Dynamic Droop Control Method for Islanded Photovoltaic Based Microgrid for Active and Reactive Power Control with Effective Utilization of Distributed Generators

Abstract

Conventional droop-control scheme shares the load amongst energy sources in proportion to their ratings. The scheme suffers from the issue of ineffective utilization of the sources when performance of some of the sources is dependent on environmental conditions. Hence, a modified droop- control strategy is proposed for a microgrid comprising of photovoltaic (PV) based distributed generators (DG) operating in parallel with other DGs. Dynamic nature applied to the droop characteristic by the primary control unit (PCU) sets the frequency reference such that the PV sources operate at their maximum power point and the energy demanded from the auxiliary source is the minimum. The margin available after supplying the active power is used to allocate the references for reactive power sharing. The reactive power sharing algorithm employed in secondary control unit (SCU) ensures that the standard deviation of the percentage utilization of the inverters is kept the minimum. Even in case of the failure of the communication between the PCU and SCU, a reasonably good performance is ensured as the control shifts to the master-slave control having dynamic droop adjustment feature. The effectiveness of the proposed strategy against other approaches is justified through the simulation results obtained in MATLAB/Simulink.