IMPEDANCE ANALYSIS AND CONTROL OF ELECTRIC SPRING BASED SMART LOADS IN A MICROGRID

Abstract

Electric spring (ES) incorporated smart loads are automatic demand response (ADR) devices which can offer voltage regulation in a microgrid by direct reactive power exchange and indirect active power exchange. This thesis investigates the voltage regulation operation of ES incorporated smart loads in a microgrid. An impedance based mathematical analysis is performed by modelling the ES as a virtual impedance and by reducing the upstream network using Thevenin's theorem. The proposed analysis brings out the importance of network impedance and load impedance in the operation ES in terms of its phase angle control architecture and operational limits. Based on the proposed impedance based analysis, a novel virtual impedance based two-loop control architecture is proposed for the ES incorporated smart loads. The application of the ES incorporated smart loads is extended to islanded microgrid, where frequency regulation is an issue in addition to voltage regulation.