An Adaptive Reclosing Scheme for Flexible DC Ring Grid Based on Residual Voltage Waveform Offset Detection

The conventional automatic reclosing scheme can cause secondary shocks to the converter station when reclosing on permanent faults. To address this issue, it is necessary to identify the type of faults to achieve adaptive reclosing. In addition, the current research on adaptive reclosing strategy tends to identify the fault type, and the calculation error of fault duration is relatively large. Thus, a new detection method of voltage waveform offset from the zero axis is proposed to identify the type of fault and enable adaptive reclosing in this article. The scheme has a calculation error of no more than 2 ms for the fault duration. To verify the effectiveness of the proposed adaptive reclosing scheme, extensive tests have been conducted under real time digital simulator (RTDS) platform. Additionally, the proposed adaptive reclosing scheme is compared objectively with conventional automatic reclosing schemes and existing adaptive reclosing schemes, demonstrating the significant effect of the proposed scheme on the optimization of closing time.