A Power Control Method for Interlinking Converters Considering Impedance Compensation and Communication Interruption

In hybrid AC/DC microgrids, normalized droop is a classic power control method for interlinking converters (IC). Line impedance not only reduces the accuracy of normalized droop, but also causes circulating power between ICs. To solve the problem of reduced global power sharing accuracy caused by line impedance, this paper proposes a high precision power control strategy that integrates line impedance compensation and communication interruption ride-through between ICs. The main idea is to use harmonic injection to transmit AC bus voltage information, and then ICs can locally derive the bus voltage and calculate the line impedance. After compensating for the line impedance voltage drop, the microgrid achieves precise power coordination between subgrids. Furthermore, in order to achieve precise power allocation between ICs of different capacities operating in parallel, a decentralized controller is designed. A reliable communication architecture is selected to ensure fault ride-through capability during communication interruption. These expectations have been verified by results obtained from Hardware-in-the-loop (HIL) experiments.