Grounding protection method for small resistance grounding system based on zero-sequence current projection coefficient

A technology of small resistance grounding and zero sequence current, applied in emergency protection circuit devices, electrical components, etc., to achieve the effect of good application prospect, wide application range and good engineering practicability

Active Publication Date: 2019-07-19
STATE GRID HUBEI ELECTRIC POWER RES INST +2
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AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the protection problem when the grounding fault occurs in the feeder line in the small resistance grounding system.

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  • Grounding protection method for small resistance grounding system based on zero-sequence current projection coefficient
  • Grounding protection method for small resistance grounding system based on zero-sequence current projection coefficient
  • Grounding protection method for small resistance grounding system based on zero-sequence current projection coefficient

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Embodiment Construction

[0022] The technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.

[0023] Such as figure 1 As shown, the present invention provides a small resistance grounding system grounding protection method based on zero-sequence current projection coefficient, including the following steps:

[0024] a. The grounding protection device collects the zero-sequence current I of each line 0i and neutral point grounding resistance zero sequence current

[0025] b. Set the starting current setting value I of the protection S , Direct action current setting I set And the projection coefficient setting value ρ set , and set I S set ;

[0026] c. Outgoing zero-sequence current I 0i Exceeding the starting current setting value I of the protection S , the outlet protection starts;

[0027] d. Outlet zero sequence current I 0i Exceeding the protection's direct action current setti...

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Abstract

The invention provides a low-resistance grounding system ground protection method based on a zero sequence current projection coefficient and belongs to the field of power distribution network relay protection. For a low-resistance grounding mode power distribution network, projection coefficients of fault line zero sequence current and sound line zero sequence current on neutral-point zero sequence current have great difference no matter how much transition resistance is when a single-phase earth fault happens; thus, the fault characteristics can be utilized to form grounding protection. Theinvention further discloses a calculating method of the zero sequence projection coefficients and a fixed value setting principle of all parameters. The low-resistance grounding system ground protection method disclosed by the invention can ensure that low-resistance grounding and metallic grounding fault protection has good selectivity and reliability; meanwhile, the problem of high-resistance grounding fault protection reliability of a low-resistance grounding system is solved; the low-resistance grounding system ground protection method has a wide actual application prospect.

Description

technical field [0001] The invention relates to the field of relay protection for distribution networks, in particular to a grounding protection method for small resistance grounding systems based on zero-sequence current projection coefficients. Background technique [0002] With the advancement of urbanization, the application scale of power cables in power distribution networks is expanding day by day, and the capacitive current of the system is also gradually increasing. Compared with the resonant grounding system, the small-resistance grounding method has advantages in overvoltage suppression. In addition, the characteristic quantity of the ground fault is outstanding, and it is easy to realize relay protection coordination. In recent years, it has been gradually promoted and implemented in the new construction and renovation projects of urban distribution networks. However, unlike the small current grounding system, the small resistance grounding system requires immedi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
CPCH02H7/26
Inventor 杨帆沈煜薛永端汪洋周志强金鑫杨志淳雷杨康兵
Owner STATE GRID HUBEI ELECTRIC POWER RES INST
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