Power Distribution Control Strategy of Hybrid Energy Storage System in Isolated DC Microgrid

Energy storage (ES) system in DC microgrid has the functions of stabilizing bus voltage and improving power quality, it is an important part of DC microgrid. The battery-supercapacitor hybrid energy storage system (HESS) has more advantages than traditional ES system. In order to make full use of the advantages of HESS and realize the reasonable distribution of power, a power distribution control strategy for HESS is studied in this paper. The virtual resistor or virtual capacitor is extended into the control loop of each ES element to change the output impedance of the converter and then the power distribution of HESS is realized. Battery is mainly responsible for the low-frequency part of power fluctuations, and supercapacitor (SC) can quickly respond to the high-frequency part of power fluctuations. The two cooperate with each other to increase the service life of ES equipment and ensure the stable operation of the system. Finally, the correctness and effectiveness of the control strategy are verified by the simulation work in real time digital simulator (RTDS).