CN101561473A

CN101561473A - Method for precisely selecting single-phase earth faulty line for system with non-effectively earthed neutral point

Info

Publication number: CN101561473A
Application number: CNA2009101470003A
Authority: CN
Inventors: 曲娜
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-06-09
Filing date: 2009-06-09
Publication date: 2009-10-21

Abstract

The invention discloses a method for precisely selecting a single-phase earth faulty line for a system with a non-effectively earthed neutral point based on transient signal analysis and externally input DC pulse signal analysis. The method comprises the following steps: firstly, initial judgment is conducted to an earth line by analyzing a distributed capacitance momentary discharge signal generated by an earthed circuit branch; and then high-voltage DC pulse current is input into an earth phase, thereby precisely selecting the faulty line. The method pertains to the field of electric system fault diagnosis. The method uses a DC pulse signal input unit and a control judging unit. When the control judging unit finds out the residual voltage of the system exceeds a threshold value, the whole system is started; firstly, the stored distributed capacitance discharge signal is analyzed and then the DC pulse signal input into a fault phase is analyzed; therefore, the method can precisely find out the earth faulty line without being affected by an extinction coil.

Description

The accurate selection method of system with non-effectively earthed neutral singlephase earth fault

Technical field:

The accurate selection method of a kind of system with non-effectively earthed neutral singlephase earth fault is made up of two steps; 1, analyze the ground connection distributed capacitance transient state discharge current of moment; 2, analyze the high-voltage dc pulse electric current that injects the fault phase through external high pressure electric capacity.Thereby draw faulty line.Belong to the power system failure diagnostic category.

Background technology:

Because isolated neutral system has series of advantages, therefore be widely used in China's mesohigh electrical network, but its singlephase earth fault is handled problems and never is well solved, along with power system development, the reliability requirement of electrical network is more and more higher, because the power distribution network framework is extremely complicated, the line length difference is very big, and former various selection methods can only competence exertion effect in particular environment, applicable situation is very little, and the route selection accuracy rate is very low.The instant of failure line distribution capacitance flash-over characteristic of utilizing that the present invention proposes is tentatively judged, inject the method that high-voltage dc pulse is judged once more in the stable back of circuit ground current mutually to fault then, eliminate the influence of arc suppression coil, can thoroughly select faulty line.

Summary of the invention:

The present invention selects the method for faulty line by analyzing ground connection moment transient current polarity and the outside adding fault high-voltage pulse DC component mutually branch road of flowing through, can both be correct in the 3-66KV small current neutral grounding system select faulty line, be not subjected to the influence of arc suppression coil.This method relates to and comprises that direct current signal injects the unit, the control judging unit.

Direct current signal injects the unit: voltage is minimum relative to the earth mutually for ground connection, the separate of direct current signal injected system is the ground connection phase, injecting the start time is ground connection phase phase-to-ground voltage highest point, both be forward crest place (resistance grounded) behind the zero crossing, and the arc suppression coil automatic tracking and compensating is finished (system that arc suppression coil is installed).When pulse is injected into the fault phase time, because the existence of arc suppression coil inductance value has stoped passing through of pulse current, the pulse current trouble spot of flowing through forms the loop, and the size by pulse current in each loop relatively just can draw faulty line.The pulse current maximum of faulty line, the pulse current of non-fault line are charging current, and amplitude is less and the time is shorter.Can be with reference to Fig. 2, the comparison of pulse waveform 2 among Fig. 3, the pulse current 2. of the pulse current 2 among Fig. 2 in Fig. 3

Control module: this unit inventory analysis is from the signal of each zero sequence current mutual inductor, and signal is judged comparison.When system's generation single-phase earthing, fault phase distributed capacitance forms discharge pulse to the earth and other separate discharges,

Faulty line so discharge pulse is opposite with the discharge pulse direction of All other routes, so pass through the relatively discharge current polarity of distributed capacitance, just can tentatively be selected faulty line owing to there is the trouble spot.

Description of drawings:

Fig. 1 is the injecting principle synoptic diagram of small current neutral grounding system dc pulse signal.

Among Fig. 1: 1: controllable silicon A 2: controllable silicon B 3: controllable silicon C 4: gate-controlled switch 5: high-voltage DC power supply 6: branch road 17: branch road 28: branch road 39: high-voltage energy storage capacitor 10: the earth 11; Earth point

Fig. 2 is faulty line capacitor discharge pulse current and plus high-pressure DC-pulse flow diagram.

1: line distribution capacitance discharge current 2: the applying pulse high-voltage direct current

Fig. 3 is non-fault line capacitor discharge pulse current and plus high-pressure DC-pulse flow diagram.

Embodiment:

Now in conjunction with Fig. 1, Fig. 2, Fig. 3 provides embodiment.

When system normally moved, whole wire selection system was in steady state (SS), and this moment, discharge capacity 9 was in the charging completion status, and gate-controlled switch 4 disconnects, controllable silicon A Figure 11, and controllable silicon B Figure 12, controllable silicon C Figure 13 is in cut-off state.When earth point Figure 111 appears in C mutually, residual voltage appears, at this moment control module to this moment each branch road of collecting zero-sequence current analyze, as distributed capacitance discharge current polarity and branch road 2 Figure 17 of finding faulty line branch road 1 Figure 16, branch road 3 Figure 18, when polarity is opposite, can judge tentatively that just branch road 1 Figure 16 is a faulty line.After ground current is stable (if there is arc suppression coil in the system, then need arc suppression coil action by the time to finish), controllable silicon A Figure 11 conducting that triggering links to each other with fault, form the high voltage direct current component, inject the fault phase, (, then need) when controllable silicon A Figure 11 closure time is in crest for the ground connection phase voltage constantly by ground connection time reckoning voltage crest if voltage is zero, finish when the high-voltage capacitance discharge, then disconnect controllable silicon A Figure 11.Gathering high-voltage pulse signal by control module, relatively draw the highest branch road of pulse amplitude, both has been fault branch.

When system failure circuit was selected to finish, closed at once gate-controlled switch Figure 14 charged to high-voltage capacitance, and charging finishes and disconnects gate-controlled switch Figure 14 at once, makes high-voltage capacitance be in charged state.

Claims

1 one kinds based on transient signal analysis and the outside system with non-effectively earthed neutral fault line selection method for single-phase-to-ground fault that injects the dc pulse signal analysis, the distributed capacitance that this method at first takes place by the uniline ground connection moment signal that sparks comes ground path is done preliminary judgement, inject the high-voltage dc pulse electric current ground connection in mutually then, thereby select faulty line accurately.This method relates to direct current signal and injects the unit, the control judging unit.

2 selection methods according to claim 1, separate when it is characterized in that system's generation single-phase earthing according to fault, inject the high direct voltage component to corresponding ground connection in mutually, form the DC pulse loop.What pulse amplitude was the highest just is fault branch.

3 selection methods according to claim 1 when it is characterized in that system's generation single-phase earthing, by analysis circuit distributed capacitance discharge current polarity, are selected current polarity and the opposite polarity branch road of other branch currents is used as fault branch.

4 selection methods according to claim 1, when it is characterized in that system's generation single-phase earthing, separate according to fault, inject the high direct voltage component to corresponding ground connection in mutually, form the DC pulse loop, the time of injected pulse electric current is the highest amplitude of the forward place of ground connection phase voltage.