Compensation of Effect of Line Parameters on Reactive Power Sharing in AC Microgrid

Abstract

The effects of mismatched interconnecting cable impedances, unequal local loads connected near to sources and difference in nominal voltages of sources lead to inaccurate reactive power sharing in ac microgrid. To ensure proportional reactive power sharing among sources, the Ideal Reactive Power Sharing (IRPS) controller is proposed in this paper. The controller shifts E-Q characteristics parallel to the voltage axis, in such a way that each converter supplies reactive power equal to its ideal value which is calculated using communication network. Ideal value of reactive power supplied by each source is the power when the equivalent output impedance of all sources as seen by loads are identical. The suggested controller shifts the E-Q droop characteristics of sources in such a way that each source supplies power in proportion to its rated capacity. The key advantages offered by proposed controller are accurate reactive power sharing and good voltage regulation. The controller provides stabilized operation even in case of error in communicated values. To validate the efficacy of proposed controller, detailed simulation studies are carried out in Real Time Digital Simulator (RTDS) platform.