Research on Insulation Coordination in MMC-HVDC for Wind Farm Integration

Flexible DC system is widely used for wind farm integration because of its unique technical advantages. To ensure reliable operation of the system, it is important to evaluate overvoltage levels and develop detailed insulation coordination schemes. Based on the main wiring and operation mode of modular multilevel converter (MMC) HVDC system for wind power integration, the insulation coordination design method of the system is studied in this paper. An MMC HVDC system model for wind farm integration is built in PSCAD/EMTDC software for simulation. Various system faults, such as AC and DC side faults in converter and DC line faults, are simulated to analyze overvoltage phenomena that may occur during operation. By calculating the peak voltage of the observation points, two kinds of arrester configuration schemes are proposed for comparison. The simulation results show that the better lightning arrester configuration scheme can achieve better overvoltage suppression effect. The insulation margin and withstand voltage of main electrical equipment are then determined to ensure the safety of the system in the face of overvoltage.