CN102928704A - Intelligent diagnosis method for corrosion failure point of transformer substation grounding grid - Google Patents

Abstract

The invention provides an intelligent diagnosis method for the corrosion failure point of a transformer substation grounding grid. The method comprises the following steps of: firstly, inputting a transformer substation grounding grid model into a computer, on the premise that the structure of the transformer substation grounding grid is analyzed, decomposing the transformer substation grounding grid and selecting an optimum point by a topology decomposition method, acquiring an electric potential signal and transmitting to an alternating current/direct current signal acquiring system by a preset sensor due to an injected sine alternating current single, transmitting the signal to the computer to be computed and displayed on a liquid crystal display by a microcontroller, computing the probable position in which the corrosion failure point is arranged by the computer according to the electric potential distribution, building a mini type grounding subgrid model, injecting a direct current large current signal into the mini type grounding subgrid, acquiring by a controller to acquire the node voltage and the current valve of the grounding grid at the time, and transmitting the acquired data to the computer to build mathematical model computation to finally obtain the specific position of the corrosion failure point.

Description

A kind of grounding net of transformer substation corrosion trouble spot intelligent diagnosing method

Technical field

This method relates to distribution transforming power station signal processing and analysis and transmission technology, more particular words it, the present invention relates to a kind of grounding net of transformer substation corrosion trouble spot intelligent diagnosing method.

Technical background

Along with large electrical network of modern times to UHV (ultra-high voltage), large capacity and remote future development, more and more higher for power system security, requirement stable and economical operation, in order to ensure the safe and stable operation of electrical network, improve power supply reliability, a good substation grounding device must be arranged.

Trace it to its cause, grounded screen is that electric system is buried at underground hidden facility, and the on-the-spot technical problem underlying that exposes is bad connection between the less than normal and grounding body in ground net corrosion, down conductor cross section, and these problems have buried hidden danger all for the fault of electric power.Ground net corrosion is the process of a gradual change, erodes to a certain degree namely to enter malfunction, and reliability reduces even performance failure, can not satisfy the requirement of safe operation of power system.China is owing to resource, economic dispatch reason, the used material of grounded screen is mainly plain carbon steel, ground net corrosion presents the local corrosion form usually, behind the corrosion grounded screen carbon steel material become fragile, aliquation, loose, attenuate, even fracture, so the electric power grounding grid seriously corroded is the most distinct issues of present China electric power grounding grid, and developed country mainly is as grounded screen with copper material abroad, its ground connection Performance Ratio iron and steel will be got well, and it is slow that extent of corrosion is wanted.

Many important electrical equipments have been concentrated in generating plant, the transformer station, such as transformer, generator, isolating switch, grounding switch, mutual inductor (voltage transformer (VT) summation current transformer), lightning arrester etc., the A of these equipment, B, C three-phase generally all are to link to each other with band steel, link to each other with grounded screen by down conductor again.Transformer station, generating plant also add concentrated grounding body except laying grounded screen under lightning rod and lightning arrester.Along with the rising of generating plant, transformer substation voltage grade, also more and more higher to the requirement of laying the used band steel of grounded screen.

Grounded screen places underground, and the grounding body cross section reduces in case grounded screen owing to other reasons such as corrosion cause fault, will cause, thermal stability inadequate, stake resistance increases.Although when carrying out ground grid design, adopt various safeguard procedures to reduce the extent of corrosion of grounded screen as far as possible, even but best design and safeguard procedures can not be predicted all situations that may occur in the service life, still various grounded screen faults can occur in actual use, jeopardize safe operation of power system.In case the grounded screen seriously corroded is defective to the stake resistance that makes grounded screen, even during local fracture, it is quite hard and difficult that overhauling of grounded screen transformed, and expense also is huge.Therefore must be frequently or termly the situation of grounded screen is detected, with the variation tendency of analysis grounding net, and the situation of grounded screen assessed, pinpointed the problems early to take corresponding safeguard procedures, prevent trouble before it happens, the maintenance of earthing device is seemed very urgent and important.

The state-detection of grounded screen is a very important course of work always, also be a very hard work simultaneously, existing method is after finding the accident that ground network ground resistance is defective or the generation earth mat causes, the method of searching grounded screen conductor breakpoint and corrosion section by dig on a wide area is very big with blindness, workload, when carrying out actual detection very large change need to be arranged to the environment of electric substation, uncertainly can accurately detect quality, affect the safe operation of electric system.Therefore the invention of grounding net of transformer substation Research on Intelligent Diagnosis system, be the power system security economical production in the urgent need to problem.

Summary of the invention

The invention provides corrosion trouble spot intelligent diagnosing method, detect data in order to gather ground net corrosion, fast, accurately and easily the ground net corrosion situation is detected.

The alleged problem of the present invention realizes with following technical proposals: the ground net corrosion trouble spot intelligent diagnosing method that matches with signal source, sensor by signal acquiring system.Both can avoid the problem that only can not accurately locate by Potential Distributing, and can avoid again grounded screen excessive and cause PC to calculate, or the inaccurate problem of result of calculation, method is easy, diagnosis efficiency is high, engineering practicability is strong.

Technical solution of the present invention: grounding net of transformer substation corrosion trouble spot intelligent diagnosing method is characterized in that: 1) analyze the structural model of grounding net of transformer substation by terminal handler, the applied topology decomposition method is decomposed grounding net of transformer substation and is chosen optimum point; 2) inject the simple alternating current electric signal to described grounding net of transformer substation, gather electric potential signal and transfer to the alternating current-direct current signal acquiring system by the ac signal acquisition sensor; 3) by a microcontroller described electric potential signal is transferred to terminal handler and calculate and be shown to a liquid crystal display; 4) terminal handler distributes according to electric potential signal and calculates the approximate region at corrosion place, trouble spot, and the zone structural model that makes up a small-sized ground connection subnet at this point, injects the D.C. high-current signal to this small-sized ground connection subnet again; 5) gather node voltage and the current value of this small-sized ground connection subnet by described microprocessor controls, data transmission to the terminal handler that collects is calculated to set up mathematical model; 6) draw the particular location that small-sized ground connection subnet corrodes the trouble spot.

Further, in a preferred embodiment of the invention, described ac signal acquisition sensor comprises detecting coil, and the signal output part of described detecting coil connects the input end of alternating current-direct current signal acquiring system.

Further, in a preferred embodiment of the invention, described alternating current-direct current signal acquiring system be used for to realize alternating current-direct current data acquisition, measurement, demonstration and and the usb communication of terminal handler, it comprises data acquisition module, usb communication module, microcontroller, liquid crystal display and power supply module, wherein said data acquisition module input end connects the output terminal of detecting coil to receive signal, and output terminal is connected to microcontroller; Described usb communication module, power supply module and liquid crystal display are connected to microcontroller.Wherein, system core module is microcontroller, and it controls data acquisition, and collection result is presented on the liquid crystal display, and the communicating by letter of alternating current-direct current signal acquiring system and terminal handler.Be connected with the USB2.0 agreement by the usb communication module between described alternating current-direct current signal acquiring system and the terminal handler.

Further, in a preferred embodiment of the invention, described data acquisition module comprises analog to digital converter and the high precision reference potential device that is attached thereto, and the preposition anti-jamming circuit that is coupled in described analog to digital converter.

Further, in a preferred embodiment of the invention, described preposition anti-jamming circuit is to be arranged between detecting coil and the analog to digital converter, is used for the on-the-spot electromagnetic interference (EMI) of filtering grounded screen.

In a preferred embodiment of the invention, at first be under the prerequisite of analyzing the substation grounding web frame, the applied topology decomposition method is decomposed grounding net of transformer substation and is chosen optimum point; Between reaching the standard grade in drawing of optimum point with sinusoidal ac signal input grounding net; The ac signal acquisition sensor that utilization presets will be induced voltage signal because of the magnetic induction density signal transition that Injection Current excites on the earth's surface, and the distribution that can measure the magnetic induction density on earth's surface this moment is used for calculating after a while; After obtaining data and send terminal handler (being preferably PC or PDA equipment) to by the alternating current-direct current signal acquiring system, calculating grounding net of transformer substation earth's surface magnetic induction density under normal circumstances distributes, then measurement result and simulation result are compared, according to both difference, the Position Approximate of diagnosing out the ground net corrosion trouble spot to occur; Behind the Position Approximate of selecting the appearance of ground net corrosion trouble spot, PC generates a small-sized grounded screen regional model automatically near this position, being external in drawing of choosing at random in this small-sized grounded screen zone with the D.C. high-current source reaches the standard grade, voltage between the measurement ground lead and the electric current in loop obtain the input pickup resistance between two ground leads; Measurement result is inputted the resistance value that PC obtains each section conductor; Resistance value during with this resistance value and normal condition compares, and can obtain just that grounded screen band iron corrosion attenuates or particular location and the degree of the defective that ruptures.The present invention can in the situation that does not have a power failure and earth mat is not excavated, can understand the extent of corrosion of each section of earth mat conductor and whether rupture safety, the reliability service of guarantee electric system.And have the advantages such as restriction that simply, accurately, are not subjected to on-the-spot service condition.

Further, in a preferred embodiment of the invention, add anti-jamming circuit at the collection signal end, effectively suppress on-the-spot electromagnetic interference (EMI), to the signal of measuring gained after notch filter, filtering, phase sensitive detection are processed, with power frequency and other interference rejection.

Description of drawings

Fig. 1 is grounding net of transformer substation corrosion diagnosis process flow diagram of the present invention;

Fig. 2 is the hardware design structure figure of the used diagnostic system of grounding net of transformer substation corrosion diagnosis of the present invention.

Embodiment

See figures.1.and.2, the preferred embodiment of grounding net of transformer substation of the present invention corrosion trouble spot intelligent diagnosing method comprises step: 1) analyze the structural model of grounding net of transformer substation 1 by the terminal handler 5 of diagnostic system, the applied topology decomposition method is decomposed grounding net of transformer substation 1 and is chosen optimum point; 2) inject the simple alternating current electric signal to grounding net of transformer substation 1, gather electric potential signal and transfer to alternating current-direct current signal acquiring system 3 by ac signal acquisition sensor 2; 3) by a microcontroller 33 described electric potential signal is transferred to terminal handler 5 and calculate and be shown to a liquid crystal display 34; 4) terminal handler 5 distributes according to electric potential signal and calculates the approximate region at corrosion place, trouble spot, and the zone structural model that makes up a small-sized ground connection subnet 11 at this point, injects the D.C. high-current signals to this small-sized ground connection subnet 11 again; 5) by node voltage and the current value of described microcontroller 33 these small-sized ground connection subnets 11 of control collection, data transmission to the terminal handler 5 that collects is calculated to set up mathematical model; 6) draw small-sized ground connection subnet 11 and corrode the particular location of trouble spots.

Further, in a preferred embodiment of the invention, described ac signal acquisition sensor 2 comprises detecting coil, and the signal output part of described detecting coil connects the input end of alternating current-direct current signal acquiring system 3.

Further, in a preferred embodiment of the invention, described alternating current-direct current signal acquiring system 3 be used for realizing alternating current-direct current data acquisition, measurement, demonstration and and the usb communication of terminal handler, it comprises data acquisition module 31, usb communication module 32, microcontroller 33, liquid crystal display 34 and power supply module 35, wherein said data acquisition module 31 input ends connect the output terminal of detecting coil to receive signal, and output terminal is connected to microcontroller 33; Described usb communication module 32, power supply module 35 and liquid crystal display 34 are connected to microcontroller 33;System core module is microcontroller 33, and it controls data acquisition, and collection result is presented on the liquid crystal display 34, and the communicating by letter of alternating current-direct current signal acquiring system and terminal handler.Be connected with the USB2.0 agreement by usb communication module 32 between described alternating current-direct current signal acquiring system 3 and the terminal handler 5.

Further, in a preferred embodiment of the invention, described data acquisition module 31 comprises analog to digital converter 311 and the high precision reference potential device 312 that is attached thereto, and the preposition anti-jamming circuit that is coupled in described analog to digital converter 311.

Further, in a preferred embodiment of the invention, described preposition anti-jamming circuit is to be arranged between detecting coil and the analog to digital converter 311.In a preferred embodiment of the invention, preposition anti-jamming circuit comprises integrator and the wave filter that AD7718 is built-in, and the filtering circuit of front end, can effectively suppress under the strong-electromagnetic field environment interference to earth mat, especially can well suppress the interference of power frequency component, so that the data that collect reach precisely, stablize, reliably requirement.

In a preferred embodiment of the invention, at first the structural model of grounding net of transformer substation 1 is inputed to terminal handler 5(and be preferably PC), under the prerequisite of analyzing grounding net of transformer substation 1 structure, the applied topology decomposition method is decomposed grounding net of transformer substation 1 and is chosen optimum point, by drawing the injection sinusoidal ac signal of reaching the standard grade to grounded screen 1, by the ac signal acquisition sensor 2 that presets the collection of grounded screen electric potential signal is transferred to alternating current-direct current signal acquiring system 3, its microcontroller 33 transfers to PC 5 with this signal and calculates and be shown to liquid crystal display 34, PC 5 calculates corrosion place, trouble spot Position Approximate according to the grounded screen Potential Distributing, and at small-sized ground connection subnet 11 models of this band of position structure, inject the D.C. high-current signal to this small-sized ground connection subnet 11 again, and by microcontroller 33 control collection grounded screen node voltage this moment and current values, data transmission to the PC that collects is set up calculated with mathematical model, obtain at last corroding the particular location of trouble spot.

The material that the present invention needs is the band iron laying state of grounding net of transformer substation 1, be that the grounded screen band iron lays figure, this figure is inputed to PC 5, perhaps on PC 5, generate in proportion fast a standard grounded screen figure by grounding net of transformer substation corrosion fault diagnosis system.

At first, the applied topology decomposition method is decomposed grounding net of transformer substation 1 and is chosen optimum point.Have N node, N for one _TThe grounded screen 1 of individual accessible node can be used the circuit network theory unreachable node of pruning, and grounded screen is carried out layer reduction.If based on one group of accessible node grounded screen is carried out node tearing, tear out a relatively independent sub-network, and the connected node of this sub-network and grounded screen remainder all is this group accessible node, claim that then this sub-network is a column.Under the prerequisite that keeps whole accessible nodes, the parallel branch that can reach in the grounded screen 1 merges to greatest extent, and yojan is called intrinsic grounded screen to the network that a branch road is arranged between any two accessible nodes at the most, the branch road that wherein comprises is called the intrinsic branch road, its quantity B _TExpression.Choose at random two remaining nodes after the decomposition, as the sinusoidal signal decanting point.

The present invention adopts the sine-wave excitation source, and two of the grounding net of transformer substation that calculates by PC 5 are drawn and reach the standard grade, and directly inject exciting current.Under transformer station's complex electromagnetic environment, the logical adjustable bandpass filter of centre frequency of band is adopted in the measurement of earth's surface magnetic induction density.By with the adjusting that cooperates of exciting signal frequency, avoid the power frequency noise spot, make measuring accuracy and resolution can satisfy the defect diagonsis requirement.PC 5 at first calculates grounded screen earth's surface magnetic induction density under normal circumstances and distributes, then measurement result and simulation result compared, and according to both difference, the Position Approximate of diagnosing out the ground net corrosion trouble spot to occur.Simultaneously, PC 5 is selected a small-sized ground connection subnet 11 around in this band of position automatically, as next step Test Network, and then obtains the particular location of trouble spot.

Measure at last small-sized ground connection subnet obtained in the previous step, as required, DC source is between each measurement point and point of excitation, to the appropriate pumping signal of grounded screen 11 inputs, then 5 pairs of selected measurement points of data collection station are measured, with signal filtering and transfer data to the corrosion diagnosis system.The corrosion diagnosis detection system runs on the PC 5, according to the physical arrangement of ground connection subnet, generates corresponding circuit accounting equation, according to the grounded screen data that collect, calculates by the resistance of computation model to each section of grounded screen again.For the grounded screen with m node, n bar branch road, the incidence matrix of grounded screen is A, and it can obtain from the topological structure of grounded screen.Suppose A={k ₀, k ₁...., k _JThe accessible node collection, specify k ₀Be reference mode, at k ₀With k _JBetween extrinsic motivated

Inductance and the electric capacity of ignoring each bar branch road, according to Circuit theory, then its node voltage KVL equation is

$U^{\left(j\right)}={(U_1^{\left(j\right)},U_2^{\left(j\right)},L,U_m^{\left(j\right)})}^T=G^{-1}\·I{s}^{\left(j\right)}---\left(1\right)$

Wherein nodal-admittance matrix then

G＝A·diag(x ₁,x ₂,L,x _n)A ^T (2)

X wherein ₁, x ₂..., x _nBe each branch node coordinate, naturally require to be

$|U_{k_i}^{\left(j\right)}-U_{k_i,0}^{\left(j\right)}|\≤{\mathrm{\ϵ}}_U$ i,j＝1,2,L,J (3)

ε wherein _UBe electric potential difference between node,

Be k under the excitation of j kind, behind the ground net corrosion _sThe measuring value of individual node voltage,

Be k under the excitation of j kind, behind the ground net corrosion _sThe calculating analogue value of individual node voltage.When electric current passed through the ground lead inflow the earth of grounded screen, its electric current distributed by the constant current field principle, and satisfies the minimum energy principle, each branch voltage

With node voltage U ^(j)Relational expression be:

$V^{\left(j\right)}={(v_1^{\left(j\right)},v_2^{\left(j\right)},L,v_n^{\left(j\right)})}^T=B\·U^{\left(j\right)}=B\·G^{-1}\·{\mathrm{Is}}^{\left(j\right)}---\left(4\right)$

Wherein B represents the transposition of incidence matrix A.At this moment, entirely network energy is

$\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\left(v_k^{\left(j\right)}\right)}^2{x}_k---\left(5\right)$

After considering ground net corrosion, resistance value necessarily increases, so the mathematical model of problem is

$\min f(x_1,x_2,L,x_n)=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\left(v_k^{\left(j\right)}\right)}^2{x}_k$

$s.t.\left\{\begin{array}{cc}|U_{k_i}^{\left(j\right)}-U_{k_i,0}^{\left(j\right)}|\≤{\mathrm{\ϵ}}_U,& i,j=\mathrm{1,2},K,J\\ 0\≤x_k\≤1/R_{k0},& k=\mathrm{1,2},L,n\end{array}\right.---\left(6\right)$

R wherein _K0Be the initial resistance of node, PC obtains the resistance value of each section of grounded screen band iron by finding the solution this mathematical model, and compares with our known original resistance value, just can obtain concrete corrosion position of failure point.

Data-transmission mode of the present invention is: the multiple signals that utilize alternating current-direct current signal acquiring system 3 synchronous acquisition grounded screen test nodes, behind high-precision adc, the 24bit digital signal is transferred to microcontroller 33(by the SPI interface is preferably CY7C68013 type MCU chip), then the usb communication module 32(by microcontroller 33 is preferably the USB2.0 interface) data are sent on the PC 5 processed, judge and analyze.Simultaneously, the I by CY7C68013 microcontroller 33 ²C meets SLC and SDA sends into liquid crystal display 34.

In the present invention, the opening of system shows the open nature of data acquisition system (DAS), data base management system (DBMS) and applied analysis system, the exchange between the data and the power acquisition communication standard usb protocol of industry.

In sum, the grounding net of transformer substation corrosion diagnosis method that the present invention introduces is that software and hardware is nested, and the measurement diagnostic method of very large extendability is arranged.The alternately input of the signal source of alternating current-direct current both can have been avoided the problem that only can not accurately locate by Potential Distributing, can avoid again grounded screen excessive and cause PC to calculate, or the inaccurate problem of result of calculation, method is easy, diagnosis efficiency is high, engineering practicability is strong.

Being preferred implementation of the present invention only below, being intended to embody outstanding technique effect of the present invention and advantage, is not to be restriction to technical scheme of the present invention.Those skilled in the art will appreciate that all modifications of having done based on the technology of the present invention content, variation or substitute technology feature, all should be covered by in the technology category of claims opinion of the present invention.

Claims (6)

1. grounding net of transformer substation corrodes the trouble spot intelligent diagnosing method, it is characterized in that:

1) analyze the structural model of grounding net of transformer substation by terminal handler, the applied topology decomposition method is decomposed grounding net of transformer substation and is chosen optimum point;

2) inject the simple alternating current electric signal to described grounding net of transformer substation, gather electric potential signal and transfer to the alternating current-direct current signal acquiring system by the ac signal acquisition sensor;

3) by a microcontroller described electric potential signal is transferred to terminal handler and calculate and be shown to a liquid crystal display;

4) terminal handler distributes according to electric potential signal and calculates the approximate region at corrosion place, trouble spot, and the zone structural model that makes up a small-sized ground connection subnet at this point, injects the D.C. high-current signal to this small-sized ground connection subnet again;

5) gather node voltage and the current value of this small-sized ground connection subnet by described microprocessor controls, data transmission to the terminal handler that collects is calculated to set up mathematical model;

6) draw the particular location that small-sized ground connection subnet corrodes the trouble spot.

2. grounding net of transformer substation according to claim 1 corrodes the trouble spot intelligent diagnosing method, and it is characterized in that: described ac signal acquisition sensor comprises detecting coil, and the signal output part of described detecting coil connects the input end of alternating current-direct current signal acquiring system.

3. grounding net of transformer substation according to claim 1 and 2 corrodes the trouble spot intelligent diagnosing method, it is characterized in that: described alternating current-direct current signal acquiring system comprises data acquisition module, usb communication module, microcontroller, liquid crystal display and power supply module, wherein said data acquisition module input end connects the output terminal of detecting coil to receive signal, and output terminal is connected to microcontroller; Described usb communication module, power supply module and liquid crystal display are connected to microcontroller; Be connected by the usb communication module between described alternating current-direct current signal acquiring system and the terminal handler.

4. grounding net of transformer substation according to claim 3 corrodes the trouble spot intelligent diagnosing method, it is characterized in that: described data acquisition module comprises analog to digital converter and the high precision reference potential device that is attached thereto, and the preposition anti-jamming circuit that is coupled in described analog to digital converter.

5. grounding net of transformer substation according to claim 4 corrodes the trouble spot intelligent diagnosing method, and it is characterized in that: described preposition anti-jamming circuit is to be arranged between detecting coil and the analog to digital converter, is used for the on-the-spot electromagnetic interference (EMI) of filtering grounded screen.

6. grounding net of transformer substation according to claim 1 corrodes the trouble spot intelligent diagnosing method, and it is characterized in that: in step 5), described mathematical model is to draw according to following equation:

$\min f(x_1,x_2,L,x_n)=\underset{j=1}{\overset{J}{\mathrm{\Σ}}}\underset{k=1}{\overset{n}{\mathrm{\Σ}}}{\left(v_k^{\left(j\right)}\right)}^2{x}_k$

$s.t.\left\{\begin{array}{cc}|U_{k_i}^{\left(j\right)}-U_{k_i,0}^{\left(j\right)}|\≤{\mathrm{\ϵ}}_U,& i,j=\mathrm{1,2},K,J\\ 0\≤x_k\≤1/R_{k0},& k=\mathrm{1,2},L,n\end{array}\right.$

Wherein,

Be each node voltage value of grounding net of transformer substation, x _kBe the inverse of k bar branch road resistance, ε _UBe electric potential difference between node, R _K0It is each node initial resistivity value of k bar branch road.

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