Decoupled controller for single‐phase grid connected rooftop PV systems to improve voltage profile in residential distribution systems

Abstract

Unity power factor injection from single-phase photovoltaics (PVs) located towards the end of a residential feeder leads to voltage rise problems. Also, unbalanced current injection due to variable solar insolation results in voltage unbalancing and makes the situation worst. A decoupled controller for a single-phase PV inverter is proposed to improve the voltage profile of the distribution feeders. The proposed controller consists of the following components: voltage regulator (to control the amount of reactive power injection), outer voltage control loop (slow controller to set the reference for the inner current loop), inner current control loop (to control the PV inverters) and modified second-order generalised integrator (to generate fundamental frequency). A sample distribution systems consisting of several PVs located in all three phases and a three-phase induction motor load is considered. The real-time hardware-in-the-loop simulations are performed to test the efficacy of the proposed controller scheme. Results show the improvement in voltage regulation of different buses.