CN101403783A

CN101403783A - Fault positioning DC injection method for low current grounding system

Info

Publication number: CN101403783A
Application number: CNA2008101577580A
Authority: CN
Inventors: 夏大洪
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-10-14
Filing date: 2008-10-14
Publication date: 2009-04-08

Abstract

The invention relates to a fault positioning technique of a transmission line in the electric power system, which is suitable for positioning the phase-to-phase short circuit and the single phase earthing of a neutrality point non-direct earthing system in a transformer, in particular to a fault positioning DC injection method in a low-current earthing system. A fault detector which has short-distance wireless communication function is used for conveying fault information into a hand-held fault locator in a relay communication way. Whatever any positions of a transmission line are close to the fault detector, all fault information which are recorded by the fault detector can be read by the hand-held fault locator so as to realize the fault-point positioning function of the line. The fault detector which is provided with a short-distance communication module is arranged along the transmission line; and besides the fault information monitoring function, the fault detector also can carry out the short-distance wireless communication together with similar fault detectors and the hand-held fault locator and convey the fault information.

Description

Fault positioning DC injection method for low current grounding system

One, technical field:

The localization method of trouble spot when the present invention relates to a kind of small current neutral grounding system generation single-phase earthing, method adopts the marking current injecting principle, come the route of flowing through of detection signal electric current by being distributed in transmission line of electricity marking current pick-up unit everywhere, thus the position of the localization of faults.

Two, background technology:

The transformer neutral point non-direct ground system is commonly called as: small current neutral grounding system.Do not have tangible short-circuit current during small current neutral grounding system transmission line of electricity generation single-phase earthing, search very difficult.The method of searching the small current neutral grounding system earth fault at present has a variety of, and what relative precision was higher should count current injection method.Current injection method comprises effective resistance injection method, reactor injection method, capacitor injection method, harmonic wave injection method etc. again.First three is planted injection method and belongs to the first-harmonic injection method, and the electric current that the first-harmonic injection method injects is bigger, and electrical network is had certain impact, realizes that difficulty is bigger.Harmonic wave injection method injection current is little, but is subjected to the influence of distributed capacitance easily.Existing various injection method all belongs to ac-current inject method when stake resistance and circuit cloth capacity ratio are big, and the situation showed increased of erroneous judgement, the equipment manufacturing cost that these injection methods use be than higher, general manyly use in electric substation.

Three, summary of the invention:

Inject the influence that signal is not subjected to distributed capacitance and stake resistance as far as possible in order to make, the invention of this reality provides a kind of method of directly injecting dc current signal on transmission line of electricity, the direct current signal detecting device that the marking current that injects can be easy to be distributed on the transmission line of electricity each point detects, by the location of judging that circuit has, no direct current signal electric current can be grounded the trouble spot.The technical solution adopted for the present invention to solve the technical problems is: select the two-phase of electrical network to inject phase as DC current arbitrarily, directly between phase and ground, insert and realize the DC current injection with current-limiting resistance and controlled half-wave rectifying circuit, when detecting the circuit phase voltage above normal value 20%, the intermittently conducting of control controllable silicon.On the measurement point that circuit distributes DC detector is installed, the current sampling mode of DC detector embeds linear hall element for the iron core of band short-circuited conducting sleeve in the slit, and the effect of short-circuited conducting sleeve is to suppress to exchange, and prevents that magnetic circuit is saturated.The metering circuit chip microcontroller of DC detector.

The present invention is subjected to the influence of distributed capacitance and stake resistance little, and the direct current method for implanting is simple, and obvious to the metering function of alternating current, DC detector is highly sensitive.

Four, description of drawings:

Fig. 1 is the Application Example structural drawing of injector of the present invention;

Fig. 2 is the Application Example rectification module circuit theory diagrams of injector of the present invention;

Fig. 3 is the Application Example structural drawing of DC detector of the present invention;

Fig. 4 is the Application Example circuit theory diagrams of DC detector of the present invention.

Five, embodiment:

In Fig. 1, current-limiting resistance 3. with rectification module 4. be installed in the hollow insulator 2. in, 1. install by standing screw.Current-limiting resistance and rectification module packet design can reduce the silicon controlled requirement, and every group of withstand voltage 2000V of present embodiment, is applied in the 6000V grade power grids by totally 6 groups.Current-limiting resistance is limited in 100 milliamperes with injection current, rectification module 12A, controllable silicon nonoverload under the thunderbolt of 2 times of lightning arrester sparking voltages.

In Fig. 2, current-limiting resistance R1 is 1 kilohm, 2 kilovolts of voltage dependent resistor (VDR) R2 voltage breakdowns, and controllable silicon G triggers setting voltage effective value 720V ~ 740V with withstand voltage unidirectional silicon more than 2 kilovolts, control circuit.The temperature of the main restricted flow resistance R 1 of time of each conducting raises and limits, and present embodiment is 10 cycles.Mainly consider the heat radiation of injector outside surface break time, present embodiment is 20 seconds, and the injector transient power is 6 kilowatts during 6KV line-to-ground like this, 30 watts of average powers.

In Fig. 3,1. be unshakable in one's determination, be short-circuited conducting sleeve 2., be mainly used in and prevent that iron core is saturated, eliminate higher hamonic wave and disturb, 3. be Hall element, 4. be circuit board, be indication window 5., rotation reddens during action, and light emitting diode is bright.

In Fig. 4,1. be power supply 4.8V rechargeable battery, 2. Hall element adopts SS495A linear Hall chip, 3. is single-chip microcomputer, adopts the ATMEGA8L chip, 4. is crystal oscillator 8MHz, 5. is light emitting diode, 6. indication rotation drive coil.Be with 10 A/D in the single-chip microcomputer, sample frequency is 3600Hz, and it is the rectangular window low-pass filtering of 20 milliseconds of integral multiples that digital filtering adopts width, the integer subwave of 50Hz can be filtered.Adopt the effective criterion of double direct current, prevent the influence of aperiodic component in the electrical network transient state process.

Claims

A kind of fault positioning DC injection method for low current grounding system, it is characterized in that: when electrical network generation single-phase earthing, inject DC current mutually to the non-ground connection of system, DC current distribution is detected with detecting device in road along the line, thereby trouble-shooting point, the polyphone current-limiting resistance is realized the DC current injection at intermittence between the phase and ground on direct-on-line road with the half-wave controlled rectification, the current sampling mode of DC detector is for embedding linear hall element in the open core slit of band short-circuited conducting sleeve, the effect of short-circuited conducting sleeve is to suppress to exchange, and prevents that magnetic circuit is saturated.