A resilient bi-level control strategy for power sharing and voltage balancing in bipolar DC microgrids

Abstract

In the three-level DC-DC converter-based bipolar DC microgrids, accurate power sharing among distributed generators and voltage balancing between the positive and negative poles are two main control objectives. This article presents a resilient bi-level control strategy which simultaneously satisfies both aforementioned objectives. The proposed control structure is a combination of a distributed consensus-based cooperative method and a washout filter-based method. In the first level, a distributed consensus-based cooperative control method with considering time delays and communication noises is developed to realize proportional power sharing. At this level, DGs operate collaboratively using only neighbour-to-neighbour feedback over a sparse communication network, even if the communication network is susceptible to additive noise and time delay. In the second level, a decentralized control method is employed to restore the voltage of each pole of a bipolar DC microgrid to the desired value. The second level, which works without any communication links and additional control loops, utilizes a dynamic feedback incorporating washout filters. The whole proposed control strategy is robust against a single point of link-failure and resilient against the communication time delays and noises as well. Comprehensive simulation studies are carried out in PLECS software to verify the effectiveness of the proposed control scheme.