CN113239132B - Online out-of-tolerance identification method for voltage transformer - Google Patents
Online out-of-tolerance identification method for voltage transformer Download PDFInfo
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Abstract
The invention provides an out-of-tolerance online identification method for a voltage transformer, which is characterized in that a mapping relation between monitoring statistics and each VT error variation is established on the basis of converting secondary measurement output values of a plurality of VTs in a transformer substation into the monitoring statistics. And taking the difference value between the VT first inspection report error value and the VT archive information error regulation limit value as an error change limit value for judging the VT error state, converting the error change limit value into monitoring statistics by using a mapping relation, dividing a plurality of control limits according to the contribution rate of each VT to the monitoring statistics, regarding the out-of-limit VT as suspected out-of-limit, and further determining whether the out-of-limit VT is out-of-limit or not for the suspected out-of-limit VT. The application of the invention can enable the detection of the out-of-tolerance VT in the long-term operation process to get rid of the dual dependence on planned power failure and a real object standard device, is beneficial to timely finding out the out-of-tolerance VT, guides the operation and maintenance work of a power company, promotes the accurate maintenance of power transmission and transformation equipment, and provides guarantee for the fair electric energy trade and the safe operation of a power grid.
Description
Technical Field
The invention relates to the field of power distribution equipment state evaluation and fault diagnosis, in particular to an out-of-tolerance online identification method for a voltage transformer.
Background
A Voltage Transformer (VT) is a general-purpose device that converts a high voltage to a low voltage and thus enables measurement. During long-term operation, VT metering errors may degrade until the profile information error specification limit is exceeded, resulting in an out-of-tolerance fault. The super-difference may cause deviation of electric energy calculated from voltage and current data, possibly causing huge electric energy trade disputes, and may also cause intervention misappropriation and abnormal actions of a power grid automation system, possibly causing instability and cracking of a power system. Therefore, it is important to find and replace the out-of-tolerance VT in time.
To identify out-of-tolerance VT, current certification protocols require the use of off-line detection methods. The method forcibly carries out first verification (first inspection) and periodic verification (weekly inspection) in a period of 4 years before the VT is accessed to the network and in the subsequent operation process, evaluates the error value of the detected VT by comparing with a high-precision calibrator, and provides a detection report. The off-line detection method has the advantages that the method not only can detect the change of the error value, but also can find out the out-of-tolerance, so that the off-line detection result is the basis for making the out-of-tolerance VT maintenance plan. However, the method has the defects that power failure is required to be carried out, and due to the fact that planned power failure windows are few and time is short, off-line detection is difficult to complete on schedule, and a basis cannot be provided for making a maintenance plan. In order to get rid of the dependence of the out-of-tolerance fault detection on the planned power failure, a non-power-failure VT error online evaluation method is provided and quickly becomes a research hotspot.
The existing research results are divided into three categories, namely methods based on accurate modeling, signal processing and information physical fusion. The accurate modeling method is based on a known accurate equivalent model of the power system, and an equation set is established to solve unknown transformer errors. The high-precision equivalent parameters of the power grid required by modeling of the method are difficult to obtain, and the engineering application difficulty is high; the signal processing method analyzes the output signal identification error change of a single mutual inductor by using methods such as wavelet transformation, frequency shift algorithm, integrated filtering and the like. The method does not depend on accurate equivalent parameters, but only can find the error mutation of VT, can not find the error gradual change, and has weak engineering applicability.
The assessment method based on the information physical fusion aims to detect the measurement error drift, a VT group with electrical physical connection in the same transformer substation is used as an assessment object, physical correlation in the group is used as a constraint condition, information contained in secondary measurement voltage real-time large-scale data output by the VT group is cooperatively analyzed through a multivariate statistical method, the real-time state of the constraint relation is mined and tracked, and the information physical fusion method is used for realizing the online assessment of the VT individual operation error change. However, currently, this method can only determine whether the VT error changes, but cannot determine whether the VT exceeds the allowable error range for the following reasons: 1. this method does not allow to obtain the absolute value of the error. Since only the measured value of VT is used for evaluation, the initial value of error is not known, and it can only be determined from the change of the statistic whether the error state has changed relatively, but the absolute value of the error cannot be obtained, and therefore it cannot be determined whether the error after abnormal change exceeds the allowable error range. 2. The magnitude of the variation in error cannot be determined. The current method is to convert the measured data into monitoring statistic, judge whether error change occurs according to the monitoring statistic change of the modeling data and the monitoring data, not establish the quantitative relation between the monitoring statistic and the error variation, and only judge whether the error changes from the statistic change, so the error variation can not be obtained. In summary, the above method cannot evaluate the error value, and therefore, the method does not have the capability of identifying the out-of-tolerance VT, and cannot guide the making of the maintenance plan.
Disclosure of Invention
The invention provides an out-of-tolerance online identification method of a Voltage Transformer (VT) aiming at the technical problems in the prior art, which comprises the following steps: collecting secondary output signal data of a plurality of same-phase voltage transformers VT of a newly-accessed network transformer substation, and constructing a modeling data setAnd monitoring the data set(ii) a Modeling-based data setCalculating the Q statistic in the modeling stage and the corresponding contribution rate index Q of each VT to the Q statistic by taking the Q statistic as the monitoring statisticxiAnd establishing the error variation delta e between the Q statistic and each VTiMapping relation Δ Q = f (Δ e) therebetweeni) (ii) a Taking the collected error value of the first inspection report of each VT as an initial error change value, and taking the difference value between the initial error change value of each VT and the specified error limit value of each VT in the archive information as an error change limit value; calculating corresponding statistic according to the error change limit value and the mapping relation, and defining the control limit t of each VT based on the statistic contribution rate indexi(ii) a For monitoring data setsCalculating its real-time contribution rate index Q from the single-point data of VT to be detectedxiWhen Q isxiGreater than the control limit tiTime, judgeSuspected out-of-tolerance VT; and calculating the evaluation error mean value of all monitoring data in the overrun time segment in which the suspected overrun VT is located, and if the evaluation error mean value exceeds the error specified limit value in the archive information, judging that the overrun of the VT to be detected in the overrun time segment occurs.
The online identification method for the out-of-tolerance of the voltage transformer provided by the invention is characterized in that a mapping relation between monitoring statistics and each VT error variation is established on the basis of converting secondary measurement output values of a plurality of VTs in a transformer substation into the monitoring statistics. The difference value between the VT first inspection report error value and the VT archive information error regulation limit value is used as an error change limit value for judging the VT error state, then the error change limit value is converted into monitoring statistic by utilizing the mapping relation, a plurality of control limits are defined according to the contribution rate of each VT to the monitoring statistic, and the over-limit VT is regarded as suspected over-limit. In order to eliminate the influence of secondary output signal fluctuation on out-of-tolerance judgment and reduce erroneous judgment, for VT suspected to be out-of-tolerance, the mapping relation is utilized to convert the out-of-tolerance time period online monitoring data into an error variation mean value isomorphic with an error initial value, an evaluation error mean value is obtained by adding the variation mean value to the initial value, and the evaluation error mean value is compared with a file information error regulation limit value to further determine whether the VT is out-of-tolerance. The application of the invention can enable the detection of the out-of-tolerance VT in the long-term operation process to get rid of the dual dependence on planned power failure and a real object standard device, is beneficial to timely finding out the out-of-tolerance VT, guides the operation and maintenance work of a power company, promotes the accurate maintenance of power transmission and transformation equipment, and provides guarantee for the fair electric energy trade and the safe operation of a power grid.
Drawings
FIG. 1 is a flow chart of an online voltage transformer over-tolerance identification method provided by the present invention;
FIG. 2 is a schematic diagram of a typical wiring and voltage transformer VT configuration of a substation;
FIG. 3 is an overall flowchart of an online voltage transformer over-tolerance identification method according to the present invention;
fig. 4 is a graph of control limit out-of-tolerance risk identification results of the voltage transformer.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Fig. 1 is a flowchart of an online voltage transformer tolerance identification method provided by the present invention, and as shown in fig. 1, the method includes: s1, collecting secondary output signal data of a plurality of same-phase voltage transformers VT of the newly-connected substation, and constructing a modeling data setAnd monitoring the data set。
It can be understood that, for a newly-put-into-operation or a recently-completed transformer substation, in the case that at least 3 (including) VT are redundantly configured on a bus and an outgoing line corresponding to the same voltage in the substation, an online over-tolerance identification method for the voltage transformer can be provided. Firstly, collecting secondary output signal data X of each in-phase voltage transformer VT, and constructing a modeling data set based on the collected secondary output signal data of each voltage transformer VTAnd monitoring the data set. Wherein the data set is modeledMonitoring a data set to model usageI.e. the data to be monitored, the monitoring data set of each VT is identified to identify whether the VT is out of tolerance.
Wherein, step S1 specifically includes the following steps:
step S11, collecting the voltage corresponding to the same voltage at the newly-connected or recently-inspected substationIn-phase VT secondary output to generate continuously updated time sequence output signal,N is VT number, m is current sampling point number, output signalThe method comprises the preferred normal data and the subsequent real-time data sampled after the network access operation or the weekly check is completed.
In step S12, considering that the switching of the line load generally has a significant periodicity per day, the unit time slices of 24 hours per day are countedA point (i.e. t sampling points in 24 hours per day) for outputting signals from a time sequenceSelecting data k multiplied by t points of integral multiple unit time segments at head end of time sequence to establish normal data setSubsequent time series data sets are established as real-time data sets。
Step S13, respectively aligning the normal data sets X0And a real-time data set X1Standardized processing is carried out to obtain a modeling data setAnd monitoring the data set
WhereinIs a normal data set X0The mean vector of (a), wherein,respectively is the average value and standard deviation matrix of normal data of each voltage transformer VT in different time sequences
,Is X0To (1) aStandard deviation of the individual measured variables. For a normal data set X0And a real-time data set X1Standardized processing is carried out to obtain a modeling data setAnd monitoring the data setThen, the monitoring data is collected in unit time slicesThe data are divided into different segments, and the monitoring data of the i +1 th segment are as follows:
and the monitoring data of each time slice comprises t monitoring data points of n voltage transformers.
It should be noted that, in step S1, the collected secondary output signal data of the multiple in-phase voltage transformers VT are preprocessed to obtain modeling data sets respectivelyAnd monitoring the data setFor subsequent use in modeling and online identification of VT out-of-tolerance.
S2, based on the modeling data setCalculating the Q statistic in the modeling stage and the corresponding contribution rate index Q of each VT to the Q statistic by taking the Q statistic as the monitoring statisticxiAnd establishing Q statistic and error variation delta eiMapping relation Δ Q = f (Δ e) therebetweeni)The mapping relationship can be understood as the variation of Q statistic and the error variation Δ e of each VTiThe mapping relationship between them.
It will be appreciated that step S2 is primarily based on modeling the data setEstablishing a contribution rate index Q of each VTxiAnd error variation Δ eiSpecifically, step S2 includes the following steps:
Is RnA set of criteria bases for the space,front of(k < n) linearly independent vectorsForm a principal component spaceThe last (n-k) linearly independent vectorsForming a residual spaceNumber of principal elementsTypically determined from variance accumulation and percentage.
Step S22, using Principal Component Analysis (PCA) to measure samples of single sampling points in the data setDecomposition into principal componentAnd residual components:
Step S23, calculating Q statistic Q for monitoring residual error component in modeling stagenorAnd its expectation over that period is E (Q)nor):
Calculating a contribution rate index Q of each voltage transformer VT in the modeling stage group to the corresponding contribution of Q statisticxiSize Qxi norAnd itThe expectation in this period is E (Q)xi nor):
It should be noted that, the formula (3) and the formula (4) are the modeling and monitoring phase data sets respectivelyQ of residual component of medium monitoring datanorStatistics and their expectation E (Q)nor) The calculation formula of (2); the formula (5) and the formula (6) are the contribution rate indexes Q corresponding to the Q statistic of each voltage transformer VTxi norAnd expectation of E (Q)xi nor) The calculation formula of (2).
Step S24, based on the modeling data setEstablishing a mapping relation delta Q = f (delta e) of Q statistic and error variationi)。
It should be noted that the secondary output signal data of each voltage transformer VT includes amplitude signal data and phase signal data, and the error of the amplitude signal dataThe difference drift is also called ratio error drift, and when the secondary output signal data of each voltage transformer VT is amplitude signal data, the ratio error drift delta ei=△εiThe mapping relation Δ Q = f (Δ ∈)i) Comprises the following steps:
in the formula,vi m(t) is the secondary output amplitude signal data of the ith station VT, ∈i norError value, K, reported for first inspection of amplitude signal data of ith station VTrRated ratio of VT, DσIs a matrix of standard deviations of the normal data set.
When the secondary output signal data of each voltage transformer VT is phase signal data, the phase error drifts delta ei=△(△φi) In time, the mapping Δ Q = f (Δ (#Φ)i) ) is:
It is noted that the modeling data set is based onEquations (7) and (8) provide a mapping of the Q statistic to different types of error variations.
S3, taking the collected error value of the first inspection report of each VT as the initial error change value, and taking the difference between the initial error change value of each VT and the error regulation limit value of each VT in the archive information as the error change limit value; calculating the error change limit value according to the mapping relationCorresponding statistic, and defining control limit t of each VT based on the size of statistic contribution rate indexi。
It is understood that step S3 specifically includes the following steps:
step S31, recording the first detection report error value e of each same-phase VTi norWherein the first inspection report error value ei norIncluding the first reported error value of the amplitude and phase signal data. Limiting the accuracy level VT file information errorelimError value e from the first inspection reporti norMaking difference, and determining positive error change limit and negative error change limit, respectively delta epi=elim-ei norAnd
△eni=-elim-ei nor。
step S32, converting Δ epiAnd Δ eniInput mapping relation Δ Q = f (Δ e)i) Then dividing the corresponding delta Q into Q statistic contribution rate indexes Q corresponding to all VTsxiCalculating the variation quantity delta Q of the corresponding contribution rate index of each VT theoretically caused when the VT in the population has single error driftxi。
Wherein, in step S32, the limit value Δ e is changed according to the positive errorpiAnd negative error regulation limit value delta eniAnd a mapping relation for calculating corresponding delta QpAnd Δ QnWill be Δ QpAnd Δ QnDividing the data into Q statistic contribution rate indexes corresponding to all VTsAnd。
for the splitting process, namely splitting the delta Q into the Q statistic contribution rate index Q which has corresponding relation with each VTxiTo (2)The process is divided into a splitting process in the case of a ratio error drift and a splitting process in the case of a phase error drift, where the ratio error drift Δ ei=△εiTime, delta QxiComprises the following steps:
phase error drift Δ ei=△(△φi) Time, delta QxiComprises the following steps:
note that the forward error variation limit Δ epiAnd negative error regulation limit value delta eniCorresponding delta Q can be obtainedpAnd Δ QnFor Δ QpAnd Δ QnCan be respectively obtained by the formula (9)Andor corresponding according to formula (10)Andthe formula (9) and the formula (10) are general formulas.
Based on、And expected value size E (Q) of the modeling phasexi nor) Determining a forward control limit t for each VTpiAnd a negative control limit tniThe calculation formula is asThe following:
similarly, for ratio error drift or phase error drift, equation (11) and equation (12) can be used to obtain the forward control limit t of each VTpiAnd a negative control limit tni。
It is noted that the modeling data set is based onAfter the analytical modeling process of steps S1, S2, and S3, the positive control limit and the negative control limit of each VT are determined, and it is determined whether the VT is suspected to be out of tolerance based on the control limits.
S4, for the monitoring data setCalculating its real-time contribution rate index Q from the single-point data of VT to be detectedxiWhen Q isxiGreater than the control limit tiIf so, the VT is judged to be out of tolerance.
It is understood that, in step S1, the monitoring data set is divided into time segments, and for the single-point monitoring data in a certain time segment, the real-time contribution rate index Q is calculated according to the above formula (5)xiTo do so byThe sign of (2) determines the error drift direction, if the sign is positive, it is determined as positive drift, and if the real-time contribution rate index Q is the same as the positivexiGreater than the forward control limit tpiAnd judging the suspected positive direction out-of-tolerance of the voltage transformer VT to be detected. Otherwise, if the sign is negative, the negative drift is determined, and at this time, if Q isxiGreater than a negative control limit tniThen, it is judgedThe suspected negative direction out-of-tolerance exists in the voltage transformer VT to be detected.
S5, calculating the mean value of the evaluation errors of all the monitoring data of the overrun time segment where the suspected overrun VT is located, and if the mean value of the evaluation errors exceeds the error specified limit value in the archive information, judging that the overrun time segment is out of tolerance.
It should be noted that the out-of-tolerance condition of the voltage transformer VT to be detected is determined according to the control limit, and only the suspected out-of-tolerance of the voltage transformer VT can be determined, and whether the out-of-tolerance condition is determined in the corresponding time slice, which needs further verification.
Specifically, step S5 includes:
s51, when the suspected out-of-tolerance voltage transformer VT exists in the time segment j of the monitoring data set, the monitoring data set in the time segment j is processedSubstituting the Q statistic calculation model shown in formula (4) to calculate the mean value of the Q statistic of the time period(Q)。
S52, in order(Q) and E (Q)nor) Magnitude of variation of (a) inverse extrapolation error variation Δ eiAnd then reporting error value with the suspected out-of-tolerance first inspection report of the power transformer VT i norThe mean value e of the evaluation errors is obtained by superpositioni est. Wherein the ratio estimates the mean of the errorsSee, e.g., equation (12), mean phase estimation errorSee, for exampleExpression of formula (13).
In the formula,. DELTA.ei=f-1(. DELTA.Q) is. DELTA.Q = f (. DELTA.e)i) Of the same sign as
Step S53, when the mean error e is evaluatedi estExceeding file information error regulation limitelimAnd judging that the voltage transformer VT suspected to be out of tolerance is out of tolerance in the time slice.
The online identification method for the out-of-tolerance of the voltage transformer, provided by the invention, is based on the in-phase VT measurement data, the first inspection record error value and the file information error regulation limit value, and can identify the out-of-tolerance VT in time on the premise of getting rid of dual dependence of a physical standard device and power failure, so that the accurate overhaul of power transmission and transformation equipment is promoted; the error value of the VT with the out-of-tolerance risk can be evaluated, the abnormal change of the error can be quantified, and the out-of-tolerance degree of the current VT can be determined.
The online over-tolerance identification method for the voltage transformer provided by the invention is described in detail by using a specific embodiment.
Fig. 2 shows a typical topological structure of a double-bus connection of a high-voltage substation, wherein a bus-tie switch for connecting buses (including two buses W1 and W2) is closed, each bus is provided with one VT, each outgoing line is selectively provided with VT, and any same-phase VT of the same voltage class corresponds to the same voltage. The online identification method for the out-of-tolerance voltage transformer in the embodiment has the steps as shown in fig. 3, and comprises the following steps:
step 1: collecting cophase VT secondary output signal of newly-network-accessed transformer substationConstructing a modeling datasetAnd monitoring the data set。
In the embodiment, a new network-connected substation as shown in fig. 2 is adopted, the substation adopts double-bus connection, and one 0.2-level VT is configured on each phase of two buses and four outgoing lines. In order to reduce the influence of errors introduced by the acquisition device, the accuracy grade of the selected data acquisition device is higher than the VT accuracy grade by two grades, the acquisition device with the accuracy grade not lower than 0.05 grade is selected, and the output frequency of the acquired characteristic quantity is 1 Hz. From 0: 01 separately collecting six A-phase VT secondary amplitude values and phases, respectively generating continuously updated time sequence output signals XεAnd X△QWherein
,VT number is 6, m is the current accumulated sampling point number, output signalIncluding normal data after recent weekly inspections and real-time data after a period of operation. The ratio of 0: 01-24: 1440 points are counted in 00 hours as unit time slices, and when the collected data meet 2880 points, the data matrix is obtainedIn selecting the timeOrder-head data creation normal data setSubsequent continuously updated time series data establishes a real-time data set。
Respectively align with a constant data set X0And a real-time data set X1The updated single point is subjected to standardization processing to obtain a modeling data setAnd monitoring data points in real timeWhereinIs X0Mean vector, standard deviation matrix,Is X0To (1) aStandard deviation of the individual measured variables. Monitoring data set in unit time sliceThe data are divided into different segments, and the monitoring data of the i +1 th segment are as follows:
step 2: establishing a calculation model by taking the Q statistic as a monitoring statistic, and calculating a modeling periodStatistics and corresponding contribution rate index Q of each VT to Q statisticsxiEstablishing a mapping relation between the Q statistic and the error variation quantity delta Q = f (delta e)i)。
From a modeling datasetEstablishing a Q statistic calculation model, and calculating the expected size E (Q) of the Q statistic of the amplitude and the phase at the modeling stage according to the formulas (3) and (4)nor)。
And E (Q) is determined according to the formulas (5) and (6)nor) Decomposed into a contribution rate index E (Q) corresponding to six VTsxi nor)(i=1,2,...,6)。
Establishing a mapping relation delta Q = f (delta e) of Q statistic and error variationi)。
Ratio error drift Δ ei=△εiThe mapping relation Δ Q = f (Δ ∈)i) Comprises the following steps:
Phase error drift Δ ei=△(△φi) In time, the mapping Δ Q = f (Δ (#Φ)i) ) is:
And step 3: collecting VT first inspection report error value as error change initial value, using the difference value of every VT initial value and positive and negative file information error regulation limit value as error change limit value delta epiAnd Δ eniBased on the mapping relation Δ Q = f (Δ e)i) According to the index QxiDimensioning different VT control limits tpiAnd tni。
Recording the error values of the first inspection reports of 6A-phase VT and calculating the boundary of the error caused by out-of-tolerance due to positive and negative drift, and the ratio difference delta ei=△εiPhase difference Δ ei=△(△φi) The results of the ratio difference and phase difference are shown in table 1:
TABLE 1 VT first inspection report error value and error drift limit
Will showInjection relationship Δ Q = f (Δ e)i) Decomposition of Delta Q in (1) into Delta QxiThe index is shown in formulas (9) and (10).
Will delta epsilonpiAnd Δ εniDelta epsilon with formula (9)iIn calculating the error drift of each ratioSize. When Δ εiIs Δ εpiWhen the temperature of the water is higher than the set temperature,is composed ofWhen Δ εiIs Δ εniWhen the temperature of the water is higher than the set temperature,is composed of。
Will be provided withAndΔ (Δ φ) substituted into equation (10)i) In which the error drift of each phase is calculatedSize. When delta (Δ φ)i) Is Δ (Δ φ)pi) When the temperature of the water is higher than the set temperature,is composed ofWhen delta (Δ φ)i) Is Δ (Δ φ)ni) When the temperature of the water is higher than the set temperature,is composed of。
Finally each delta QxiSubstituting into equation (11) to obtain the ratio error control limit of positive and negative directions of each VT、And a phase error control limit tpi △φ、tni △φ. When in useIs composed ofAndwhen the temperature of the water is higher than the set temperature,are respectively asAnd. When Δ QxiIs composed ofAndwhen t isiAre each tpi △φAnd tni △φ。
And 4, step 4: calculating a real-time contribution rate index Q of a monitoring data setxiWhen Q isxiGreater than the control limit tiIf so, the VT is judged to be out of tolerance.
Respectively inputting the monitored amplitude data and phase data into formulas (5) and (6) to calculate real-time QxiSize ofThe sign judges the error drift direction, the sign judges the forward drift, the real-time contribution rate index QxiAnd the control limit tpiComparison, QxiGreater than tpiJudging that the VT to be detected has the risk of positive out-of-tolerance, otherwise, QxiGreater than tniAnd judging that the negative over-tolerance risk exists, wherein the control limit identification effect is shown in fig. 4, wherein the X axis represents different voltage transformers VT, the Y axis represents the number of sampling points, and the Z axis represents the statistic Qxi.
And 5: and calculating the evaluation error mean value of the over-limit time segment VT, and judging that the VT to be detected is over-error when the evaluation error mean value exceeds the specified limit value of the file information error.
If the amplitude data of the VT to be detected in the step 4 exceeds the condition of the i +1 th monitoring data segment, the data segment is processed
After normalization, the values are substituted into formulas (3) and (4), and the expected size of the statistic of the time interval Q is calculatedThen, againWill be provided withAndsubstituting the estimated ratio difference of VT calculated by equation (12)If there is a risk of forward out-of-tolerance andis greater thanAt the risk of a negative over-tolerance andis less thanAnd judging that the VT to be detected is out of tolerance in the (i + 1) th monitoring data segment, and sending out-of-tolerance alarm and evaluation ratio difference.
The online identification method for the voltage transformer out-of-tolerance provided by the embodiment of the invention fuses three types of heterogeneous data, namely, voltage transformer VT secondary output signal data, a first inspection report error value and a file information error regulation limit value, so as to realize online identification of out-of-tolerance VT. The identification method establishes a mapping relation between monitoring statistics and each VT error variation on the basis of converting secondary measurement output values of a plurality of VTs in a transformer substation into the monitoring statistics. Then, the VT first inspection report error value is taken as an initial value, the difference value between the initial value and the VT archive information error regulation limit value is taken as an error change limit value for judging the VT error state, the error change limit value is converted into monitoring statistics by utilizing a mapping relation, a plurality of control limits are defined according to the contribution rate of each VT to the monitoring statistics, and the out-of-limit VT is taken as suspected out-of-limit, so that the problem of obtaining the absolute value of the VT error is solved. In order to eliminate the influence of secondary output signal fluctuation on out-of-tolerance judgment and reduce erroneous judgment, aiming at out-of-tolerance VT, the mapping relation is further utilized to convert the online monitoring data of the out-of-tolerance time segment into an error variation mean value which is isomorphic with an error initial value, the variation mean value is added to the initial value to obtain an evaluation error mean value, and the evaluation error mean value is compared with a file information error regulation limit value to judge whether the VT is out-of-tolerance. The application of the invention can enable the detection of the out-of-tolerance VT in the long-term operation process to get rid of the dual dependence on planned power failure and a real object standard device, is beneficial to timely finding out the out-of-tolerance VT, guides the operation and maintenance work of a power company, promotes the accurate maintenance of power transmission and transformation equipment, and provides guarantee for the fair electric energy trade and the safe operation of a power grid.
It should be noted that, in the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to relevant descriptions of other embodiments for parts that are not described in detail in a certain embodiment.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (5)
1. An out-of-tolerance online identification method for a voltage transformer is characterized by comprising the following steps:
collecting secondary output signal data of a plurality of same-phase voltage transformers VT of a newly-accessed network transformer substation, and constructing a modeling data setAnd monitoring the data set;
Modeling-based data setCalculating the Q statistic in the modeling stage and the corresponding contribution rate index Q of each VT to the Q statistic by taking the Q statistic as the monitoring statisticxiAnd establishing the error variation delta e between the Q statistic and each VTiMapping relation Δ Q = f (Δ e) therebetweeni);
Taking the collected error value of the first inspection report of each VT as an initial error change value, and taking the difference value between the initial error change value of each VT and the specified error limit value of each VT in the archive information as an error change limit value; calculating corresponding statistic according to the error change limit value and the mapping relation, and defining the control limit t of each VT based on the statistic contribution rate indexi;
For monitoring data setsCalculating its real-time contribution rate index Q from the single-point data of VT to be detectedxiWhen Q isxiGreater than the control limit tiJudging that VT is suspected to be out of tolerance;
calculating the evaluation error mean value of all monitoring data in the overrun time segment in which the suspected overrun VT is located, and if the evaluation error mean value exceeds the error specified limit value in the archive information, judging that the to-be-detected VT is overrun in the overrun time segment;
collecting secondary output signal data of a plurality of same-phase voltage transformers VT of a newly-accessed network transformer substation, and constructing a modeling data setAnd monitoring the data setThe method comprises the following steps:
acquisition of new network access power transformationSecondary output signal data of station in-phase voltage transformer,N is the number of voltage transformers, m is the number of sampling points, X is a measurement time sequence output signal containing a plurality of columns which sequentially change along with time, and the time sequence output signal X comprises normal data sampled after first inspection and real-time data of subsequent operation;
selecting data at the head end of the time sequence from the time sequence output signal X to establish a normal data set, and establishing a real-time data set by using subsequent time sequence data;
respectively carrying out standardization processing on the normal data set and the real-time data set to obtain a modeling data setAnd monitoring the data setAnd monitoring the data setDividing the time slices into different time slices;
the modeling-based data setCalculating the Q statistic in the modeling stage and the corresponding contribution rate index Q of each VT to the Q statistic by taking the Q statistic as the monitoring statisticxiThe method comprises the following steps:
modeling-based data setCalculating the Q statistic of the modeling stage and the expected value E (Q) of the modeling stagenor) The Q statistic calculation formula is as follows:
in the formula (I), the compound is shown in the specification, emodeling a data setThe last n-k (k < n) load matrixes of the unitary matrix obtained by the singular value decomposition of the covariance matrix,modeling a data setThe single sample point data of (1);
converting the Q statistic into a contribution rate index Q corresponding to each VTxiCalculate each QxiExpected value magnitude E (Q) at modeling stagexi nor),QxiThe calculation formula of (a) is as follows:
the mapping relation Δ Q = f (Δ e)i) Error variation Δ e for each set of VTiQuantitative relation between Q statistic variation quantity delta QFurther establishing the error variation delta e of each VTiWith corresponding contribution rate index QxiAmount of change of (A) Δ QxiWherein the data set is modeledIncluding amplitude signal data and phase signal data;
when modeling a data setWhen the data in (1) is amplitude signal data, the ratio error variation value
△ei=△εiThe mapping relation of (1) is as follows:
in the formula,KrIs the rated transformation ratio of VT, vi m(t) is the secondary output amplitude of the ith station VT,. epsiloni norError value, D, reported for first check of VTσA standard deviation matrix for the normal data set;
△ei=△(△φi) The mapping relation of (1) is as follows:
2. The method of claim 1, wherein the step of collecting error values of the first inspection report of each VT as initial error variation values and the step of determining the difference between the initial error variation values of each VT and the predetermined error limit of each VT in the profile information as the error variation limit comprises:
collecting error value e of first inspection report of each VTi norPositive error regulation limit + e of voltage transformer file informationlimAnd negative error specification limit-elim;
Reporting the first inspection error value e of each VTi norDetermining a positive error variation limit Δ e by the difference from the error specification limit of the file informationpi=elim-ei norAnd negative error variation limit
△eni=-elim-ei nor。
3. The method of claim 2, wherein the error variation limit and the mapping relation are used to calculate a corresponding statistic, and the control limit t of each VT is defined based on the contribution rate of the statisticiThe method comprises the following steps:
according to the positive error variation limit value delta epiAnd negative error regulation limit value delta eniAnd the mapping relation is calculatedAnd;
based on、And expected value size E (Q) of the modeling phasexi nor) Determining a forward control limit t for each VTpiAnd a negative control limit tniThe calculation formula is as follows:
4. the method for online identification of voltage transformer according to claim 3, wherein said monitoring data setThe real-time contribution rate index Q of the single point data is calculatedxiWhen Q isxiGreater than the control limit tiAnd then, judging the suspected over-tolerance of VT, comprising the following steps:
based on QxiJudging the error drift direction of VT, and according to the error drift direction of VT, making QxiControl limits t associated with respective directionsiMake a comparison if QxiIf the corresponding control limit is exceeded, the VT is suspected to be out of tolerance.
5. The online identification method for the out-of-tolerance of the voltage transformer according to claim 4, wherein the step of calculating an evaluation error mean value of all monitoring data of the out-of-limit time segment where the suspected out-of-tolerance VT is located, and if the evaluation error mean value exceeds an error regulation limit value in the archive information, determining that the out-of-limit time segment is out-of-tolerance comprises the steps of:
calculating the mean value E (Q) of the Q statistic of the monitoring data of the time slice based on the monitoring data of the suspected out-of-tolerance VT in the time slice, and calculating the mean value E (Q) and the mean value E (Q) of the Q statistic of the monitoring data of the time slicexi nor) Size of the variation ofDetermining a corresponding error variation Δ ei;
Error variation quantity delta eiError value e from the first inspection reporti norThe mean value e of the evaluation errors is obtained by superpositioni est;
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