CN104820169A - Single-phase ground fault positioning method for neutral grounding system via arc suppression coil - Google Patents

Abstract

The invention discloses a single-phase ground fault positioning method for a neutral grounding system via an arc suppression coil. When a fault happens to the neutral grounding system via a capacitance-adjustment arc suppression coil, and a fault line is selected, a thyristor of the capacitance-adjustment arc suppression coil is controlled to be connected instantaneously. At this moment, the system will generate an instantaneous perturbation pulse, and the perturbation pulse will flow to the ground through a fault point. A pulse detection device is used for detecting the voltage and current disturbing signals of a starting end of the fault line at a bus, and then the FFT analysis of the disturbing signals is carried out, thereby obtaining harmonic waves at all orders. The theory of harmonic impedance is used for calculating a fault distance. The method is based on the capacitance-adjustment arc suppression coil, does not depend on excessive external equipment, and is simple and economical. The amplitudes of the disturbing signals can be controlled, and the sufficient intensity of the disturbing signals can be detected under the conditions of different grounding resistances. Moreover, the intensity of the disturbing signals cannot be high enough to affect the operation of a system.

Description

A kind of neutral by arc extinction coil grounding system single-phase earth fault localization method

Technical field

The present invention relates to the localization method of earth fault in electric system, particularly relate to a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method.

Background technology

Neutral by arc extinction coil grounding system in China's power distribution network in occupation of very important position.Its complex structure, branch is numerous, makes it easily earth fault occur, at this wherein, singlephase earth fault is situation the most common, when singlephase earth fault occurs for it, due to neutral by arc extinction coil grounding, so the short-circuit current at fault place is not large especially, and three-phase line voltage in circuit is still symmetrical, so system can allow to continue operation 1 ~ 2h again, but now, the voltage-to-ground of healthy phases can raise as original doubly, may intermittent arc grounding be produced between trouble spot and ground, threaten the insulativity of electrical equipment, if do not taken measures as soon as possible, search, fix a breakdown a little, the fault pervasion of or multiple spot may be caused at 2, serious harm is produced to the operation of electrical network.So, fast, accurately singlephase earth fault is positioned and the safe operation of electrical network and economic interests are had a very important role.

Research at present about localization of fault mainly concentrates in fault section location and fault localization two.Fault section location refers to that the power supply section to breaking down positions, and isolation, to recover the normal operation of non-faulting section.It is mainly divided into two classes, one class is based on the electric information in the automation equipment (as FTU) on circuit in real time detection line, integrates, judge information, determine fault section with this, but this automatization level to electrical network requires compared with high and maintenance cost is large.Another kind of is the relevant information grasped based on power consumer Trouble call phone and power supply unit, as telephone number, geography information, facility information and personal code work etc. position fault section, but these class methods must be based upon on the basis that regional communication level is smooth and easy and power supply unit self information is perfect.

Fault localization refers to and utilizes the electric information on faulty line directly to calculate fault distance, mainly contains impedance method and traveling wave method two class methods.Voltage when impedance method mainly utilizes fault on circuit, the impedance of current information computational scheme, and then calculate fault distance, impedance method application is simple, and cost is cheap, but is easily subject to stake resistance, the impact of load.The time that traveling wave method mainly utilizes the transient state travelling wave produced when breaking down to arrive check point calculates fault distance.But consider that distribution net work structure is complicated, branch is numerous, makes the refraction wave of transient state travelling wave, and reflection wave is too much, should not differentiate, and produces certain impact to the precision of range finding.

To sum up, in order to improve reliability and the economy of power supply, the research of the singlephase earth fault location of centering point compensated distribution network seems particularly important.

Summary of the invention

Object of the present invention is exactly to solve the problem, and provides a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method, based on adjustable capacitive-based arc-suppression coil self, does not rely on too much external unit, simple economy. accurate positioning.

To achieve these goals, the present invention adopts following technical scheme:

A kind of neutral by arc extinction coil grounding system single-phase earth fault localization method, neutral point is through adjustable capacitive-based arc-suppression coil earthed system generation singlephase earth fault, and select faulty line, control the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil, now, system can produce instantaneous perturbation pulse, this perturbation pulse signal can flow into the earth by trouble spot, pulse detecting equipment is utilized to detect the voltage and current disturbing signal at faulty line top, bus place, again fft analysis is carried out to this disturbing signal, obtain each harmonic, recycling harmonic impedance theory calculate is out of order distance.

The method of voltage and current disturbing signal being carried out to fft analysis is:

Disturbance voltage signal u (t) and current signal i (t) is extracted in the initial end of faulty line, respectively fft analysis is carried out to voltage signal u (t) and current signal i (t), obtain the voltage harmonic component U (jn ω) under the different frequency and current harmonics component I (jn ω), wherein n be not equal to 0 natural number, in analytic process, give up the harmonic component of amplitude size lower than first-harmonic 1%; Utilize the voltage harmonic component and current harmonics component and harmonic impedance theory calculate fault distance that obtain.

When utilizing harmonic impedance theory calculate fault distance, by harmonic impedance theory calculate near the faulty line port of bus to the line impedance of trouble spot, then utilize the unit distance impedance parameter of circuit to calculate fault distance, detailed process is as follows:

From circuit initial end to the harmonic impedance of trouble spot be:

$Z\left(\mathrm{jn\ω}\right)=\frac{U\left(\mathrm{jn\ω}\right)}{I\left(\mathrm{jn\ω}\right)}=R+\mathrm{jn\ωL}---\left(1\right)$

Wherein, R is line resistance and stake resistance sum, and L is line inductance, after obtaining the line harmonic impedance under the different frequency, carries out Fitting Analysis to the result of calculation of harmonic impedance, thus obtains correct line electricity inductance value L _line, recycling formula (2) calculates fault distance:

X=L _line/ l (2)

Wherein, x is fault distance, and l is the inductance value of circuit unit distance.

The method controlling the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil is:

When adjustable capacitive-based arc-suppression coil is operated in malfunction, for realizing circuit arc extinguishing and eliminating grounding surge, utilize anti-parallel thyristor that its some groups of secondary capacitance load windings are devoted oneself to work; Now, control the capacitance load winding short time input circuit that the instantaneous conducting of anti-parallel thyristor makes a group not put into operation, so can produce a perturbation pulse signal at arc suppression coil primary side inductive current, this signal can through the popular the earth in the trouble spot of faulty line.

Beneficial effect of the present invention:

(1) the present invention is based on adjustable capacitive-based arc-suppression coil self, do not rely on too much external unit, simple economy.

(2) amplitude of disturbing signal is controlled, by controlling the conduction angle of thyristor, making disturbing signal in different grounding resistance situation, enough intensity can be had to be detected, and being unlikely to again the operation of arriving greatly influential system.

(3) generation time of disturbing signal is controlled, makes the detection of disturbing signal proactive, improves the operability of scheme.

(4) current characteristic of disturbing signal is controlled, makes disturbing signal be different from other undesired signals, and what improve signal can identification.

Accompanying drawing explanation

Fig. 1 is single-phase ground fault distance measuring schematic diagram;

Fig. 2 is schematic flow sheet of the present invention

Embodiment

Below in conjunction with accompanying drawing and embodiment, the invention will be further described.

As shown in Figure 1, neutral point is through adjustable capacitive-based arc-suppression coil earthed system generation singlephase earth fault.

As shown in Figure 2, a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method, there is singlephase earth fault, and select faulty line, control the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil, now, system can produce instantaneous perturbation pulse, the major part of this perturbation pulse signal can flow into the earth by trouble spot, pulse detecting equipment is utilized to detect the voltage and current disturbing signal at faulty line top, bus place, carry out fft analysis to this disturbing signal again, obtain each harmonic, recycling harmonic impedance theory calculate is out of order distance.

The method of voltage and current disturbing signal being carried out to fft analysis is:

Disturbance voltage signal u (t) and current signal i (t) is extracted in the initial end of faulty line, respectively fft analysis is carried out to voltage signal u (t) and current signal i (t), obtain the voltage harmonic component U (jn ω) under the different frequency and current harmonics component I (jn ω), wherein n be not equal to 0 natural number, in analytic process, give up the harmonic component of amplitude size lower than first-harmonic 1%; Utilize the voltage harmonic component and current harmonics component and harmonic impedance theory calculate fault distance that obtain.

When utilizing harmonic impedance theory calculate fault distance, by harmonic impedance theory calculate near the faulty line port of bus to the line impedance of trouble spot, then utilize the unit distance impedance parameter of circuit to calculate fault distance, detailed process is as follows:

From circuit initial end to the harmonic impedance of trouble spot be:

$Z\left(\mathrm{jn\ω}\right)=\frac{U\left(\mathrm{jn\ω}\right)}{I\left(\mathrm{jn\ω}\right)}=R+\mathrm{jn\ωL}---\left(1\right)$

Wherein, R is line resistance and stake resistance sum, and L is line inductance, after obtaining the line harmonic impedance under the different frequency, carries out Fitting Analysis to the result of calculation of harmonic impedance, thus obtains correct line electricity inductance value L _line, recycling formula (2) calculates fault distance:

X=L _line/ l (2)

Wherein, x is fault distance, and l is the inductance value of circuit unit distance.

The method controlling the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil is:

When adjustable capacitive-based arc-suppression coil is operated in malfunction, for realizing circuit arc extinguishing and eliminating grounding surge, utilize anti-parallel thyristor that its some groups of secondary capacitance load windings are devoted oneself to work; Now, control the capacitance load winding short time input circuit that the instantaneous conducting of anti-parallel thyristor makes a group not put into operation, so can produce a perturbation pulse signal at arc suppression coil primary side inductive current, this signal can through the popular the earth in the trouble spot of faulty line.

By reference to the accompanying drawings the specific embodiment of the present invention is described although above-mentioned; but not limiting the scope of the invention; one of ordinary skill in the art should be understood that; on the basis of technical scheme of the present invention, those skilled in the art do not need to pay various amendment or distortion that creative work can make still within protection scope of the present invention.

Claims (4)

1. a neutral by arc extinction coil grounding system single-phase earth fault localization method, neutral point is through adjustable capacitive-based arc-suppression coil earthed system generation singlephase earth fault, and select faulty line, it is characterized in that, control the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil, now, system can produce instantaneous perturbation pulse, this perturbation pulse signal can flow into the earth by trouble spot, pulse detecting equipment is utilized to detect the voltage and current disturbing signal at faulty line top, bus place, again fft analysis is carried out to this disturbing signal, obtain each harmonic, recycling harmonic impedance theory calculate is out of order distance.

2. a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method as claimed in claim 1, it is characterized in that, the method for voltage and current disturbing signal being carried out to fft analysis is:

Disturbance voltage signal u (t) and current signal i (t) is extracted in the initial end of faulty line, respectively fft analysis is carried out to voltage signal u (t) and current signal i (t), obtain the voltage harmonic component U (jn ω) under the different frequency and current harmonics component I (jn ω), wherein n be not equal to 0 natural number, in analytic process, give up the harmonic component of amplitude size lower than first-harmonic 1%; Utilize the voltage harmonic component and current harmonics component and harmonic impedance theory calculate fault distance that obtain.

3. a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method as claimed in claim 2, it is characterized in that, when utilizing harmonic impedance theory calculate fault distance, by harmonic impedance theory calculate near the faulty line port of bus to the line impedance of trouble spot, then utilize the unit distance impedance parameter of circuit to calculate fault distance, detailed process is as follows:

From circuit initial end to the harmonic impedance of trouble spot be:

$Z\left(\mathrm{jn\ω}\right)=\frac{U\left(\mathrm{jn\ω}\right)}{I\left(\mathrm{jn\ω}\right)}=R+\mathrm{jn\ωL}---\left(1\right)$

Wherein, R is line resistance and stake resistance sum, and L is line inductance, after obtaining the line harmonic impedance under the different frequency, carries out Fitting Analysis to the result of calculation of harmonic impedance, thus obtains correct line electricity inductance value L _line, recycling formula (2) calculates fault distance:

X=L _line/ l (2)

Wherein, x is fault distance, and l is the inductance value of circuit unit distance.

4. a kind of neutral by arc extinction coil grounding system single-phase earth fault localization method as claimed in claim 1, is characterized in that, the method controlling the instantaneous conducting of thyristor of adjustable capacitive-based arc-suppression coil is:

When adjustable capacitive-based arc-suppression coil is operated in malfunction, for realizing circuit arc extinguishing and eliminating grounding surge, utilize anti-parallel thyristor that its some groups of secondary capacitance load windings are devoted oneself to work; Now, control the capacitance load winding short time input circuit that the instantaneous conducting of anti-parallel thyristor makes a group not put into operation, so can produce a perturbation pulse signal at arc suppression coil primary side inductive current, this signal can through the popular the earth in the trouble spot of faulty line.