DC Side Over-Voltage Characteristics Analysis of AC/DC Hybrid Distribution Power System

AC/DC hybrid power distribution network are adopted to replace traditional AC power distribution network with the continuous access of distributed renewable energy to power grid, which can solve the source and load power supply as well as power consumption demand comprehensively. However, the over-voltage characteristics of AC/DC hybrid system are quite different from traditional AC system for their different structure. For this reason, the over-voltage generation mechanism on DC side of a proposed AC/DC hybrid distribution system was analyzed. Then based on the system simulation model established in MATLAB/Simulink, the over-voltage characteristics under DC side pole-to-pole short-circuit fault were obtained. The simulation results show that the maximum over-voltage of 10kV DC pole-to-pole fault can reach 121.8kV and the maximum over-voltage of ±375V DC pole-to-pole fault can reach 12kV. An over-voltage suppression method by applying arresters was proposed. Simulation results show that the maximum over-voltage of 10kV DC side drops to 12kV and the maximum over-voltage of ±375V DC side drops to 1.2kV. The above analyses provide basis for the design of over-voltage and insulation of AC/DC hybrid distribution system.