Method, apparatus and system for state evaluation of metrological characteristics of capacitor voltage transformer

Abstract

A method, apparatus and system for state evaluation of metrological characteristics of a capacitor voltage transformer, relating to the technical field of voltage measurement. The method comprises the following steps: acquiring operation data of a capacitor voltage transformer, establishing a metrological performance evaluation model, and obtaining a statistical control threshold (S1); collecting in real time the operation data of the capacitor voltage transformer, and calculating a statistic of the operation data by means of the metrological performance evaluation model (S2); comparing the statistic of the operation data with the statistical control threshold to determine whether a fault occurs in the capacitor voltage transformer (S3); and detecting a change trend of a primary signal and a secondary signal of the tested capacitor voltage transformer to determine whether metrological characteristics are abnormal (S4). In the method, the concept of time is introduced, by providing a timestamp, the influence of newly obtained data on the metrological performance evaluation model is greater, and by means of real-time update, the metrological performance evaluation model can be updated, so that when in a stable state, the detection time is reduced, and the model calculation is reduced.

Description

Methods, devices and systems for assessing the metering characteristics of capacitive voltage transformers Technical Field

[0001] This invention relates to the field of voltage detection technology, and in particular to a method, apparatus and system for evaluating the metering characteristics of capacitive voltage transformers. Background Technology

[0002] Capacitive voltage transformers, as crucial measuring devices in power systems, are widely used, especially in 110kV and above high-voltage power grids, serving as a vital source of voltage data. Capacitive voltage transformers primarily consist of capacitors and electromagnetic units. However, their operation is susceptible to influences from environmental factors such as temperature, humidity, and electromagnetic fields, leading to capacitor aging and breakdown. In severe cases, this can result in out-of-tolerance operation or even insulation damage. Once a voltage transformer exceeds its tolerances, its measurement results become unreliable, energy metering becomes inaccurate, and the safe and stable operation of the power system may be compromised. To ensure the fairness and impartiality of energy metering, the accuracy of operating capacitive voltage transformers must be guaranteed. Current technologies often employ periodic offline power outages for capacitive voltage transformer performance testing. However, limitations in manpower and resources, or equipment damage during periods, mean that some faulty voltage transformers may remain undetected. Furthermore, the condition of capacitive voltage transformers detected during offline power outages differs from that under actual operating conditions. Therefore, the accuracy of capacitive voltage transformer measurement is difficult to guarantee.

[0003] Summary of the Invention

[0004] In view of the problems existing in the current capacitive voltage transformer metering characteristic status assessment and system, this invention is proposed.

[0005] Therefore, the problem that this invention aims to solve is that the metering performance detection of capacitive voltage transformers is not accurate enough, and there are also differences between the voltage transformer status under actual operating conditions.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] In a first aspect, embodiments of the present invention provide a method for evaluating the metering characteristics of a capacitive voltage transformer, comprising the following steps:

[0008] Obtain the operating data of the capacitive voltage transformer, establish a metering performance evaluation model, and obtain the statistical control threshold.

[0009] Real-time acquisition of operating data from the capacitive voltage transformer; calculation of statistical quantities of the operating data using the metering performance evaluation model.

[0010] Compare the statistical quantity of the operation data with the statistical control threshold value to determine whether the capacitor voltage transformer is faulty;

[0011] Detect the change trend of the primary signal and the secondary signal of the capacitor voltage transformer under test to determine whether the measurement characteristic is abnormal.

[0012] As a preferred scheme of the capacitor voltage transformer measurement characteristic state evaluation method, the measurement performance evaluation model is expressed as,

[0013] In the formula, Q represents the statistical quantity, The control threshold value of the statistical quantity of the monitoring level α is represented by X, the load matrix on the principal component space is represented by P, and P e represents the load matrix on the residual space;

[0014] The control threshold value is calculated in the following manner,

[0015] In the formula, C α represents the critical value of the normal distribution under the monitoring level α, λ i represents the eigenvalue, θ i represents the sum of the corresponding eigenvalue λ i , and h0 represents the normalized statistical quantity.

[0016] As a preferred scheme of the capacitor voltage transformer measurement characteristic state evaluation method, the method for determining whether the capacitor voltage transformer is faulty includes,

[0017] A corresponding time stamp is generated when the operation data of the capacitor voltage transformer is collected, the statistical quantity of the operation data is compared with the statistical control threshold value, and the time of the next collection is determined, and the specific formula is expressed as:

[0018] G t =f(ΔS,ΔE,P t , T h )

[0019] Wherein,

[0020] ΔS=S t -S t-1

[0021] ΔE=E t -E t-1

[0022] In the formula, ΔS represents the change amount of the system state after the last time stamp, ΔE represents the change amount of the external environment parameter, and Pt represents the system behavior or risk level predicted at a certain time point t, T h represents the threshold value indicating whether the timestamp granularity needs to be adjusted, S t represents the system state at time t, S t-1 represents the system state at the last time t-1, E t represents the external environment state at time t, G t represents the granularity at time t;

[0023] The function f is specifically defined as,

[0024] f (ΔS, ΔE, P t , T h ) = G {text ba × (1 + k_s × text norm ΔS + k_e × text norm ΔE + k_p × P t )}

[0025] where k_s, k_e and k_p represent the weights of the system state, the external environment and the prediction model respectively, P t , the value of which is in the range of [0, 1], represents the probability from no risk (0) to high risk (1), and the function text norm is used to normalize the variable ΔS and the normalized variable ΔE, so that the influence of the function f remains stable.

[0026] As a preferred scheme of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer, when the collected operation data of the capacitive voltage transformer is determined to be normal, the collected data is input to the measurement performance evaluation model, and the measurement performance evaluation model is updated, and the specific method comprises,

[0027] Q new = (Q past +N) / 2

[0028] where Q new represents a new statistical control threshold value, Q past represents a last statistical control threshold value, and N represents the operation data determined to be normal.

[0029] As a preferred scheme of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer, the method for determining whether the measurement characteristics are abnormal comprises,

[0030] The change trend of the primary signal and the secondary signal of the measured capacitive voltage transformer satisfies the formula:

[0031] T = V1 / V2

[0032] In the formula, T represents the conversion ratio of the capacitive voltage transformer, V1 represents the primary signal value, and V2 represents the secondary signal value;

[0033] When actually running, the change trend of the measured capacitive voltage transformer secondary signal and the secondary signal is detected in real time, and the formula is satisfied:

[0034] T_actual = V1_actual / V2_actual

[0035] ΔT = |T - T_actual|

[0036] In the formula, T_actual represents the real-time conversion ratio, V1_actual represents the actual value of the primary signal, V2_actual represents the actual value of the secondary signal, and ΔT represents the conversion ratio error limit;

[0037] When ΔT ≤ ΔTmax, it is judged as a normal state;

[0038] When ΔT > ΔTmax, it is judged as an abnormal state, and an alarm is given to remind the fault.

[0039] As a preferred scheme of the capacitive voltage transformer measurement characteristic state evaluation method, wherein the measurement characteristic query mode of the abnormal state comprises,

[0040] The sliding window average is introduced to calculate the moving average conversion ratio error, which is represented by the formula:

[0041] MAΔ(t) = (1 / n) ∑_{k=t-n+1}^{t} ΔT(k)

[0042] In the formula, MAΔ(t) represents the moving average conversion ratio error at time t, and n represents the total number;

[0043] The time concept is introduced to give different weights to signal values of different timestamps, and the newer the timestamp, the heavier the weight, which is represented by the formula:

[0044] WMAΔT(t) = (1 / W) ∑_{k=t-n+1}^{t} w(k) * ΔT(k)

[0045] In the formula, W = ∑_{k=t-n+1}^{t} w(k)), and w(k) represents the weight of the time point k;

[0046] It is calculated by the following recursive form:

[0047] EMAΔT(t) = β * ΔT(t) + (1-β) * EMAΔT(t-1)

[0048] In the formula, β represents a smoothing factor, and is specifically a positive number less than 1.

[0049] In a second aspect, an embodiment of the present application provides a capacitive voltage transformer measurement characteristic state evaluation system, which comprises a data acquisition module, a calculation module, a comparison module, and a change trend analysis module.

[0050] The data acquisition module is configured to acquire operation data of the capacitive voltage transformer.

[0051] The calculation module is configured to establish a measurement performance evaluation model and calculate a statistic quantity.

[0052] The comparison module is configured to compare the statistic quantity with a predetermined control threshold value and detect a fault according to a comparison result.

[0053] The change trend analysis module is configured to detect change trends of primary signals and secondary signals and determine whether the measurement characteristic is abnormal.

[0054] In a third aspect, an embodiment of the present application provides a capacitive voltage transformer measurement characteristic state evaluation device, which comprises a body comprising a bearing frame, a box body mounted on a surface of the bearing frame, and a box door arranged on a side surface of the box body.

[0055] A magnetic shielding film is attached to outer surfaces of the box body and the box door.

[0056] The box body is internally provided with an evaluation system and a plurality of standard voltage transformers, and the standard voltage transformers comprise primary windings and secondary windings.

[0057] The magnetic shielding film comprises an adhesive layer, a first metal film layer, a nanofiber metal wire mesh layer, a second metal film layer, and a polyester fiber layer.

[0058] The evaluation system is configured to execute a capacitive voltage transformer measurement characteristic state evaluation method.

[0059] In a fourth aspect, an embodiment of the present application provides a computer device, comprising a memory and a processor, and the memory stores a computer program, wherein the processor executes the computer program to implement any step of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer.

[0060] In a fifth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program, wherein the computer program is executed by a processor to implement any step of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer.

[0061] The present application has the following beneficial effects:

[0062] Compared with the traditional voltage transformer online monitoring device which is affected by electromagnetic interference, the device avoids the electromagnetic coupling interference between the integrated components on the circuit board and the voltage transformer, and the external magnetic shielding film of the closed box is of a nanofiber structure, so that the electromagnetic interference outside the box does not affect the inside of the box.

[0063] Compared with the offline detection device, the present application can realize online monitoring of the measurement performance of the voltage transformer without power interruption, and compared with the traditional voltage transformer online monitoring device which realizes online monitoring of the measurement performance by analyzing a single secondary signal, the present application combines the primary signal and the secondary signal and performs analysis and calculation, so that the evaluation of the measurement performance is more accurate.

[0064] The time concept is introduced, the influence of newly obtained data on the measurement performance evaluation model is greater through the setting of the time stamp, and the measurement performance evaluation model can be updated through real-time data, so that the detection time is reduced and the model calculation is reduced when in a stable state. BRIEF DESCRIPTION OF DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0066] Fig. 1 is a flowchart of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer.

[0067] Fig. 2 is a model updating schematic diagram of the method for evaluating the state of the measurement characteristics of the capacitive voltage transformer.

[0068] Fig. 3 is a front view of the device for evaluating the state of the measurement characteristics of the capacitive voltage transformer. DETAILED DESCRIPTION

[0069] In order to make the above objectives, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present application.

[0070] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application, however, can be practiced in a variety of ways beyond the specific embodiments described herein without departing from the scope of the present application. It can be appreciated by those skilled in the art that the present application can be practiced without such specific details.

[0071] Secondly, "one embodiment" or "an embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one implementation of the present application. The appearances of "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of other embodiments.

[0072] The present application is described in detail below with reference to the accompanying drawings. In describing the embodiments of the present application, the cross-sectional view of the device structure is partially enlarged without the general proportion for the convenience of description, and the schematic view is only an example, which should not limit the scope of protection of the present application. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual production.

[0073] Meanwhile, in the description of the present application, it should be noted that the terms "upper, lower, inner and outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first, second or third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0074] Unless otherwise specifically defined and limited, the terms "mounting, connecting, connection" in the present application should be understood broadly, for example: it can be fixed connection, detachable connection or integral connection; it can also be mechanical connection, electrical connection or direct connection, it can also be indirectly connected through intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0075] Example 1

[0076] Referring to FIG. 1 and FIG. 2, for a first embodiment of the present application, the embodiment provides a method for evaluating the state of the measurement characteristics of a capacitive voltage transformer, comprising the following steps:

[0077] S1, obtaining the operation data of the capacitive voltage transformer, establishing a measurement performance evaluation model, and obtaining a statistical control threshold.

[0078] The measurement performance evaluation model is expressed as,

[0079] In the formula, Q represents a statistic, represents a control threshold of the statistic at a monitoring level a, X represents sample data, P represents a load matrix on a principal component space, and P e represents a load matrix on a residual space;

[0080] The control threshold is calculated in the following manner,

[0081] In the formula, C α represents a critical value of a normal distribution at a monitoring level a, λ i represents an eigenvalue, θ i represents a sum of corresponding eigenvalues λ i , and h0 represents a normalized statistic.

[0082] S2, collecting the operation data of the capacitive voltage transformer in real time, and calculating the statistic of the operation data through the measurement performance evaluation model.

[0083] S3, comparing the statistic of the operation data with the statistical control threshold, and determining whether the capacitive voltage transformer has failed.

[0084] The method for determining whether the capacitive voltage transformer has failed comprises,

[0085] generating a corresponding time stamp when collecting the operation data of the capacitive voltage transformer, and calculating the statistic of the operation data through the measurement performance evaluation model;

[0086] comparing the statistic of the operation data with the statistical control threshold, and determining the time for the next collection, which is specifically expressed as:

[0087] G t =f(ΔS,ΔE,P t , T h )

[0088] wherein,

[0089] ΔS=S t -St-1

[0090] ΔE = E t -E t-1

[0091] In the formula, ΔS represents the change of the system state after the last time stamp, ΔE represents the change of the external environment parameter, P t represents the predicted system behavior or risk level at a certain time point t, T h represents the threshold value of whether the time stamp granularity needs to be adjusted, S t represents the system state at time t, S t-1 represents the system state at the last time t-1, E t represents the external environment state at time t, G t represents the granularity at time t.

[0092] The function f is specifically defined as,

[0093] f(ΔS, ΔE, P t , T h ) = G{text ba × (1 + k_s × text norm ΔS + k_e × text norm ΔE + k_p × P t )}

[0094] In the formula, k_s, k_e and k_p respectively represent the weights of the system state, the external environment and the prediction model, P t The value of P norm is in the range of [0, 1], indicating the probability from no risk (0) to high risk (1), and the function text norm is used to standardize the variable ΔS and the standardized variable ΔE, so that the influence of the function f remains stable.

[0095] When the collected operation data of the capacitive voltage transformer is judged to be normal, the collected data is input to the metering performance evaluation model, and the metering performance evaluation model is updated, and the specific method comprises,

[0096] Q new = (Q past +N) / 2

[0097] In the formula, Q new represents a new statistical control threshold, Q past represents the last statistical control threshold, and N represents the operation data judged to be normal.

[0098] S4, detecting the change trend of the primary signal and the secondary signal of the measured capacitive voltage transformer, and judging whether the measurement characteristic is abnormal.

[0099] The method for judging whether the metering characteristic is abnormal comprises,

[0100] The change trend of the primary signal and the secondary signal of the measured capacitive voltage transformer satisfies the formula:

[0101] T = V1 / V2

[0102] In the formula, T represents the conversion ratio of the capacitive voltage transformer, V1 represents the primary signal value, and V2 represents the secondary signal value;

[0103] When actually running, the change trend of the primary signal and the secondary signal of the measured capacitive voltage transformer is detected in real time, and the formula is satisfied:

[0104] T_actual = V1_actual / V2_actual

[0105] ΔT = |T-T_actual|

[0106] In the formula, T_actual represents the real-time conversion ratio, V1_actual represents the actual value of the primary signal, V2_actual represents the actual value of the secondary signal, and ΔT represents the conversion ratio error limit;

[0107] When ΔT≤ΔTmax, it is judged as a normal state;

[0108] When ΔT>ΔTmax, it is judged as an abnormal state, and an alarm is given to remind the fault.

[0109] The detection method further comprises: comparing the change trend of the primary signal of the measured capacitive voltage transformer, judging whether irreversible change occurs, when the irreversible change amplitude of the primary signal is greater than the ratio of the main capacitor to the auxiliary capacitor of the measured capacitive voltage transformer, the metering characteristic of the capacitive voltage transformer is abnormal, and comparing the change trend of the primary signal and the secondary signal of the measured capacitive voltage transformer, judging whether irreversible change occurs, when the irreversible change amplitude of the ratio is greater than k times the error limit value of the measured capacitive voltage transformer, the metering characteristic of the capacitive voltage transformer is abnormal;

[0110] The query mode of the metering characteristic in the abnormal state comprises,

[0111] The moving average conversion ratio error is calculated by introducing a sliding window average, and is represented by the formula:

[0112] MAΔ(t) = (1 / n)∑_{k=t-n+1}^{t}ΔT(k)

[0113] In the formula, MAΔ(t) represents the moving average conversion ratio error at time t, and n represents the total number;

[0114] Introducing the concept of time, different weights are given to signal values of different timestamps, the newer the timestamp, the heavier the weight, which is expressed by the formula:

[0115] WMAΔT(t)=(1 / W)∑_{k=t-n+1}^{t}w(k)*ΔT(k)

[0116] In the formula, W=∑_{k=t-n+1}^{t}w(k)),w(k) represents the weight of time point k;

[0117] It is calculated by the following recursive form:

[0118] EMAΔT(t)=β*ΔT(t)+(1-β)*EMAΔT(t-1)

[0119] In the formula, β represents a smoothing factor, which is a positive number less than 1.

[0120] In summary, compared with offline detection devices, the present application can realize online monitoring of measurement performance under the condition that the voltage transformer is not powered off, compared with traditional voltage transformer online monitoring devices which realize measurement performance online monitoring through single secondary signal analysis, the present application combines primary signal and secondary signal and analyzes and calculates, and the evaluation of measurement performance is more accurate; Introducing the concept of time, through the setting of timestamp, the influence of newly obtained data on the measurement performance evaluation model is greater, and through real-time updating, the measurement performance evaluation model can be updated, the detection time is reduced when in a stable state, and the model calculation is reduced.

[0121] Embodiment 2

[0122] On the basis of the first embodiment, the present embodiment further provides a capacitive voltage transformer measurement characteristic state evaluation system, comprising a data acquisition module, a calculation module, a comparison module, and a change trend analysis module;

[0123] The data acquisition module is used to obtain the running data of the capacitive voltage transformer;

[0124] The calculation module is used to establish a measurement performance evaluation model and calculate a statistic;

[0125] The comparison module is used to compare the statistic with a predetermined control threshold, and detect faults according to the comparison result;

[0126] The change trend analysis module is used to detect the change trend of the primary signal and the secondary signal, and judge whether the measurement characteristic is abnormal.

[0127] The embodiment also provides a computer device suitable for the capacitor voltage transformer measurement characteristic state evaluation method, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to realize the capacitor voltage transformer measurement characteristic state evaluation method proposed in the above embodiment.

[0128] The computer device can be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operating system and the computer program in the non-volatile storage medium to run. The communication interface of the computer device is used to communicate with external terminals in a wired or wireless manner. The wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device can be a touch layer overlaid on the display screen, or a key, trackball or touchpad arranged on the shell of the computer device, or an external keyboard, touchpad or mouse, etc.

[0129] The embodiment also provides a storage medium having a computer program stored thereon, and the program is executed by a processor to realize the capacitor voltage transformer measurement characteristic state evaluation method proposed in the above embodiment.

[0130] The storage medium proposed in the embodiment belongs to the same inventive concept as the data storage method proposed in the above embodiment, and the technical details not described in detail in the embodiment can be referred to the above embodiment, and the embodiment has the same beneficial effects as the above embodiment.

[0131] Embodiment 3

[0132] With reference to FIG. 3, on the basis of the first two embodiments, the embodiment further provides a capacitor voltage transformer measurement characteristic state evaluation device, including:

[0133] The body 100 includes a bearing frame 101, a box 102 mounted on the surface of the bearing frame 101, and a box door 103 arranged on the side surface of the box 102;

[0134] The magnetic shielding film 200 is pasted on the outer surface of the box 102 and the box door 103;

[0135] The inside of the box body 102 is provided with an evaluation system and a plurality of standard voltage transformers, the standard voltage transformers comprising primary windings and secondary windings, the primary windings being used to be electrically connected with the secondary windings of the measured capacitive voltage transformers one by one, and the secondary windings of the plurality of standard voltage transformers being electrically connected with the data acquisition module of the evaluation system through a voltage reduction module;

[0136] The magnetic shielding film 200 comprises a sticking layer, a first metal film layer, a nanofiber metal wire mesh layer, a second metal film layer and a polyester fiber layer, the sticking layer is made of rubber or plastic, the first metal film layer is formed on the outer surface of the sticking layer, the first metal film layer shields the internal electromagnetic field through the shielding property of the metal itself, the nanofiber metal wire mesh layer is between the first metal film layer and the second metal film layer, the nanofiber metal wire mesh layer is woven into a mesh structure, the second metal film layer shields the external electromagnetic field, and the polyester fiber layer is arranged at the outermost side.

[0137] The evaluation system is used for executing the capacitive voltage transformer measurement characteristic state evaluation method.

[0138] Compared with the traditional voltage transformer online monitoring device which is affected by electromagnetic interference, the device avoids the electromagnetic coupling interference between the integrated components on the circuit board and the voltage transformer, and the outside of the closed box body is provided with a magnetic shielding film, the magnetic shielding film is a nanofiber structure, so that the electromagnetic interference outside the box body does not form an influence on the inside of the box body.

[0139] Embodiment 4

[0140] On the basis of the first three embodiments, the embodiment provides a capacitive voltage transformer measurement characteristic state evaluation method, in order to verify the beneficial effects of the application, the economic benefit calculation and simulation experiment are used for scientific demonstration.

[0141] Comparative example: a traditional measurement performance detection method is used;

[0142] Table 1: measurement performance detection values of the capacitive voltage transformer under different conditions

[0143] As can be seen from Table 1, the calculation speed of embodiment 1 can be obviously improved, and the accuracy can be increased through real-time updating of the model, and the influence of external factors can be greatly reduced in embodiment 2, and the shielding effect of the electromagnetic field is strengthened through the use of the magnetic shielding film.

[0144] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

A method for evaluating the state of the measurement characteristics of a capacitive voltage transformer, characterized in that: The method comprises the following steps, Obtain the running data of the capacitor voltage transformer, establish a metering performance evaluation model, and obtain a statistical control threshold; Real-time collection of the running data of the capacitor voltage transformer, calculation of the statistical quantity of the running data by the metering performance evaluation model; Comparison of the statistical quantity of the running data and the statistical control threshold to determine whether the capacitor voltage transformer has failed; Detection of the change trend of the primary signal and the secondary signal of the measured capacitor voltage transformer to determine whether the metering characteristic is abnormal. The method for evaluating the metering characteristic state of a capacitive voltage transformer according to claim 1, characterized in that: The metrology performance evaluation model is represented as, In the formula, Q represents a statistic, a control threshold expressed as a statistical quantity of monitoring level a, X represents sample data, P represents a loading matrix on a principal component space, P e represents a loading matrix on a residual space; wherein the control threshold The manner of calculating includes, where C α denotes the critical value at the monitoring level a, λ i denotes the eigenvalue, θ i denotes the corresponding eigenvalue λ i and h0denotes the normalized statistic. The method for evaluating the metering characteristic state of a capacitive voltage transformer according to claim 2, characterized in that: The method for determining whether the capacitor voltage transformer has failed comprises, Generation of a corresponding time stamp when collecting the running data of the capacitor voltage transformer, comparison of the statistical quantity of the running data and the statistical control threshold, and determination of the time of the next collection, and the specific formula is: G t = f(AS, AE, P t , T h ) Wherein, ΔS = S t - S t-1 ΔE = E t - E t-1 where ΔS represents a change in system state since the last timestamp, ΔE represents a change in external environment parameters, P t represents a predicted system behavior or risk level at a certain point in time t, T h represents a threshold value for whether the timestamp granularity needs to be adjusted, S t represents the system state at time t, S t-1 represents the system state at the last time t-1, E t represents the external environment state at time t, G t represents the granularity at time t; The function f is specifically defined as, f(ΔS, ΔE, P t , T h ) = G{text ba × (1 + k_s×text norm ΔS + k_e×text norm ΔE + k_p×P t )} where k_s, k_e and k_p represent the weights for the system state, the external environment and the prediction model, respectively, P t has a value in the range [0, 1] and represents the probability from no risk (0) to high risk (1), and the function text norm is used to normalize the variable ΔS with the normalized variable ΔE, so that the influence of the function f remains constant. The method for evaluating the metering characteristic state of a capacitive voltage transformer according to claim 3, characterized in that: When the collected running data of the capacitor voltage transformer is determined to be normal, the collected data is input to the metering performance evaluation model, and the metering performance evaluation model is updated, and the specific method comprises, Q new = (Q past +N) / 2 where Q new is expressed as a new statistical control threshold, Q past is expressed as the previous statistical control threshold, N is expressed as the running data judged to be normal. The method for evaluating the metering characteristic state of a capacitive voltage transformer according to claim 4, characterized in that: The method for determining whether the metering characteristic is abnormal comprises, The change trend of the primary signal and the secondary signal of the measured capacitor voltage transformer satisfies the formula: T = V1 / V2 In the formula, T represents the conversion ratio of the capacitor voltage transformer, V1 represents the primary signal value, and V2 represents the secondary signal value; When actually running, the change trend of the primary signal and the secondary signal of the measured capacitor voltage transformer is detected in real time, and the formula is satisfied: T_actual = V1_actual / V2_actual ΔT = |T-T_actual| In the formula, T_actual represents the real-time conversion ratio, V1_actual represents the actual value of the primary signal, V2_actual represents the actual value of the secondary signal, and ΔT represents the conversion ratio error limit; When ΔT≤ΔTmax, it is determined to be in a normal state; When ΔT>ΔTmax, it is determined to be in an abnormal state, and an alarm is given to remind of the failure. The query method of the metering characteristic in the abnormal state comprises, The method for evaluating the metering characteristic state of a capacitive voltage transformer according to claim 5, characterized in that: A sliding window average is introduced to calculate the moving average conversion ratio error, and the formula is: MAΔ(t) = (1 / n)∑_{k=t-n+1}^{t}ΔT(k) In the formula, MAΔ(t) represents the moving average conversion ratio error at time t, and n represents the total number; The time concept is introduced to give different weights to the signal values of different time stamps. The newer the time stamp, the heavier the weight ratio. The formula is: WMAΔT(t) = (1 / W)∑_{k=t-n+1}^{t}w(k)*ΔT(k) In the formula, W = ∑_{k=t-n+1}^{t}w(k), and w(k) represents the weight of the time point k; The calculation is as follows: EMAΔT(t) = β*ΔT(t) + (1-β)*EMAΔT(t-1) In the formula, β represents a smoothing factor, which is a positive number less than 1. The method comprises a data collection module, a calculation module, a comparison module, and a change trend analysis module; A kind of capacitive voltage transformer measurement characteristic state evaluation system based on the capacitive voltage transformer measurement characteristic state evaluation method described in any one of claims 1-6, characterized in that: The data collection module is used to obtain the running data of the capacitor voltage transformer; ​ The computing module is configured to establish a metrological performance evaluation model and calculate a statistical quantity; The comparison module is configured to compare the statistical quantity with a predetermined control threshold and detect a fault according to a comparison result; The change trend analysis module is configured to detect change trends of the primary signal and the secondary signal and determine whether the metrological characteristics are abnormal. A kind of capacitive voltage transformer measurement characteristic state evaluation device, it is characterized in that: The machine body (100) comprises a bearing frame (101), a box body (102) mounted on the surface of the bearing frame (101), and a box door (103) arranged on the side surface of the box body (102). A magnetic shielding film (200) is attached to the outer surfaces of the box body (102) and the box door (103). The inside of the box body (102) is provided with an evaluation system and a plurality of standard voltage transformers. The standard voltage transformers comprise primary windings and secondary windings, the primary windings are electrically connected with the secondary windings of the measured capacitive voltage transformers one by one, and the secondary windings of the plurality of standard voltage transformers are electrically connected with the data acquisition module of the evaluation system through a voltage reduction module. The magnetic shielding film (200) comprises an adhesive layer, a first metal film layer, a nanofiber metal wire mesh layer, a second metal film layer, and a polyester fiber layer. The adhesive layer is made of rubber or plastic, the first metal film layer is formed on the outer surface of the adhesive layer, the first metal film layer shields the internal electromagnetic field by the shielding property of the metal itself, the nanofiber metal wire mesh layer is between the first metal film layer and the second metal film layer, the nanofiber metal wire mesh layer is woven into a mesh structure, the second metal film layer shields the external electromagnetic field, and the polyester fiber layer is arranged on the outermost side. The evaluation system is configured to execute the capacitive voltage transformer metrological characteristic state evaluation method of any one of claims 1-6. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that: The processor executes the computer program to realize the steps of the capacitive voltage transformer metrological characteristic state evaluation method of any one of claims 1-6. A computer-readable storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to realize the steps of the capacitive voltage transformer metrological characteristic state evaluation method of any one of claims 1-6.

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