A method of inverse time zero-sequence current protection

A zero-sequence current, inverse-time technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problem of low quickness, and achieve the goal of improving quickness, quickness and selectivity, and setting efficiency. Effect

Active Publication Date: 2019-06-28
CENT CHINA BRANCH OF STATE GRID CORP OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to overcome the defects and problems of low quick action existing in the prior art, and provide a high quick action inverse time-limit zero-sequence current protection method

Method used

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  • A method of inverse time zero-sequence current protection
  • A method of inverse time zero-sequence current protection
  • A method of inverse time zero-sequence current protection

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0068] A method for inverse time zero-sequence current protection, the method comprising the following steps:

[0069] A. Establish the characteristic equation of inverse time zero-sequence current protection:

[0070]

[0071] In formula (1), t is the action time of inverse time-limit zero-sequence current protection, r, q, s are constants, 3I 0 is the zero-sequence current after a fault, I p It is the starting current of inverse time zero-sequence current protection; the value range of s is 0.1~1.9;

[0072] B. The maximum zero-sequence current after the line fault is 3I 0.max Substitute into formula (1) to determine the minimum action time t of the inverse time-lag zero-sequence current protection min :

[0073]

[0074] The starting current I of the inverse time zero-sequence current protection p Substitute into formula (1) to determine the maximum action time t of the inverse time-lag zero-sequence current protection max :

[0075]

[0076] t min with t ...

Embodiment 2

[0090] Basic content is the same as embodiment 1, the difference is:

[0091] When the selectivity of the main protection and the backup protection are mismatched, the longest action time T+t of the inverse time-lag zero-sequence current protection is increased by increasing the time difference T min , to ensure the rapidity and selectivity of protection.

[0092] Take Q=20, s=0.5, t min =0.05s, and calculate T=0.6s, T=1.0s and T=1.4s respectively, get as follows figure 2 The time-current characteristic curve of the inverse time zero-sequence current protection shown. From figure 2 It can be seen that with the increase of the time difference T, the action time of the inverse time limit protection will gradually increase.

[0093] I / I assumed to protect 1 P =8, I / I of protection 2 P =12, then when T=0.6s, the action time t of protection 1 1 =0.334s, action time t of protection 2 2 =0.224s, time interval △t=0.11s;

[0094] When T=1.0s, the action time of protection 1 ...

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Abstract

The invention discloses an inverse-time zero-sequence current protection method. The minimum motion time and maximum motion time of protection are set, motion time is allocated according to the minimum zero-sequence current and maximum zero-sequence current of over-current protection, and the motion time at the head end and the motion time at the tail end of the protected circuit of a curve are determined, so that the purposes that the whole curve is restrained and the speed of protection motion is improved are achieved; besides, the longest motion time of inverse-time zero-sequence current protection is increased, so that the speed and selectivity of protection are ensured at the same time. By means of the design, not only is the speed of protection ensured and improved, but also the selectivity of protection is ensured and improved.

Description

technical field [0001] The invention belongs to the technical field of electric power system relay protection, and in particular relates to an inverse time-limit zero-sequence current protection method, which is mainly suitable for ensuring and improving the quickness and selectivity of protection. Background technique [0002] At this stage, inverse time overcurrent protection has been widely used in North American power grids, and many grids and provincial dispatchers in my country have tried to introduce inverse time protection as backup protection for line ground faults. Zero-sequence current is the fault component, and the fault point is the only one. zero-sequence current source. The zero-sequence current at the fault point is the largest, and the zero-sequence current on both sides of the fault line is a shunt of the current at the fault point. Since the substation of the ultra-high voltage power grid has a grounding transformer, the largest zero-sequence current branc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
CPCH02H7/26
Inventor 金明亮李勇王兴国陈祥文余越谢俊李会新郭雅蓉吕东晓王英英柳焕章
Owner CENT CHINA BRANCH OF STATE GRID CORP OF CHINA
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