A novel power quality enhancement strategy for single phase islanded microgrid

Abstract

The aim of the present work is to improve the Power Quality (PQ) under the islanded mode of operation for single phase MicroGrid (MG). For this purpose, a novel voltagesensorless, selective harmonic compensation scheme and a unified two-dimensional modified droop control strategy for resonance damping using only the inverter side current measurements is utilized. Due to the lack of grid support under the islanded operation of MG, load sharing of both fundamental and harmonic load power among parallel inverters relies on the inverter control strategy and the effective impedance between inverter and Point of Common Coupling (PCC). Thus, the sensorless voltage method is utilized to reshape effective impedance at various selected harmonic components and subsequent resonance propagation is controlled using resonance damping strategy by simultaneous control of inverter output resistance and reactance between inverter and PCC. The proposed method not only improves the voltage quality at PCC but also reduces the reactive and harmonic sharing errors in accordance with the ratings. The method is validated on a simple system of parallel connected DGs in PSCAD software.