A Faulty Pole Detection Method for the VSC-HVDC System Based on the Aperiodic Component Energy

Abstract

Compared with a cable line, an overhead line is vulnerable to failures. When a fault occurs on a VSC-HVDC overhead line, the DC current increases sharply, thus threatening the operation safety of the VSC-HVDC system. Also, the fault current can cause irreversible damage to the power device. Therefore, it is necessary to define a principle for fast and reliable identification of faulty poles. Taking a single-pole fault as a research object, this paper analyzes the equivalent circuit of a VSC-HVDC system's fault and derives the fault current expression considering both under- and over-damping of the system. In both considered cases, the fault current contains a significant aperiodic component. The discrete wavelet packet is used to extract the aperiodic component of the fault current, and a protection principle based on the aperiodic component energy is proposed. The VSC-HVDC system model is constructed on the PSCAD/EMTDC and RTDS. The results of a large number of simulations and experiments show that the proposed protection principle can identify a faulty pole in 2 ms. In addition, the proposed principle can be used to respond to remote faults under high transition resistance and noise interference.