A Strategy of Adaptive Reclosure for AC Lines on the Inverter Side of AC/DC Hybrid Grid

The electrical characteristics of the AC lines on the inverter-side of HVDC and AC system are comparatively analyzed when different types of faults occur. A three-phase adaptive reclosing criterion based on the differential current of the power frequency traveling wave is proposed. The method utilizes the voltage and the shunt reactor current to construct the power frequency traveling wave. After the three-phase tripping out at both ends of the transmission line, the phases of the power frequency line mode traveling wave differential current have different trends under different phase fault properties, in which the phase change period during permanent faults is much smaller than that during transient faults. By utilizing this characteristic, a three-phase adaptive reclosing criterion is proposed for the inverter-side AC line of HVDC. The criterion is calculated by using the traveling wave quantity of power frequency, which can quickly and accurately distinguish transient faults from permanent faults, and at the same time, it has excellent resistance to transition resistance.