CN105182168A - Defect screening detection apparatus of grounding network upper guide body wire - Google Patents

Defect screening detection apparatus of grounding network upper guide body wire Download PDF

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Publication number
CN105182168A
CN105182168A CN201510655178.4A CN201510655178A CN105182168A CN 105182168 A CN105182168 A CN 105182168A CN 201510655178 A CN201510655178 A CN 201510655178A CN 105182168 A CN105182168 A CN 105182168A
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CN
China
Prior art keywords
guide
impedance
defect
line
grounded screen
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CN201510655178.4A
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Chinese (zh)
Inventor
郑卫民
王凯武
杨萌
徐健
赵宇
王昌
邓一帆
冯浩
李志东
Original Assignee
国网山西省电力公司临汾供电公司
国家电网公司
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Priority to CN201510655178.4A priority Critical patent/CN105182168A/en
Publication of CN105182168A publication Critical patent/CN105182168A/en

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Abstract

The invention belongs to the technical field of power system accurate measurement and analysis detection, specifically relates to a defect screening detection apparatus of a grounding network upper guide body wire, and mainly solves technical problems of serious blindness, large workload, poor determination result reliability, and high detection cost of a conventional method for detecting the defect of the grounding network upper guide body wire. The apparatus singles out defective upper guide body wires by means of actual measurement, compares an impedance value with an impedance threshold subjected to strict theoretical calculation and accurately measured and set when a grounding network is normal in order to confirm an upper guide body wire defect. The apparatus solves a technical problem for a power system operation overhaul department, especially detects the defect of the grounding network upper guide body wire, and has advantages of convenient operation, high detection result reliability, and high detection efficiency.

Description

The device of guide body line defect selective mechanisms in a kind of grounded screen

Technical field

The invention belongs to electric system accurately to measure and technical field of analysis and detection, be specifically related to the device of guide body line defect selective mechanisms in a kind of grounded screen.

Background technology

The transformer of generating plant and transformer station, mutual inductor, the power system devices such as reactor are all connected with grounded screen by upper guide body line, on these, guide body line plays a very important role in safe operation of power system, they are paths that equipment is connected with grounded screen, by these lead-in wires, various electrical equipments for whole electric system provide a public grounded screen with reference to meet need of work, when system is short-circuited or be struck by lightning, drain fault current rapidly by these lead-in wires and reduce the earth potential liter of protected area, in protection perform region, the personal safety of technical work personnel and the safety of various electrical equipment are run with normal.

A upper guide body line part for grounded screen exposes in atmosphere, a part imbeds underground, usually utilize the material such as band steel or round steel by welding mode and grounded screen be connected as a single entity, grounded screen generally imbeds the degree of depth that underground is less than 1 meter, plays fault current of releasing, all presses and reduce the effect of impedance ground.Guide body line on ground connection is had to be connected with the electrical equipment on ground at grounded screen diverse location place as required.When electric system be short-circuited or to be struck by lightning etc. fault time, the big current of moment is dispensed into ground through upper guide body line and grounded screen, thus plays the effect to equipment and worker safety's protection.But the grounding body of steel material is along with the increase running the time limit, because of failure welding, there is the reasons such as corrosion, earth conductor sectional area may be caused to reduce or fracture, thus lose defencive function.

Searching the breakpoint of grounded screen and etch state is one of important preventive damage control of one, electric system Yun Jian department.The breakpoint of guide body line and corrosion default in Timeliness coverage grounded screen, and repair in time, the normal table for system runs most important.After power department diagnoses the common method of ground net corrosion or fracture defect to cross certain time limit exactly, sampling excavates inspection, the primitive approach such as general employing is shaken, knock, by observing and feeling to judge its breakpoint and corrosion condition, according to general configuration and the rate of corrosion of grounded screen distribute soil, estimate the etch state of grounded screen by rule of thumb.This method has blindness, and workload is large, needs to consume a large amount of human and material resources and financial resources, is also subject to the restriction of on-the-spot service condition simultaneously, is difficult to the defect diagnosing earthing device accurately.For the detection of upper guide body line, judged result poor reliability.

Summary of the invention

The method that the object of the invention is the defect solving guide body line in existing detection grounded screen exists that blindness is large, workload is large, judged result poor reliability and the high technical matters of testing cost, provides the device of guide body line defect selective mechanisms in a kind of grounded screen.

For solving the problems of the technologies described above, the technical solution used in the present invention is:

A device for guide body line defect selective mechanisms in grounded screen, comprises 1kHz sine-wave current transmitter and impedance measurement analytic system, and described 1kHz sine-wave current transmitter is used for providing sine-wave current signal; Described impedance measurement analytic system is used for potential difference (PD) and the branch-path electric current of synchro measure 1kHz simple sinusoidal alternating current source output terminal mouth, and calculate the impedance of tributary port, compared by the impedance of branch road and the threshold value of setting, judge this branch road whether existing defects, thus judge the breakpoint or the etch state that detect guide body line in whole grounded screen, to diagnose the defect state of guide body line in grounded screen;

Described 1kHz sine-wave current transmitter is made up of regulation unit, buffer cell, signal waveform generating unit, power amplification unit and isolating transformer output unit, described regulation unit is connected with buffer cell and signal waveform generating unit respectively, buffer cell is connected with signal waveform generating unit, signal waveform generating unit is connected with power amplification unit, and power amplification unit is connected with isolating transformer output unit;

Described impedance measurement analytic system is made up of voltage transformer (VT), current transformer, A/D translation data capture card and host computer, described voltage transformer (VT) summation current transformer is connected with the input end of A/D translation data capture card respectively, and the output terminal of A/D translation data capture card is connected with the input end of host computer.

Adopt the device of guide body line defect selective mechanisms in above-mentioned grounded screen to carry out the method for guide body line defect selective mechanisms in grounded screen, this step is:

1) the earth's surface exposed part of upper for grounded screen one guide body line is connected with the cathode output end in 1kHz simple sinusoidal alternating current source by an earth's surface return wire, then centered by guide body line, palp upper guide body lines all around it is all connected in parallel with the positive pole in 1kHz simple sinusoidal alternating current source simultaneously and forms each branch road on this;

2) impedance measurement system is utilized, the potential difference (PD) of synchro measure 1kHz simple sinusoidal alternating current source positive pole and cathode output end mouth and the loop current of each branch road, the impedance of each tributary port of computational analysis, calculates the mean value of each tributary port impedance and filters out that branch road of maximum impedance;

3) again by step 1) method, the negative pole connection status in 1kHz simple sinusoidal alternating current source is constant, only by step 2) in filter out the positive pole that the maximum branch road of impedance is connected to separately 1kHz simple sinusoidal alternating current source, strengthen Injection Current intensity, the potential difference (PD) of synchro measure 1kHz simple sinusoidal alternating current source output terminal mouth and this branch-path electric current, again calculate the impedance of this tributary port, and the impedance of this branch road and the threshold value of setting are compared, if this tributary port impedance is greater than threshold value, then judge the upper guide body line existing defects of this branch road 2; If this tributary port impedance is less than or equal to threshold value, then judge the upper guide body line zero defect of this branch road 2;

4) 1 is adopted)-3) detection method of step detects breakpoint or the etch state of guide body line in whole grounded screen, to diagnose the defect state of guide body line in grounded screen.

The present invention adopts above technical scheme, guide body line on suspected defects is filtered out by actual measurement, again with by through strict theory calculate and grounded screen normal time accurately measure setting impedance threshold compare, determine upper guide body line defect, the method solving the defect of guide body line in existing detection grounded screen exist that blindness is large, workload is large, judged result poor reliability and the high technical matters of testing cost.Therefore, compared with background technology, the present invention has easy and simple to handle, that testing result reliability is high and detection efficiency is high advantage.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of 1kHz sine-wave current transmitter of the present invention;

Fig. 2 is the structured flowchart of impedance measurement analytic system of the present invention;

Fig. 3 is the connection diagram of the present invention when detecting each branch impedance;

Fig. 4 is the principle schematic of the present invention when detecting the maximum branch road of impedance;

Fig. 5 is inspection software routine analyzer figure of the present invention.

Embodiment

The device of guide body line defect selective mechanisms in a kind of grounded screen in the present embodiment, comprises 1kHz sine-wave current transmitter and impedance measurement analytic system, and described 1kHz sine-wave current transmitter is used for providing sine-wave current signal; Described impedance measurement analytic system is used for potential difference (PD) and the branch-path electric current of synchro measure 1kHz simple sinusoidal alternating current source output terminal mouth, and calculate the impedance of tributary port, compared by the impedance of branch road and the threshold value of setting, judge this branch road whether existing defects, thus judge the breakpoint or the etch state that detect guide body line in whole grounded screen, to diagnose the defect state of guide body line in grounded screen;

As shown in Figure 1, described 1kHz sine-wave current transmitter is made up of regulation unit 1, buffer cell (MAX421) 2, signal waveform generating unit (MAX038) 3, power amplification unit (CA1500) 4 and 1:1 isolating transformer output unit 5, described regulation unit 1 is made up of the first chip (MX7541) and the second chip (MC1451), 2 of described first chip (MX7541), 3 pin are connected with 11 pin of the second chip (MC1451) and ground connection, 8 of second chip (MC1451), 9 pin respectively with 2 of buffer cell (MAX421) 2, 3 pin connect, 2 pin of the first chip (MX7541) are connected with 1 pin of signal waveform generating unit (MAX038) 3, 6 pin output terminals of the second chip (MC1451) are connected with 8 pin of signal waveform generating unit (MAX038) 3, 19 pin output terminals of signal waveform generating unit (MAX038) 3 are connected with the input end of power amplification unit (CA1500) 4, the output terminal of power amplification unit (CA1500) 4 is connected with the primary coil of 1:1 isolating transformer, the output unit sine wave output current signal of 1:1 isolating transformer,

As shown in Figure 2, described impedance measurement analytic system is made up of voltage transformer (VT) 6, current transformer 7, A/D translation data capture card (USB6210) 8 and host computer 9, described voltage transformer (VT) 6 structure is: on the nanocrystalline magnet core ring of an internal diameter 20mm, external diameter 30mm, armature winding 2000 circle, secondary winding 1000 circle, wire diameter φ is 0.1mm; The structure of described current transformer 7 is: be respectively on the nanocrystalline magnet core ring of 10mm and 20mm in an inside and outside footpath, armature winding 2 circle, wire diameter 1mm, secondary winding 2000 circle, wire diameter 0.17mm; Described voltage transformer (VT) summation current transformer is connected with the input end of A/D translation data capture card respectively, and the output terminal of A/D translation data capture card is connected with the input end of host computer.

Adopt the device of guide body line defect selective mechanisms in grounded screen described in the present embodiment to carry out the method for the defect selective mechanisms of guide body line in grounded screen, this step is:

1) as shown in Figure 3, the earth's surface exposed part of upper for grounded screen one guide body line is connected with the cathode output end in 1kHz simple sinusoidal alternating current source by an earth's surface return wire, then centered by guide body line, palp upper guide body lines all around it is all connected in parallel with the positive pole in 1kHz simple sinusoidal alternating current source simultaneously and forms each branch road on this;

2) impedance measurement system is utilized, the potential difference (PD) of synchro measure 1kHz simple sinusoidal alternating current source positive pole and cathode output end mouth and the loop current of each branch road, the impedance of each tributary port of computational analysis, calculates the mean value of each tributary port impedance and filters out that branch road of maximum impedance;

3) again by step 1) method, the negative pole connection status in 1kHz simple sinusoidal alternating current source is constant, only by step 2) in filter out the positive pole that the maximum branch road of impedance is connected to separately 1kHz simple sinusoidal alternating current source, strengthen Injection Current intensity [to illustrate: general initial current about 5A-10A, during targeted detection, electric current can be strengthened gradually, 80A-100A can be reached, if lead-in wire seriously corroded, so electric current adds to a certain extent, just cannot increase], the potential difference (PD) of synchro measure 1kHz simple sinusoidal alternating current source output terminal mouth and this branch-path electric current, again calculate the impedance of this tributary port, and the impedance of this branch road and the threshold value of setting are compared, if this tributary port impedance is greater than threshold value, then judge the upper guide body line existing defects of this branch road 2, if this tributary port impedance is less than or equal to threshold value, then judge the upper guide body line zero defect of this branch road 2,

4) 1 is adopted)-3) detection method of step detects breakpoint or the etch state of guide body line in whole grounded screen, to diagnose the defect state of guide body line in grounded screen.

Cleaning Principle of the present invention is:

As shown in Figure 3, with n1 node in Fig. 3 for reference point, be connected to the cathode output end mouth in 1kHz simple sinusoidal alternating current source, be adjacent near upper guide body line contact n2, n3, n4 and n5 are all connected in 1kHz simple sinusoidal alternating current source cathode output end mouth by earth's surface return lead, if 1kHz simple sinusoidal alternating current source positive pole and cathode output end mouth potential difference (PD) are u, each branch current is designated as i successively 12, i 13..., i 1n, each branch impedance is designated as Z successively 12, Z 13..., Z 1n.Because the resistivity of metal grounding network conductor is much smaller than soil resistivity, the impact of soil leakage current can be ignored, then can set up following Matrix division:

Z 12 Z 13 . . . Z 1 n i 12 i 13 . . . i 1 n = u 12 u 13 . . . u 1 n - - - ( 1 )

In the hope of node n1 and allly adjacently internodal resistance value Z can be touched by Matrix division (1) 12, Z 13..., Z 1n, more each branch impedance value, filter out that branch road of wherein maximal value, its impedance is designated as Z 1x, then this branch road is suspected defects node.Press again shown in Fig. 4, separately 1kHz simple sinusoidal alternating current source cathode output end is connected on this suspected defects Nodes, strengthen Injection Current, accurately measure its impedance Z 1X, and compare with setting threshold value.

Utilize method of moment and electric network theory, the resulting impedance that can obtain each branch conductor is:

Z A C = 0.076 rR D C f - - - ( 2 )

(2) in formula, Z aCby the AC impedance of analysis branch road under 1kHz frequency, r is the radius of the equivalent circular conductor of grounding grids sectional area S r dCby the DC resistance of analysis branch road, f is power frequency.Can obtain at whole branch road resistance value under normal circumstances, in addition, through testing the resistance value Z between the similar node of identical newly-built grounded screen under same frequency through calculating 0, by Z aCand Z 0mean value be set as impedance threshold Z bas benchmark.Pass through measured value Z 1Xwith threshold value Z bcompare, if measured value Z 1Xbe greater than Z b, just can judge the node n of this branch road xon place there is heavy corrosion defect in guide body line.

Inspection software routine analyzer of the present invention is:

As shown in Figure 5, start and initialization after, the impedance magnitude Z that when input grounding net is normal, original measurement obtains 0, calculate branch impedance theoretical value Z simultaneously aC, the mean value both then calculating, determines impedance threshold Z b.Synchro measure computing node n 1with the impedance Z of all adjacent node branch roads 12, Z 13..., Z 1n, contrast obtains the branch impedance Z of each branch road maximal value 1x, independent high current precision measurement suspected defects branch impedance Z ' again 1x.Relatively Z ' 1xwith threshold value Z bobtain defect state and the security performance of down conductor, after all upper guide body line detects, terminate program.

Claims (1)

1. the device of guide body line defect selective mechanisms in grounded screen, it is characterized in that: comprise 1kHz sine-wave current transmitter and impedance measurement analytic system, described 1kHz sine-wave current transmitter is used for providing sine-wave current signal; Described impedance measurement analytic system is used for potential difference (PD) and the branch-path electric current of synchro measure 1kHz simple sinusoidal alternating current source output terminal mouth, and calculate the impedance of tributary port, compared by the impedance of branch road and the threshold value of setting, judge this branch road whether existing defects, thus judge the breakpoint or the etch state that detect guide body line in whole grounded screen, to diagnose the defect state of guide body line in grounded screen;
Described 1kHz sine-wave current transmitter is made up of regulation unit, buffer cell, signal waveform generating unit, power amplification unit and isolating transformer output unit, described regulation unit is connected with buffer cell and signal waveform generating unit respectively, buffer cell is connected with signal waveform generating unit, signal waveform generating unit is connected with power amplification unit, and power amplification unit is connected with isolating transformer output unit;
Described impedance measurement analytic system is made up of voltage transformer (VT), current transformer, A/D translation data capture card and host computer, described voltage transformer (VT) summation current transformer is connected with the input end of A/D translation data capture card respectively, and the output terminal of A/D translation data capture card is connected with the input end of host computer.
CN201510655178.4A 2015-10-10 2015-10-10 Defect screening detection apparatus of grounding network upper guide body wire CN105182168A (en)

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CN201229381Y (en) * 2008-07-30 2009-04-29 湖南省电力公司试验研究院 Anomalous frequency test system for ground resistance of grounded screen
CN102495291A (en) * 2011-12-13 2012-06-13 武汉大学 Impedance frequency response method for measuring corrosion state of grounding network of transformer substation
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