Current Sharing Control Strategy of Parallel Inverters Using Instantaneous Symmetrical Component Theory

This paper presents a power sharing control algorithm for parallel grid interactive multifunctional voltage source inverters (PGMVSIs) which are connected to distributed renewable energy sources. The main objective of this scheme is to get proportional power sharing among PGMVSIs, so as to make the grid current balanced sinusoidal and at unity power factor. The control algorithm is derived using instantaneous symmetrical component theory (ISCT) to ensure a proper sharing of active, reactive, unbalance and harmonic power among parallel inverters. This scheme requires a central controller and communication among inverters in contrary to the droop control based techniques. However, the proposed control scheme has perfect decoupling of active and reactive power sharing, proportional unbalance and harmonic power sharing, and a very good dynamic response. The steady state and transient performance of the proposed control strategy have been verified through detailed simulation.