Capacitive voltage transformer frequency characteristic measurement method, system, terminal and medium

Abstract

The present invention discloses a method, system, terminal and medium for measuring the frequency characteristics of a capacitive voltage transformer, and relates to the technical field of voltage transformers. The key points of the technical solution are: using the transient voltage of the power system as the excitation voltage of the primary side of the CVT, and collecting the response of the secondary side of the CVT to the transient voltage to obtain the transient voltage response; performing spectrum analysis on the transient voltage response, identifying the valley point and the peak point, and extracting the valley frequency corresponding to the valley point and the peak frequency corresponding to the peak point; calculating the spurious parameters of the CVT according to the valley frequency and / or the peak frequency, and obtaining the frequency characteristic measurement result. The present invention can realize the online measurement of the frequency response characteristics of the CVT; and there is no need to apply the excitation voltage to the primary side of the CVT, nor to measure the primary voltage of the CVT, and no interference is introduced to the equipment and the system itself.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage transformers, and more specifically, to a method, system, terminal and medium for measuring frequency characteristics of a capacitive voltage transformer. Background Art

[0002] The frequency characteristics of capacitor voltage transformers (CVTs) are very important for harmonic measurement in power systems. Due to the nonlinear impedance and inherent capacitance of CVTs, ferromagnetic resonance is sometimes caused within the CVT, so a damping device is needed to suppress the resonance. In addition, the harmonic transfer characteristics of CVTs at high frequencies may be affected by stray capacitance, which needs to be considered in design and application.

[0003] At present, there are two main methods for measuring the frequency response characteristics of CVT: the intrusive method and the non-intrusive method. The intrusive method applies an excitation voltage such as a sinusoidal signal or a pulse signal to the primary side of the CVT, and simultaneously measures the response of the secondary side of the CVT to calculate the frequency response characteristics of the CVT. The intrusive method requires the CVT to be disconnected from the power grid, which is usually performed during the power outage maintenance of the CVT. However, this is not always possible in engineering. The non-intrusive method connects a standard voltage transformer with known frequency characteristics in parallel with the CVT to be tested to the same voltage bus, and calculates the frequency characteristics of the CVT to be tested by comparing the voltages on the secondary sides of the two. However, this method requires that a standard transformer be connected in parallel to each CVT for measurement, which has the disadvantages of cumbersome operation and low frequency resolution.

[0004] Therefore, how to study and design a method, system, terminal and medium for measuring the frequency characteristics of a capacitive voltage transformer that can overcome the above-mentioned defects is a problem that we urgently need to solve. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a method, system, terminal and medium for measuring the frequency characteristics of a capacitive voltage transformer, which can realize online measurement of the frequency response characteristics of a CVT.

[0006] The above technical objectives of the present invention are achieved through the following technical solutions:

[0007] In a first aspect, a method for measuring the frequency characteristics of a capacitor voltage transformer is provided, comprising the following steps:

[0008] The transient voltage of the power system is used as the excitation voltage of the primary side of the CVT, and the response of the secondary side of the CVT to the transient voltage is collected to obtain the transient voltage response;

[0009] Perform spectrum analysis on transient voltage response, identify valley points and peak points, and extract valley frequencies corresponding to valley points and peak frequencies corresponding to peak points;

[0010] The spurious parameters of the CVT are calculated according to the valley frequency and / or the peak frequency to obtain the frequency characteristic measurement result.

[0011] Furthermore, the transient voltage is any one of a voltage sag process voltage, a voltage swell process voltage, an operating overvoltage and a lightning overvoltage.

[0012] Furthermore, the calculation process of the stray parameters is specifically as follows:

[0013] Establish an equivalent circuit taking into account the CVT stray parameters;

[0014] The CVT is simplified according to the RL-C type parallel branch to obtain a simplified circuit;

[0015] Establish the solution expression of the impedance of each part in the simplified circuit;

[0016] The simplified circuit is considered as two subsystems in cascade, and the solution model of stray parameters is established by combining the solution expressions of the corresponding partial impedances;

[0017] The valley frequency and / or peak frequency are input into the solution model to calculate the spurious parameters of the CVT.

[0018] Furthermore, the stray parameters include the stray capacitance of the compensating reactor, the stray capacitance of the primary winding of the intermediate transformer to ground, the stray capacitance of the secondary winding of the intermediate transformer to ground, and the distributed capacitance between the primary and secondary windings.

[0019] Furthermore, if the stray parameter is the stray capacitance of the compensation reactor, the expression for solving the model is:

[0020] ;

[0021] in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the first valley point; Indicates the valley frequency corresponding to the first valley point; Indicates the impedance corresponding to the stray capacitance of the compensation reactor.

[0022] Furthermore, if the stray parameter is the distributed capacitance between the primary and secondary windings, the expression for solving the model is:

[0023] ;

[0024] in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the second valley point; Indicates the valley frequency corresponding to the second valley point; It represents the impedance corresponding to the distributed capacitance between the primary and secondary windings.

[0025] Further, if the stray parameter is the stray capacitance of the primary winding of the intermediate transformer to the ground and / or the stray capacitance of the secondary winding of the intermediate transformer to the ground, the expression for solving the model is:

[0026] ;

[0027] in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the first peak point; Indicates the angular frequency corresponding to the second peak point; Indicates the peak frequency corresponding to the first peak point; Indicates the peak frequency corresponding to the second peak point; Indicates the capacitive reactance corresponding to the stray capacitance of the primary winding of the intermediate transformer to ground; It represents the capacitive reactance corresponding to the stray capacitance of the secondary winding of the intermediate transformer to ground; Indicates the impedance corresponding to the stray capacitance of the compensation reactor; Indicates the impedance corresponding to the distributed capacitance between the primary and secondary windings; Indicates the impedance corresponding to the stray capacitance of the secondary winding of the intermediate transformer to ground; Indicates parallel connection.

[0028] In a second aspect, a capacitive voltage transformer frequency characteristic measurement system is provided, comprising:

[0029] A response acquisition module is used to use the transient voltage of the power system as the excitation voltage of the primary side of the CVT, and to acquire the response of the secondary side of the CVT to the transient voltage to obtain the transient voltage response;

[0030] The spectrum analysis module is used to perform spectrum analysis on the transient voltage response, identify valley points and peak points, and extract the valley frequency corresponding to the valley point and the peak frequency corresponding to the peak point;

[0031] The parameter calculation module is used to calculate the spurious parameters of the CVT according to the valley frequency and / or the peak frequency to obtain the frequency characteristic measurement result.

[0032] In a third aspect, a computer terminal is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, a method for measuring the frequency characteristics of a capacitive voltage transformer as described in any one of the first aspects is implemented.

[0033] In a fourth aspect, a computer-readable medium is provided, on which a computer program is stored, and the computer program is executed by a processor to implement the method for measuring the frequency characteristics of a capacitor voltage transformer as described in any one of the first aspects.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The method for measuring the frequency characteristics of a capacitive voltage transformer provided by the present invention can realize online measurement of the frequency response characteristics of a CVT;

[0036] 2. The present invention does not need to apply an excitation voltage to the primary side of the CVT, nor does it need to measure the primary voltage of the CVT, and does not introduce interference to the equipment and the system itself;

[0037] 3. The present invention uses the transient process of the power grid itself to analyze the frequency characteristics of CVT, and the required data is easy to obtain and the data volume is sufficient;

[0038] 4. The frequency response characteristics and unit impulse response analytical forms of the CVT designed in the present invention do not require fitting and are more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0040] Figure 1 is an equivalent circuit diagram of Example 1 of the present invention taking into account the CVT stray capacitance;

[0041] Figure 2 is a graph showing the amplitude-frequency characteristic of a typical CVT in Example 1 of the present invention;

[0042] Figure 3 is a RL-C type parallel branch diagram in Example 1 of the present invention;

[0043] Figure 4 is a simplified circuit diagram of the CVT in Example 1 of the present invention;

[0044] Figure 5 is an overvoltage waveform diagram measured by the CVT in Example 1 of the present invention;

[0045] Figure 6 is an overvoltage spectrum diagram measured by CVT in Example 1 of the present invention;

[0046] Figure 7 It is a system block diagram in Example 2 of the present invention. DETAILED DESCRIPTION

[0047] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0048] Embodiment 1: A method for measuring the frequency characteristics of a capacitive voltage transformer, which realizes online measurement of the frequency response characteristics of a CVT, comprises the following steps:

[0049] S1: Use the transient voltage of the power system as the excitation voltage of the primary side of the CVT, and collect the response of the secondary side of the CVT to the transient voltage to obtain the transient voltage response;

[0050] S2: Perform spectrum analysis on the transient voltage response, identify valley points and peak points, and extract valley frequencies corresponding to valley points and peak frequencies corresponding to peak points;

[0051] S3: Calculate the spurious parameters of the CVT according to the valley frequency and / or the peak frequency to obtain the frequency characteristic measurement result.

[0052] Since the design parameters in the CVT structure (parameters of the capacitor voltage divider, compensation inductor, and intermediate transformer, etc.) are all known quantities, and all stray parameters have also been obtained, its frequency characteristics can be calculated in combination with the equivalent circuit of the CVT.

[0053] In step S1 , the transient voltage is any one of a voltage sag process voltage, a voltage swell process voltage, an operation overvoltage and a lightning overvoltage, and the lightning overvoltage refers to a peak value that does not exceed the saturation voltage of the CVT.

[0054] The frequency response characteristics of CVT and the voltages on its primary and secondary sides satisfy the following relationship in the frequency domain:

[0055] ;

[0056] in, H ( ω ) is the frequency response characteristic of CVT, X ( ω ), Y ( ω ) are the voltage spectra of the primary and secondary sides of the CVT, ω is the angular frequency.

[0057] H ( ω) usually has zero poles, which is manifested in its amplitude-frequency characteristic | H ( ω )|The peak value on the curve. Figure 2 As shown, this is the amplitude-frequency curve of a typical CVT. It can be seen that it has two peak points and valley points, corresponding to the frequency f max_1 and f max_2 (peak frequency), f min_1 and f min_2 (valley frequency). If the CVT secondary voltage spectrum is required Y ( ω ) has the same frequency characteristics as CVT H ( ω ) have the same zero-pole, that is, the valley-peak frequency, then X ( ω ) should meet the following requirements:

[0058] (1) X ( ω ) should have the following characteristics: H ( ω )The frequency spectrum range of zero poles;

[0059] (2) X ( ω )exist H ( ω ) The value of the zero and pole should be a non-zero constant, and cannot be the same as the pole and zero, to avoid H ( ω )'s poles and zeros cancel each other out.

[0060] The unit pulse voltage meets the above conditions. When used as the excitation voltage on the primary side of the CVT, it can stimulate the CVT secondary side to output a wide-band response. The spectrum of this response will form peaks and valleys at the peak and valley frequencies of the CVT. However, it is difficult to apply pulse excitation to the online CVT at the engineering site, and it will introduce interference to the power system, which is not conducive to the stable operation of the system. Therefore, a method is proposed to calculate the spurious parameters by observing the transient response spectrum characteristics of the CVT using the transient voltage of the power system itself as the excitation. The specific derivation is as follows.

[0061] The following formula gives the empirical relationship between the rising edge or falling edge time of a signal and its effective bandwidth: the shorter the rising time or falling time of the signal, the richer the frequency components, that is, the wider the bandwidth.

[0062] ;

[0063] in, is the effective bandwidth, is the time of the rising or falling edge.

[0064] For example, the effective bandwidth of an overvoltage with a rise time of 17.5us can reach 20kHz, which can cover the valley-peak frequency of a general CVT and meet the frequency range requirements for harmonic measurement in engineering.

[0065] Taking double exponential overvoltage as an example, its time domain and frequency domain are:

[0066] ;

[0067] In the formula, U m Overvoltage peak, α and β is the waveform control parameter; j represents an imaginary number; t Indicates time.

[0068] It can be seen that the frequency range and spectrum characteristics of the double exponential overvoltage meet the conditions for exciting the CVT to produce a valley-peak response, that is, the frequency domain is wide and there is no valley peak at the peak-valley frequency of the CVT. Other typical overvoltages, such as Heidler-shaped overvoltage and pulse-type overvoltage, also have similar characteristics.

[0069] In addition to operational overvoltage, temporary voltage sags and swells caused by ground short-circuit faults commonly seen in engineering also satisfy the above properties. That is to say, the transient signals commonly seen in engineering can be used to excite the CVT to produce a frequency response in a wide frequency domain, and the spurious parameters and frequency response characteristics of the CVT can be calculated based on the peak and valley frequencies in the response spectrum.

[0070] In step S2, if Figure 1 As shown in Figure 1, the internal structural parameters of CVT are divided into design parameters and stray parameters. The design parameters are known parameters designed by the manufacturer. These parameters include: capacitor voltage divider equivalent capacitor parameters C e , impedance parameters of compensation reactor R k , L k , impedance parameters of primary and secondary windings of intermediate transformer R σ1 , L σ1 , R σ2 , L σ2 , impedance parameters of the excitation winding L m , R m , the impedance parameter of the damper R d ,L d , C k Represents the stray distributed capacitance of the compensation reactor; up Represents the primary side voltage, us Indicates the secondary side voltage.

[0071] Stray parameters are difficult to measure and have significant individual differences. They are also the main reason for the differences in frequency response characteristics of different CVTs. These parameters include the stray capacitance of the compensation reactor, the stray capacitance of the primary and secondary windings of the intermediate transformer to the ground, and the stray capacitance of the secondary windings of the intermediate transformer to the ground. C p , C s , distributed capacitance between primary and secondary windings C ps .

[0072] Figure 2 The frequency in the amplitude-frequency curve of a typical CVT is shown f max_1 and f max_2 (peak frequency), f min_1 and f min_2 The formation principle of (valley frequency) is as follows:

[0073] First, connect the CVT in RL-C parallel branches (such as Figure 3 ) is simplified to obtain a simplified circuit, such as Figure 4 As shown, the impedance of each part is as follows:

[0074] ;

[0075] Among them, “ / / ” represents parallel connection, , They are the total winding resistance and leakage converted to the primary side of the transformer respectively.

[0076] Then, CVT can be viewed as a cascade of two subsystems, such as Figure 4 As shown:

[0077] .

[0078] If you separately , Recorded as and So:

[0079] ;

[0080] From the above formula, we can see that when and When they reach their maximum values, the first subsystem H 1( ω ) and the second subsystem H 2( ω ) tends to a minimum value, which is manifested as a valley point in the CVT amplitude-frequency characteristic curve, such as Figure 2 In f min_1 and f min_2 The corresponding amplitude-frequency characteristics.

[0081] ;

[0082] ;

[0083] in, for The minimum value of .

[0084] because H 1( ω ) Will make peace H 2( ω ) in the molecule offset, so the CVT corresponds to H ( ω ) maximum value in the amplitude (expressed as Figure 2 In f max_1 , f max_2 The corresponding amplitude-frequency characteristic) depends on H 2( ω ) in which the denominator is minimal:

[0085] ;

[0086] in, for H 2( ω ), that is, , for The maximum value of .

[0087] In summary, we can conclude that H ( ω ) f min_1 and f min_2 Only with C k and C ps About, when C k orC ps When the capacitance of other stray capacitors is fixed and changes, the valley frequency f min_1 and f min_2 Always remain the same; H ( ω )'s peak frequency f max_1 , f max_2 It is related to all spurious parameters. When any spurious parameter changes, the peak frequency f max_1 , f max_2 There will be different degrees of deviation.

[0088] In step S3, only the known H ( ω ) H ( ω ) peak and valley frequencies) f max_1 , f max_2 , f min_1 and f min_2 , without knowing the specific amplitude and phase corresponding to these frequencies, using the valley frequency f min_1 and f min_2 They are and The characteristics of the stationary point are firstly determined by C k Solving the univariate equation C k ; Through about C ps Solving the univariate equation C ps , as follows:

[0089] ;

[0090] in, and They are and Is about The derivative function of , .

[0091] Then, using the peak frequency f max_1 and fmax_2 They are The characteristics of the stationary point, C ps and C s It can be solved by the following system of equations:

[0092] ;

[0093] in, for about The derivative function of , .

[0094] Note that although is a multivariate function of all stray parameters, but due to C ps and C k The valley frequencies have been obtained respectively, so the above equations are about C p and C s The system of two-variable equations.

[0095] Example description: Combine PSCAD and MATLAB simulation platform to build a CVT frequency response characteristic test system. After 2s of normal operation of CVT, add a lightning wave overvoltage to the line, and synchronously record the line voltage and CVT secondary side measurement voltage. Figure 5 shown.

[0096] The spectrum of the voltage measured by the CVT is f max_1 =252Hz and f max_2 =2117Hz forms a peak value, and f min_1 =448Hz and f min_2 =3856Hz forms a valley value, such as Figure 6 As shown. According to the calculation using the valley frequency C k and C ps The principle of using the valley / peak frequency is then used to calculate the stray capacitance of the primary and secondary windings to ground. C p and C s According to the principle of , the parameters of stray capacitance and their relative errors with the theoretical true values ​​can be calculated as follows: C k=774.12pF (relative error: 0.75%); C ps =201.15 pF (relative error: 0.58%); C s =991.65 pF (relative error: 0.84%); C p =200.45 pF (relative error: 0.22%), so it can be considered that the proposed method can accurately identify the valley / peak value from the transient response of the CVT and calculate the spurious parameters.

[0097] Embodiment 2: A capacitor voltage transformer frequency characteristic measurement system, the system is used to implement the capacitor voltage transformer frequency characteristic measurement method as described in Embodiment 1, such as Figure 7 As shown, it includes a response acquisition module, a spectrum analysis module and a parameter calculation module.

[0098] Among them, the response acquisition module is used to use the transient voltage of the power system as the excitation voltage of the primary side of the CVT, and collect the response of the secondary side of the CVT to the transient voltage to obtain the transient voltage response; the spectrum analysis module is used to perform spectrum analysis on the transient voltage response, identify the valley points and peak points, and extract the valley frequency corresponding to the valley point and the peak frequency corresponding to the peak point; the parameter calculation module is used to calculate the stray parameters of the CVT based on the valley frequency and / or peak frequency to obtain the frequency characteristic measurement results.

[0099] The present invention also records a computer terminal, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for measuring the frequency characteristics of a capacitive voltage transformer as described in Example 1 is implemented.

[0100] The present invention also describes a computer-readable medium on which a computer program is stored. The computer program is executed by a processor to implement the method for measuring the frequency characteristics of a capacitive voltage transformer as described in Example 1.

[0101] Working principle: The method for measuring the frequency characteristics of a capacitive voltage transformer provided by the present invention can realize online measurement of the frequency response characteristics of a CVT; the present invention does not need to apply an excitation voltage to the primary side of the CVT, nor does it need to measure the primary voltage of the CVT, and does not introduce interference to the equipment and the system itself; the present invention uses the transient process of the power grid itself to analyze the frequency characteristics of the CVT, and the required data is easy to obtain and the amount of data is sufficient; the frequency response characteristics of the CVT designed in the present invention and the analytical form of the unit impulse response do not require fitting and are more accurate.

[0102] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0103] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0104] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0105] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0106] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the frequency characteristics of a capacitive voltage transformer, characterized in that: The following steps are involved: The transient voltage of the power system is used as the excitation voltage of the primary side of the CVT, and the response of the secondary side of the CVT to the transient voltage is collected to obtain the transient voltage response; Perform spectrum analysis on transient voltage response, identify valley points and peak points, and extract valley frequencies corresponding to valley points and peak frequencies corresponding to peak points; The stray parameters of the CVT are calculated according to the valley frequency and / or the peak frequency to obtain the frequency characteristic measurement result; the calculation process of the stray parameters is specifically as follows: Establish an equivalent circuit taking into account the CVT stray parameters; The CVT is simplified according to the RL-C type parallel branch to obtain a simplified circuit; Establish the solution expression of the impedance of each part in the simplified circuit; The simplified circuit is regarded as two subsystems in cascade, and the solution model of the stray parameters is established in combination with the solution expression of the corresponding partial impedance; if the stray parameter is the stray capacitance of the compensation reactor, the expression of the solution model is: ； in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the first valley point; Indicates the valley frequency corresponding to the first valley point; Represents the impedance corresponding to the stray capacitance of the compensation reactor; if the stray parameter is the distributed capacitance between the primary and secondary windings, the expression for solving the model is: ； in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the second valley point; Indicates the valley frequency corresponding to the second valley point; Represents the impedance corresponding to the distributed capacitance between the primary and secondary windings; if the stray parameter is the stray capacitance of the primary winding of the intermediate transformer to ground and / or the stray capacitance of the secondary winding of the intermediate transformer to ground, the expression for solving the model is: ； in, express About angular frequency The derivative of Indicates the angular frequency corresponding to the first peak point; Indicates the angular frequency corresponding to the second peak point; Indicates the peak frequency corresponding to the first peak point; Indicates the peak frequency corresponding to the second peak point; Indicates the capacitive reactance corresponding to the stray capacitance of the primary winding of the intermediate transformer to ground; It represents the capacitive reactance corresponding to the stray capacitance of the secondary winding of the intermediate transformer to ground; Indicates the impedance corresponding to the stray capacitance of the compensation reactor; Indicates the impedance corresponding to the distributed capacitance between the primary and secondary windings; Indicates the impedance corresponding to the stray capacitance of the secondary winding of the intermediate transformer to ground; Indicates parallel connection; The valley frequency and / or peak frequency are input into the solution model to calculate the spurious parameters of the CVT.

2. The method for measuring the frequency characteristics of a capacitor voltage transformer according to claim 1, wherein: The transient voltage is any one of a voltage sag process voltage, a voltage swell process voltage, an operating overvoltage and a lightning overvoltage.

3. The method for measuring the frequency characteristics of a capacitor voltage transformer according to claim 2, wherein: The stray parameters include the stray capacitance of the compensating reactor, the stray capacitance of the primary winding of the intermediate transformer to the ground, the stray capacitance of the secondary winding of the intermediate transformer to the ground, and the distributed capacitance between the primary and secondary windings.

4. Capacitive voltage transformer frequency characteristic measurement system, characterized in that: include: A response acquisition module is used to use the transient voltage of the power system as the excitation voltage of the primary side of the CVT, and to acquire the response of the secondary side of the CVT to the transient voltage to obtain the transient voltage response; The spectrum analysis module is used to perform spectrum analysis on the transient voltage response, identify valley points and peak points, and extract the valley frequency corresponding to the valley point and the peak frequency corresponding to the peak point; The parameter calculation module is used to calculate the spurious parameters of the CVT according to the valley frequency and / or the peak frequency to obtain the frequency characteristic measurement result.

5. A computer terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for measuring the frequency characteristics of a capacitive voltage transformer as described in any one of claims 1 to 3 is implemented.

6. A computer readable medium having a computer program stored thereon, characterized in that: The computer program is executed by a processor to implement the method for measuring the frequency characteristics of a capacitive voltage transformer as described in any one of claims 1 to 3.

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