ESRFT WITH ISCT FUNDAMENTAL EXTRACTOR THEORY BASED DVR CONTROLLER USED FOR POWER QUALITY IMPROVEMENT

Abstract

Most of the devices at present using in the automation industry are non-linear type and they are sensitive to
voltage disturbances. Super computers, patient monitoring systems in hospitals and manufacturing industry desires balanced
voltage continuously. But due to fault occurrence in the distribution network supply voltage will become unbalanced and
hence connected load starts malfunctioning. To ensure the healthy working of the sensitive load devices during fault
condition Flexible AC Transmission System (FACTS) equipment’s are used in the transmission and distribution networks. In
the FACTS family dynamic voltage restorer (DVR) is an important device used to control the power flow and provide
protection of sensitive loads against voltage issues in the modern power system. In this paper, Instantaneous Symmetrical
Component Theory (ISCT) based control process implemented to die out the electrical power quality difficulties like voltage
sag/swell, transients, harmonics, interruption and distortion, from the supply voltage at the load bus. Extended Synchronous
Reference Frame Theory (ESRFT) with ISCT based Controller uses the concept of positive sequence extraction to balance
the phasors with the restoration of voltage and limit the third harmonic distortion (THD). In this case, extract positive
sequence from voltage at PCC which then transformed to d-q components. Subsequently Controller performance the output
is transformed back to a-b-c component known as reference signals and matched with real voltage signals at the load
terminal or bus. PWM generator start working with difference of the signals as input excitation generate a sequence of six
pulses through which functioning of IGBT based convertor can be controlled.