Enhanced Active and Reactive Power Sharing in Islanded Microgrids

Abstract

The intermittency of renewable energy makes the control of islanded microgrids more difficult than that of the grid-connected mode. In conventional methods, the controller is designed to regulate the system frequency and voltage only based on the droop control theory. Consequently, the system frequency and voltage regulation are mostly provided by the fast response distributed generators (DGs), e.g., energy storage systems. This controller design will reduce the availability of DGs with lower droop gains for future dispatches. The main novelty of this article relies on proposing an intelligent power sharing (IPS) approach to regulate the system frequency and voltage based on DGs' operating power capabilities and their droop control gains. The communication infrastructure is involved in the proposed IPS to diminish the dependence on fast response DGs. Moreover, the IPS is equipped with an adaptive virtual impedance to reduce the impact of coupling between the active and reactive power on the voltage regulation. The performance of the controller is evaluated through different simulation studies based on a 14-bus CIGRE test system. Time-domain simulations prove the effectiveness of the IPS approach in achieving acceptable frequency and voltage regulation along with high-power sharing accuracy. Also, a small-perturbation stability analysis is developed to study the IPS control robustness under different scenarios.