Capacitive voltage transformer transient voltage measurement method, device, apparatus and medium

Abstract

This application discloses a method, apparatus, equipment, and medium for measuring transient voltage of a capacitive voltage transformer (CVT), relating to the field of power grid transient voltage measurement technology. The method includes: performing piecewise linear fitting of the flux linkage-current curve of the intermediate CVT transformer and obtaining the relationship function between the piecewise current and flux linkage; constructing a voltage numerical equation from the secondary side to the primary side of the CVT, the voltage numerical equation taking into account the distributed capacitance parameter of the CVT to ground; substituting the real-time acquired CVT secondary side voltage value into the voltage numerical equation, and combining it with the relationship function between the piecewise current and flux linkage, calculating the CVT primary side voltage. This application, by constructing a voltage numerical relationship from the secondary side to the primary side of the CVT and combining it with the flux linkage-current relationship curve, can obtain the CVT primary side voltage from the measured secondary side voltage value, improving the transient response performance of the CVT and providing a technical basis for power grid transient voltage measurement and related research.

Description

Technical Field

[0001] This application belongs to the field of power grid transient voltage measurement technology, specifically relating to a method, device, equipment, and medium for measuring transient voltage of a capacitive voltage transformer. Background Technology

[0002] The presence of multiple energy storage elements in capacitive voltage transformers (CVTs) leads to poor transient performance. In particular, the saturation characteristics of the intermediate transformer cause excitation saturation in CVTs under transient overvoltage conditions exceeding 1.5 times their rated voltage, resulting in nonlinear characteristics and making their transient response process exceptionally complex. Given that accurate monitoring and measurement of grid transient overvoltages is crucial for the safe and stable operation of the power grid, it is necessary to measure grid-side transient overvoltages to improve the transient response performance of CVTs and provide a basis for grid transient voltage measurement and related research. Summary of the Invention

[0003] This application proposes a method, apparatus, equipment, and medium for measuring transient voltage of a capacitive voltage transformer (CVT). This method can recover the transient overvoltage on the primary side of the CVT under saturation conditions, improve the transient response performance of the CVT, and provide technical support for power grid transient voltage measurement and related research.

[0004] This application is achieved through the following technical solution:

[0005] A method for measuring the transient voltage of a capacitive voltage transformer includes:

[0006] The flux linkage-current curve of the CVT intermediate transformer is piecewise linearized and fitted to obtain the relationship function between piecewise current and flux linkage.

[0007] A numerical voltage equation is constructed from the secondary side to the primary side of the CVT, and the numerical voltage equation takes into account the CVT's distributed capacitance to ground parameter;

[0008] The CVT secondary voltage value acquired in real time is substituted into the voltage numerical equation, and the CVT primary voltage is calculated by combining the relationship function between the segmented current and the magnetic flux.

[0009] In some implementations, the step of performing piecewise linear fitting of the flux linkage-current curve of the CVT intermediate transformer and obtaining the relationship function between piecewise current and flux linkage includes:

[0010] The flux linkage-current curve is piecewise linearized and fitted to obtain multiple piecewise linear functions of flux linkage-current.

[0011] Based on each of the linear piecewise flux-current functions, its corresponding inverse function is obtained, which serves as the relationship function between the current and flux in that segment.

[0012] In some implementations, constructing the voltage numerical equations from the secondary side to the primary side of the CVT includes:

[0013] The numerical relationship between the secondary current and the secondary voltage of the CVT is obtained based on the forward difference method;

[0014] Ignoring the coupling capacitance between windings, the secondary current of the winding is equal to the secondary side current.

[0015] The excitation branch voltage is obtained based on the secondary winding current and the secondary side voltage.

[0016] The magnetic flux linkage is obtained by gradient integration of the excitation branch voltage;

[0017] The voltage of the distributed capacitance to ground is obtained from the excitation branch current, the excitation branch voltage, and the secondary winding current.

[0018] The current of the distributed capacitance to ground is obtained from the voltage of the distributed capacitance to ground.

[0019] The voltages of the compensation reactor and the capacitor divider are obtained based on the current of the distributed capacitance to ground, the current of the excitation branch, and the secondary winding current.

[0020] The primary voltage of the CVT is obtained based on the voltages of the compensating reactor and the capacitive voltage divider, as well as the voltage of the distributed capacitance to ground.

[0021] In some implementations, the calculation of the CVT primary-side voltage includes:

[0022] The CVT secondary side voltage value is acquired in real time according to the acquisition interval. The CVT secondary side voltage value is substituted into the voltage numerical equation to calculate the winding secondary current, excitation branch voltage and flux linkage.

[0023] Substitute the calculated flux linkage into the corresponding piecewise function to calculate the excitation branch current;

[0024] Substitute the calculated excitation branch current, excitation branch voltage, and secondary winding current into the voltage numerical equation to calculate the voltage of the distributed capacitance to ground, as well as the voltage of the compensating reactor and the capacitor divider.

[0025] The voltage of the distributed capacitance to ground calculated is added to the voltage of the compensation reactor and the capacitor divider to obtain the primary voltage of the CVT.

[0026] Secondly, this application proposes a transient voltage measuring device for a capacitive voltage transformer, comprising:

[0027] The fitting unit is used to perform piecewise linear fitting of the flux linkage-current curve of the CVT intermediate transformer and obtain the relationship function between piecewise current and flux linkage.

[0028] The numerical relationship construction unit is used to construct the voltage numerical equation from the secondary side to the primary side of the CVT, and the voltage numerical equation takes into account the CVT's distributed capacitance to ground parameter.

[0029] In addition, the calculation unit substitutes the real-time acquired CVT secondary voltage value into the voltage numerical equation and, in conjunction with the relationship function between the segmented current and the magnetic flux, calculates the CVT primary voltage.

[0030] In some implementations, the fitting unit is configured to perform the following steps:

[0031] The flux linkage-current curve is piecewise linearized and fitted to obtain multiple piecewise linear functions of flux linkage-current.

[0032] Based on each of the linear piecewise flux-current functions, its corresponding inverse function is obtained, which serves as the relationship function between the current and flux in that segment.

[0033] In some implementations, the numerical relation construction unit is configured to perform the following steps:

[0034] The numerical relationship between the secondary current and the secondary voltage of the CVT is obtained based on the forward difference method;

[0035] Ignoring the coupling capacitance between windings, the secondary current of the winding is equal to the secondary side current.

[0036] The excitation branch voltage is obtained based on the secondary winding current and the secondary side voltage.

[0037] The magnetic flux linkage is obtained by gradient integration of the excitation branch voltage;

[0038] The voltage of the distributed capacitance to ground is obtained from the excitation branch current, the excitation branch voltage, and the secondary winding current.

[0039] The current of the distributed capacitance to ground is obtained from the voltage of the distributed capacitance to ground.

[0040] The voltages of the compensation reactor and the capacitor divider are obtained based on the current of the distributed capacitance to ground, the current of the excitation branch, and the secondary winding current.

[0041] The primary voltage of the CVT is obtained based on the voltages of the compensating reactor and the capacitive voltage divider, as well as the voltage of the distributed capacitance to ground.

[0042] In some implementations, the computing unit is configured to perform the following steps:

[0043] The CVT secondary side voltage value is acquired in real time according to the acquisition interval. The CVT secondary side voltage value is substituted into the voltage numerical equation to calculate the winding secondary current, excitation branch voltage and flux linkage.

[0044] Substitute the calculated flux linkage into the corresponding piecewise function to calculate the excitation branch current;

[0045] Substitute the calculated excitation branch current, excitation branch voltage, and secondary winding current into the voltage numerical equation to calculate the voltage of the distributed capacitance to ground, as well as the voltage of the compensating reactor and the capacitor divider.

[0046] The voltage of the distributed capacitance to ground calculated is added to the voltage of the compensation reactor and the capacitor divider to obtain the primary voltage of the CVT.

[0047] Thirdly, this application proposes an electronic device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement any of the embodiments of the above-described methods.

[0048] Fourthly, this application proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the embodiments of the above-described methods.

[0049] This application proposes a method for measuring transient voltage of a capacitive voltage transformer (CVT). By constructing the voltage numerical relationship between the secondary and primary sides of the CVT and combining it with the flux linkage-current relationship curve, the primary voltage of the CVT can be obtained from the measured voltage value of the secondary side. This improves the transient response performance of the CVT and provides a technical basis for the measurement of transient voltage in the power grid and related research.

[0050] Accordingly, the transient voltage measuring device, equipment and medium for a capacitive voltage transformer proposed in this application also have the same technical effects as described above. Attached Figure Description

[0051] The accompanying drawings, which are included to provide a further understanding of the embodiments of this application and form part of this application, do not constitute a limitation on the embodiments of this application. In the drawings:

[0052] Figure 1 This is a schematic diagram of the CVT transient voltage measurement method proposed in the embodiments of this application;

[0053] Figure 2 This is a general CVT equivalent circuit;

[0054] Figure 3 This is a schematic diagram of the CVT transient voltage measurement device proposed in the embodiments of this application;

[0055] Figure 4 This is a block diagram illustrating the principle of the CVT transient voltage measurement system proposed in this application.

[0056] Figure 5This is a schematic block diagram of the electronic device proposed in the embodiments of this application;

[0057] Figure 6 This is a schematic diagram of a computer-readable storage medium proposed in an embodiment of this application;

[0058] Figure 7 This refers to the excitation current of the intermediate transformer in the CVT.

[0059] Figure 8 For the magnetic flux of the intermediate transformer of the CVT;

[0060] Figure 9 To simulate the current-magnetic flux linkage curve of a CVT;

[0061] Figure 10 This is a schematic diagram of the flux linkage-current curve and the piecewise linearization result of a transformer.

[0062] Figure 11 This refers to the transient response voltage on the secondary side of the CVT.

[0063] Figure 12 A comparison chart of the actual CVT primary side voltage and the CVT primary side voltage calculated using the method proposed in the embodiments of this application;

[0064] Figure reference numerals and corresponding component names:

[0065] 200-Measuring device, 201-Fitting unit, 202-Numerical relationship construction unit, 203-Calculation unit, 300-Measuring system, 301-Input device, 302-Output device, 303-Processor A, 304-Memory A, 400-Electronic device, 410-Memory B, 420-Processor B, 411-Computer program A, 500-Computer-readable storage medium, 511-Computer program B. Detailed Implementation

[0066] In the following, the terms “comprising” or “may include” as used in the various embodiments of this application indicate the presence of a function, operation, or element of the invention and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in the various embodiments of this application, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or adding one or more combinations of the foregoing.

[0067] In various embodiments of this application, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0068] The terms used in the various embodiments of this application (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above terms do not limit the order and / or importance of the elements. The above terms are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0069] It should be noted that if a description is made of "connecting" one component to another, then the first component can be directly connected to the second component, and a third component can be "connected" between the first and second components. Conversely, when a component is "directly connected" to another component, it can be understood that there is no third component between the first and second components.

[0070] The terminology used in the various embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of this application pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of this application.

[0071] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.

[0072] Example 1:

[0073] This embodiment proposes a method for measuring transient voltage of a capacitive voltage transformer. This method solves for transient overvoltage on the primary side (i.e., the grid side) by inversely calculating the transient response on the secondary side of the CVT, providing technical support for the measurement and research of transient voltage on the power grid.

[0074] like Figure 1 As shown, the method proposed in this embodiment includes the following steps:

[0075] Step 110: Perform piecewise linear fitting on the flux linkage-current curve of the CVT intermediate transformer and obtain the relationship function between the piecewise current and flux linkage.

[0076] Step 120: Construct the voltage numerical equation from the secondary side to the primary side of the CVT. This voltage numerical equation needs to take into account the CVT's distributed capacitance to ground.

[0077] Step 130: Substitute the real-time acquired CVT secondary voltage value into the voltage numerical equation, and combine it with the relationship function between piecewise current and magnetic flux to calculate the CVT primary voltage.

[0078] Optionally, step 110 is implemented as follows:

[0079] Piecewise linear fitting of the flux linkage-current curve of the intermediate transformer yields the piecewise linear function of flux linkage-current as shown in equation (1):

[0080] (1)

[0081] Among them, i m This represents the excitation current of the intermediate transformer; Represents the flux linkage-current function; , The linearization parameter for the j-th segment is determined through fitting. The j-th segment represents the starting excitation current value; the K-th segment represents the number of segments. It can be understood that this embodiment performs piecewise linear fitting on the flux linkage-current curve of the intermediate transformer, that is, transforms the flux linkage-current curve into a piecewise function composed of several line segments. Specifically, the functional relationship for each segment can be determined using existing linear fitting techniques, which will not be elaborated here.

[0082] According to equation (1), the flux linkage-current relationship of the intermediate transformer is obtained. inverse function That is, the functional relationship between the excitation branch current and the magnetic flux linkage:

[0083] (2)

[0084] in, For magnetic linkage; This represents the flux linkage value at the beginning of segment j.

[0085] This embodiment first uses a linear fitting method to transform the flux linkage-current curve of the CVT intermediate transformer into an expressible mathematical function relationship. The flux linkage-current curve is typically provided by the transformer manufacturer.

[0086] Optionally, step 120 constructs the voltage numerical equation from the secondary side to the primary side of the CVT based on the CVT equivalent circuit. This embodiment uses... Figure 2 The following is an example of a general CVT equivalent circuit. Figure 2 In the middle, C e C is the equivalent capacitive reactance of the capacitor divider; p Z is the distributed capacitance of the primary winding of the transformer to ground. k For compensating reactors; Z p and Z s The impedances formed by the winding resistance and leakage inductance of the primary and secondary sides are respectively; L m For magnetizing inductance; Z L To take into account stray capacitance C s The equivalent load; the intermediate transformer turns ratio is k:1; u1 and u2 are the primary and secondary voltages of the CVT, respectively; u k To compensate for the total voltage across the reactor and capacitor divider; p This refers to the primary voltage of the intermediate transformer; u m i is the excitation voltage; i1 and i2 are the CVT primary and secondary winding currents; i Cp i is the current on the step capacitor to ground of the primary winding of the intermediate transformer; ps i represents the current across the coupling capacitor between the primary and secondary windings of the intermediate transformer. σ1 i is the current on the leakage reactance of the primary winding of the intermediate transformer; σ2 i is the current on the leakage reactance of the secondary winding of the intermediate transformer; m This is the excitation current of the intermediate transformer. The specific process is as follows:

[0087] Based on the forward differential method, the numerical relationship between current and voltage of the following RL-C circuit (a branch in which the resistor and inductor are connected in series and then in parallel with the capacitor) is obtained, namely, equation (3). This numerical relationship can characterize the RL-C type structure existing inside the CVT, such as the load branch, the compensation reactor branch, etc.

[0088] (3)

[0089] in, This is the (n+1)th sampled value of the current; This is the nth sample value of the current; This refers to the capacitance value in the RL-C circuit. The sampling time interval; The resistance value in the RL-C circuit; The inductance value in the RL-C circuit; , Let these represent the first and second order forward differences of the voltage, respectively:

[0090] (4)

[0091] in, , , These are the (n+2)th, (n+1)th, and (n)th sampled values ​​of the voltage, respectively.

[0092] Neglecting the coupling capacitance between windings, we have (That is, the secondary winding current equals the secondary side current), thus obtaining the excitation branch voltage. Numerical relationship between the winding secondary current and the winding secondary current:

[0093] (5)

[0094] in, This refers to the resistance of the secondary winding of the CVT intermediate transformer. This is the nth sampled value of the current on the leakage reactance of the secondary winding of the intermediate transformer; For leakage inductance of the CVT secondary winding; This is the first-order forward differential of the current on the leakage reactance of the secondary winding of the intermediate transformer; This is the nth sampled value of the CVT secondary voltage.

[0095] By measuring the voltage of the excitation branch Trapezoidal integrals can be used to calculate the flux linkage in the magnetic core of the excitation magnet. :

[0096] (6)

[0097] in, This is the (n-1)th sample value of the magnetic flux linkage; It is the first-order forward differential of the flux linkage voltage.

[0098] Based on the excitation branch current Excitation branch voltage and secondary winding current (i.e., secondary current) The voltage of the distributed capacitance to ground can be obtained. :

[0099] (7)

[0100] in, The resistance of the primary winding of the CVT intermediate transformer. Leakage inductance of the primary winding of the CVT.

[0101] Based on the voltage of the distributed capacitance to ground The current of the distributed capacitance to ground can be obtained. :

[0102] (8)

[0103] in, This represents the first-order forward differential of the primary side voltage of the intermediate transformer.

[0104] Based on the current of the distributed capacitance to ground And combined with the excitation branch current and secondary winding current (i.e., secondary current) The total voltage of the compensating reactor and the capacitive voltage divider can be obtained. :

[0105] (9)

[0106] In the formula,

[0107] in, This is the nth sampled value of the CVT primary winding current; The resistance of the CVT compensation reactor. For the inductance of the CVT compensation reactor, The capacitor is the capacitor in the capacitor voltage divider; This is the (n-1)th sampled value of the CVT primary winding current; It is the first-order forward differential of the CVT primary winding current.

[0108] Based on the voltage of the compensating reactor and the capacitive voltage divider and the voltage of the distributed capacitance to ground The primary voltage of the CVT can then be obtained. :

[0109] (10)

[0110] Optionally, step 130 is implemented as follows:

[0111] The secondary side voltage value of the CVT is obtained in real time according to the sampling interval. Based on this voltage value, the secondary winding current, excitation branch voltage and flux linkage can be obtained by combining equations (3)-(6).

[0112] Substitute the flux linkage into the corresponding piecewise function of equation (2) to calculate the excitation branch current;

[0113] Based on the excitation branch current, excitation branch voltage, and secondary winding current, the voltage of the distributed capacitance to ground, the voltage of the compensating reactor, and the voltage divider are calculated using equations (7)-(9).

[0114] Substituting the voltage of the distributed capacitor to ground and the voltages of the compensating reactor and the capacitor divider into equation (10), the primary voltage of the CVT can be obtained.

[0115] In another embodiment, this embodiment also proposes a transient voltage measuring device for a capacitive voltage transformer, such as... Figure 3 As shown, the measuring device 200 includes:

[0116] Fitting unit 201 is used to perform piecewise linear fitting of the flux linkage-current curve of the CVT intermediate transformer and obtain the relationship function between piecewise current and flux linkage. The specific fitting process is as described in the method above and will not be repeated here.

[0117] The numerical relationship construction unit 202 is used to construct the voltage numerical equation from the secondary side to the primary side of the CVT. This voltage numerical equation needs to take into account the CVT's distributed capacitance to ground. The specific process is as described in the method above and will not be repeated here.

[0118] Furthermore, the calculation unit 203 substitutes the real-time acquired CVT secondary voltage value into the voltage numerical equation and, combined with the relationship function between piecewise current and flux linkage, calculates the CVT primary voltage. The specific process is as described in the above method and will not be repeated here.

[0119] In another embodiment, this embodiment also proposes a transient voltage measurement system for a capacitive voltage transformer, such as... Figure 4 As shown, the measurement system 300 proposed in this embodiment includes:

[0120] The system comprises an input device 301, an output device 302, a processor A303, and a memory A304; wherein the number of processors A303 and memory A304 can be one or more. Figure 4 The following description uses a processor A303 and a memory A304 as an example. The input device 301, output device 302, processor A303, and memory A304 can be connected via a bus or other means. Figure 4 Taking the example of a connection between China and Israel via a bus.

[0121] Specifically, by calling the operation instructions stored in memory A304, processor A303 executes the following steps:

[0122] The flux linkage-current curve of the CVT intermediate transformer is piecewise linearized and fitted to obtain the relationship function between piecewise current and flux linkage.

[0123] Construct a numerical voltage equation from the secondary side to the primary side of the CVT. This numerical voltage equation needs to take into account the CVT's distributed capacitance to ground.

[0124] The CVT secondary voltage value acquired in real time is substituted into the voltage numerical equation, and the CVT primary voltage is calculated by combining the relationship function between piecewise current and magnetic flux.

[0125] Optionally, by calling the operation instructions stored in memory A304, processor A303 is also used to execute any of the embodiments in the corresponding examples of the above measurement method.

[0126] In another embodiment, this embodiment also proposes an electronic device, such as Figure 5 As shown, the electronic device 400 includes: a memory B410, a processor B420, and a computer program A411 stored in the memory B410 and executable on the processor B420. When the processor B420 executes the computer program A411, it performs the following steps:

[0127] The flux linkage-current curve of the CVT intermediate transformer is piecewise linearized and fitted to obtain the relationship function between piecewise current and flux linkage.

[0128] Construct a numerical voltage equation from the secondary side to the primary side of the CVT. This numerical voltage equation needs to take into account the CVT's distributed capacitance to ground.

[0129] The CVT secondary voltage value acquired in real time is substituted into the voltage numerical equation, and the CVT primary voltage is calculated by combining the relationship function between piecewise current and magnetic flux.

[0130] Optionally, when processor B420 executes computer program A411, it can implement any of the embodiments in the corresponding examples of the above measurement method.

[0131] It should be noted that the electronic device proposed in this embodiment is a device used to implement the above measurement method. Therefore, based on the above measurement method proposed in this embodiment, those skilled in the art can understand the specific implementation method and various variations of the electronic device in this embodiment. Therefore, how the electronic device specifically implements the above measurement method will not be described in detail here. Any electronic device used by those skilled in the art to implement the above measurement method falls within the scope of protection of this application.

[0132] In another embodiment, this embodiment also proposes a computer-readable storage medium, such as Figure 6 As shown, the computer-readable storage medium 500 stores a computer program B511, which, when executed by a processor, performs the following steps:

[0133] The flux linkage-current curve of the CVT intermediate transformer is piecewise linearized and fitted to obtain the relationship function between piecewise current and flux linkage.

[0134] Construct a numerical voltage equation from the secondary side to the primary side of the CVT. This numerical voltage equation needs to take into account the CVT's distributed capacitance to ground.

[0135] The CVT secondary voltage value acquired in real time is substituted into the voltage numerical equation, and the CVT primary voltage is calculated by combining the relationship function between piecewise current and magnetic flux.

[0136] Optionally, when the computer program B511 is executed by the processor, it can implement any of the embodiments corresponding to the above measurement method.

[0137] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0138] Example 2:

[0139] This embodiment uses a simulation model built on the Matlab platform to test the transient voltage measurement technology of the capacitive voltage transformer proposed in the above embodiment.

[0140] Simulation tests under CVT saturation conditions yielded the following results: Figure 7 The core current shown and as Figure 8 The iron core magnetic flux shown, thus obtaining Figure 9 The flux linkage-current relationship is shown. Based on... Figure 7 The waveforms of the excitation current and flux linkage of the intermediate transformer shown indicate that when the core enters saturation, its permeability decreases, requiring a larger current to maintain the magnetic flux. Therefore, the current waveform exhibits a peak shape. Correspondingly, due to the decrease in the rate of flux linkage growth, its waveform becomes relatively flat during this period. Figure 8 As shown. According to Figure 9 It can be seen that under CVT saturation conditions, the relationship between the core flux linkage and the current is nonlinear, resulting in an exceptionally complex transient response process. This embodiment utilizes the method proposed in the previous embodiments to accurately measure the transient overvoltage on the primary side, thereby improving the transient response performance of the CVT.

[0141] First, the flux linkage-current curve of the CVT intermediate transformer is piecewise linearized to obtain the following result: Figure 10 The diagram shows the segmentation.

[0142] Based on the measured value of the secondary voltage (e.g.) Figure 11 As shown), by combining the voltage numerical equation and the piecewise relationship function, the primary voltage of the CVT can be obtained, such as... Figure 12 As shown.

[0143] The average relative error between the CVT primary voltage obtained by calculating using equation (11) and the actual CVT primary voltage is only 2.52%. This demonstrates that the CVT transient voltage analysis method proposed in this application can accurately reproduce the CVT primary voltage. In reality, the error of this method is related to the precision of the piecewise linearization of the flux linkage-current curve and measurement errors. If the errors introduced by these two factors are ignored, the theoretical error of this method is almost zero.

[0144] (11)

[0145] in, This represents the total number of sampling points; This represents the primary voltage of the CVT obtained from the solution; This refers to the actual primary side voltage of the CVT. This represents the average relative error.

[0146] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can 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, etc.) containing computer-usable program code.

[0147] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, 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, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0148] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0149] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0150] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for measuring the transient voltage of a capacitive voltage transformer, characterized in that, include: The flux linkage-current curve of the CVT intermediate transformer is piecewise linearized and fitted to obtain the relationship function between piecewise current and flux linkage. A numerical voltage equation is constructed from the secondary side to the primary side of the CVT, and the numerical voltage equation takes into account the CVT's distributed capacitance to ground parameter; The CVT secondary voltage value acquired in real time is substituted into the voltage numerical equation, and the CVT primary voltage is calculated by combining the relationship function between the segmented current and the magnetic flux. The construction of the voltage numerical equation from the secondary side to the primary side of the CVT includes: The numerical relationship between the secondary current and the secondary voltage of the CVT is obtained based on the forward difference method; If we ignore the coupling capacitance between the windings, then the secondary current of the winding is equal to the secondary side current. The excitation branch voltage is obtained based on the secondary winding current and the secondary side voltage. The magnetic flux linkage is obtained by gradient integration of the excitation branch voltage; The voltage of the distributed capacitance to ground is obtained from the excitation branch current, the excitation branch voltage, and the secondary winding current. The current of the distributed capacitance to ground is obtained from the voltage of the distributed capacitance to ground. The voltages of the compensation reactor and the capacitor divider are obtained based on the current of the distributed capacitance to ground, the current of the excitation branch, and the secondary winding current. The primary voltage of the CVT is obtained based on the voltages of the compensating reactor and the capacitive voltage divider, as well as the voltage of the distributed capacitance to ground.

2. The transient voltage measurement method for a capacitive voltage transformer according to claim 1, characterized in that, The method of performing piecewise linear fitting of the flux linkage-current curve of the CVT intermediate transformer and obtaining the relationship function between piecewise current and flux linkage includes: The flux linkage-current curve is piecewise linearized and fitted to obtain multiple piecewise linear functions of flux linkage-current. Based on each of the linear piecewise flux-current functions, its corresponding inverse function is obtained, which serves as the relationship function between the current and flux in that segment.

3. A method for measuring transient voltage of a capacitive voltage transformer according to claim 1 or 2, characterized in that, The calculation of the CVT primary side voltage includes: The CVT secondary side voltage value is acquired in real time according to the acquisition interval. The CVT secondary side voltage value is substituted into the voltage numerical equation to calculate the winding secondary current, excitation branch voltage and flux linkage. Substitute the calculated flux linkage into the corresponding piecewise function to calculate the excitation branch current; Substitute the calculated excitation branch current, excitation branch voltage, and secondary winding current into the voltage numerical equation to calculate the voltage of the distributed capacitance to ground, as well as the voltage of the compensating reactor and the capacitor divider. The voltage of the distributed capacitance to ground calculated is added to the voltage of the compensation reactor and the capacitor divider to obtain the primary voltage of the CVT.

4. A transient voltage measuring device for a capacitive voltage transformer, characterized in that, include: The fitting unit is used to perform piecewise linear fitting of the flux linkage-current curve of the CVT intermediate transformer and obtain the relationship function between piecewise current and flux linkage. The numerical relationship construction unit is used to construct the voltage numerical equation from the secondary side to the primary side of the CVT, and the voltage numerical equation takes into account the CVT's distributed capacitance to ground parameter. And, the calculation unit substitutes the real-time acquired CVT secondary voltage value into the voltage numerical equation, and calculates the CVT primary voltage by combining the relationship function between the segmented current and the magnetic flux. The numerical relation construction unit is configured to perform the following steps: The numerical relationship between the secondary current and the secondary voltage of the CVT is obtained based on the forward difference method; If we ignore the coupling capacitance between the windings, then the secondary current of the winding is equal to the secondary side current. The excitation branch voltage is obtained based on the secondary winding current and the secondary side voltage. The magnetic flux linkage is obtained by gradient integration of the excitation branch voltage; The voltage of the distributed capacitance to ground is obtained from the excitation branch current, the excitation branch voltage, and the secondary winding current. The current of the distributed capacitance to ground is obtained from the voltage of the distributed capacitance to ground. The voltages of the compensation reactor and the capacitor divider are obtained based on the current of the distributed capacitance to ground, the current of the excitation branch, and the secondary winding current. The primary voltage of the CVT is obtained based on the voltages of the compensating reactor and the capacitive voltage divider, as well as the voltage of the distributed capacitance to ground.

5. A transient voltage measuring device for a capacitive voltage transformer according to claim 4, characterized in that, The fitting unit is configured to perform the following steps: The flux linkage-current curve is piecewise linearized and fitted to obtain multiple piecewise linear functions of flux linkage-current. Based on each of the linear piecewise flux-current functions, its corresponding inverse function is obtained, which serves as the relationship function between the current and flux in that segment.

6. A transient voltage measuring device for a capacitive voltage transformer according to claim 4 or 5, characterized in that, The computing unit is configured to perform the following steps: The CVT secondary side voltage value is acquired in real time according to the acquisition interval. The CVT secondary side voltage value is substituted into the voltage numerical equation to calculate the winding secondary current, excitation branch voltage and flux linkage. Substitute the calculated flux linkage into the corresponding piecewise function to calculate the excitation branch current; Substitute the calculated excitation branch current, excitation branch voltage, and secondary winding current into the voltage numerical equation to calculate the voltage of the distributed capacitance to ground, as well as the voltage of the compensating reactor and the capacitor divider. The voltage of the distributed capacitance to ground calculated is added to the voltage of the compensation reactor and the capacitor divider to obtain the primary voltage of the CVT.

7. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the transient voltage measurement method for a capacitive voltage transformer as described in any one of claims 1-3.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the transient voltage measurement method for a capacitive voltage transformer as described in any one of claims 1-3.

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