AN ENHANCED REACTIVE POWER SHARING METHOD IN ISLANDED AC MICROGRID

Abstract

Conventional droop control is the commonly used method for obtaining proportional sharing of real and reactive power in an autonomous microgrid. The distributed generators share power with respect to their ratings in an autonomous microgrid. By adopting conventional droop control, sharing of true power becomes equal. However, sharing of reactive power is not equal. Reason for this inequality is the resistive impedance of the feeder, unequal feeder lengths, and uneven or random distribution of load in the power system network. Unequal reactive power sharing is not acceptable as it results in heavy loading of distributed generators with small ratings. These small rated generators that are close to large loads are mostly affected. Unequal reactive power sharing also lead to uneven voltage profile, increases circulating current and cascaded tripping. Here a strategy which improves reactive power sharing and removing its dependency on communicationis used. In this a nominal voltage of each VSI adjust itself thus updating the reference voltage each time furthur enhancing the sharing of reactive power is utilized. Significant enhancement of this wattles power is obtained compared to a strategy which use fixed nominal voltage. Also in the presence of a load locally placed the mentioned effective strategy could maintain a stable voltage along with enhancing wattles power. This method reduces the reactive power sharing error by keeping the voltage stable. The simulation of the system done through MATLAB SIMULINK