Short-circuit Current Improvement Control of Grid-forming Controlled Wind Turbine

Abstract

Grid-forming controlled wind turbine is the key equipment to build the new power system. However, under the grid fault, the short-circuit current of it is limited, far less than the value that synchronous generator can output to support fault voltage recovery. The key is that the power devices of converter can bear limited thermal stress. The thermal model of switching devices is established and the thermal behavior of grid-forming controlled wind turbine is researched. It has been found that adjusting the switching frequency and adopting to discontinuous PWM(DPWM) can effectively reduce the junction temperature of power devices, thus increasing the short- circuit current of wind turbine to 4 times during the fault. The effectiveness of the proposed method is validated in PLECS software.