A new control strategy for multifunctional PV grid interface converter considering the inverter rating

Abstract

Several studies have shown the benefits of using auxiliary functions in the control strategy of PV grid interface converters. Most studies do not consider the necessity of prioritizing the injection of PV power into the grid and limiting the compensation according to the available capacity of the inverter. The main goal of this paper is to propose a new control strategy for the multifunctional PV grid interface converter to improve the power quality at the PCC by considering the capacity of the inverter. This strategy considers the inverter's rated capacity in terms of the maximum current factor. This method limits the inverter current to prevent overrating operations of the inverter and also manages the functions of the PV grid interface converter. Limiting the inverter's rated capacity in terms of maximum current is very important not only to preserve the life of semiconductors but also to ensure the primary role of the inverter in injecting active power into the grid. In this strategy, injecting active power into the network along with load imbalance compensation has priority over improving power quality. The control strategy is based on extracting active and reactive components of the current per phase with a variable reference frame. The proposed control strategy for a two-stage grid-connected PV interface converter was implemented in a three-phase, four-wire power distribution system. The simulation was carried out by MATLAB/Simulink software. The simulation results and comparison with the conventional control strategy demonstrated the good performance of the proposed strategy.