CN104655980B  A kind of this nonside voltage class adjacent lines short trouble method for quickly identifying based on db4 wavelet decomposition  Google Patents
A kind of this nonside voltage class adjacent lines short trouble method for quickly identifying based on db4 wavelet decomposition Download PDFInfo
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 CN104655980B CN104655980B CN201410618188.6A CN201410618188A CN104655980B CN 104655980 B CN104655980 B CN 104655980B CN 201410618188 A CN201410618188 A CN 201410618188A CN 104655980 B CN104655980 B CN 104655980B
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 phase
 short trouble
 non
 adjacent lines
 side voltage
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 238000000354 decomposition Methods 0.000 title claims abstract description 16
 238000005070 sampling Methods 0.000 claims description 7
 239000000284 extracts Substances 0.000 claims description 4
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 238000000034 methods Methods 0.000 description 1
Abstract
Description
Technical field
The present invention relates to a kind of, and this nonside voltage class adjacent lines short trouble based on db4 wavelet decomposition quickly identifies Method belongs to Relay Protection Technology in Power System field.
Background technique
Route protection is concentrated mainly on the protection to this route and possesses higher reliability at present, and for across voltage The fault message when line failure of grade determines that aspect but lacks capable and effective method.220kV and with online at present The main protection on road specifically includes that vertical connection distance (direction) route protection and current comparison pilot protection.The vertical UNPROFOR of socalled route The protective device at transmission electric wire road both ends, is exactly longitudinally tied with certain communication channel by shield, by the electrical quantity (electricity at each end Stream, direction of power etc.) opposite end is passed to, the electrical quantity at both ends is compared, to judge that failure is in this line range or online Outside the range of road, to decide whether to cut off protected circuit.And with the promotion of current electric power line voltage grade, a route Failure can cause the electrical quantity in neighboring voltage levels adjacent lines to fluctuate, and current power line main protection does not have to across voltage The reliable judgement of grade line fault information, thus, the difficult point of route protection be that different voltage grade line fault can It leans on, identify rapidly, to ensure to protect correct movement, even if excision failure, prevents failure from influencing extension.
Summary of the invention
The technical problem to be solved by the present invention is to propose a kind of this nonside voltage class adjacent lines based on wavelet decomposition Short trouble method for rapidly judging, can not be to this nonside voltage class adjacent lines short circuit event in current route protection for overcoming The shortcomings that barrier is reliably determined.
The technical scheme is that a kind of this nonside voltage class adjacent lines short circuit event based on db4 wavelet decomposition Hinder method for quickly identifying, when short trouble occurs for this nonside voltage class adjacent lines, measuring unit measures the three of transformer Phase voltage, threephase voltage data when extracting 2ms in windowIt is rightDb4 wavelet decomposition is carried out, is asked Take the absolute value of the high fdrequency component under the first scaleThen the integral maximum value of each phase absolute value of gained is sought It finally seeks the denary logarithm value M of the maximum value: when M is more than or equal to 2, being determined as that this nonside voltage class is neighbouring Line short fault；Otherwise determine its normal operation.
Specific steps are as follows:
(1) it when short trouble occurs for this nonside voltage class adjacent lines, is detected by measuring unit and records threephase Voltage；
(2) extract route occur short trouble when 2ms when window in threephase voltage data u_{A}[n]、u_{B}[n]、u_{C}[n], A, B, C For the number of ThreePhase Transformer, n is nth of sampling node of discrete signal；
(3) rightDb4 wavelet decomposition is carried out, the absolute value sequence of high fdrequency component under the first scale is sought
(4) each phase is sought using following formulaIntegrated value
Take its maximum valueNumber of sampling points in window, i indicate the ith sample of discrete signal when wherein N is 2ms Point,
(5) it is sought using following formulaDenary logarithm value M:
If M >=2, it is determined as this nonside voltage class adjacent lines short trouble；
Otherwise, it is determined that it is operated normally.
The principle of the present invention is:
One, wavelet transformation high fdrequency component is sought
To the threephase voltage of extractionDb4 wavelet transformation is carried out, seeks the high fdrequency component under the first scale using following formula
In formula h [p] be small echo highpass filter coefficient, h [p]=[0.2304,0.7148,0.6309, 0.0280,  0.1870,0.0308,0.0329,0.0106]；P is pth of sampled point of discrete signal,
Two, integrated value is sought
When short trouble occurs for this nonside voltage class adjacent lines, device starts immediately, and measuring unit starts recording, Threephase voltage data u in window when extracting 2ms_{A}[n]、u_{B}[n]、u_{C}[n], A, B, C are the number of route threephase.To each phase voltage into Row wavelet decomposition obtains the high fdrequency component absolute value under the first scaleIt is calculate by the following formula to obtain each phaseProduct Score value
In formula: number of sampling points in window when N is 2ms, i are discrete signal ith sample point；
Three, the judgement of short trouble occurs for this nonside voltage class adjacent lines
It include the high frequency division of faulty generation after short trouble occurs for this nonside voltage class adjacent lines, in each phase voltage Amount,Value is answered larger；And high fdrequency component will not be then generated when route operates normally,Maximum value is intended to 0.With formula (2) to obtained by each phaseIt integrates and is maximized
It is rightIts denary logarithm value M is sought, then short trouble occurs for this nonside voltage class adjacent lines Criterion are as follows:
M≥2 (3)
The beneficial effects of the present invention are:
(1) threephase voltage data of 2ms after this method only needs failure or interference to occur, taken window is shorter, without introducing The magnitude of current.
(2) this method only needs to compare Fmax, and whether the denary logarithm value of φ is more than or equal to 2, does not need for not Threshold value is adjusted respectively with operating condition.
Detailed description of the invention
Fig. 1 is that the present invention utilizes this nonside voltage class adjacent lines short trouble built in pscad emulation platform Simulation Model；
Fig. 2 is threephase voltage when A phase ground fault occurs for step down side of the present invention；
Fig. 3 is the absolute value sequence of high fdrequency component that each phase voltage when A phase ground fault occurs for step down side of the present invention；
Fig. 4 is threephase voltage when three phase short circuit fault occurs for step down side of the present invention；
Fig. 5 is the high fdrequency component absolute value sequence that each phase voltage when three phase short circuit fault occurs for step down side of the present invention Column；
Fig. 6 is threephase voltage when step down side of the present invention operates normally；
Fig. 7 is the absolute value sequence of high fdrequency component of each phase voltage when step down side of the present invention operates normally；
Fig. 8 is steps flow chart schematic diagram of the present invention.
Specific embodiment
With reference to the accompanying drawings and detailed description, the invention will be further described.
A kind of this nonside voltage class adjacent lines short trouble method for quickly identifying based on db4 wavelet decomposition, when non When short trouble occurs for this side voltage class adjacent lines, measuring unit measures the threephase voltage of transformer, when extracting 2ms in window Threephase voltage dataIt is rightDb4 wavelet decomposition is carried out, the high frequency division under the first scale is sought The absolute value of amountThen the integral maximum value of each phase absolute value of gained is soughtFinally seek the maximum value with 10 be the logarithm M at bottom: when M is more than or equal to 2, being determined as this nonside voltage class adjacent lines short trouble；Otherwise determine It is operated normally.
Specific steps are as follows:
(1) it when short trouble occurs for this nonside voltage class adjacent lines, is detected by measuring unit and records threephase Voltage；
(2) extract route occur short trouble when 2ms when window in threephase voltage data u_{A}[n]、u_{B}[n]、u_{C}[n], A, B, C For the number of ThreePhase Transformer, n is nth of sampling node of discrete signal；
(3) rightDb4 wavelet decomposition is carried out, the absolute value sequence of high fdrequency component under the first scale is sought
(4) each phase is sought using following formulaIntegrated value
Take its maximum valueNumber of sampling points in window, i indicate the ith sample of discrete signal when wherein N is 2ms Point,
(5) F is sought using following formula_{max,φ}Denary logarithm value M:
If M >=2, it is determined as this nonside voltage class adjacent lines short trouble；
Otherwise, it is determined that it is operated normally.
Embodiment 1: establishing Simulation Model as shown in Figure 1, and wherein transformer is a threephase transformer, uses △/y connection, parameter are as follows: rated capacity 600MVA, nominal transformation ratio 220kV/525kV.
It is now assumed that A phase ground fault occurs for the side transformer 220kV in route TLineM2, ground resistance is assumed to be 0, at this Under model, each phase voltage data are as shown in Figure 2.The change of db4 small echo is carried out to the data after the starting of each phase device when 2ms in window respectively It changes, and the absolute value sequence for seeking high fdrequency component under such failure under each the first scale of phase is as shown in Figure 3.To each mutually resulting Absolute value sequence is integrated, and the maximum value 0.0439 in threephase integrated value is sought with max function.Its logarithm is greater than Equal to 2, it is determined as that short trouble occurs for 220kV side line road according to criterion, correct judgment consistent with hypothesis.
Embodiment 2: establishing Simulation Model as shown in Figure 1, and parameter elaborates in embodiment 1, this In be not repeated.It is now assumed that three phase short circuit fault occurs for the side transformer 220kV in route TLineM2, and under the model, each mutually electricity Pressure is as shown in Figure 4.
Data when after selecting device starting in 2ms in window carry out db4 wavelet transformation, seek each phase first under such failure The absolute value sequence of high fdrequency component under scale is as shown in figure 5, respectively integrate absolutely value sequence obtained by each phase, and take it Maximum value 0.0593.Know that its logarithm is clearly to be more than or equal to 2 by embodiment 1, is determined as that 220kV side line road occurs according to criterion Short trouble, correct judgment consistent with hypothesis.
Embodiment 3: establishing Simulation Model as shown in Figure 1, and parameter elaborates in embodiment 1, this In be not repeated.It is now assumed that the side transformer 220kV operates normally in route TLineM2, and under the model, each phase voltage such as Fig. 6 It is shown.
Data when after selecting device starting in 2ms in window carry out db4 wavelet transformation, seek each phase first under such failure The absolute value sequence of high fdrequency component under scale is as shown in fig. 7, be approximately zero.Absolutely value sequence obtained by each phase is accumulated respectively Point, and take its maximum value 3.1378e07.Its logarithm is centainly less than 2, is determined as that 220kV side line road is normally transported according to criterion Row, correct judgment consistent with hypothesis.
Following table is the statistical data when different faults occur for this nonside voltage class adjacent lines, wherein Ag, AB, ABN A phase short circuit grounding, AB phase fault, AB phase fault ground connection are respectively indicated, Rg indicates ground resistance:
Above in conjunction with attached drawing, the embodiment of the present invention is explained in detail, but the present invention is not limited to abovementioned Embodiment within the knowledge of a person skilled in the art can also be before not departing from present inventive concept Put that various changes can be made.
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