Design of LMS Based Control Algorithm with Optimal Step for a Three-Phase Four-Leg Grid Interfacing Inverter in Distribution System

Abstract

A new control strategy is proposed to a three-phase Four-Leg Grid Interfacing Inverter (FLGII) to perform as a multifunctional device for improving power quality in interconnected power system. The control strategy is achieved by implementing proposed Least Mean Square (LMS) algorithm with optimal steps in the FLGII to compensate harmonics and reactive power compensation. This proposed adaptive LMS algorithm estimates the step size automatically in the 3-phase FLGII to obtain desired active as well as reactive weight determination. The required trigger pulse and reference current pulse are derived for the IGBTs of the Voltage Source Converter (VSC) from the already obtained active and reactive weights. The proposed adaptive three-phase FLGII system works well and maintains balanced 3-phase source current with sinusoidal nature within the 5% of bandwidth prescribed by IEEE-519-1992.

Keywords- Three Phase Four-Leg Grid Interfacing Inverter; LMS; Optimal Step size; Load Balancing; VSC;