CN105044559B - The subregion method for diagnosing faults of grounding net of transformer substation - Google Patents
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Abstract
A kind of subregion method for diagnosing faults of grounding net of transformer substation carries out layer reduction for given ground grid design topological structure to grounded screen topological structure；According to original design data, the nominal value parameter of branch resistance is calculated, select common node, generate incidence matrix A and branch admittance matrix Y；Simulation circuit model is built, node i is chosen in circuit, applies direct current source forcing I between j0, test it is selected can and node voltage Uij, i is obtained, the port resistive R between jij；After grounded screen fault, node i, the port resistive measured value between j becomes R 'ij, under grounded screen normal condition can and port resistive compare, obtain port resistive difference value vector Δ Rij, according to fault diagnosis model, establish diagnosis equation group；Diagnosis equation group is solved, result of calculation to the end is obtained；According to solving result, branch resistance value is with respect to the multiple of nominal value, failure judgement situation after calculating intrinsic grounded screen fault.
Description
It is August in 2014 20 this application claims the applying date, application No. is 201410412091.X, entitled " substations
The priority of the subregion method for diagnosing faults of grounded screen ".
Technical field
The present invention relates to technical field of electric power, and in particular, to a kind of subregion failure of grounding net of transformer substation is examined
Disconnected method.
Background technology
Grounding net of transformer substation usually uses band steel or round steel horizontal laying, is arranged in long pass or square groove, is embedded to underground 0.6
~0.8m, area are substantially identical as the area of power plant and substation.Grounded screen is to the safe operation of electrical equipment to closing weight
It wants, in recent years, substation operation accident caused by due to the reduction of grounded screen electric property increases year by year, the wherein corruption of conductor
Erosion, fracture or solder skip etc. are the latencies for causing ground connection performance to decline, will if meeting electric system occurs ground short circuit failure
Cause earth mat partial potential difference itself and earth mat potential anomalies to increase, except to the safety belt of operations staff come in addition to threatening, it is also possible to
Because counterattack or cable skin circulation so that the insulation of secondary device is destroyed, high pressure scurries into control room, makes monitoring or control device
Malfunction or tripping occurs and expands accident, brings huge economic loss and undesirable social influence.It can be seen that grounded screen
Failure has been a mortal malady of safe operation of power system, and the corrosion condition of the breakpoint and earth mat that diagnose grounded screen has become electric power
One great anti-accident measures of department.The ground connection performance of grounded screen is generally sentenced by the size of measure field ground resistance indirectly
It is disconnected, but ground net corrosion situation can not be judged accordingly, when the corrosion of earth mat conductor is even broken, ground resistance still may be normal.I.e.
So that ground resistance is measured display exception, can not also learn the specific location of failure, and extensive excavate is needed to search fault point, work
Work amount is huge and with high costs.Fault Diagnosis for Grounding Grids for scent a hidden danger and take in time corresponding measure have directive significance,
Due to by can and interstitial content and its distributing position limited, the difficulty of this work is very big.
Currently, domestic and foreign scholars have been achieved for some achievements in research in Fault Diagnosis for Grounding Grids field, it is mainly reflected in
In two class methods：One kind is the detection method based on electromagnetic field method or surface potential, passes through the electromagnetic field parameters or electricity of ground surface
The physical signals such as position parameter feedback signal judge that the crack conditions of sub-surface conductors, result lack good criterion at present, seriously
It relies on the precision of equipment and is vulnerable to the interference at scene, and diagnostic result whether fracture can only be made and can not be known specific
Corrosion condition.Also one kind is the method for establishing Fault Diagnosis for Grounding Grids equation based on electric network theory, by grounded screen
Equivalent model is established, the relationship side of port resistive value and branch resistance value is established based on the model and using conservation of the similar power principle
Journey, and the optimal solution that equation obtains nonlinear equation is solved using the alternative manner of least square.There is scholar to further study
Application of the novel intelligent optimization algorithm in solving diagnosis equation, achieves certain effect, but due to fault diagnosis side
The Degree of Ill Condition of journey is high, can be obtained that data are relatively fewer, and the result reliability that the above method obtains is still relatively low.It is examined to improve
Disconnected reliability, researcher propose according to the structure of grounded screen can and node at network is layered and yojan, obtain
Containing only can and node intrinsic grounded screen, and clear-branch branch at all levels is further determined using the method successively traced back
Resistance situation reduces the Degree of Ill Condition of diagnostic equation, but wherein uncertain-branch is still more, and algorithm structure complexity,
Calculation amount is very big.
Due to the ground lead of its power transformation station equipment be it is limited, no matter the grounded screen fault of which kind of method structure
Diagnostic equation is all underdetermined equation, and the result obtained has uncertainty.For engineering reality, if it is possible to determine grounded screen
Fault zone position, for guidance scene targetedly excavate safeguard it is very significant, therefore, how according to such
Model is imitated, validity and the accuracy to Fault Diagnosis for Grounding Grids is improved using a kind of new method, is to special procure solution at present
The problem of.
Invention content
The purpose of the present invention is to provide a kind of subregion method for diagnosing faults of grounding net of transformer substation, this method is a kind of
Grounded screen subregion method for diagnosing faults based on topological hierarchy yojan, theme be for grounded screen can and node distribution
Situation carries out layer reduction to grounded screen to grounded screen topological structure subregion, according to division result and obtains intrinsic grounded screen, to this
The changing value of each branch resistance is calculated in intrinsic grounded screen application and trouble diagnostic equation group model and optimization algorithm, according to every
Fault condition in branch corresponding grounded screen region decision region, underdetermined problem when this method avoids solving equation group,
Significantly improve the reliability and accuracy of diagnostic result.
In order to achieve the above objectives, the present invention provides a kind of subregion method for diagnosing faults of grounding net of transformer substation, this method,
Include the following steps：
Step 1：For given grounded screen original design topological structure, application circuit network theory is to grounded screen topology knot
Structure carries out yojan, prunes unreachable node,:By a grounded screen be decomposed into grounded screen, accurate first column, first column, metanetwork, can
And 6 levels of grounded screen and intrinsic grounded screen；
Step 2：The result decomposed according to accurate first column stage topology divides the geographic location area of grounded screen, and compiles successively
Number；
Step 3：To every branch in intrinsic grounded screen successively trace each branch region or by which region about
Letter obtains, and records the corresponding zone number of each branch in the table；
Step 4：According to the original design data of grounded screen, the nominal value parameter of the branch resistance of intrinsic grounded screen is calculated,
Common node is selected, incidence matrix A and branch admittance matrix Y is generated；
Step 5：According to intrinsic grounded screen topological structure, simulation circuit model is built, scheme is measured using abundant, in circuit
Middle selection node i applies direct current source forcing I between j0, test it is selected can and node voltage Uij, i is obtained, the port electricity between j
Hinder Rij；
Step 6：After grounded screen fault, node i, the port resistive measured value between j becomes R 'ij, with grounded screen normal condition
Under can and port resistive comparison, obtain port resistive difference value vector Δ Rij, according to Fault Diagnosis for Grounding Grids model, establish failure and examine
Disconnected equation group；
Step 7：Diagnosis equation group is solved using Least-squares minimization algorithm, obtains result of calculation to the end；
Step 8：According to the solving result in step 7, branch resistance value is relatively nominal after calculating intrinsic grounded screen fault
The multiple of value, according to the fault condition in each item intrinsic branch trouble situation region decision corresponding with its each region.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, in step 1：
The accurate first column be one group can and node at grounded screen is torn after obtained minimum unit network；
The member column is merged to obtain by accurate first version series and parallel branch in the block, at the same retain it is all can and node；
The metanetwork be by each piece in first column by conversion of circuits be changed into containing only can and node it is equivalent
Network；
It is described can and grounded screen be in whole metanetworks with same node point branch be attached composition containing only can and
The network of node；
The intrinsic grounded screen be by can and grounded screen in whole parallel branches merge to obtain, any two can and section
At most there are a branch, referred to as intrinsic branch between point.
Step 3 is specially：Since every branch in intrinsic grounded screen is by all accurate first versions several columns in the block
What interior branch obtained after conversion of circuits, and each accurate first column corresponds to a region in original grounded screen.Cause
This successively traces its region or by which according to conversion of circuits process to every branch in intrinsic grounded screen
Branch in quasi- member column converts to obtain, and corresponds to each region in step 2 according to its region or these accurate first columns
Number, records the corresponding zone number of each branch in the table.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, in step 4, tool
Body is the resistance value that each branch of original grounded screen is calculated according to the original design data of grounded screen, each of original grounded screen
Obtain connecing after the equivalent transformation of Lu Jing oversampling circuits accurate first column, first column, metanetwork, can and grounded screen and intrinsic grounded screen,
According to conversion of circuits principle, the resistance value of each branch of each level grounded screen is successively calculated, finally reckoning obtains intrinsic
The nominal value parameter of the branch resistance of grounded screen；Then, it selects common node and defines A to select network after a reference mode
Incidence matrix；YbFor branch admittance matrix；YnFor node admittance matrix；Have between branch admittance matrix and node admittance matrix
There is following relationship：
Yn=A*Yb*AT (1)
In formula, ATFor the transposed matrix of incidence matrix A.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, step 5 is specific
For：
If a normal ground connection pessimistic concurrency control N has b+1 branch, n+1 node, to the grounded screen equivalent resistance network
All nodes and branch press following rule numbers：Node serial number：It is subject to final topology figure, from top to down, until it is left and right, into
Row number, the last one node is not numbered, and is set to datum mark, and when measurement does not also allow to use；Branch number：With final
Subject to topological diagram, from top to down, until it is left and right, it is numbered, first transverse legs is numbered, then to longitudinal branch number.B+1
Branch is connected to the i of ground lead, and the ends j add DC current source forcing, current value I in the ports i-th, j0, according to electricity
Road principle seeks Rij, define IbFor branch current square；UnFor node voltage column vector；InIt is non-actuated for the current source column vector of node
The current value of node is 0；
The Kirchhoff's current law (KCL) and Kirchhoff's second law equation of resistor network are expressed as：
AIb=0 (2)
Ub=ATUn (3)
U in formulabIndicate the voltage of node b.
It can be obtained in conjunction with formula (1), (2), (3)
YnUn=In (4)
Port resistive RijCalculating formula is：
Rij=Ub+1/I0 (5)
U in formulab+1Indicate the voltage of node b+1.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, step 6 is specific
For：
Grounded screen to that the illustraton of model after corrosion failure occur and is considered as Wang LuoN ', still in its i, the ends j add the current source, current value to be
I0, find out Rij'；Network N and Wang LuoN 'Topological structure is identical；To circuit N and N&apos with identical topological structure;, and corresponding branch
Road and node, which take, to be identically numbered, and the reference direction of each branch is identical, is then had with theorem according to Teller：
In formula, Ik'、Uk'Respectively electric network N'Branch current and branch voltage, Ik、UkThe respectively branch of electric network N
Road electric current and branch voltage；When corrosion or fracture defect occur for branch k, branch resistance is by RkBecome Rk', i.e.,：
ΔRk=Rk'-Rk (8)
The resistance at the both ends i at this time, j is by RijBecome Rij'I.e.：
ΔRij=Rij'-Rij (9)
Because two networks in i, the electric current of the b+1 articles branch at the ends j is all I0, i.e.,：
Ib+1=I'b+1=I0 (10)
Ub+1=-RijI0 (11)
U'b+1=-R'ijI0 (12)
Formula (10), (11), (12) are substituted into formula (6), in (7)：
Formula formula (13) subtracts formula (14) and obtains：
Formula (8), (9) are substituted into formula (15) and obtained：
Formula (16) indicates the relationship of branch resistance changing value and the variation of port resistive value, due to branch resistance in the network
Variable have b, it is therefore desirable to measure a series of port resistive, it is assumed that the different port numbers of measurement are m, to obtain
Equation group：
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, step 7 includes
Following steps：
Step 71：The topological structure and branch resistance R of grounded screen are obtained from design drawingk；It is calculated according to circuit theory
Ik(s), choose measuring node group and find out resistance R between theoretical nodeij(s)(s=1~m)；
Step 72：Measurement port resistance R 'ij(s), calculate port resistive changing value Δ Rij(s)=R 'ij(s)-Rij(s)；
Step 73：Enable I 'k(s)(0)=Ik(s), I 'k(s)(0) when being first iteration each branch current value；
Step 74：With equation group (17) Δ R is calculated in conjunction with least square optimizationk (t)(s), t=0,1 ..., t are
Iterations, Δ Rk (t)(s) when being the t times iteration branch resistance difference；Since original leg resistance is Rk, in addition the t times changes
For when branch resistance difference DELTA Rk (t)(s), the t times branch resistance value is obtained
Step 75：If the Er Qies of t >=1 |ΔRk (t)-ΔRk (t-1)|< ε are obtained then stopping iterative calculationIt is last
As a result, ε is the constant of setting；It is no to then follow the steps 76；
Step 76：WithCalculate I 'k(s) (t+1), I 'k(s) (t+1)The current value of each article of branch when being the t+1 times iteration；Weight
Multiple step 74 and step 75.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, described minimum two
Multiplying optimization method formula is：
In formula,The resistance calculations difference of the b articles branch when being the t times iteration,It is the t times and t-1 iteration
When port resistive difference.
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, least square is excellent
The value lower limit of parameter in change method is the nominal value of branch resistance, and the upper limit is 50 times of nominal value, the upper limit value, lower limiting value
Constraints in corresponding formula (18).
According to the subregion method for diagnosing faults of the grounding net of transformer substation described in present pre-ferred embodiments, in step 8, electricity
It is as follows that resistance value increases multiple situation corresponding with fault degree：
It is normal if μ is 1~2 if it is μ that resistance value, which increases multiple,；There is minor failure if μ is 2~4；If μ is
4~10 there is moderate failure；There is heavier failure if μ is 10~20；There is catastrophe failure if μ is 20~40；If μ is
40 or more are then broken.
Compared with prior art, the present invention has the following advantages due to taking above technical scheme：
1, the mathematical model that grounded screen subregion fault diagnosis is established in the present invention, by complicated Fault Diagnosis for Grounding Grids
Problem is converted into the solution to mathematical model, quantifies to grounded screen fault degree, and diagnostic result is easy to understand.
2., the present invention avoid solve equation group when underdetermined problem grounded screen is changed by topological structure layer reduction
For containing only can and node intrinsic network, using abundant testing scheme, it is less qualitative to reduce diagnostic equation group, significantly improves diagnosis knot
The reliability and accuracy of fruit.
3., the present invention to grounded screen dividing regions domain, diagnostic result is as a result reliable accurate for the fault condition in region,
The reference that grounded screen is excavated when checking is may be used as to be easy to use for instructing substation field maintenance more efficient and practical
Into Practical Project.
Description of the drawings
Fig. 1 is the subregion method for diagnosing faults method flow diagram of grounding net of transformer substation of the present invention；
Fig. 2 is the grounded screen equivalent model figure of the present invention；
Fig. 3 is the grounded screen topological diagram of the present invention；
Fig. 4 is the first column figure of standard of the present invention；
Fig. 5 is first column figure of the present invention；
Fig. 6 is the metanetwork figure of the present invention；
Fig. 7 be the present invention can and grounded screen figure；
Fig. 8 is the intrinsic grounded screen figure of the present invention；
Fig. 9 is the grounded screen subregion figure of the present invention；
Figure 10 is that Matlab exports branch resistance with respect to nominal value multiple block diagram.
Specific implementation mode
Below with reference to the attached drawing of the present invention, technical solution in the embodiment of the present invention carries out clear, complete description
And discussion, it is clear that as described herein is only a part of example of the present invention, is not whole example, based on the present invention
In embodiment, the every other implementation that those of ordinary skill in the art are obtained without making creative work
Example, belongs to protection scope of the present invention.
For the ease of the understanding to the embodiment of the present invention, make further by taking specific embodiment as an example below in conjunction with attached drawing
It illustrates, and embodiment does not constitute the restriction to the embodiment of the present invention.
First principles analysis：
Be embedded in underground grounded screen water mean pressure conductor be connected with each other constitute circuit network, ignore the influence of edphic factor,
Grounded screen can regard pure resistance network as.After net is completed, since the length of each section of conductor, sectional area and conductivity are true
It is fixed, their resistance value, i.e. nominal value can be calculated；Rear certain section of conductor occurs fracture or corrodes local network operation for many years
When (its topological structure is unchanged), its branch resistance becomes larger compared with nominal value at this time.Meanwhile Substation Electric Equipment have and
The ground lead that earth mat is connected, if grounded screen to be regarded as to the black box of a resistive network, and ground lead can
With regard as it can and port, as shown in Figure 2.Wherein original network port resistance (resistance i.e. between ground lead, similarly hereinafter)
Because of topological structure, branch resistance according to electric network theory it is known that can be calculated；And corrode after grounded screen port resistive
Value can measure corrosion by ground lead and be followed by because Substation Electric Equipment has the ground lead being connected with grounded screen
The port resistive value of earth mat.It can be obtained by port resistive changing value in this way, port electricity can be found out using Tellegen
The relationship for hindering changing value and branch resistance changing value, reapplies mathematical method appropriate, can be released from node-resistance changing value
The increased resistance value of grounded screen branch, to judge Grounding Grid and breakpoint situation.
A kind of subregion method for diagnosing faults of grounding net of transformer substation, includes the following steps：
Step 1：For given grounded screen original design topological structure, application circuit network theory is to grounded screen topology knot
Structure carries out yojan, prunes unreachable node, by a grounded screen be decomposed into grounded screen, accurate first column, first column, metanetwork, can
And 6 levels of grounded screen and intrinsic grounded screen；
The accurate first column be one group can and node at grounded screen is torn after obtained minimum unit network；
The member column is merged to obtain by accurate first version series and parallel branch in the block, at the same retain it is all can and node；
The metanetwork be by each piece in first column by conversion of circuits be changed into containing only can and node it is equivalent
Network；
It is described can and grounded screen be in whole metanetworks with same node point branch be attached composition containing only can and
The network of node；
The intrinsic grounded screen be by can and grounded screen in whole parallel branches merge to obtain, any two can and section
At most there are a branch, referred to as intrinsic branch between point.
Step 2：The result decomposed according to accurate first column stage topology divides the geographic location area of grounded screen, and compiles successively
Number.
Step 3：To every branch in intrinsic grounded screen successively trace each branch region or by which region about
Letter obtains, and records the corresponding zone number of each branch in the table；
Specifically, every branch in intrinsic grounded screen is to be passed through by the branch in all accurate first versions several columns in the block
It is obtained after oversampling circuit equivalent transformation, and each accurate first column corresponds to a region in original grounded screen.Therefore, according to circuit
Equivalent transformation process successively traces its region or by which accurate first column to every branch in intrinsic grounded screen
Branch converts to obtain, and corresponds to the number in each region in step 2 according to its region or these accurate first columns, in the table
Record the corresponding zone number of each branch.
Step 4：According to the original design data of grounded screen, the nominal value parameter of the branch resistance of intrinsic grounded screen is calculated,
The resistance value of each branch of original grounded screen is specially calculated according to the original design data of grounded screen, original grounded screen is each
Branch obtain connecing after the equivalent transformation through oversampling circuit accurate first column, first column, metanetwork, can and grounded screen and intrinsic ground connection
Net successively calculates the resistance value of each branch of each level grounded screen according to conversion of circuits principle, finally calculates and obtains this
Levy the nominal value parameter of the branch resistance of grounded screen；Then selection common node generates incidence matrix A and branch admittance matrix Y.
Define the incidence matrix that A is network after selecting a reference mode；YbFor branch admittance matrix；YnFor node admittance
Matrix；There is following relationship between branch admittance matrix and node admittance matrix：
Yn=A*Yb*AT (1)
In formula, ATFor the transposed matrix of incidence matrix A.
Step 5：According to intrinsic grounded screen topological structure, simulation circuit model is built in Multisim simulation softwares, is answered
Scheme is measured with abundant, node i is chosen in circuit, applies direct current source forcing I between j0, test it is selected can and node voltage
Uij, i is obtained, the port resistive R between jij。
If a normal ground connection pessimistic concurrency control N has b+1 branch, n+1 node, to the grounded screen equivalent resistance network
All nodes and branch press preset rule numbers node serial number：Be subject to final topology figure, from top to down, until it is left and
The right side is numbered, the last one node opened up in complement is not numbered, and is set to datum mark and (is used as incidence matrix below
Reference mode), when measurement, does not also allow to use；Branch number：It is subject to final topology figure, from top to down, until it is left and right, into
Row number first numbers transverse legs, then to longitudinal branch number.The b+1 articles branch is connected to the i of ground lead, the ends j,
The port i-th, j adds DC current source forcing, current value I0, R is asked according to circuit theoryij, define IbFor branch current square；
UnFor node voltage column vector；InCurrent value for the current source column vector of node, non-actuated node is 0；
The KCL (Kirchhoff's current law (KCL)) and KVL (Kirchhoff's second law) journey of resistor network are expressed as：
AIb=0 (2)
Ub=A'Un (3)
U in formulabIndicate the voltage of node b.
It can be obtained in conjunction with formula (1), (2), (3)
YnUn=In (4)
Port resistive RijCalculating formula is：
Rij=Ub+1/I0 (5)。
U in formulab+1Indicate the voltage of node b+1.
Step 6：After grounded screen fault, node i, the port resistive measured value between j becomes R’ ij, with grounded screen normal condition
Under can and port resistive comparison, obtain port resistive difference value vector Δ Rij, according to Fault Diagnosis for Grounding Grids model, establish failure and examine
Disconnected equation group.
Grounded screen to that the illustraton of model after corrosion failure occur and is considered as Wang LuoN ', still in its i, the ends j add the current source, current value to be
I0, find out Rij'；Network N and Wang LuoN 'Topological structure is identical；To circuit N and N&apos with identical topological structure;, and corresponding branch
Road and node, which take, to be identically numbered, and the reference direction of each branch is identical, is then had with theorem according to Teller：
In formula, Ik'、Uk'Respectively electric network N'Branch current and branch voltage, Ik、UkThe respectively branch of electric network N
Road electric current and branch voltage；When corrosion or fracture defect occur for branch k, branch resistance is by RkBecome Rk', i.e.,：
ΔRk=Rk'-Rk (8)
The resistance at the both ends i at this time, j is by RijBecome Rij'I.e.：
ΔRij=Rij'-Rij(9)
Because two networks in i, the electric current of the b+1 articles branch at the ends j is all I0, i.e.,：
Ib+1=I'b+1=I0 (10)
Ub+1=-RijI0 (11)
U'b+1=-R'ijI0 (12)
Formula (10), (11), (12) are substituted into formula (6), in (7)：
Formula formula (13) subtracts formula (14) and obtains：
Formula (8), (9) are substituted into formula (15) and obtained：
Formula (16) indicates the relationship of branch resistance changing value and the variation of port resistive value, due to branch resistance in the network
Variable have b, it is therefore desirable to measure a series of port resistive, it is assumed that the different port numbers of measurement are m, to obtain
Equation group：
Step 7：Diagnosis equation group is solved using Least-squares minimization algorithm in MATLAB softwares, is obtained
Last result of calculation.
Formula (17) belongs to Nonlinear System of Equations, can not direct solution, alternative manner can be introduced.First, I ' is enabledk(0)=
Ik, equation group becomes system of linear equations, but m < b equation groups owe fixed, need to use Optimization Method, herein be it is non-negative most
Small square law.Thus find out Δ Rk(0) and R 'k(0), R ' is then usedk(0) I ' is calculatedk(1)；Then I ' is usedk(1) R ' is calculatedk
(1).Calculating above is repeated, until the resistance delta found out is met the requirements, obtains result of calculation to the end.It specifically includes following
Step：
Step 71：The topological structure and branch resistance R of grounded screen are obtained from design drawingk；It is calculated according to circuit theory
Ik(s), choose measuring node group and find out resistance R between theoretical nodeij(s)(s=1~m)；
Step 72：Measurement port resistance R 'ij(s), calculate port resistive changing value Δ Rij(s)=R 'ij(s)-Rij(s)；
Step 73：Enable I 'k(s)(0)=Ik(s), I 'k(s)(0) when being first iteration each branch current value；
Step 74：With equation group (17) Δ R is calculated in conjunction with least square optimizationk (t)(s) (t=0,1 ..., t are
Iterations), Δ Rk (t)(s) when being the t times iteration branch resistance difference；Since original leg resistance is Rk, in addition the t times
The difference DELTA R of branch resistance when iterationk (t)(s), the t times branch resistance value is obtained
Step 75：If the Er Qies of t >=1 |ΔRk (t)-ΔRk (t-1)|< ε are obtained then stopping iterative calculationFor most
Afterwards as a result, ε is the constant of setting；It is no to then follow the steps 76；
Step 76：WithCalculate I 'k(s) (t+1), I 'k(s) (t+1)The current value of each article of branch when being the t+1 times iteration；Weight
Multiple step 74 and step 75.
Because the number of unknown quantity is b in equation group (17), the exact value of these variables is obtained, the number of equation number is answered
It is less than the branch quantity of grounded screen for the quantity of b, but general substation grounding lead, solution of equations is not unique.In view of engineering
Practical problem often only has range very small percentage to be reasonable, introduces constrained linear programming problem in these solutions
To obtain optimal solution.Preferable exact value in order to obtain needs to use Techniques of Optimum, specifically, least square optimization
Formula is：
In formula,The resistance calculations difference of the b articles branch when being the t times iteration,It is the t times and t-1 iteration
When port resistive difference.The formula is during solution formula (17) as adaptation value function so that the difference of port resistive
Variation reaches minimum.
Limitation with constraints to domain can make solution more reasonable, while be also beneficial to planning problem in reality
The effect that border calculates.Being constrained to for lower variable is non-negative, ensures that solution is of practical significance in engineering；Step-length limit is made to upper variable
System, it is ensured that the solution acquired is the optimal solution near every single-step iteration initial value, meets the actual conditions of iterative process.Specifically
Ground, the value lower limit (descending variable) of the parameter in least square optimization are the nominal value of branch resistance, and the upper limit is (i.e. upper to become
Amount) it is 50 times of nominal value.
Step 8：According to the solving result in step 7, branch resistance value is relatively nominal after calculating intrinsic grounded screen fault
The multiple of value, according to the fault condition in the corresponding region decision each region of each branch.
Specifically, it is as shown in table 1 to increase multiple situation corresponding with fault degree for resistance value.
1 resistance value of table increases multiple situation corresponding with fault degree
The subregion method for diagnosing faults of the grounding net of transformer substation of the present invention is done further below in conjunction with specific embodiment
It is described in detail.
Embodiment one
Fig. 3 show certain grounding net of transformer substation network topological diagram, have 16 nodes, wherein 2,4,5,7,8,10,11,
14,16 for can and node, the grounded screen it is specific decompose can be referring to Fig. 4~8 this paper.Under normal condition, every branch is nominally electric
Resistance value is 60m Ω, and existing three branches break down, are followed successively by：1-2 branches become 300m Ω, and 7-8 branches become 600m
Ω, 11-15 branch become 900m Ω.Fig. 4~8 are the quasi- member that the Grounding net topology structural stratification yojan obtains respectively
Column, first column, metanetwork, can and grounded screen and intrinsic grounded screen, Fig. 9 be that grounded screen divides administrative division map.Then according to accurate first version
Block yojan is the process of intrinsic grounded screen, successively traces back every branch in intrinsic grounded screen to grounded screen, every branch in Fig. 8
Shown in the correspondence situation table 1 converted by ground connection web area.
1 intrinsic branch of table situation corresponding with ground connection web area
Ground connection pessimistic concurrency control is built in Multisim, applies the continuous current excitation of 10A, according to ideal optimal abundant test side
Case selects measurement port, and the port resistive situation of change for measuring intrinsic grounded screen before and after failure is as shown in table 2.
2 intrinsic grounded screen port resistive situation of change of table
Using the method for the invention, diagnosis equation group is established, least square is applied in Matlab calculation procedures
Iterative algorithm is solved, and it is as shown in Figure 10 to obtain diagnostic result.
From diagnostic result as can be seen that obvious fault, wherein branch 2-5 electricity occur in branch 2-5,7-8,11-14,11-16
Resistance is increased to original 2.5 times, and branch 7-8 resistance is increased to original 9.4 times, and branch 11-14 resistance is increased to original 10.6 times, branch
Road 11-16 resistance is increased to original 1.9 times, and the region of grounded screen is corresponded to according to branch, it can be determined that 1., 4., 5., 9.,Area
There are fault branches in domain.Since 4., 9. other branches of the intrinsic grounded screen corresponding to region do not have failure, so 4., 9.
Region is pseudo- fault zone.Therefore, in grounded screen there are the region of failure be 1., 5.,, and 1. region is minor failure, 5.,For more serious failure.The diagnostic result is consistent with the case where actual set, illustrates that the method for diagnosing faults of this paper can be just
The fault condition being really diagnosed to be in small-sized grounded screen each region.
Disclosed above is only several specific embodiments of the present invention, but the present invention is not limited to this, any this field
Technical staff can think variation, should all be within the scope of the present invention.
Claims (9)
1. a kind of subregion method for diagnosing faults of grounding net of transformer substation, which is characterized in that include the following steps：
Step 1：For given grounded screen original design topological structure, application circuit network theory to grounded screen topological structure into
Unreachable node is pruned in row yojan, and a grounded screen is decomposed into grounded screen, accurate first column, first column, metanetwork, can and be connect
6 levels of earth mat and intrinsic grounded screen；
Step 2：The result decomposed according to accurate first column stage topology divides the geographic location area of grounded screen, and number consecutively；
Step 3：Each branch region is successively traced to every branch in intrinsic grounded screen or is obtained by which region yojan
It arrives, and records the corresponding zone number of each branch in the table, specially：
According to conversion of circuits process, its region is successively traced to every branch in intrinsic grounded screen or by which
Branch in quasi- member column converts to obtain, and corresponds to each region in step 2 according to its region or these accurate first columns
Number, records the corresponding zone number of each branch in the table；
Step 4：According to the original design data of grounded screen, the nominal value parameter of the branch resistance of intrinsic grounded screen is calculated, select
Common node generates incidence matrix A and branch admittance matrix Y；
Step 5：According to intrinsic grounded screen topological structure, simulation circuit model is built, scheme is measured using abundant, selects in circuit
Node i is taken, applies direct current source forcing I between j0, test it is selected can and node voltage Uij, i is obtained, the port resistive R between jij；
Step 6：After grounded screen fault, node i, the port resistive measured value between j becomes R 'ij, and can under grounded screen normal condition
And port resistive comparison, obtain port resistive difference value vector Δ Rij, according to Fault Diagnosis for Grounding Grids model, establish fault diagnosis side
Journey group；
Step 7：Diagnosis equation group is solved using Least-squares minimization algorithm, obtains result of calculation to the end；
Step 8：According to the solving result in step 7, branch resistance value is with respect to nominal value after calculating intrinsic grounded screen fault
Multiple, according to the fault condition in each item intrinsic branch trouble situation region decision corresponding with its each region.
2. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 1, which is characterized in that in step 1：
The accurate first column be one group can and node at grounded screen is torn after obtained minimum unit network；
The member column is merged to obtain by accurate first version series and parallel branch in the block, at the same retain it is all can and node；
The metanetwork be by each piece in first column by conversion of circuits be changed into containing only can and node equivalent network；
It is described can and grounded screen be in whole metanetworks with same node point branch be attached composition containing only can and node
Network；
The intrinsic grounded screen be by can and grounded screen in whole parallel branches merge to obtain, any two can and node between
At most there are a branch, referred to as intrinsic branch.
3. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 1, which is characterized in that in step 4,
Define the incidence matrix that A is network after selecting a reference mode；YbFor branch admittance matrix；YnFor node admittance matrix；Branch
There is following relationship between admittance matrix and node admittance matrix：
Yn=A*Yb*AT (1)
In formula, ATFor the transposed matrix of incidence matrix A.
4. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 3, which is characterized in that step 5 has
Body is：
One normal grounded screen is equivalent to equivalent resistance network N, which has b+1 branch, n+1 a
Node, all nodes and branch to the equivalent resistor network N press following rule numbers：Node serial number：It is with final topology figure
Standard until left and right, is numbered from top to down, the last one node is not numbered, and is set to datum mark, when measurement also not
Allow to use；Branch number：It is subject to final topology figure, from top to down, until it is left and right, it is numbered, first to transverse legs volume
Number, then to longitudinal branch number；The b+1 articles branch is connected to the i of ground lead, and the ends j add DC current in the ports i-th, j
Source forcing, current value I0, R is asked according to circuit theoryij, define IbFor branch current square；UnFor node voltage column vector；In
Current value for the current source column vector of node, non-actuated node is 0；The Kirchhoff's current law (KCL) of resistor network and Kiel are suddenly
Husband's voltage law equation is expressed as：
AIb=0 (2)
Ub=ATUn (3)
U in formulabIndicate the voltage of node b；
It can be obtained in conjunction with formula (1), (2), (3)
YnUn=In (4)
Port resistive RijCalculating formula is：
Rij=Ub+1/I0 (5)
U in formulab+1Indicate the voltage of node b+1.
5. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 4, which is characterized in that step 6 has
Body is：
Grounded screen after generation corrosion failure is equivalent to resistor network N', still in its i, the ends j add current source, current value I0, ask
Go out Rij'；Equivalent resistance network N and resistor network N'Topological structure is identical；To the equivalent resistance network N with identical topological structure
With resistor network N', and corresponding branch and node take and are identically numbered, and the reference direction of each branch is identical, according to Teller
Then have with theorem：
In formula, Ik'、Uk'Respectively resistor network N'Branch current and branch voltage, Ik、UkRespectively equivalent resistance network N
Branch current and branch voltage；When corrosion or fracture defect occur for branch k, branch resistance is by RkBecome Rk', i.e.,：
ΔRk=Rk'-Rk (8)
The resistance at the both ends i at this time, j is by RijBecome Rij'I.e.：
ΔRij=Rij'-Rij (9)
Because two networks in i, the electric current of the b+1 articles branch at the ends j is all I0, i.e.,：
Ib+1=I'b+1=I0 (10)
Ub+1=-RijI0 (11)
U'b+1=-R'ijI0 (12)
Formula (10), (11), (12) are substituted into formula (6), in (7)：
Formula (13) subtracts formula (14) and obtains：
Formula (8), (9) are substituted into formula (15) and obtained：
Formula (16) indicates the relationship of branch resistance changing value and the variation of port resistive value, due to the change of branch resistance in the network
Amount has b, it is therefore desirable to measure a series of port resistive, it is assumed that the different port numbers of measurement are m, to obtain equation
Group：
6. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 5, which is characterized in that step 7 is wrapped
Include following steps：
Step 71：The topological structure and branch resistance R of grounded screen are obtained from design drawingk；I is calculated according to circuit theoryk(s), choosing
Resistance R between taking measuring node group to find out theoretical nodeij(s)S=1~m；
Step 72：Measurement port resistance R 'ij(s), calculate port resistive changing value Δ Rij(s)=R 'ij(s)-Rij(s)；
Step 73：Enable I 'k(s)(0)=Ik(s), I 'k(s)(0) when being first iteration each branch current value；
Step 74：With equation group (17) Δ R is calculated in conjunction with least square optimizationk (t)(s), t=0,1 ..., t are iteration
Number, Δ Rk (t)(s) when being the t times iteration branch resistance difference；Since original leg resistance is Rk, in addition when the t times iteration
The difference DELTA R of branch resistancek (t)(s), the t times branch resistance value is obtained
Step 75：If the Er Qies of t >=1 |ΔRk (t)-ΔRk (t-1)|<ε is obtained then stopping iterative calculationFor final result,
ε is the constant of setting；It is no to then follow the steps 76；
Step 76：WithIt calculatesThe current value of each article of branch when being the t+1 times iteration；Repeat step 74
With step 75.
7. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 6, which is characterized in that the minimum
Two, which multiply optimization method formula, is：
In formula,The resistance calculations difference of the b articles branch when being the t times iteration,End when being the t times and t-1 iteration
The difference of mouth resistance.
8. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 7, which is characterized in that least square
The value lower limit of parameter in optimization method is the nominal value of branch resistance, and the upper limit is 50 times of nominal value, the upper limit value, lower limit
Constraints in the corresponding formula (18) of value.
9. the subregion method for diagnosing faults of grounding net of transformer substation according to claim 1, which is characterized in that in step 8,
It is as follows that resistance value increases multiple situation corresponding with fault degree：
It is normal if μ is 1~2 if it is μ that resistance value, which increases multiple,；There is minor failure if μ is 2~4；If μ be 4~
10 there is moderate failure；There is heavier failure if μ is 10~20；There is catastrophe failure if μ is 20~40；If μ is 40
It is then broken above.
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| CN105425049A (en) * | 2015-10-29 | 2016-03-23 | 国网浙江省电力公司台州供电公司 | Method of testing geodetic network earthing resistance |
| CN105445615A (en) * | 2015-11-12 | 2016-03-30 | 有能集团有限公司 | Corrosion diagnosis method for transformer station grounding network |
| CN105741016B (en) * | 2016-01-22 | 2020-10-27 | 中国电力科学研究院 | Static reliability probability index obtaining method for medium-term power grid planning |
| CN105652155A (en) * | 2016-03-03 | 2016-06-08 | 国网山东省电力公司章丘市供电公司 | Transformer substation grounding grid fault corrosion monitoring method and system |
| CN107632231B (en) * | 2017-10-30 | 2021-04-13 | 陕西省地方电力设计有限公司 | Transformer substation grounding grid corrosion fault online diagnosis method using multiple excitation sources |
| CN109580463B (en) * | 2018-11-22 | 2021-08-20 | 国网天津市电力公司电力科学研究院 | Method for measuring corrosion degree of grounding grid |
| RU2705517C1 (en) * | 2018-12-26 | 2019-11-07 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Российский университет транспорта (МИИТ)" РУТ (МИИТ) | Stand for calculation of short circuit currents of inter-substation zone of traction ac network |
| CN110161368A (en) * | 2019-03-01 | 2019-08-23 | 河海大学 | A kind of small network fault diagnosis method |
| CN111830361B (en) * | 2019-04-18 | 2022-04-22 | 中国石油化工股份有限公司 | Method for detecting corrosion fault of grounding grid of oil field tank field |
| CN111830362B (en) * | 2019-04-18 | 2021-10-29 | 中国石油化工股份有限公司 | Non-excavation detection method suitable for grounding grid of oil field tank field |
| CN110703037A (en) * | 2019-10-16 | 2020-01-17 | 国网陕西省电力公司电力科学研究院 | Method and device for monitoring corrosion state and corrosion rate of grounding grid branch |
| CN112180211B (en) * | 2020-09-25 | 2021-08-31 | 华中科技大学 | Power distribution network ground fault positioning method and device based on node comprehensive injection current |
| CN113687191B (en) * | 2021-09-28 | 2024-04-12 | 国网上海市电力公司 | Grounding grid fault diagnosis method based on combination of electrical impedance imaging technology and electrical network theory method |
| CN114707283B (en) * | 2022-04-02 | 2022-10-21 | 中铁电气化铁路运营管理有限公司 | Grounding grid corrosion diagnosis method based on Lasso theory |
| CN116983574B (en) * | 2023-09-27 | 2024-01-19 | 国网吉林省电力有限公司松原供电公司 | Fault positioning device and method for direct-current system of transformer substation |
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