High-voltage direct-current transmission line high-resistance grounding fault identification method based on distributed parameters

Abstract

The invention discloses a high-voltage direct-current transmission line high-resistance grounding fault identification method based on distributed parameters. The method comprises the following steps that step 1, direct-current line current at a rectification station side and direct-current line current at an inversion station side are monitored in real time, if the condition (||IR|-|II||) I set is satisfied in continuous 3ms, the existence of a fault point in a high-voltage direct-current transmission line is judged, and then a step 2 is conducted; step 2, fault point residual voltage URFm is calculated at the rectification station side and fault point residual voltage UIFm at the inversion station side is calculated respectively, and if URFM>=0.1IdR, an in-zone high-resistance grounding fault is judged, and a protecting outlet t1 is delayed; if URFm< 0.1IdR, an in-zone metal fault is judged, and a protecting outlet t2 is delayed. According to the high-voltage direct-current transmission line high-resistance grounding fault identification method based on the distributed parameters, the fault point residual voltage when the high-voltage direct-current transmission line grounding fault occurs is compared with initial stable voltage when high-resistance grounding fault occurs, whether the high-resistance grounding fault occurs or not is judged, so that the protecting outlet is started, the protecting outlet is not influenced by transition resistance, the shortage of protection of motion rejection when the high-resistance grounding fault occurs in a current direct-current line is compensated, and the flexibility of protection motion is improved.

Description

technical field [0001] The invention relates to the technical field of high-voltage direct current transmission, in particular to a method for identifying high-resistance grounding faults of high-voltage direct current transmission lines based on distributed parameters. Background technique [0002] Most HVDC transmission lines use traveling wave protection as fast main protection, and current differential protection as slow backup protection. Traveling wave protection has a fast action speed and is not easily affected by factors such as load and long-line distributed capacitance, but it is easy to refuse to operate when there is a high-impedance ground fault. When a high-impedance ground fault such as a flashover to ground occurs on a DC line, it is very difficult to extinguish the arc if no measures are taken to cut off the DC power supply. If the fault persists, it will seriously affect the stable operation of the DC transmission system and the safety of the surrounding e...

AI Technical Summary

Problems solved by technology

[0008] 3. Insufficiency of existing traveling wave protection

Transition resistance reduces the voltage change rate and change amount, which is the main reason why it is difficult for current traveling wave protection to detect high-resistance grounding faults on lines

[0010] Fault traveling wave is a non-stationary high-frequency transient signal, which is a function of time and frequency. It is difficult to comprehensively and accurately extract traveling wave fault information and describe traveling wave fault characteristics using traditional mathematical methods.

It is difficult for traditional transformers to accurately transmit this high-frequency traveling wave transient signal. The current sampling frequency used by traveling wave protection is not enough to capture the head of traveling wave. When the sampling value is disturbed by noise, traveling wave protection may be wrong verb: move

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