A PLL less VAr generator based on one-cycle control

Abstract

A STATCOM based VAr generator for medium power applications, utilizing one-cycle control is proposed here. The control structure neither requires the service of a PLL nor the sector information of the utility voltages. This makes the control scheme robust and simple. Moreover, one-cycle control makes the switching frequency of the devices constant. This simplifies the process of design of passive filters to eliminate higher order switching harmonics. The semiconductor devices are operated with a switching frequency of 1kHz so that GTOs or high power IGBTs can be used for medium power applications. The viability and effectiveness of the scheme are confirmed through detailed simulation studies.