UPQC-S: A Novel Concept of Simultaneous Voltage Sag/Swell and Load Reactive Power Compensations Utilizing Series Inverter of UPQC

CONTENTS :

Introduction Power quality Power quality problems Upqc block diagram Operation of Upqc Types of Upqc Advantages Conclusion

INTRODUCTION:

This project introduces a new concept of optimum unified power quality conditioner. Here the series inverter of Upqc plays vital role in this Upqc-s Due to this series inverter operation Upqc-p is turned into Upqc-s.

. POWER QUALITY: Power quality means variation of voltage ,current and frequency in permissible limits.

POWER QUALITY PROBLEMS: VOLTAGE SAG VOLTAGE SWELL TRANSIENTS FLICKERS NOTCHES VOLTAGE UNBALANCE VOLTAGE INTERRUPTION POOR POWER FACTOR

VOLTAGE SOURCE CONVERTER: Generally we use the voltage source inverters in all facts devices.

In VSI input voltage maintained constant and the amplitude of output voltage does not depend on the load.

How ever the waveform of the current as well as its magnitude depends upon the nature of a load.

BLOCK DIAGRAM OF UPQC :

EQUIVALENT CIRCUIT FOR A UPQC

TYPES OF UPQC:

Depending upon the series inverter operation operation the UPQC is to be classified in to three types .They are UPQC-P UPQC-Q UPQC-S

OPERATION OF UPQC-P:

CONT….

CASE V: series inverter injects the voltage harmonics to source voltage to neutralize the voltage harmonics in the source side.

CASE Vl: shunt inverter injects the current harmonics to the load current to neutralize the harmonics in the load current.

CONCEPT OF PAC OF UPQC-S :

QshQsr

OPERATION OF UPQC-S:

Apparent power flow during under voltage sag condition

Case 1:

Qsr Qsh

Apparent power flow during under voltage swell condition

Case2 :

Qsr Qsh

Reactive power flow under normal condition

Case 3:

ADVANTAGES:ADVANTAGES OF UPQC-P OVER UPQC-Q:

In UPQC-P minimum injected voltage magnitude required to get the nominal voltage compared to UPQC-Q .

UPQC-P rectify the both voltage sag and voltage swell but UPQC-Q rectifies voltage swell only.

ADVANTAGES OF UPQC-S OVER UPQC-P:

UPQC-S is a optimum utilization of UPQC-P .

In UPQC-S the series inverter reduces the burden to shunt inverter .

In UPQC-S we use minimum KVA rating of shunt inverter.

CONCLUSION:

It is not a separate upqc but by using power angle control ,we can use the upqc optimally.In this, a concept of controlling of apparent power through a series inverter is implemented.