Power factor angle consistency control for decentralised power sharing in cascaded-type microgrid

The microgrid with cascaded H-bridge micro-converters (cascaded-type microgrid) is an effective way to integrate the distributed generators (DGs) into medium/high-voltage distribution energy system. Just like the islanded microgrid composed of paralleled inverters, achieving accuracy in power sharing and high voltage quality is a serious challenge in cascaded-type microgrid without communication. In this article, a decentralised control scheme is proposed to share the active and reactive power accurately under the resistance-inductance and resistance-capacitance loads. The power factor angle of each DG is assigned to be consistent in the steady state via regulating both the frequency and voltage. The proposed scheme can be easily implemented only based on the local measured signals. Meanwhile, excellent load voltage quality is achieved. Small-signal analysis method is performed to verify the effectiveness of the proposed scheme, and a guide for designing the power sharing coefficient is given. The cascaded-type microgrid model is developed through simulations and experiments to verify the performance of the proposed scheme.