A virtual resistance based reactive power sharing strategy for networked microgrid

Different from the traditional microgrid with a common ac bus, networked microgrid always suffers more serious reactive power sharing problems due to its complex inner configurations. In such a situation, the reactive power sharing errors among distributed generation (DG) units can´t be eliminated effectively. Thus, an advanced reactive power sharing strategy that employs communication and virtual resistance control is hereby proposed for networked microgrid. First of all, the relation between reactive power output and virtual impedance regulation (VRR) is discussed. After that, communication is introduced to assign reactive power reference to each DG unit for their respective VRR, which is able to compensate the mismatch in network. The method is immune to the load change during the regulation stage, and also to the time delay in communication channels. From the small signal analysis, it also can be seen that in the designed regulation range, VRR has no significant effect on the system stability. The feasibility and effectiveness of the proposed strategy are validated by the simulation and real time digital simulator (RTDS) test results from a 50 kVA networked microgrid system.