Research on Neutral Line Ground Fault Identification of PT Secondary Multi-Branch Cable based on Transient Current Probability Analysis
The health status of the potential transformer(PT)secondary circuit in a substation is crucial for the reliability of relay protection actions,making it difficult to identify grounding faults in PT secondary circuit cables and select the grounding branch cable.To address this challenge,this article introduces a line selection scheme for identifying grounding faults and PT cable grounding branches using transient information of branch cable grounding current.The Hilbert transform to is employed to obtain the transient information that filters out the fundamental frequency component,and the estimated values of three random variables-decaying DC component,high-frequency energy,and branch cable current similarity-are calculated.The Copula function is used to calculate the joint probability distribution density function of the three indicators,and the risk of grounding faults in each branch cable is calculated to select the grounding branch.Finally,a simulation model is built to verify the secondary circuit cable branch grounding selection scheme.The results show that the fusion fault criterion based on the Copula proposed in this paper is not affected by fault types,and can accurately identify multiple cable fault branches,verifying the effectiveness and adaptability of the scheme.
PT secondary circuitfault line selectionfundamental frequency shiftjoint probability distributionCopula function
万方数据
维普
