National Institute of Technology

Meghalaya

Project Title:-Study of Reactive Power Compensation Using STATCOM

Under the guidance of

Dr. Supriyo Das

(Asst.Prof. EEE Dept.)

By:-

Amit Kumar Meena

Manish Kumar Singh

Avinash Kumar

CONTENTS

Introduction

Reactive power

Power Triangle

Need for reactive power

Need for reactive power compensation

Static Synchronous Compensators (STATCOM)

Simulation Diagram of Voltage Source Converter (VSC)

Simulation Output

Conclusion & Future Work

References

INTRODUCTION

Reactive power (VAR) compensation is defined as themanagement of reactive power to improve the performanceof ac systems. There are two aspects:-

a) Load Compensation – The main objectives are to :-

i) increase the power factor of the system

ii) to balance the real power drawn from the system

iii) compensate voltage regulation

iv) to eliminate current harmonics.

b) Voltage Support – The main purpose is to decrease thevoltage fluctuation at a given terminal of transmission line.

Therefore the VAR compensation improves the stability of acsystem by increasing the maximum active power that can betransmitted.

WHAT IS REACTIVE POWER ?

Power is referred as the product of voltage and current

i.e. Total power = V x I

The portion of power that establishes and sustains theelectric and magnetic fields of alternating-current equipmentis called reactive power.

Reactive power must be supplied to most types of magneticequipment, such as motors and transformers.

In an ac transmission, when the voltage and current go upand down at the same time, only real power is transmittedand when there is a time shift between voltage and currentboth active and reactive power are transmitted.

POWER TRIANGLE

Power factor = cosø

= real power / apparent power

= kW/ kVA

Whenever there is a phase shift

between V and I we have:-

a) real power (kW)

b) reactive (imaginary ) power (kVAR)

c) The combination is a complex or

apparent power (kVA)=√(kW)² + (kVAR)²

WHY DO WE NEED REACTIVE

POWER?

In resistive loads the current produces the heat energy

which produces the desired output but incase of

inductive loads the current creates the magnetic field

which further produces the desired work. Therefore

reactive power is the non working power caused by the

magnetic current to operate and sustain magnetism in

the device .

Reactive power (vars) is required to maintain the voltage

to deliver active power (watts)through transmission

lines.

Need for Reactive Power

Compensation

To increase system stability.

Better utilization of the machines connected to the system.

Reducing losses associated with the system.

To avoid oscillation of reactive power between load and

source.

Also to regulate the power factor of the system and maintain

the voltage stability we need to compensate reactive power .

Methods of Reactive Power

Compensation

Shunt compensation

Series compensation

Synchronous condensers

Static VAR compensators

Static Synchronous Compensators

Static Synchronous Compensator

The devices use synchronous voltage sources for

generating or absorbing reactive power. A

synchronous voltage source (SVS) is constructed

using a voltage source converter (VSC). Such a

shunt compensating device is called static

compensator or STATCOM .

A STATCOM usually contains an SVS that is driven

from a dc storage capacitor and the SVS is

connected to the ac system bus through an

interface transformer. The transformer steps the ac

system voltage down such that the voltage rating of

the SVS switches are within specified limit.

Structure of STATCOM

Basically, the

STATCOM

system is

comprised of

Power converters

Set of coupling

reactors or a

step-up

transformer

Controller

Advantages of STATCOM

The components used in the STATCOM are much

smaller than those in the SVC.

The characteristics of STATCOM are superior.

The output voltage of STATCOM is nearly equal to the

input DC voltage.

Better transient response.

Reduction of harmonic to minimum level.

Reduction of size of high value air-cored reactor.

Reduction of equipment volume and foot-print.

Simulation model of VSC used in

STATCOM

Simulation output

Conclusion & Future Work

From all the previous discussion we can conclude reactive powercompensation is a must for improving the performance of the acsystem. By reactive power compensation we can control thepower factor and reduce the consumption of electricity.

So far we have designed a VSC using thyristor. From a DCsource we generated three-phase voltage each having a phasedifference of 120 degree.

Using MATLAB programming we have to create non-stopalternating pulsations.

Using pulse width modulation technique (PWM) we will get a puresinusoidal wave.

Finally using a step-up transformer of suitable turn ratio we willinject this sine wave into the main power line at a particular phaseangle which will give the resultant phase difference betweenvoltage and current to be zero i.e Φ = 0. So, sinΦ becomes 0 andhence the reactive power is compensated.

References

Zhiping Yang, Chen Shen, Mariesa L. Crow, LingliZhang, An Improved STATCOM Model for Power FlowAnalysis, University Of Missouri, 2000.

Alper Cetin, Design and Implementation of VSC basedSTATCOM For Reactive power Compensation AndHarmonic Filtering, Middle East Technical University,2007.

Ashok Kumar Bajia, Development of power flow modelof a STATCOM, Delhi College of Engineering, 2009.

Timothy J. E. Miller-“Reactive Power Control in ElectricalSystems”.

Dr. P S Bimbhra- “Power Electronics” KhannaPublishers, Thapar Institute of Engineering andTechnology, 2012.

THANK YOU!!