Wireless fundamental frequency-based variable mode power sharing strategy for autonomous microgrid

This paper proposes a variable mode control (VMC) for the power mismatch among inverters in autonomous microgrid. With this method, power mismatch, usually difficult to sense in traditional droop control, can be tackled easily by varying the control mode of inverters synchronously in a wireless manner without central controller. In order to synchronously vary the control mode in a wireless manner, this paper first analyses the phase relationship between inverter output voltage and power point coupling voltage to demonstrate the feasibility of adopting inverter output voltage as the quasi-synchronous signal for mode varying. This results in the wireless VMC of fundamental frequency, which greatly reduces the control complexity by removing the central control signals. Based on this strategy, this paper shows that many typical methods for power sharing, such as virtual impedance, voltage compensation, variable droop coefficient and coupling control, can be used for accurate power sharing in a VMC manner without central controller. Moreover, the VMC is based on the output voltage regulation rather than impedance match principle. Furthermore, power fluctuations and small signal models are analysed for parameter selection. Finally, simulations using MATLAB/Simulink and experiments are carried out to evaluate the performance of the proposed method.