© 2018 IJRAR January 2019, Volume 6, Issue 1 (E …ijrar.org/papers/IJRAR19J1023.pdf · 2019-01-09 · MATLAB/SIMULINK. Index Terms - Active Power Filter (APF), Distributed Generation

© 2018 IJRAR January 2019, Volume 6, Issue 1 www.ijrar.org (E-ISSN 2348-1269, P- ISSN 2349-5138)

IJRAR19J1023 International Journal of Research and Analytical Reviews (IJRAR) www.ijrar.org 157

Performance Improvement of Renewable Energy

Sources Inverter for Interface with Smart Grid

1Manoj D. Patil, 2K. Vadirajacharya 1Assistant Professor, 2 Professor

1Department of Electrical Engineering, 2Department of Electrical Engineering 1ADCET, Ashta, Sangli, Maharashtra, India. 2DBATU, Lonere, Raigad, Maharashtra, India

Abstract: The aim of this project is to analysis and improve the performance of the power quality problems (voltage sag,

swell and harmonics) to grid connection with the help of inverter used in distributed generation. Renewable energy resources

demand is continuously increasing nowadays, it connected in distribution systems utilizing power electronic converters. This

paper presents the concept of grid tied solar inverter as hardware and software in MATLAB/SIMULINK to improve the

performances of PQ. It is also interfacing with RES (Renewable Energy Resources) with the electric grid. The grid interface

inverter can improve the performance of following functions they are (1) power converter to inject power generated from

renewable energy sources to the grid, (2) Shunt Active power filter to compensate current unbalance, load current harmonics, load

reactive power demand. The controller controls the real power and reactive power supplied by the distributed generation at the

PCC. In the gird side currents always maintained as balanced and the unity power factor. This work is carried out using software

MATLAB/SIMULINK.

Index Terms - Active Power Filter (APF), Distributed Generation (DG), Power Quality (PQ), Renewable Energy Sources

(RES), Point of Common Coupling (PCC).

I. INTRODUCTION

In recent years there has been an increasing interest in moving away from large centralized power generation towards distribution

energy resources. But increasing air pollution, global warming concerns, diminishing fossil fuels and their increasing cost have

made it necessary to look towards renewable sources as a future energy solution. There are many advantages for use as a

distributed energy resource, mainly as a peaking power source. Renewable energy source utilized because of its environment

friendliness, sufficient availability, and it produces the good efficiency [1][2].

Inverter

Load

Control

Technique

Renewable

Energy Soures

Grid

Fig. 1: Basic block diagram of solar grid tie Inverter

Renewable energy source (RES) synthesis distribution level is termed as distributed generation (DG). The utility is concerned due

to the high penetration level of intermittent RES in distribution systems. By using proposed technology it improve the voltage

stability, voltage regulation and power-quality (PQ) problems. With the power electronics and digital control technology, the

distribution energy systems can now be easily controlled to improve the circuit operation with improving the power quality

performances at the place of the Point of Common Coupling (PCC). The non-linear load current harmonics may result in voltage

harmonics and can create a power quality problem in the power system network. Active Power Filter (APF) is mainly used to

compensate the load current harmonics and load unbalance at distribution level [3][4].

The grid-interfacing inverter can excellently be utilized to produced functions as transfer of active power harvested from the

renewable energy resources (wind, solar, etc.), load reactive power demand, current harmonics compensation at the point of

common coupling , current unbalance and neutral current compensation in case of 3-phase 4-wire system as shown in fig.2.

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Grid

Set of

3-

phase

and 1-

phase

loads

DSP

Control

External Hysteresis

Board

Renewable

Energy

Sources

P1 P4 P3 P6 P5 P2 P7 P8

Ia*

Ib*

In*

Ic*

S1 S3 S5 S7

S4 S6 S2 S8

Lsh

ILa

ILb

ILc

ILn

I in

vb

I invc

I in

vn

I inva

Ia Ib Ic InVa Vb Vc

Δ-ΥDistribution

Transformer

AB

C

N

VDC

Fig. 2: Schematic Diagram of a Proposed Circuit with Renewable Energy System

II. OVERVIEW OF A PHOTOVOLTAIC (PV) MODULE

To understand the PV module characteristics it is necessary to study about the PV cell at first. A PV cell is the basic structural

unit of the PV module that generates current carriers when sunlight falls on it. The power generated by these PV cell is very

small. To increase the output power the PV cells are connected in series or parallel to form PV module.

Rsh

Rs

Fig. 3: Equivalent Circuit of PV Cell

The main characteristics equation of the PV module is given by

𝐼 = 𝐼𝑝𝑣 − 𝐼𝑜 [𝑒𝑥𝑝(𝑞(𝑣+𝐼𝑅𝑠))

∝𝐾𝑇− 1] − 𝑉+𝐼𝑅𝑠

𝑅𝑠ℎ …(1)

Solar PV Module in MatLab Simulation




Fig.4: MatLab Solar PV model

Solar PV & IV Characteristics

Prepared the MatLab simulation model Fig.4 according to Eq. (1) & we got following results

Fig. 5(a): Solar Cell PV Characteristics

Fig. 5(b): IV Characteristics




III. SYSTEM DESCRIPTION

The RES may be a DC source or an AC source with rectifier coupled to dc-link. Usually, the fuel cell and photovoltaic energy

sources generate power at variable low dc voltage, while the variable speed wind turbines generate power at variable ac voltage.

Thus, the power generated from these renewable sources needs power conditioning (i.e., dc/dc or ac/dc) before connecting dc-

link.

1. DC-Link Voltage and Power Control Operation

2. Control of Grid Interfacing Inverter

3a. DC-Link Voltage and Power Control Operation

Due to the intermittent nature of RES, the generated power is of variable nature. The dc-link plays an important role in

transferring this variable power from the renewable energy source to the grid. RES are represented as current sources connected

to the dc-link of a grid-interfacing inverter. The current injected by RES into dc-link at voltage level can be given

𝐼𝑑𝑐1 =𝑃𝑅𝐸𝑆

𝑉𝑑𝑐 …(2)

Renewable

Energy

Sources

Power Grid

DC-Link

PRES PG

Pinv = PG + Ploss

Idc2Idc1

Vdc

Fig. 6: DC-Link Equivalent Diagram

3b. Control of Grid Interfacing Inverter

The control diagram of grid- interfacing inverter for a 3-phase 4-wire system as shown fig.2 the fourth leg of inverter is used to

compensate the neutral current of the load. The approach is to regulate the power at PCC. It is shown in this paper that the grid

interfacing inverter can effectively be utilized to perform following important functions: 1) to transfer of active power harvested

from the renewable resources (wind, solar, etc.); 2) load reactive power demand support; 3) current harmonics compensation at

PCC; and 4) current unbalance and neutral current The duty ratio of inverter switches are varied in a power cycle such that the

combination of load and inverter injected power appears as the balanced resistive load to the grid. The regulation of dc-link

voltage carries the information regarding the exchange of active power in between renewable source and grid. Thus the output of

dc-link voltage regulator results in an active current[5].

Components Used in the System

The components used in the systems are PLL, PIC controller, MOSFET switches and filter circuit.

Phase-Locked-Loop (PLL)

For dominant totally different operations in many communication systems, computers and lots of electronic applications, part

fastened loop are often used as an effect system. It's used for generating associate in nursing signal that has a part associated with

signaling part. PLL circuit in FM transmitter may be a control system feedback system. This part latched loop keeps the generated

signal and reference signal in a much fastened relationship. The most unusefulness of victimization associate FM transmitter is

counteracted by victimization this part latched loop scheme. If we tend to use a straightforward semiconductor unit based mostly

generator circuit, then we are able to observe the drift in frequency. This drift in frequency is caused because of completely

different instabilities like load-induced in power rails, inherent generator, thermally evoked, mechanical phenomenon forces, and

so on. This drift in frequency causes downside at the receiving finish and therefore, the receiving person needs to retune the radio

or FM transmitter radio like car-radio or hand-held radio.

PIC Controller

By using PIC controller triggering pulses are generated to the inverter side. It uses Single-supply 5V In-Circuit Serial

Programming circuit. It has wide operating voltage range (2.0V to 5.5V). It consumes Low-power. It has five input/output pins.

Triggering pulses are given to the MOSFET switch.

PI controller

The actual dc link voltage is sensed and passed through a first order low pass filter (LPF) to eliminate the presence of switching

ripples on the dc link voltage and in the generated reference current signals. The difference of the filtered dc link voltage and

reference dc link voltage (Vdc*) is given to a discrete PI regulator to maintain a constant dc link voltage under varying generation

and load conditions. The dc link voltage error Vdcerr(n) at nth sampling instant is given as

𝑉𝑑𝑐𝑒𝑟𝑟(𝑛) = 𝑉𝑑𝑐(𝑛)∗ − 𝑉𝑑𝑐(𝑛) …(3)

The output of discrete PI regulator at nth sampling instant is expressed as

𝐼𝑚(𝑛) = 𝐼𝑚(𝑛−1) + (𝑉𝑑𝑐𝑒𝑟𝑟(𝑛) − 𝑉𝑑𝑐𝑒𝑟𝑟(𝑛−1)) + 𝐾𝐼𝑉𝑑𝑐𝑉𝑑𝑐𝑒𝑟𝑟(𝑛) …(4)

Filter

A filter may be a device or method that removes from an indication some unwanted element or feature. Filtering may be a

category of signal process, the shaping feature of filters being the whole or partial suppression of some side of the signal.




IV. FINAL SIMULATION MODEL WITH SOLAR GRID TIE INVERTER FOR PQ IMPROVEMENT

Fig. 7: Simulation Circuit Diagram




V. SIMULATION RESULTS

It has observed that the THD value for PI is 64.16% for 60cycles

Grid Active and Reactive Power Results with Both Controllers

It observed that the reference signal generated by inverter to compensate the reactive power is same as grid signal with 180deg

phase shift.

Fig. 8: Load Current THD with PI Controller

Fig. 9: Grid Active & Reactive Power

Inverter Active and Reactive Power Results

Fig. 10: Inverter Active and Reactive Power




VI. HARDWARE RESULTS

As shown in Fig. 1 Basic block diagram of grid tie inverter. Single phase Prototype Hardware is prepared & shown that voltage

amplitude & waveform at grid side & inverter side are mating so inverters are synchronized with grid. Waveforms are shown in

fig.11 and Fig.12 with hardware photographs.

Fig. 11: Hardware Board with Output Verification

Fig. 12: Grid and Inverter Output Waveform.

VII. CONCLUSION

In this project improved the performance of the power quality problems (voltage sag, swell and harmonics) and to grid connection

with the help of inverter used in distributed generation. This paper presented a PI logic controller in order to improve the

performances of PQ. It is also interfaced with RES (Renewable Energy Resources) with the electric grid with 1ph prototype

hardware. The grid interfacing inverter has improved the performance of power converter to inject power generated from

Renewable energy sources to the grid, shunt Active power filter to compensate current unbalance, load current harmonics, load

reactive power demand. The controller controls the real power and reactive power supplied by the distributed generation at the

PCC. In the gird side currents always maintained as balanced and the unity power factor.

REFERENCES

[1] Mukhtiar Singh, Vinod Khadkikar, Ambrish Candra, “Grid interconnection of renewable Energy sources at the distribution

level with power-quality improvement features,” IEEE Trans. Power Delivery, vol. 26, no. 1, pp. 307-315, Jan. 2011

[2] Manoj D. Patil, K. Vadirajacharya, “ALO optimized Neural Network Controlled Three Phase Five Level Cascaded H-Bridge

Inverter for Integrating PV Panel with Smart Grid” in Institute of Advanced Scientific Research Publications; Journal of

Advanced Research in Dynamical and Control Systems (JARDCS), Volume-10, Special Issue-09, pp.2127-2139.

[3] Manoj D. Patil, Mithun Aush, K. Vadirajacharya, “Grid Tied Solar Inverter at Distribution Level with Power Quality

Improvement” in Research India Publications; International Journal of Applied Engineering Research, Print ISSN: 0973-

4562, Online ISSN: 1087-1090, April 2015, Special Issues, Volume-10, Number-9, pp.8741-8745.

[4] Manoj D. Patil, K. Vadirajacharya, “Grid Tied Solar using 3-Phase Cascaded H-Bridge Multilevel Inverter at Distribution

level with Power Quality Improvement” in International Journal of Advance Foundation and Research in Science and

Engineering, ISSN 2349-4794, Volume-2, Special Issue, Vivruti-2016, 2016, pp.178-191.

[5] Manoj D. Patil, Rohit G. Ramteke, “L-C Filter Design Implementation and Comparative Study with Various PWM

Techniques for DCMLI” in IEEE Xplore Digital Library & International Conference on Energy Systems and Applications

(ICESA-2015) organised by Dr. D. Y. Patil Institute of Engineering and Technology Pune in association with IEEE pune

section, held from 30th October to 1st November 2015, pp.347-352.


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© 2018 IJRAR January 2019, Volume 6, Issue 1 (E …ijrar.org/papers/IJRAR19J1023.pdf · 2019-01-09 · MATLAB/SIMULINK. Index Terms - Active Power Filter (APF), Distributed Generation