A New Method of Core and Grounding Short Circuit Detection of Secondary DC Cable in Substation

The problems of secondary DC cable in substation mainly include grounding fault and core anomaly. Traditional grounding failure and core detection methods require power outage operation, which not only increases the workload, but also may cause interference to the operation of the power grid. Therefore, the development of a short circuit detection method for core and grounding has important application value. To address this problem, a new approach is proposed. This method first obtains the equivalent capacitance parameters of the cable to be tested, then constructs the oscillation detection loop, and takes the equivalent capacitance as part of the oscillation detection loop. Next, by monitoring the change of the oscillation frequency, judge the core information or ground fault information. With the help of cable equivalent capacitance parameters, this method can realize the core detection and grounding fault detection of DC cable. When the DC cable is grounded or abnormal, the equivalent capacitor will change significantly. By monitoring the equivalent cable capacitance value parameters and the oscillation frequency, the grounding state or the core condition of the DC cable can be reflected. Compared with the traditional methods, this new method has the advantages of being safe, reliable, simple and efficient. It does not require a power outage operation, but can detect and check the cable online, reducing the work burden and maintaining the normal operation of the power grid.