Design Simulation of UPQC to improve power quality and

transfer wind energy to Grid

Student’s Name: K.JEYKAR R.PRASAD M.A.P.NARESH KUMAR

Guided by: Mr.G.T.GANESH KUMAR

Aim

To simulate UPQC to improve power quality and transfer wind energy to Grid

Abstract This study proposes a combined operation of the Unified Power

Quality Conditioner (UPQC) with wind power generation system considering investment cost.

The proposed system consists of a series inverter, a shunt inverter and an induction generator connected in the DC link through a converter.

The proposed system can compensate voltage sag, voltage interruption, harmonics and reactive power.

The speed of the induction generator is controlled according to the variation of the wind speed in order to produce the maximum output power.

The investment cost of proposed system is compared with investment cost of separated use of UPQC and wind energy conversion system (WECS) and the economic saving due to use of proposed system is estimated.

The validity of the proposed system is verified by the results of computer simulation.

Objectives

• To improve the power quality• To compensate the voltage sag• To control the reactive power

Scope of the Project

• To simulate UPQC model• To simulate Wind energy system• To simulate UPQC with voltage sag• To simulate WEG with voltage sag• To simulate both UPQC + WEG with

voltage sag• To improve the power quality

UPQC (Unified Power Quality Conditioner)

• A Unified Power Quality Conditioner (UPQC) is a device that is similar in construction to a Unified Power Flow Conditioner (UPFC). The UPQC, just as in a UPFC, employs two voltage source inverters (VSIs) that connected to a d.c. energy storage capacitor. One of these two VSIs is connected in series with a.c. line while the other is connected in shunt with the a.c. system.

• A UPQC that combines the operations of a Distribution Static Compensator (DSTATCOM) and Dynamic Voltage Regulator (DVR) together.

• A UPQC is employed in a power transmission system to perform shunt and series compensation at the same time. A power distribution system may contain unbalance, distortion and even d.c. components. Therefore a UPQC operate, better than a UPFC, with all these aspects in order to provide shunt or series compensation.

• The UPQC is a relatively new device and not much work has yet been reported on it. Sometimes it has been viewed as combination of series and shunt active filters.

UPQC (Unified Power Quality Conditioner)

• We have analyzed the operation of a UPQC that combines the operations of a Distribution Static Compensator (DSTATCOM) and Dynamic Voltage Restorer (DVR) together.

• The series component of the UPQC inserts voltage so as to maintain the voltage at the Point of Common Coupling (PCC) balanced and free of distortion.

• Simultaneously, the shunt component of the UPQC injects current in the A.C system such that the currents entering the bus to which the UPQC is connected are balanced sinusoids.

• Both these objectives must be met irrespective of unbalance or distortion in either source or load sides.

Block Diagram

Source

Shunt Transformer

Load

Wind Turbine

Series Transformer

Rectifier Shunt Inverter

Induction Generator Rectifier

UPQC circuit

WIND ENERGY SYSTEM

Circuit Diagram

RL

Conventional System Drawbacks

• Requires separate shunt inverter• Increase the overall initial cost• High cost

Advantages of Proposed system

• WEG gives supply to source and load • No need for separate shunt inverter• Less initial cost• Improve the power quality• Less harmonics• control voltage interruption

Applications

• Power quality improvement in Grid• Voltage stability improvement in Grid• Power Control improvement in Grid

CONCLUSION• It is found that research in recent years has placed more emphasis

on CPDs, especially on UPQC, and its application in DG or microgrid system.

• Single or modular type UPQC has been proposed to deal with power quality issues, with an addition to voltage interruption compensation, active power transfer, related to DG with integrated or microgrid mode.

• Capacity enhancement has been achieved using multi-level or multi-module and central control mode, however, the flexibility of UPQC to increase its capacity in future and to cope up with the increase load demand in low voltage distribution level has not been achieved.

• The economics for the capacity enhancement of UPQC should also be analysed.

References1. Basu, M., S.P. Das and G.K. Dubey, 2007. Comparative evaluation

of two models of UPQC for suitable interface to enhance power quality. Elec. Power syst. Res., 77:821-830.

2. Cavalcanti, M.C., G.M.S. Azevedo, B.A. Amaral and F.A.S. Neves, 2005. A Photovoltaic generation system with unified power quality conditioner function. 31st Annual conference of IEEE Industrial Electronics society, Nov. 6-10, IEEE, Brazil, pp:750-755.

3. Datta, R. and V.T. Ranganathan, 2002. Variable-speed wind power generation using doubly fed wound rotor induction machine; A comparison with alternative schemes, IEEE Trans. Energy Convers, 17: 414-421.

4. Han, B., B. Bae, H. Kim and S. Baek, 2006. Combined operation of unified power quality conditioner with distributed generation. IEEE Trans. Power Del., 21:330-338.

5. Power Electronics, Muhammad H. Rashid.6. Power Electronics, B.C. Sen.7. www.ieee.org8. www.mathwork.com