Low-resistance grounding system earth fault centralized protection new method

Abstract

The invention belongs to the field of power distribution network relay protection, relates to a low-resistance grounding system earth fault centralized protection new method and provides an earth fault centralized protection new method, which combines the existing zero-sequence over-current protection and phase comparison of zero-sequence current of outgoing lines and neutral points. After the protection is started, a centralized protection device directly controls the action of an outgoing line circuit breaker whose zero-sequence current amplitude exceeds an existing protection value; when the zero sequence current amplitudes of all outgoing lines are lower than the existing protection value, the centralized protection device compares phase information of the zero-sequence current of theoutgoing lines and the neutral points; when zero-sequence current phase of some outgoing line is more advanced by a certain phase than the zero-sequence current phase of some neutral point, the centralized protection device controls the outgoing line circuit breaker with the maximum zero-sequence current amplitude to act; if there are multiple outgoing lines whose zero-sequence current amplitudesare maximum, multiple outgoing line circuit breaker act; and if phase difference of the outgoing lines is within a certain range, it is judged that the fault is a bus grounding fault.

Description

technical field [0001] The invention belongs to the field of distribution network relay protection. The invention relates to a centralized protection method for grounding faults of a small resistance grounding system, which is suitable for a 10kV small resistance grounding system applying zero-sequence overcurrent protection. The centralized protection device participates in the control and the circuit breaker participates in the action. Background technique [0002] When the small resistance grounding system fails, the fault characteristics are obvious, and the fault can be eliminated more reliably. Many large cities have begun to use the small resistance grounding system. In the Huizhou area of ​​Guangdong Province, a grounding transformer misoperation accident occurred due to the ground fault of the two outgoing lines of the system. The existing zero-sequence overcurrent protection cannot operate accurately when the outgoing line is grounded, which may easily cause the g...

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Problems solved by technology

[0005] In order to overcome at least one defect described in the above-mentioned prior art, the present invention provides a new method for centralized protection of grounding faults in small resistance grounding systems, which solves the problem of grounding faults in small resistance grounding systems, and solves the problem of multiple outgoing line grounding faults and High-resistance grounding faults are prone to refusal to operate and malfunction. Based on the analysis of traditional zero-sequence overcurrent protection, a method is proposed that utilizes the existing zero-sequence overcurrent protection setting and combines zero-sequence current phase comparison and The ground fault protection method of the small resistance grounding system based on the phase comparison of the zero-sequence current between each outgoing line and the neutral point grounding resistance, the centralized protection device participates in the control, and the circuit breaker participates in the action

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