Design of controller for power quality management in presence of unbalanced load integrated with solar PV

Abstract

Distributed generation units with small energy sources, such as fuel cells, micro-turbines, and photovoltaic devices, are generally connecting to micro grid and distribution grid for improvement of power quality. In distributed system, generation units are connected with micro grid/distribution grid using three phase inverters. The presence of unbalanced load structure in micro-grid directly affects the supply voltage and current. In this paper, a grid connected inverter with unique control is proposed to solve this problem. It can maintain a stable voltage and current in presence of an unbalanced load. The scheme employs instantaneous active and reactive power theory for unbalanced load compensation. At the point of common coupling current is decoupled into active and reactive component by abc/dq0 transformation and also active and reactive component of load current is derived from active and reactive power of load for achieving of active and reactive power control independently. On the one hand, the active component of the point of common coupling current is adjusted to the reference value given by the active component of load current in order to meet the active power demand of unbalanced load and the reactive component of the point of common coupling current is adjusted to the reference value given by the reactive component of load current in order to meet the reactive power demand of unbalanced load. Thus a stable supply voltage and current can be maintained with an unbalanced load. The operational principle and the controller strategy have been presented and simulated results were shown for performance demonstrations.