CN1110707C - Diagnosis method of earth screen corrosion and breakpoint of electric substation and its measurement and diagnosis system - Google Patents
Diagnosis method of earth screen corrosion and breakpoint of electric substation and its measurement and diagnosis system Download PDFInfo
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Abstract
The present invention belongs to the technical fields of the precision measurement and the analysis of electric quantity. A direct current power supply is externally connected between two grounding leads of a ground network to measure voltage and loop current between the grounding leads, and thus, an inlet end resistance value between the two grounding leads can be obtained. A measuring result and a topological structure of the ground network are input into diagnostic software to obtain resistance values of conductors of each section, and the resistance values are compared with the resistance values for undamaged time. Under the conditions of no power cut and no excavation of the ground network, the corrosion degree of conductors of each section and the condition whether the conductors are ruptured or not can be known. Thus the safety and the reliable operation of an electric power system can be guaranteed. The present invention has the advantages of simplicity, accuracy, no limit of site operating conditions, etc.
Description
The invention belongs to the precision measurement and the analysis field of electrical quantities, be particularly related under the situation of the normal operation of electric system, determine the rosin joint of the corrosion of grounding net of transformer substation and breakpoint and new earth mat and leak accurate, the reliable and simple diagnostic method of faults such as weldering, the corrosion that also can be used for metallic conduit (water pipe, steam pipe, oil pipe) is diagnosed.
In power house, transformer station, concentrate a large amount of important electrical equipments, needed good earthing device, satisfied the requirement of working earthing, safety ground and lightning protection.The earthing device of engineering practicality is a grounded screen, and it mainly comprises the grid 11 that is welded to form with band steel, round steel, angle steel or steel pipe etc., and the node place of this grid is connected with ground lead 13, as shown in Figure 1.This grid is embedded in underground certain depth, presses, shunts and reduce the effect of stake resistance to reach all, and lead-in wire one end bassets and links to each other with power equipment with drawing.
When transmission transformer station was short-circuited accident, the fault current I grounded screen of flowing through was gone into ground, and R is more little for stake resistance, and the potential rise U of grounded screen is just low more, and this moment, the current potential of ground ground connection object was also just lower, guaranteed electrical equipment and personal safety.
The grounded screen of transformer station is the important measures of safeguarding the power system security reliability service, ensureing operations staff's safety.The conductor that constitutes grounded screen is embedded in underground, the reasons such as burn into earth short circuit current electrodynamic action of failure welding and leakage weldering, soil during often because of construction, may cause the burn into even the fracture of earth mat conductor and ground lead, make earth mat be electrically connected performance depreciation, stake resistance increases.If meet electric system generation ground short circuit fault, to cause local potential difference of earth mat own and earth mat potential anomalies to increase, except that bringing the threat to the operations staff, also may because of the counterattack or cable sheath circulation make that the insulation of secondary device is destroyed, high pressure seals in the pulpit, make monitoring or opertaing device generation malfunction or tripping and the expansion accident, bring enormous economic loss and social influence, in the stronger soil of corrosivity, the annual corrosion rate of earth mat metal can reach 2.0mm, can reach 8.0mm in the extremely strong soil of corrosivity.Because of earth mat corrosion or the accident that fracture causes takes place happen occasionally, each accident all causes huge direct economic loss.
At present, the understanding means for earth mat corrosion and breakpoint are very original.The common method that earth mat corrosion and breakpoint are understood in electric system now is exactly the way of sampling excavation of having a power failure, promptly cross certain year number after, according to the soil corrosion rate in area, grounded screen conductor resistance extent of corrosion is estimated on experience ground, sampling excavates inspection then.This method has blindness, workload is big, speed is slow, and is subjected to the restriction of on-the-spot service condition, can accurately not judge breakpoint and extent of corrosion.Simultaneously, transmission transformer station is being born the huge task of national product and people's lives, has a power failure each time all to bring the tremendous economic loss inevitably, has brought the difficulty in the practical operation like this.
And the inspection of lead wire fault is judged, at present usually the way that adopts is: the maintainer's corrosion situation of ground lead at the ground matrix section that detect by an unaided eye, and firmly shake the shallow-layer part that ground lead looks into below the face of land with sight and whether rupture, because the ground lead face of land usually scribbles antirust coat with top, adopt the corrosion condition and the degree of the acomia at all judgement lead-in wire of this method antirust coat inside; Moreover, because ground lead is band steel or the such rigid material of round steel mostly, whether rupturing even firmly shake the lead-in wire that can not judge than the depths, this method is also powerless for the corrosion situation below the ground lead face of land.
Other method is exactly to analyze the corrosion situation of earth mat by the stake resistance of measuring whole grounded screen.This method has problems on principle.When earth mat corroded or has breakpoint, the stake resistance of earth mat did not change basically.Even earth mat is because heavy corrosion causes the parallel off of earth mat, because the effect of the mutual resistance between two parts earth mat, the stake resistance that measures behind the parallel off does not still have bigger variation.Stake resistance has bigger variation with the variation in the seasonal variations of soil resistivity, measuring method, measurement orientation in addition, and the stake resistance that promptly measures changes because earth mat corrosion and fracture cause.From another point of view, even the stake resistance of earth mat can reflect the corrosion situation of earth mat, but also accurate fault location point.Have to artificial sampling excavation check that perhaps excavation is checked on a large scale, caused drawbacks such as cost costliness, testing amount are big.
The fault of grounded screen has been a mortal malady of safe operation of power system, and the breakpoint and the heavy corrosion section of searching grounded screen have become great anti-accident measures of power department.
The objective of the invention is for overcoming the weak point of prior art, the diagnostic method of a kind of transmission transformer station ground net corrosion and breakpoint and measurement thereof, diagnostic system are proposed, can be under the situation that does not have a power failure and earth mat is not excavated, 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.
The present invention proposes the diagnostic method of a kind of transmission transformer station ground net corrosion and breakpoint, it is characterized in that, may further comprise the steps:
1) adopts direct supply to be external between two ground leads of earth mat, earth mat is applied big DC current;
2) electric current in voltage between measurement earth mat two ground leads and measurement loop obtains input resistance or transfer impedance between two ground leads then;
3) measure input resistance and transfer resistance between all ground leads that the measurement scheme determined in base area net topology structure and all ground lead positions requires to measure;
4), obtain the resistance value of each section conductor by the diagnostic software analysis with the topological structure input diagnostic software of measurement result and earth mat; The resistance value of each section earth mat conductor that analysis the is obtained design resistance value (or historical measurement result assay value) that computational analysis obtains when intact with the hypothesis earth mat compares, and whether ruptures the degree of corrosion according to the conductor of this section of threshold decision earth mat.
The above-mentioned the 1st) step specifically can may further comprise the steps;
1) with the topological structure of earth mat and the position input diagnostic software of ground lead, determines measurement scheme, promptly determine to measure input resistance or transfer resistance between which ground lead by diagnostic software;
2) inject D.C. high-current to earth mat, being added in two of earth mats needs between the ground lead of measurement.
The above-mentioned the 2nd) in the step, specifically can comprise:
Measure voltage between each lead-in wire and the size of current that applies, adopt the metering system of sampling/maintenance, realize voltage U and electric current I synchro measure, obtain voltage, the same instantaneous value of electric current, i.e. input resistance between the amount of obtaining ground lead or transfer resistance.
Repeat above-mentioned steps, can obtain input resistance or transfer resistance between all ground leads that measurement scheme require to measure.
The present invention proposes also that a kind of earth mat corrosion and breakpoint of the diagnostic method that adopts above-mentioned transmission transformer station ground net corrosion and breakpoint are measured, diagnostic system, comprise computing machine and be stored in the diagnostic software of establishment in advance in the storer of this computing machine, and with the small electric resistance measuring apparatus of diagnostic software communication.Said small electric resistance measuring apparatus comprises the analog input circuit of gathering measuring-signal, convert the analog measurement of each sampling moment on each road the hyperchannel analog to digital conversion circuit of digital quantity to, and will convert single-chip microcomputer and digital circuit thereof that the signal of digital quantity carries out computing and processing to; Said input circuit is made up of voltage-limiting protection and amplifying circuit; Said hyperchannel analog to digital conversion circuit is made up of multi-way switch, sampling/maintenance, range conversion and analog to digital conversion, the circuit of said single-chip microcomputer comprises data processing, system reset and data communication, also comprise the measurement data interpretation software of establishment in advance that is stored in the single-chip microcomputer storer, data communication is sent to diagnostic software in the computing machine with measurement result.The diagnostic software of establishment in advance in the said storer that is stored in computing machine, by topological structure input, measurement scheme determine, corrosion and functional modules such as breakpoint analysis and analytical structure graphic presentation form.
Above-mentioned measuring system can be taked careful electromagnetic screen by casing, hardware system adopts that mimic channel separates with digital circuit, the power decoupling of digital circuit chip, ground wire overstriking, property-line are surrounded, separate measures such as each functional block and employing " house dog " circuit, and whole antijamming capability is guaranteed in measures such as the function setting that adopts the master routine inlet to increase delay time software, programmable I/O mouth on the software design carries out repeatedly, steering order execution repeatedly, instruction redundancy, digital filtering, data processing.
Ultimate principle of the present invention is exactly the measured value according to input resistance or transfer resistance between the earth mat ground lead, topological structure by known earth mat, use suitable computing method, obtain the resistance of each section of earth mat conductor, determine corresponding extent of corrosion according to the numbering of resistance.If the resistance of earth mat somewhere conductor obviously raises, just illustrate that fracture or corrosion have taken place at this place.
The present invention sets up the mathematical model and the iteration form thereof of corrosion diagnosis according to Circuit theory, adopts the quadratic programming of optimum theory to find the solution morbid state and owe fixed mathematical model; The threshold value criterion whether conductor ruptures adopts Artificial Neural Network to determine.Utilize the device of the precision measurement small resistor that the present invention develops to obtain measurement data accurately, measurement mechanism adopts the method for digital filtering, eliminates the influence of disturbing.Because the resistance of grounded screen itself is less, therefore the accuracy for guaranteeing to measure improves anti-jamming capacity, injects earth mat with bigger direct supply and measures.The measured value optimized choice has been studied a kind of system of selection of determining measuring method automatically by pivot analysis.When fracture or corrosion take place in earth mat section conductor, the resistance of this section conductor must raise, the various electrical equipments of transformer station all have the ground lead that links with earth mat in addition, because the resistivity of the metallic conductor of soil resistivity and earth mat is compared big a lot, therefore can be a lumped parameter pure resistance network with the earth mat equivalence, the ground lead of earth mat is the reached node of this network, get final product measuring point, regard earth mat as a number of endpoint and the same number of multiport resistor network of ground lead, ground lead is exactly the reached contact of this network, but measuring point just; So just the problem that the earth mat trouble spot is detected is converted into one and determines the inverse problem of the network analysis of network internal parameter, the i.e. diagnosis problem of resistor network according to the port identity of multiport network.Therefore can be according to the measured value of the electric parameter between the ground lead of earth mat, and the topological structure of known earth mat, the utility theory analytical approach, then can obtain each section of earth mat conductor resistance value, just can judge the breakpoint location of earth mat and the extent of corrosion of each section conductor, carry out the reparation of earth mat targetedly, and estimate what years are the operation life of earth mat also have.
The method of the invention as shown in Figure 2.Adopted direct supply (accumulator) 21 to be external in earth mat 11, earth mat has been applied big DC current (about 20A).A, B are that two of earth mat ground lead 13 can reach node.101 and 101 ' is the current sample port of measuring system 22; 102 and 102 ' is the voltage sample port of measuring system, measures the voltage between earth mat all right one way or the other and branch road A, B.R is the precision resistance that dividing potential drop is used, and calculates the electric current of measuring the loop by the voltage of measuring on it, also the measurement electric current that promptly injects to earth mat.The measurement mechanism that this method adopts is gathered multichannel data simultaneously, obtains voltage drop on the voltage difference and precision resistance between ground lead simultaneously, obtains the input resistance between two ground leads then.
The mathematical model of the earth mat corrosion diagnosis that the present invention adopts is summarized as follows:
The mathematical model of earth mat diagnosis adopts Tellegen to derive the transfer impedance matrix of multiport network and the relation between the network internal parameter, and directly derives corresponding iteration form.
The various complexity of the grounded screen fault of transmission transformer station, and the earth mat node is many, scale is big, mostly is soft fault.Consider that adjaiont network method can be located, the definite value multiple faults, can obtain each section of earth mat conductor resistance value, and determine branch trouble according to its variable quantity, this just the present invention require and wish.Therefore, the problem that must solve be diagnostic equation owe to decide problem (number of unknown number is less than the number of known number), the present invention adopts the diagnostic equation that is similar to adjaiont network method, with the mathematical method of iteration it is converged to actual separating.
Grounded screen network N before the corrosion shown in Fig. 3 a and the grounded screen network N after corroding ' shown in Fig. 3 b, have identical node and branch road and a numbering (breakpoint finds out it is a kind of special shape of corroding), identical reference mode promptly has identical topological structure.13a among the figure, 11b, and 13m, 13a ', 13b ', and 13m ' is the numbering of the ground lead 13 of earth mat.This Linear Network has n node (comprise and can reach node), b bar branch road, m is individual can reach node.Each symbol definition is as follows:
V
b=[v
B1, v
B2..., v
Bb] be the branch voltage vector;
I
b=[i
B1, i
B2..., i
Bb] be the branch current vector; If certain branch road resistance of working as network is by R
kBe changed to R
k' time, that is:
R
k'=R
k+ Δ R
k(1) then network N just becomes network N ', the self-resistance between its i end and the j end is also corresponding to R
IjBe changed to R
Ij', that is:
R
Ij'=R
Ij+ Δ R
Ij(2) according to the Teller root like power theorem:
And
V
kAnd V
k' be before the corrosion and the voltage after the corrosion for branch road, I
kAnd I
k' be before the corrosion and the voltage after the corrosion for branch road.If the electric current that injects to earth mat when measuring is I
0, have
V
Ij=-R
IjI
0And V
IjThe R of '=-
Ij' I
0(4) and I
Ij=I
Ij'=I
0, thus:
With formula (1), formula (2), formula (4), formula (5) difference substitution formula (6):
Behind the abbreviation promptly:
Therefore can get the mathematical iterations model of measuring junction input resistance:
Wherein, n is an iterations.
Mathematical relation between each section of earth mat conductor resistance value and earth mat ground lead between the electric parameter is a nonlinear relationship, must adopt alternative manner to find the solution, and this just involves the iteration form and the convergence problem of algorithm.The independent data of electric parameter is less than the conductor number of earth mat between the ground lead that measures usually, therefore the problem of finding the solution that must consider to owe to decide nonlinear equation.Because the variation of electric parameter value is not fairly obvious between the caused ground lead of variation of each section of earth mat conductor resistance, therefore its result of calculation is very responsive to measuring error, this is a serious ill-conditioning problem theoretically, must take certain method to be overcome.Reduce the susceptibility of result of calculation to measuring error.Always there are concrete conditions such as error in measured value in addition, need set up a kind of quick and precisely, noise resisting ability is strong, the computing method that can effectively overcome the influence of matrix morbid state.
For the mathematical model of deriving previously, the present invention adopts the method for optimization to find the solution, and has used the optimum solution that quadratic programming seeks to satisfy certain constraint condition here.By various mathematic programming methods are compared, the present invention has adopted the Richardson method in the quadratic programming algorithm.
For making the error in all equations obtain simultaneously proofreading and correct, adopted the simplest SIRT algorithm (Simultaneous Iterative Reconstruction Techniques), its matrix expression is:
Corresponding functional is k (x)=(p-Mx)
T(p-Mx) Dui Ying matrix D is a pair of angular moment battle array, its i element D
iFor
Since matrix M important all be non-negative, so this algorithm convergence.
The present invention has write earth mat corrosion diagnostic software according to mathematical model of saving previously and numerical computation method etc.This software full graphics interface, easy and simple to handle, as long as input earth mat conductor data, Automatic Program generates topology diagram, measurement scheme figure, after program is read in and respectively can be reached the node measurement data file, just can be by calculating the diagnosis section of being out of order, and by graph direct express.Figure 4 shows that the diagnostic software process flow diagram.Its basic process is the topological structure file that reads in earth mat earlier
*.brh, determine the measurement scheme of diagnosis earth mat corrosion by the topological structure of earth mat.Measure input resistance or transfer resistance between each ground lead according to measurement scheme, obtain measuring file
*.msr.Below calculation procedure for analyze the situation of the corrosion and the fracture of each section conductor according to topological structure and measurement result: according to topological structure structure admittance matrix, carry out the triangle analysis, carry out the nodal method operation of circuit, analyze the resistance value Rk that obtains each section conductor according to diagnostic equation optimization, if analysis result reaches the accuracy requirement of regulation, then stop analytical calculation, preservation result of calculation Rk is
*.out, judge according to the threshold value criterion whether each section conductor ruptures, and calculates the extent of corrosion of each section conductor, saves as
*.dia, output analysis result.
Owing on principle, breakpoint is regarded as a kind of corrosion of special shape, is needed therefore to consider that when extent of corrosion reaches much be the conductor corrosion cracking.Always there are certain error in each section of the earth mat conductor resistance calculated value and the actual value of trying to achieve according to the measured value of electric parameter between the earth mat ground lead on absolute value, relative value between each section conductor resistance calculated value is just meaningful to the judgement of trouble spot, therefore must determine breakpoint automatically and not have resistance boundary between the breakpoint according to the distribution situation of these resistance values, and carry out determining of threshold value criterion.
The present invention is by a large amount of simulation calculation, and the employing artificial neural network has been set up the threshold model under the different tolerance situations.
When earth mat was diagnosed, drawing in the time of can practice of construction occurring inevitably and topology of networks had the influence of certain difference, cable duct etc.The analysis showed that the Error Diagnostics that these tolerances are quoted is little, can solve by adjusting threshold value the influence of breakpoint.
Another part of diagnostic system is the measuring system of small electric parameter between precision measurement earth mat ground lead (input resistance or transfer resistance).Input resistance between ground lead has only m Ω level, and this diagnostic system has solved the problem of accurately measuring the small resistor of m Ω level under the situation of external interference existing.
The microcomputer measuring equipment of the small resistor that the present invention designs, this measurement mechanism possesses the function of digitized accurate measurement under external interference.Its principle is that (20～30A) improve noises recently potential difference (PD) between measuring lead wire and input current to the big electric current of injection between the earth mat ground lead, obtain input resistance, or the potential difference (PD) of measuring between other lead-in wire obtains transfer resistance.Consider that measurement mechanism should be able to carry out the corrosion diagnosis of earth mat when the transmission transformer station operate as normal, electromagnetic environment is very abominable, has taked a series of general interference protection measures to guarantee the antijamming capability of single-chip microcomputer and Single Chip Microcomputer (SCM) program in the measurement mechanism.
The basic function of the measuring device part of earth mat corrosion diagnostic system is the accurate detection to small-signal under the interference effect.For this reason, the design entire circuit comprises several module sections such as overvoltage protection, range conversion, sampling/maintenance, A/D, digital mainboard.
If the electric parameter between all ground leads is all measured, the one, workload is big, the 2nd, some measurement result is repetition, therefore the present invention has added in diagnostic software according to the definite automatically method of the measurement scheme of pivot analysis principle, behind position input diagnostic software with the topological structure of grounded screen and ground lead, by analyzing definite ground lead numbering that needs the electric parameter of measurement, provide measurement scheme.
Technical characterstic of the present invention and effect:
The input resistance that the measurement earth mat of the present invention design is small or the single-chip microcomputer instrument of transfer resistance and based on the patterned diagnostic software of Windows constitute a cover diagnostic system.Being one is that core, collection measurements and calculations are the earth mat breakpoint of one and the diagnostic system of corrosion with the computing machine, promptly is used for the industry CT of the examination of earth mat breakpoint and corrosion diagnosis and new earth mat.
The corrosion situation basically identical of the actual earth conductor that the diagnostic result that adopts the inventive method and substantial portion excavation obtain, error in 8%, the crack conditions of energy efficient diagnosis grounded screen conductor.Have higher accuracy, can satisfy the requirement of in-site measurement.
This corrosion diagnostic method simply, accurately, is not subjected to the restriction of on-the-spot service condition, be implemented under the situation that does not have a power failure and do not excavate, fault to earth mat is carried out effective diagnosis, has guaranteed construction quality and the hidden danger of having eliminated earth mat, helps maintenance and scientific management to earth mat.Owing to can prevent the generation of major accident, have very big economic benefit and social benefit.Therefore have broad application prospects and economic benefit.
The present invention is except being applied to earth mat corrosion generaI investigation system, also becomes in the earth work back of being completed the earth mat in the construction is leaked weldering and the rosin joint means of effectively inspecting for acceptance, and promptly the rosin joint of diagnostic analysis earth mat and leak the weldering situation is guaranteed the construction quality that earth mat is constructed.Equally, also can be used for the corrosion diagnosis of metallic conduit (water pipe, tracheae, oil pipe).
Brief Description Of Drawings:
Fig. 1 is the grounded screen synoptic diagram.
Fig. 2 is a measuring method synoptic diagram of the present invention.
Fig. 3 is the network diagram before and after the fault.Wherein, Fig. 3 a is the network before and after the fault, and Fig. 3 b is the network before and after the fault.
Fig. 4 is a computing module schematic flow sheet of the present invention.
Fig. 5 is a measuring system structural representation of the present invention.
Fig. 6 is a measuring system scm software process flow diagram of the present invention.
Fig. 7 is the earth mat partial structurtes figure of the embodiment of the invention.
Fig. 8 is the diagnostic result of the embodiment of the invention.
Fig. 9 is that each branch road calculated resistance of the embodiment of the invention increases multiple (corresponding extent of corrosion).
The diagnostic method of a kind of transmission transformer station ground net corrosion of the present invention and breakpoint and measurement, diagnostic system embodiment accompanying drawings are as follows:
Present embodiment has carried out the breakpoint diagnostic test to newly-built 220kV transformer station.Disconnected earth mat conductor of artificial weldering during test.The corrosion of the diagnosis transmission transformer station grounded screen of present embodiment and the operation steps of breakpoint are as follows: step 1: determine measurement scheme: with the topological structure of earth mat and the position input diagnostic software of ground lead, by diagnostic software earth mat being carried out piecemeal handles, determine measurement scheme, promptly determine to measure input resistance or transfer impedance between which ground lead.Step 2:, measure input resistance or transfer resistance according to the measurement scheme that step 1 is determined:
(a) inject D.C. high-current (about 25 amperes) to earth mat., be added between two certain two ground leads of earth mat as additional power source with about 25 amperes dc constant current power supplies.In engineering site, constant current source is more difficult to get, and can adopt the accumulator of 180 ampere-hours to replace.Can avoid the influence of the induced potential of AC power with direct supply.The increasing electric current can suppress the undesired signal in the earth mat conductor.
(b) amount obtains the voltage between each lead-in wire.Measuring system adopts the metering system of sampling/maintenance to external signal, the identical instantaneous value that can keep multiple signals, realize voltage U and electric current I synchro measure, can obtain the same instantaneous value of U, I, thereby the influence of degradation labile factor under the elimination battery tension obtains between two ground leads input resistance accurately.
(c) measurement result and diagnostic analysis software communication are directly sent into diagnostic software.
Step 3: corrosion and the crack conditions of determining each section of earth mat conductor:
(a) determine the resistance of corrosion back each section of earth mat conductor:, by input resistance or the transfer resistance between the earth mat ground lead that measures, and the earth mat topological structure of input, obtain the resistance of each section of earth mat conductor by the diagnostic software (as shown in Figure 4) of establishment.
(b) each section conductor dbus being crossed the design resistance value that each conductor resistance that the measurement structure analysis obtains and computational analysis obtain compares, situation of change according to corrosion back (or new earth mat construction finish after) each section conductor resistance, judge according to the threshold value criterion whether each section conductor ruptures, judge the degree of corrosion, if new earth mat is then judged rosin joint or leaked the situation of welding.After the grounded screen design, being completed, because length, sectional area and the material of its each section conductor are determined, its design resistance value is certain, and therefore, the difference of the resistance value of each conductor that calculates has been represented the difference of extent of corrosion.
The structure of the measurement mechanism of present embodiment as shown in Figure 5, first module be input circuit, comprise voltage-limiting protection and amplifying circuit two parts.Can select suitable amplifying circuit, to reduce the distortion of signal, drift, the temperature of strict control amplifier are floated.
Second module is the hyperchannel analog to digital conversion circuit, comprises multi-way switch, sampling/maintenance, range conversion and analog to digital conversion, converts each sampling moment analog measurement on each road to digital quantity and sends into the single-chip microcomputer mainboard.
The 3rd module is the core circuit of single-chip microcomputer, comprise data processing, system reset and data communication, the function that realizes is after microprocessor obtains analog-to-digital result, by the algorithm of design in advance it is carried out computing, and the operation result communication is reached computing machine.Above-mentioned used module all can adopt the commercially available prod.
Figure 6 shows that present embodiment measurement mechanism scm software process flow diagram.Between the lead-in wire that needs are measured, apply DC current as requested earlier, after arranging the measuring lead wire of potential difference (PD) between measuring lead wire, measuring process is for carrying out initialization process with the various piece of measuring system earlier, measure the order of beginning by the computing machine issue, determine the test time interval, data sampling, carry out digital-to-analog conversion, if measurement result unusually resampling once, carry out 300 samplings altogether, sampling is revised measurement result after finishing, and revised result transmission is sent into the measurement file of the diagnostic software in the main frame
*.msr.
The present embodiment measurement mechanism is taked careful electromagnetic screen by casing, hardware system adopts that mimic channel separates with digital circuit, the power decoupling of digit chip, ground wire overstriking, property-line are surrounded, separate measures such as each functional block and employing " house dog " circuit, and whole antijamming capability is guaranteed in measures such as the function setting that adopts the master routine inlet to increase delay time software, programmable I/O mouth on the software design carries out repeatedly, steering order execution repeatedly, instruction redundancy, digital filtering, data processing.These all are the jamproof measures of using always of microsystem.
Present embodiment earth mat partial structurtes figure as shown in Figure 7.Cut off the 5-6 conductor before the test.Diagnostic software directly exports the result with graphics mode, see Fig. 8.Gray scale among the figure is represented extent of corrosion, and black is fracture.
According to the diagnostic result file, with each horizontal branches computational data as shown in Figure 9,12 branch roads are the 5-6 conductor among the Fig. 7 that determines among the figure.Setting resistance, to increase multiple be 1.2 when following, and conductor does not corrode, and is that 3 conductors when above rupture and set resistance increase multiple.From Fig. 6, can failure judgement be the 5-6 branch road, in full accord with actual result.The in-site measurement diagnostic result is gratifying.
Analyze by measurement data and employing diagnostic software, analyze the breakpoint location that obtains and finish consistent with actual conditions fully.Experimental result is satisfactory, has verified earth mat corrosion and the accuracy of breakpoint diagnosis principle and method and the feasibility of system that the present invention proposes.To the result of the earth mat corrosion diagnosis corrosion situation basically identical with the actual earth conductor that mesh portions excavation is practically obtained, error is in 8% in addition.
Claims (6)
1, the diagnostic method of a kind of transmission transformer station ground net corrosion and breakpoint is characterized in that, may further comprise the steps:
1) adopts direct supply to be external between two ground leads of earth mat, earth mat is applied big DC current;
2) electric current in voltage between measurement earth mat two ground leads and measurement loop obtains input resistance or transfer impedance between two ground leads then;
3) measure input resistance and transfer resistance between all ground leads that the measurement scheme determined in base area net topology structure and all ground lead positions requires to measure;
4), obtain the resistance value of each section conductor by the diagnostic software analysis with the topological structure input diagnostic software of measurement result and earth mat; The resistance value of each section earth mat conductor that analysis the is obtained design resistance value that computational analysis obtains when intact with the hypothesis earth mat compares, and whether ruptures the degree of corrosion according to the conductor of this section of threshold decision earth mat.
2, the diagnostic method of transmission transformer station ground net corrosion as claimed in claim 1 and breakpoint, it is characterized in that, the said the 1st) Bu employing direct supply is external between two ground leads of earth mat, and earth mat is applied the method for big DC current, specifically may further comprise the steps;
(1) with the topological structure of earth mat and the position input diagnostic software of ground lead, determines measurement scheme, promptly determine to measure input resistance or transfer resistance between which ground lead by diagnostic software;
(2) inject D.C. high-current to earth mat, being added in two of earth mats needs between the ground lead of measurement.
3, the diagnostic method of transmission transformer station ground net corrosion as claimed in claim 1 and breakpoint, it is characterized in that, the said the 2nd) electric current in voltage between Bu measurement earth mat two ground leads and measurement loop, then obtain the input resistance between two ground leads or the method for transfer impedance, specifically comprise:
Measure voltage between each lead-in wire and the size of current that applies, adopt the metering system of sampling/maintenance, realize voltage U and electric current I synchro measure, obtain voltage, the same instantaneous value of electric current, promptly obtain these two input resistance or the transfer resistances that need to measure between ground lead.
4, a kind of employing according to claim 1 the earth mat corrosion and the breakpoint of the diagnostic method of transmission transformer station ground net corrosion and breakpoint measure, diagnostic system, it is characterized in that, comprise computing machine and be stored in the diagnostic software of establishment in advance in this computer memory, and with the small electric resistance measuring apparatus of this diagnostic software communication; Said small electric resistance measuring apparatus comprises the analog input circuit of gathering measuring-signal, convert the analog measurement of each sampling moment on each road the hyperchannel analog to digital conversion circuit of digital quantity to, and will convert single-chip microcomputer and digital circuit thereof that the signal of digital quantity carries out computing and processing to; Said input circuit is made up of voltage-limiting protection and amplifying circuit; Said hyperchannel analog to digital conversion circuit is made up of multi-way switch, sampling/maintenance, range conversion and analog to digital conversion, the circuit of said single-chip microcomputer is made up of data processing, system reset and data communication, also comprise the measurement data interpretation software of establishment in advance that is stored in the single-chip microcomputer storer, this data communication is sent to diagnostic software in the computing machine with measurement result.
5, earth mat corrosion as claimed in claim 4 and breakpoint measurement, diagnostic system, it is characterized in that, the diagnostic software of establishment in advance in the said storer that is stored in computing machine, by topological structure input, measurement scheme determine, corrosion and breakpoint analysis and analytical structure graphical display function module form.
6, earth mat corrosion as claimed in claim 4 and breakpoint measurement, diagnostic system, it is characterized in that, said measurement mechanism is installed in the casing with electromagnetic screen, and said mimic channel and digital circuit branch are arranged, also comprise with the power decoupling of the chip of digital circuit, with ground wire overstriking, property-line encirclement, separate each functional block and employing " house dog " circuit; The function setting that said software adopts the master routine inlet to increase time-delay software, programmable I/O mouth carries out repeatedly, steering order execution repeatedly, instruction redundancy, digital filtering, data processing function module.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 99109622 CN1110707C (en) | 1999-07-02 | 1999-07-02 | Diagnosis method of earth screen corrosion and breakpoint of electric substation and its measurement and diagnosis system |
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| CN 99109622 CN1110707C (en) | 1999-07-02 | 1999-07-02 | Diagnosis method of earth screen corrosion and breakpoint of electric substation and its measurement and diagnosis system |
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| CN1110707C true CN1110707C (en) | 2003-06-04 |
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