A Distributed Coordinated Control Strategy for Unbalanced Voltage Suppression in Bipolar DC Microgrids with Flexible ZIP Load

With the growing integration of distributed generations (DGs) and renewable energy sources, bipolar DC microgrids have attracted increased attention due to their high efficiency, cost-effectiveness, and flexibility. However, bipolar DC microgrids are susceptible to severe unbalanced voltage problems that threaten their safe and stable operation. To tackle this challenge, this paper introduces a distributed coordinated control strategy for unbalanced voltage regulation in bipolar DC microgrids featuring flexible ZIP loads. The proposed strategy comprises primary and secondary control mechanisms. The proposed control facilitates power distribution among DGs while maintaining the average bus voltage at its rated value. Meanwhile, the secondary control exploits the consensus theory and the relationship between bipolar voltages and the voltage unbalanced factor (v(hb)%), enabling convergence of v(hb)% across poles and maintaining of the average bus voltage at its rated value. Simulation results validate the effectiveness of the proposed strategy, demonstrating its ability to effectively mitigate unbalanced voltage and enhance voltage stability in bipolar DC microgrids.