Improved reactive power management strategy for photovoltaic based distributed generators

Abstract

Reactive power sharing amongst photovoltaic based distributed generators (DGs) operating in parallel is a challenging task. As the active power supplied by these DGs depend on environmental conditions, reactive power margin (the maximum reactive power that DG can supply) varies.  Hence, the reactive power supplied by these DGs must be varied accordingly, to avoid unequal utilization and/or overloading of the DGs. Few reactive power sharing algorithms have tried to target this issue. However, they do not ensure equal percentage utilization of the DGs. Further hardly any of these algorithms have focused on the efficiency of the system in relation to apparent power shared by the inverters. The proposed reactive power sharing algorithm, referred as equal apparent power sharing with least losses (EAPS-LL), focuses on these two objectives. It assigns the reactive power amongst the DGs based on the reactive power margins of the DGs. Hence, it ensures nearly equal utilization of inverters thereby avoiding overloading of the inverters. The algorithm also evaluates various possible sequences in which reactive power allocation can be carried out and identifies the sequence that results into the least losses. The effectiveness of the proposed algorithm over other algorithms is highlighted through results obtained in MATLAB/Simulink.