CN102035172A

CN102035172A - Injection leakage protection method

Info

Publication number: CN102035172A
Application number: CN201010597483XA
Authority: CN
Inventors: 孔文军; 徐建兵; 郭东兵; 常杰; 张朝平; 卜海滨
Original assignee: Shanxi Jincheng Anthracite Mining Group Co Ltd
Current assignee: Shanxi Jincheng Anthracite Mining Group Co Ltd
Priority date: 2010-12-21
Filing date: 2010-12-21
Publication date: 2011-04-27

Abstract

The invention relates to a leakage protection method, in particular to an injection leakage protection method, and solves the problem of low selectivity of the conventional leakage protection method. The injection leakage protection method comprises the following steps of: (1) determining a ground fault phase according to the change of each phase voltage in a distribution network system; (2) arranging a signal source between a secondary winding of the ground fault phase and the ground; (3) starting the signal source to inject signal current into the secondary winding of the ground fault phase, inducing the signal current in the secondary winding to a primary winding, and returning a neutral ground point of the primary winding along a ground fault point; and (4) searching the exact positions of a grounding branch and the ground point by detecting whether the signal current is injected into each outgoing line of the distribution network system or not. The method effectively solves the problem of low selectivity of the conventional leakage protection method, is suitable for leakage protection in various fields, and is particularly suitable for the leakage protection of a mine power supply system.

Description

Pouring-in earth leakage protecting method

Technical field

The present invention relates to earth leakage protecting method, specifically is a kind of pouring-in earth leakage protecting method.

Background technology

Earth leakage protective in the mine power supply system plays irreplaceable important function to the power supply safety of mine; but for a long time; there is the problem of poor selectivity in existing earth leakage protecting method, and this is not only perplexing numerous engineers and technicians all the time, and has had a strong impact on the power supply safety of mine.Based on this, be necessary to invent a kind of brand-new earth leakage protecting method.

Summary of the invention

The present invention provides a kind of pouring-in earth leakage protecting method in order to solve the problem of existing earth leakage protecting method poor selectivity.

The present invention adopts following technical scheme to realize: pouring-in earth leakage protecting method, this method are to adopt following steps to realize: (1) judges the earth fault phase according to the variation of each phase voltage in the distribution network system; (2) between the secondary winding of earth fault phase and ground, add a signal source; (3) signal code is injected in the enabling signal source in the secondary winding of earth fault phase, and the signal code in the secondary winding is sensed in winding, and returns the neutral ground point of a winding along earth fault; (4) inject the definite position that signal code finds out ground connection branch and earth point by having or not in each outlet that detects distribution network system.

The essence of pouring-in earth leakage protecting method of the present invention is the zero-sequence current that has artificially increased failure system; According to principle of stacking, the electric current that system's positive sequence power supply provides is constant, but the electric current of actual flow is the electric current sum that two power supplys (comprising signal source) provide in the system; From injecting the angle of signal source, the total impedance ground when system's total impedance and neutral-point solid ground electric power system generation single phase ground fault is suitable; Like this, the terminal voltage of injecting signal source does not need very that the higher position can provide comparatively ideal zero-sequence current for failure system, and for fault detect usefulness, the big I of injection current is decided according to detecting this electric current desirable strength; Compare with existing earth leakage protecting method; pouring-in earth leakage protecting method of the present invention has adopted the signal injection method to carry out the route selection of single phase ground fault; this scheme has the advantages that not influenced by system earth mode and zero-sequence current size; have higher route selection accuracy rate, so its selectivity is better.

The present invention efficiently solves the problem of existing earth leakage protecting method poor selectivity, is applicable to the earth leakage protective in each field, is particularly useful for the earth leakage protective of mine power supply system.

Embodiment

Pouring-in earth leakage protecting method, this method are to adopt following steps to realize:

(1) judges system according to the variation of residual voltage in the distribution network system whether earth fault takes place, judge the earth fault phase according to the variation of each phase voltage; When distribution network system generation single phase ground fault, the fault phase voltage reduces to zero, and non-fault phase voltage raises and is that it is phase voltage that line voltage, residual voltage raise;

(2) between the secondary winding of earth fault phase and ground, add a signal source; Signal source is added on the secondary winding of earth fault phase and is equivalent to add an asymmetric three phase mains;

(3) signal code is injected in the enabling signal source in the secondary winding of earth fault phase, and the signal code in the secondary winding is sensed in winding, and returns the neutral ground point of a winding along earth fault;

(4) inject the definite position that signal code finds out ground connection branch and earth point by having or not in each outlet that detects distribution network system; Injecting signal code has following characteristics: a. in the circulation of a winding of distribution network system and injects signal code and only circulate at faulty line; B. injecting signal code only circulates mutually in the fault of faulty line; C. inject signal code and turn back to PT neutral ground point once through earth fault in fault; According to characteristics a, during distribution network system generation single phase ground fault, injecting signal code only circulates at ground path, do not inject signal code in the non-ground path, like this, have or not the injection signal code in each outlet as long as detect, just can find out faulty line easily, Here it is based on the single-phase earth fault line selection principle of injecting signal code; According to characteristics b and c, during distribution network system generation single phase ground fault, injection signal code only one section circuit between transformer station and fault point circulates, after crossing the fault point, injecting signal code will no longer exist, therefore exist between transformer station and the earth point under the situation of branch, injecting the branch that signal code also can not flow into no earth fault; Utilize this characteristics, can find out the definite position of ground connection branch and earth point, Here it is based on the single phase ground fault positioning principle that injects signal code;

In the described step (2), signal source is the alien frequencies signal source; In the described step (3), the frequency of injecting signal code is different with the intrinsic signal frequency of distribution network system, and frequency and the amplitude of injecting signal code can be adjusted according to the detection needs.

During concrete enforcement, characteristics and existing protective device configuring condition in conjunction with underground power supply system, formulation is improved rational single-phase earth fault line selection scheme and (is comprised the selection of signal injection mode and injection phase, inject determining of signal frequency and amplitude, inject the selection of signal detecting mode, the configuration of relevant device and installation, the formulation of testing scheme etc.), and develop corresponding single phase ground fault detecting unit, promptly behind system's generation single phase ground fault, the single phase ground fault detecting unit is can indication fault separate, signal is injected to failure system in the enabling signal source simultaneously, after single phase ground fault disappears, can cut off the injection signal; The injection signal source of single-phase earth fault line selection requirement is satisfied in exploitation simultaneously, this signal source can produce sinusoidal ac signal, the frequency of the signal that produces can not only be distinguished mutually with the frequency of electric power system intrinsic signal, and can adjust frequency and the amplitude of injecting signal easily as required, to satisfy the requirement of input; Further, exploitation enough sensitivity, inject detecting signal unit reliably, utilize high-resolution A/D converter to gather, and the method that adopts high-precision analog filtering and digital filtering to combine, separate accurately and extract injecting signal to injecting signal; Simultaneously, formulation is tripped tactful fast, reliably, guarantees quick, the accurately excision of single phase ground fault, and further formulates testing scheme and carry out on-the-spot test.

Claims

1. pouring-in earth leakage protecting method, it is characterized in that: this method is to adopt following steps to realize: (1) is judged system according to the variation of residual voltage in the distribution network system whether earth fault is taken place, and judges the earth fault phase according to the variation of each phase voltage; (2) between the secondary winding of earth fault phase and ground, add a signal source; (3) signal code is injected in the enabling signal source in the secondary winding of earth fault phase, and the signal code in the secondary winding is sensed in winding, and returns the neutral ground point of a winding along earth fault; (4) inject the definite position that signal code finds out ground connection branch and earth point by having or not in each outlet that detects distribution network system.

2. pouring-in earth leakage protecting method according to claim 1 is characterized in that: in the described step (2), signal source is the alien frequencies signal source; In the described step (3), the frequency of injecting signal code is different with the intrinsic signal frequency of distribution network system, and frequency and the amplitude of injecting signal code can be adjusted according to the detection needs.