to solve this problem.

Methodology:


Literature review of the foreign conductive objects analysis detection methods

Simulation of the influence of foreign objects on DIPT systems

Analysis of a kind a foreign object detection method


Modeling method of the foreign conductive objects effect on DIPT systems

Design methodology of a kind of foreign object detection method

Contact details:




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A V2X SMART CHARGING ALGORITHM DEVELOPMENT CONSIDERING BATTERY DEGRADATION AND USER SATISFACTION


Scope:

Smart charging is a series of intelligent functionalities to control the EV charging power in order to create a flexible, sustainable, low cost, and efficient charging environment. This project aims at developing a smart charging algorithm focusing on V2X functions. However, the charging demand of the user, the battery lifetime, as well as the economic profit of each party should be taken into consideration as well.

Problem definition:

Apart from the normal charging process that the power flows from the grid to the battery, the battery power can flow from the vehicle to some other utilities. For example, to the grid, to a home, to a building, to another vehicle. and it is called V2G, V2H, V2B, V2V, respectively. V2X is the generic term that is used to include all such applications.

The functionality of V2X can help with distributing the power as well as the energy in a more efficient way. However, not well-planned V2X might cause the car be under-charged, or it might reduce the lifetime of the battery. Therefore, an algorithm that implements the expected smart charging and mitigates the conflicts of interests in the meanwhile can be beneficial.

Methodology:

The student is expected to study the state of the art of the smart charging algorithms including V2X functions and to find the challenge. Then the work will be focused on developing the algorithm which takes the aforementioned problems into consideration. Finally, the student is expected to do the simulations to compare the developed algorithm with the uncontrolled EV charging. The platform will be applied can be but not limited to Matlab, Simulink, Python, PowerFactory.


Literature study of the state of the art of the smart charging algorithm including V2X functions

Develop the smart charging algorithm

Operate the simulations to compare the developed algorithm with the uncontrolled EV charging

Contact details:

PhD student: Yunhe Yu, [email protected]

Supervisor: Prof. Dr. ir. Pavol Bauer, [email protected] Dr. Gautham Ram [email protected]

Time

Am

ou

nt

Load power

Grid failureBack up from EV,

V2G

Grid back up from EV

Gridrecovery

Wind power generation

Grid power




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HARDWARE-IN-LOOP SIMULATION FOR CONTROLLED/UNCONTROLLED CHARGING OF ELECTRIC VEHICLE IN DISTRIBUTION GRID


Source: OSCD, Elaad

Scope:

This project aims at developing a hardware-in-loop (HIL) simulation system for Electric vehicle (EV) charging in the distribution grid, and simulate the impact of EV charging on the grid, with and without the smart charging algorithm.

Problem definition:

HIL is a cost-effective and time-efficient method to implement large-scale grid experiments. In this system, a power amplifier, an AC or DC charger and a battery will be connected to the simulator to model the real charging environment. OPAL-RT will be employed as the HIL platform.

Methodology:

The student is expected to set up the OPAL-RT facility and rebuild the given grid model in the HIL system. Then operate the EV charging simulations with/without smart charging algorithm. The target of this project is to accomplish the HIL system, and compare the impact of controlled/uncontrolled EV charging on the distribution grid with the established HIL system.


Set up the OPAL-RT HIL simulation system

Implement the given grid model in the HIL system

Real-time simulation and compare the controlled/controlled EV charging in the distribution grid

Contact details:

PhD student: Yunhe Yu, [email protected]

Supervisor: Prof. Dr. ir. Pavol Bauer, [email protected] Dr. Gautham Ram [email protected]




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High Voltage DC Diagnostics and Monitoring DC systems, Energy conversion & Storage

TITLE: CONTROL SYSTEM FOR ELECTROSTATIC VOLTMETER

Type of project: <Extra project>

Scope:

<The goal is to construct a control unit for electrostatic voltmeter to measure potential distribution along a surface. The device will then be used to measure surface charge decay over commonly used dielectrics.>

Problem definition:

< Surface charges may accumulate on the surface of DC insulator and alter electric field distribution. In gas insulated substations due to field emission from the enclosure, electric charges are injected to SF6 and deposits on the surface of the spacer. In outdoor polymeric insulator surface charges are formed on the insulator due to corona activity. The presence of surface charges may decrease the breakdown strength of the insulator, leading to failure of HVDC component (in the event of lightning impulses) and hence interrupting power transmission. Therefore understanding how surface charges form and decay on the surface of insulator is very important for HVDC insulation design. HV laboratory has recently bought an electrostatic voltmeter. The voltage probe must be mounted a 2 axis CNC unit to scan the surface potential at a fix distance between the probe and the plate. Proper rails, bearing and stepper motors, type of microcontroller, together with flexible control algorithm (speed of scan, initial point setting) must be purchased, programmed and constructed. The final product will be used to measure surface charge decay over commonly used dielectric materials.>

Methodology:

<Proper components for a 2 axis CNC control unit must be chosen and purchased. A code must be written to control the stepper motors with the required flexibility. Final product should be assembled and used to measure charge decay over known dielectric sample. The results of the measurement must be compared with literature.>


<Purchasing the proper components for 2 axis CNC unit and development of the control code>

<Assembling of the product and testing its performance by means of surface charge decay over known dielectric material and comparison with literature.>

<Writing the final report and user manual for the developed device.> Contact details:

Supervisor: <Mohamad Ghaffarian Niasar, [email protected]>

Rob Ross, [email protected], Peter Vaessen [email protected]


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TITLE: DESIGN AND PROTOTYPING A SOLID STATE MARX IMPULSE GENERATOR

Type of project: Master thesis

Traditional Marx generator Solid state monopolar pulse generator J. Rao, et. al, “All Solid-State Rectangular Sub-Microsecond Pulse Generator for Water Treatment Application”, IEEE TRANSACTIONS ON PLASMA SCIENCE, VOL. 46, NO. 10, OCTOBER 2018

Scope:

To design, model and prototype a 10 kV solid state Marx impulse generator.

Problem definition:

TU Delft and KEMA laboratories are collaborating to create a universal high voltage test source capable of generating arbitrary waveforms including lightning impulses. The high current passed through the switches and the electromagnetic disturbances created during the lightning impulse impose limitation on switch sizing and required shielding of the communication and control system of the test generator. To identify challenges related to actual design of the high voltage arbitrary waveform generator, in this project a solid state 10 kV impulse generator will be designed, modelled and prototyped.

Methodology:

Accurate Spice/ Simulink model of the impulse generator including the important parasitic components will be made. This is check influence of different design parameters and to avoid overstress of switches during operation. Based on the simulation result, 3 stages of the pulse generator will be made and tested. At this stage isolation is created by means of 20 kV fast opt-coupler. Upon successful achievement in the first part, synchronization method will be replaced by fibre optics or laser pulses and the full scale test generator will be developed.


Literature review of different topology used in solid state pulse generators

Simulation of the Marx pulse generator considering parasitic parameters. Calculate voltage distribution along the stages of the generator.

Prototyping and testing the developed solid state impulse generator

Contact details:

Supervisor: Mohamad Ghaffarian Niasar, [email protected]

Tiago Batista Soeiro, [email protected]

Peter Vaessen, [email protected]




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TITLE: MODELLING OF CHARGE DECAY IN HVDC CABLES


Scope:

< To develop a model that can demonstrate charge decay and recovery voltage phenomenon on HVDC cables>

Problem definition:

<Space charges can accumulate in DC cables and alter the electric field distribution in the cable. Space charge build up and decay depends on insulation parameters, temperature, and environment. Charge decay can happen very quick or can take many days. When voltage is removed from a DC cable, trapped space charges can remain in the insulation for a long time. A de-energized cable can therefore develop potential difference between conductor and the sheath due to the available space charges. This is important from the safety point of view as such electric potential can be lethal. In this project a finite element model and a circuit model will be develop to demonstrate how the potential decay occurs when the voltage is removed from the cable. The model must be validated by means of experiment.>

Methodology:

<The work consists of development of a numerical model that can simulate charge decay and voltage recovery phenomenon in HVDC cables. The work also involve experimental work which will be done in high voltage laboratory.>


literature review of mechanism of charge decay and voltage recovery measurement as a

diagnostic method>

<Development of a FEM model in COMSOL Multiphysics that simulate charge decay in HVDC

cable. Development of a circuit model that can represent voltage recovery phenomenon>

<Comparison of the developed model with experiment>

Contact details:


Peter Vaessen [email protected], Rob Ross, [email protected],



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TITLE: STUDY OF TRICHEL PULSES IN AIR

Type of project: < Extra Project>

Scope:

<To numerically model negative corona (Trichel pulses) in air using COMSOL Multiphysics software and Matlab. The aim is to control solver’s step size during the whole simulation to minimize the simulation time.>

Problem definition:

<High electric field around sharp points can cause local breakdown of air known as corona discharge. If the polarity of applied voltage is negative and the dielectric medium has electronegative gas (such as oxygen) repetitive pulses of the same magnitude is usually observed during corona discharge. The goal of this project is to solve hydrodynamic equations of charged particles coupled with Poisson’s equation, to model the so called Trichel pulses in 2D-axis symmetric domain. Proper meshing, type of solver and step size taken by the solver are important parameters. In this extra project it is expected that the model is controlled from Matlab and proper algorithm is developed to control step size during the whole simulation in order to lower the simulation time.

Methodology:

<The work is simulation based and can be performed on the high end computer available in HV laboratory. Experimental verification has to be done when a functional model is developed>


<literature review, getting use to the existing model (how is it made, boundary conditions, functionality and limitations)>

<Implementing and controlling the existing COMSOL model by Matlab. Identifying the most suitable meshing strategy and controlling solver’s step size to obtain shorter simulation time >

Contact details:

Supervisor: < Mohamad Ghaffarian Niasar, [email protected]> Rob Ross, [email protected], Peter Vaessen [email protected]



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High Voltage DC Materials and Components


[1] D.A. Ganeshpure, “Modular Multilevel Converter (MMC) based High Voltage Test Source”, Master thesis in Electrical Engineering, Delft University of Technology, 2018

[2] G.P. Lourduraj, “Feasibility study of oil immersed power electronics based high voltage test source for onsite testing purpose”, Master thesis in Electrical Engineering, Delft University of Technology, 2019

TITLE: DESIGN OF CASCADED H BRIDGE (CHB) TOPOLOGY AND ITS SIZE ESTIMATION TO USE AS A HV TEST SOURCE


(a)

(b)

Cascaded H bridge topology Different ways to implement a DC source in CHB topology

Scope: The goal is to design CHB topology to generate arbitrary wave shapes for HV testing and estimate the size of the converter.

Problem definition: TU Delft and KEMA laboratories are collaborating to create a universal high voltage test source capable of generating arbitrary waveforms using multilevel converter topologies. Design of Modular Multilevel Converter (MMC) and its size estimation are performed with two MSc theses [1] [2]. To make a choice of suitable converter topology, the design requirement and size of both converter topologies need to be compared.

Methodology: The main focus of this master’s thesis is to compare different types of DC source implementation. Some of these implementations are shown in figure (a) and (b). This will have a huge impact with respect to the size, complexity, and scalability of the HV test source. Other aspects of design will be similar to the design of MMC.


Literature review on various options for DC source implementation in CHB

Size estimation with various chosen options

Complete design guidelines of CHB topology

Contact details:

PhD student: <Dhanashree Ganeshpure, [email protected] >

Supervisors: <Mohamad Ghaffarian Niasar, [email protected]> <Thiago Batista Soeiro, [email protected]>




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[1] S.A.A. Houtepen, “Dielectric loss estimation using damped AC voltages”, Master thesis in Electrical Engineering, Delft University of Technology, 2010

TITLE: LOSS MODEL OF HV INSULATION DUE TO REPETITIVE HIGH CURRENT SHORT PULSES


The existing model for loss calculation [1] Current pulse passing through HV insulation

Scope: The goal is to develop a loss model of HV insulation in the presence of harmonics such as current pulse shown in figure and verify the model using hardware experiment in the HV lab.

Problem definition: TU Delft and KEMA laboratories are collaborating to create a universal high voltage test source capable of generating arbitrary waveforms using multilevel converter topologies such as Modular Multilevel Converter (MMC). When MMC is controlled in an open-loop with resistive damping, it generates current pulses as shown in the figure. It is important to understand if this behaviour will degrade the HV insulation under the test. When the existing loss model is applied with the given output characteristic, it does not show enough difference between losses generated due to current with harmonics and fundamental current. Hence, it is required to improve the loss model which includes the effect of how fast charges move through insulation. Hardware experiments will answer more about insulation degradation, but it is time-consuming and expensive compared to a model.

Methodology: The project needs to draw the relation between physical processes happening in the insulation material to losses when voltage and current harmonics are flowing. Developed loss model will be verified with experimental results at the HV lab.


Literature review on the insulation material behaviour when subjected to different electric stresses such as sinusoidal with power frequency or current pulses

A novel approach for the loss model

Verification of the new model with hardware results

Contact details:

PhD student: <Dhanashree Ganeshpure, [email protected] >

Supervisors: <Mohamad Ghaffarian Niasar, [email protected]> <Peter Vaessen, [email protected] >

Lossless

Lossy




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DESIGN AND MODELLING OF FAST RISE TIME MARX GENERATOR

Type of project: Extra Project

Scope:

The scope of this project is to develop a finite element model and design a fast rise time Marx generator. Fast rise time pulse generator is used to test insulation materials under high pulsed voltages.

Problem definition:

High voltage impulse generators are capable to generate impulse with a rise time of 1.2 µs (See figure above). This impulse generators are useful to full fill the power system standardized tests. However, in recent years, by introducing power electronics converters, the shape and rise time of the pulses is going to change. To test insulation materials under faster rise time than standard lightning impulse generator, reconsidering the pulse generator and design of the pulse generator is needed.

Methodology:

The work is mostly focused on the detailed design of fast rise time Marx pulse generator on computer simulation. After the development of the model, a prototype has to build to verify the accuracy of the constructed model and design procedure. The experimental part will be done in a high voltage laboratory of TU Delft.


A literature review of existing Marx generator and their design

To be able to couple different physics in COMSOL Multiphysics software

Development of a FEM model that can accurately predict the electrical parameter of the pulse generator

Experimental verification of the constructed model

Contact details:

Babak Gholizad, [email protected]


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MODELLING OF METALLIZED CERAMIC SUBSTRATE FOR HIGH VOLTAGE POWER MODULES

Type of project: Extra Project (15 ECTS)

Scope:

The aim of this project is studying and designing an insulation system based on a metalized ceramic substrate architecture to allow the elaboration and demonstration of a medium-voltage (>10 kV) power module.

Problem definition:

The ceramic substrate is the standard packaging technology for power electronic modules, this element provides electrical insulation in one hand and dissipate the heat on the other hand. This element plays a major rule to the rise in the voltage rating of these power modules for 10 kV and above. The ceramic substrate requires a specific design on both sides, combining simultaneously the clever distribution of the electrical stress on the insulating materials (reduction of field reinforcements on the front side), and a better thermal cooling (on the back side). High voltage power electronic module is a crucial component for energy transition and plays an important rule for applications such as HVDC (High Voltage Direct Current transmission network of electrical energy), where it would offer a spectacular simplification of the global system (from hundreds of power modules currently to a few dozen).

Methodology:

The work is based on literature review and numerical modelling to design an innovative high voltage metalized substrate structures and including the physical and technological constrains.


Literature review

Understanding the physical parameters

Studying the degradation mechanisms, intrinsic or extrinsic

Developing numerical simulation model

Contact details:

Babak Gholizad: [email protected]

Wire Bond

Heat Sink

Cu-Base Plate

Solder

Metalized Ceramic Substrate

Silicon Chip

Thermal interface

Terminal Lead

Package Case

Insulating Gel


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DESIGN OF HIGH VOLTAGE SUPERCONDUCTING TRANSFORMER

Type of project: Extra Project/ MSc Thesis

Superconducting transformer (left) and copper transformer (right) with comparable nominal power (medium voltage traction transformer)

Source: M. Noe, EUCAS Short Course: Superconducting transformer

Scope:

The scope of this project is to develop a finite element (FEM) model and design a high voltage superconducting transformer.

Problem definition:

Superconductors are materials that can conduct a stationary electrical current without resistance. Higher current carrying capability of the superconductors provide a great opportunity to reduce the size of the power

components. The size and weight of the component become an important factor in dense areas. Physics and working temperature of the superconducting materials are different. Modelling the physics and behaviour of the material require good understanding. Several numerical approaches to model the superconducting material has been developed. Applying those numerical approaches to design a component is the goal of this project.

Methodology:

The work is mostly focused on modelling and preliminary design of high voltage superconducting transformers. Analytical design and FEM design of the transformer to predict the losses and size of the transformer is expected.


Literature review

To be able to couple different physics in COMSOL Multiphysics software and build a physics of superconductor

Development of a FEM model that can accurately predict the electrical parameter of the transformer

Comparison between FEM and analytical design of the transformer

Contact details:


Rob Ross, [email protected]



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THERMAL AGING AND ITS IMPACT ON LIFE TIME OF ELECTRICAL INSULATION MATERIAL

Type of project: Extra Project/ MSc Thesis

Scope:

The scope of this project is to understand the effect of thermal aging of insulation on lifetime of electrical insulation system is power system grid.

Problem definition:

Electrical insulation system ages because of different stresses. Electrical, mechanical, chemical, and thermal stresses are the main causes of aging. Loading profile of the power component changes the operating temperature of the insulation system. 10°C increase in working temperature of insulation reduces thermal lifetime of the insulation by half. Dynamic loading of the cables and excess of energy demands requires higher loading of the power component which translates the higher working temperature of the insulation material.

Relation between thermal ageing and lifetime of the power components is not well-known. This projects aims

to understand this relation.

Methodology:

The work is consist of experimental and modelling task to understand the impact of thermal ageing on lifetime of the power system components.


Literature review

Modelling thermal profile of power component by using loading profile of the component

Preparing experimental set-up

Studying the relationship between thermal ageing and lifetime of the insulation using experimental set-up

Contact details:


Failure due to temperature rise in insulation material phase to ground failure


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30KH HIGH POWER DENSITY TRANSFORMER WITH 35 KV ISOLATION REQUIREMENT THERMAL DESIGN INVESTIGATION

Type of project: < Master thesis>

Figure 1 The proposed medium frequency transformer construction and 2D FEM thermal simulation

Scope & Problem definition:

Most of recent research on power electronics have been focused on the solid state transformer as it comprises all types of power conversion required in energy supply. SST uses a medium frequency power transformer to replace the traditional line frequency power transformer thus the size and weight can be reduced. The to be designed transformer is operated at 30 kHz, at 50 kW power rating and needs to handle 35 kV isolation. The biggest challenges are to realize both isolation requirement and thermal requirement at a high power density level.

The transformer size is largely reduced when operating at medium frequency compared with conventional power frequency transformer which provides the possibility of higher power density. However, there is a trade-off between the high power density and thermal performance. First of all, the exposed cooling surface is also reduced accordingly. And it is safe to assume that the dissipated heat is proportional to the exposed cooling surface directly. Secondly with higher frequencies, effects such as skin and proximity and hysteresis losses are significantly increased compared to operation at 50/60 Hz. Besides the design process should consider high isolation requirement. And this again defects the transformer thermal performance and this is because firstly insulation material adds extra losses to the system, secondly the construction of the insulation will block some cooling surfaces and thirdly those insulation materials normally have relatively low thermal conductivity. As a consequence, the thermal design should be carefully considered and evaluated. Methodology:

Develop transformer losses analytical tools (core, copper and dielectric losses)

Develop analytical and 3D FEM thermal models for transformer

Optimize the thermal design according the simulation results Research Objectives:

Develop an accurate transformer thermal analyse method

Compare the different materials thermal properties Contact details:

Supervisor: Mohamad G Niasar, [email protected] Peter Vaessen [email protected]



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30KH HIGH POWER DENSITY TRANSFORMER WITH 35 KV ISOLATION REQUIREMENT INSULATION DESIGN INVESTIGATION

Type of project: < Master thesis>

Figure 2 A example of the medium frequency transformer cross section constructions

Scope:

Most of recent research on power electronics have been focused on the solid state transformer as it comprises all types of power conversion required in energy supply. SST uses a medium frequency power transformer to replace the traditional line frequency power transformer thus the size and weight can be reduced. The to be designed transformer is operated at 30 kHz, at 50 kW power rating and needs to handle 35 kV isolation. The biggest challenges are to realize both isolation requirement and thermal requirement at a high power density level.

Problem definition:

Current power frequency high voltage cast resin dry type transformers insulation configuration are usually made of air and solid material that are able to achieve the desired isolation level. In order to increase the power density, we have proposed to ground the resin cast high voltage side windings using semiconductors and use multi-layer insulation materials construction. To verify our concepts, the insulation performance of such design should be investigated first.

Methodology:

Develop 2D analytical and 3D FEM electrostatic models for the winding electric field

Choose different insulation materials and compare those designs

Develop experimental prototypes and test its insulation performance (lab work)


Develop an electrostatic analyse and design tool for windings

Compare the properties of different insulation materials

Evaluate the manufacture feasibility of the proposed multi-layer insulation concept

Contact details:

Supervisor: Mohamad G Niasar, [email protected] Peter Vaessen [email protected],



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TITLE: 200 KV INSULATION CLASS WIRELESS POWER TRANSFER ARRAY


Scope:

<The goal of this project is to design a wireless power transfer array with 200 kV insulation level capable of transferring 500 W per cell.>

Problem definition:

< High frequency pulses and harmonics are the type of stress that are being added to the grid following the increase penetration of power electronics. To ensure reliability of power component it is necessary to test them under actual stress present in the grid. It is therefore requested by number of testing companies, to design and prototype a high voltage arbitrary voltage waveform test generator. The goal of the project is to design a power electronics based HV test generator capable of generating 200 kV arbitrary voltage waveform. One candidate topology for such test generator is cascaded H-bridge topology. Isolated power supply is required in cascaded H-bridge topology with insulation clearance sufficient for the operating voltage of the test generator. Using ferrite core/iron core transformers at 200 kV insulation level requires a complicated insulation system which ends up into a bulky structure. In this regard, a novel idea of using wireless power transfer with high voltage insulation clearances is being proposed for this master thesis. The goal is to use existing knowledge in wireless power transfer, in combination with high voltage consideration required for this project, and come up with the most suitable design.

Methodology:

<Existing designs for wireless power transfer will be reviewed first. The best transfer ratio that results in the most compact design, with suitable insulation clearances must be chosen. At least two cells should be built and tested. Mutual interaction between the cells, and insulation performance of the array must be analysed with experiments.


<Literature review of existing topologies for wireless power transfer>

<Design and construction of the power array based on HV requirements and desired power transfer capability. Suitable dielectric and cooling system must be chosen>

<Experimental verification of the concept design with at least two cells >…

Contact details:

Supervisor: <Mohamad Ghaffarian Niasar, [email protected]> Peter Vaessen [email protected]

Oil FerriteHV coil

LV coil SE layerPB


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TITLE: DESIGN OF LOW VOLTAGE MULTI-LEVEL CASCADED H-BRIDGE, CONTROLLED AND PROGRAMMED OVER WI-FI

Type of project: Extra project/Master thesis

H-Bridge and gate driver

DC/DC

AC/DC MC


DC/DC

AC/DC MC


DC/DC

AC/DC MC

25 kHz high current H-bridge

DC Source

3 level cascaded H-bridge converter

Scope:

To design and prototype a low voltage multilevel cascaded H-bridge converter with separate microcontroller on each stage controlled and programmed over Wi-Fi and synchronized by a master microcontroller.

Problem definition:

TU Delft and KEMA laboratories are collaborating to create a universal high voltage test source capable of generating arbitrary waveforms. Multilevel cascaded H-Bridge topology is one of the candidate for the final topology of this test generator. Since the final test generator has many stages, it is convenient to avoid lots of fiber optic connections for the communication system. Low cost low voltage motor driver, Wi Fi Arduino, isolating transformers and DC/DC converters will be used to develop the sub-module. Each sub-module will be made with its own Wi Fi equipped microcontroller. The goal is to code the microcontroller over Wi Fi and to generate the desired output waveform. Synchronization of the microcontrollers is done using a master microcontroller.

Methodology:

To construct low voltage sub-module of a multilevel cascaded H-bridge using low cost components. To develop control and communication system with Wi-Fi equipped microcontroller.


To construct sub-module of multilevel cascaded H-bridge converter

To programme the microcontroller over Wi-Fi

To control and synchronize three stages of the test generator using a master microcontroller

Contact details:

Supervisor: Mohamad Ghaffarian Niasar, [email protected]

Tiago Batista [email protected]



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TITLE: DYNAMIC CURRENT RATING MODEL FOR HVAC AND HVDC CABLES CONSIDERING MULTILEYER SOILS

Type of project: < Master project>

Scope:

<To develop a model for dynamic rating of HVAC and HVDC cables taking into account electric field dependency of the insulation loss, field distribution, current harmonics and soil multilayer structure with different properties.

Problem definition:

<Dynamic rating is to better use the capacity of cable system without exposing it to risk of overheating and consequence lifetime reduction. In the cable course students learn how to evaluate cable ampacity, taking into account different losses and thermal model of the cable system at 50 HZ AC for a constant current. In this project the existing FEM models must be rebuild using MATLAB-COMSOL interface and controlled such that dynamic rating of power cables is possible. Field dependency of dielectric loss and temperature dependency of field distribution must be taken into account at the same time. This is to avoid over stressing HVDC cable insulation above the rated stress. An easy to use software must be developed for cable ampacity calculation. Influence of Current harmonics and multi-layer soil properties will be investigated.

Methodology:

<The work is simulation based and is performed using COMSOL Multiphysics. Experimental setup consisting of current varying heating element immersed under water will be made to verify the accuracy of the model developed. An open access software for cable dynamic rating will be developed based on the outcome>


<literature review, to learn standard method for cable ampacity calculation

<development of a Matlab controlled COMSOL model for dynamic cable rating >

<construction of experimental setup and verification of the developed model>

Contact details:

Supervisor: < Mohamad Ghaffarian Niasar, [email protected]>

Rob Ross, [email protected], Peter Vaessen [email protected]



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HIGH POWER DENSITY TRANSFORMER TESTING CIRCUIT SIMULATION

Type of project: < Extra Project>

Figure 3 The LLC circuit and the voltage and current across the tranformer

Scope & Problem definition:

Most of recent research on power electronics have been focused on the solid state transformer as it comprises all types of power conversion required in energy supply. SST uses a medium frequency power transformer to replace the traditional line frequency power transformer thus the size and weight can be reduced. Before diving into the transformer design, it is important to get the exact waveform across the transformer. LLC topology is used in the converter which maintains merits as ZVS for all primary side main switches and ZCS for secondary side diodes under wide range inputs, and the three-level technique, which is suitable for high voltage input applications, together.

Methodology:

Using matlab simulink to simulate the circuit operation and achieve the waveform across the transformer


Modelling the circuit operation conditions

Investigate the transformer magnetizing inductance and leakage inductance’s influence on the converter

Contact details:

Supervisor: Mohamad G Niasar, [email protected] Peter Vaessen [email protected],

is1



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TITLE: THERMAL MODELLING OF OIL IMMERSED POWER CONVERTERS

Type of project: <Extra project>

Scope:

<The goal of this project is to identify possible degradation and failure mechanisms of power switches induced by long term oil exposure>

Problem definition:

<DNVGL in cooperation with DCE&S group aims to build a power electronic based high voltage arbitrary waveform test generator. The ultimate goal is to immerse this test generator under oil in order to reduce the size of the device. This is important since the test generator can be used for mobile testing purposes. To long term ensure reliable operation of the test generator, it is necessary to identify any possible degradation mechanism of power switched due to long term oil exposure. Initial study was performed by previous master student and interesting observation has been made. In this work we want to expand the previous research.

Methodology:

<different power switches will be aged thermally and electrically under oil and in air. Various of characterization methods will be used before and after each aging test. The difference of characterization between oil-immersed switches and air exposed switches will be used to identify possible degradation mechanism induced by oil>


<Literature review of power switches internal structure and failure mechanisms>

<Expanding the existing setup for aging of oil-immersed power switches>

<Interpretation of the results and writing final report>

Contact details:


Peter Vaessen [email protected]


Documents

DC Systems, Energy Conversion & Storage Matchmaking Event de... · high-power converter. Methodology: After initial literature review into the topologies used for high power and low