Research On Fault Location Of ±800kV UHV DC Grounding Electrode Lead Based On Pulse Injection Method

Ultra High Voltage Direct Current(UHVDC)plays a vital role in long-distance,high-capacity transmission projects,and the grounding lead is an important part of it.Therefore,it is decided whether the grounding lead can operate normally.One of the important factors for the normal operation of UHVDC transmission systems.The grounding lead is often built in a cross-mountain area.During the summer,thunderstorms are frequently prone to failure.The structure is specially designed for parallel connection of the same tower and two wires.The traditional fault location method is difficult to quickly and accurately identify the grounding lead.The location of the type fault.Therefore,in order to ensure the safe and stable operation of UHVDC transmission system,this paper studies the failure of the grounding pole lead of UHVDC transmission system.When the DC system is in a short time without grounding pole,the pulse signal is injected to measure different types of faults.In this paper,through the analysis of the special problems existing in the grounding lead,the UHVDC system simulation model with grounding lead is established,and the different types of fault characteristics are obtained by the voltage and current signals collected on the grounding lead in the simulation model.The analysis is performed by using an energy mutation algorithm that detects the low-frequency component of the current to identify the fault state of the grounding lead.For the on-line fault monitoring of the grounding lead,it is difficult to use the fault source information for accurate ranging under the high bipolar balance of the UHVDC system.A comprehensive fault location algorithm is proposed: firstly,the current mutual inductance is used.The pulse reflection signal collected by the device is used for fault location.If a near-end fault occurs,the corrected distance measurement is performed.If a two-wire short-circuit ground fault occurs and the pulse current reflected wave cannot be collected,the voltage measured at the head end of the grounding lead is used.The signal is used for backup ranging.In addition,the reason for the increase in error near the grounding point of the grounding lead of this ranging method is also analyzed.The simulation shows that the method can effectively measure the various faults in the long range of the grounding lead,and the ranging accuracy has high precision.