Advanced localized reactive power sharing in microgrids

The droop characteristics have gained much attention for controlling the distributed generation (DG) units in an islanded microgrid, since they obviate the requirements for communication infrastructure and have relatively fast response time. However, inability to properly share the reactive power due to line impedance mismatches is one of the major drawbacks of droop characteristics. In this paper, a method for decreasing the reactive power sharing error is proposed which is based on changing the operating points of the microgrid resources by correcting the voltage droop characteristic. The proposed method consists of three stages, namely, initial load sharing using the conventional droop characteristics, estimating the appropriate amount of correction which in operating point of each source, and applying this correction by changing the y-intercept of voltage droop characteristic. Deployment of this method does not disturb the microgrid voltage and frequency stability and preserves the plug and play attribute of sources. Additionally, the proposed method can be implemented locally at each DG without the requirement of communication infrastructure. Simulation and experimental results are presented to verify the validity of proposed method.