Accurate Reactive Power Sharing for Microgrid Using Distributed Adaptive Virtual Impedance

Distributed generators (DGs) are usually dispersed along with the microgrids, which may spread out in a wide area, the impedances of transmission lines between every two DGs may be different. Therefore, uneven distribution of reactive power among parallel DG inverters with fixed virtual impedance would be induced eventually, which not only results in decreased system efficiency, but also makes some DGs impossible to operate under their rated power conditions. To address this issue, a distributed adaptive virtual impedance control method, which depends on the reactive power deviation related to their capacity between previous DG inverter and current DG inverter and needs low-bandwidth wireless communication network, for the DG inverters is proposed. With the help of the proposed method, accurate reactive power sharing among DGs under various operating conditions can be obtained regardless of the changes of microgrid structure or the load condition. Furthermore, the proposed control strategy can be implemented directly without any knowledge of the detailed microgrid configuration or the required load power measurement, which decreases the complexity and cost of the system. Finally, the validity and feasibility of the proposed method is finally verified via simulations.