Test method and device for examining broadband measurement performance of capacitor voltage transformer

Abstract

The invention relates to a test method and device for examining broadband measurement performance of a capacitor voltage transformer. The method comprises the following steps: frequency response test: acquiring sine wave voltage signals and first output voltage signals output by the capacitor voltage transformer to be tested for multiple times; processing the signals at different frequency points to obtain gain, phase characteristics and steady-state response capability at each frequency point; a square wave signal transmission test: collecting a square wave voltage signal and a second output voltage signal output by the capacitor voltage transformer to be tested; carrying out signal time-frequency domain analysis to obtain rapid voltage change transient response capability and broadband measurement accuracy; an operation / lightning impulse transmission test: collecting a transient operation / lightning impulse wave voltage signal and a third output voltage signal output by the capacitor voltage transformer to be tested; signal processing is carried out, and the response capability and high-frequency measurement accuracy of the transient high-frequency voltage signal are obtained; and the broadband measurement performance is obtained. Compared with the prior art, the method has the advantages of comprehensively examining the broadband measurement performance of the capacitor voltage transformer and the like.

Description

Technical Field

[0001] The invention relates to the technical field of capacitor voltage transformers, and in particular to a test method and a device for assessing the broadband measurement performance of a capacitor voltage transformer. Background Art

[0002] In the context of building a new power system, policy-driven, continuous innovation of new energy storage technologies, construction of modern smart grids, and growing demand for green power market have promoted the continuous increase in the proportion of new energy in the energy structure. However, the intermittent and volatile characteristics of new energy generation have significantly changed the structure and operation mode of the power system, which is prone to measurement errors, excessive harmonics, transient voltage changes, broadband oscillations and other problems, making the system reflect broadband characteristics, and putting forward higher requirements for the accuracy and reliability of voltage measurement. In addition, with the continuous advancement of economic development and industrialization, people's demand for electricity has continued to increase, which has promoted the continuous improvement of the voltage level of the power system. By increasing the voltage level, the efficiency of power transmission has been significantly enhanced, especially in long-distance and high-capacity transmission systems, which can effectively reduce energy loss. However, the gradual increase in voltage levels is also accompanied by many risks. Among them, high-frequency voltage signal interference caused by external interference such as lightning strikes, operations, and electromagnetic induction in the power system has become one of the main factors of power system failure. Especially in high-voltage systems, electrical equipment is prone to overvoltage when it is disturbed by overvoltage, which in turn threatens the safe operation of the equipment and even triggers a larger chain reaction in extreme cases.

[0003] Traditional capacitor voltage transformer (CVT) is widely used in the field of voltage measurement, protection and control in power systems. Traditional CVT realizes voltage measurement based on the principle of capacitor voltage division, and has the characteristics of simple structure and fast response speed. However, since it was not designed to deal with broadband signals in the power grid, it has certain limitations in working principle and field operation. The limitations of the working principle are mainly manifested in the limited response of high-frequency voltage signals, uneven response of high-order harmonics, and voltage waveform distortion. It is impossible to effectively divide all broadband voltage signals accurately, resulting in distortion of the output voltage. The limitations in the actual field operation process are manifested in the poor responsiveness of transient voltage changes, large measurement errors of overvoltage high-frequency signals, and weak anti-interference ability, which cannot truly reflect the voltage state of the power grid. Therefore, as the frequency components of the power grid voltage signal become more and more complex, the traditional capacitor voltage transformer (CVT) has become difficult to cope with the problems of harmonic pollution, transient voltage changes, complex frequency components, waveform distortion, and high-frequency signal intrusion in the power grid.

[0004] In order to deal with the above-mentioned power grid and electricity risks, in recent years, many research teams at home and abroad have focused on the research and development of broadband voltage monitoring devices, one of which is a 500kV CVT based on transient voltage coupling technology that has been put into operation. Considering that the power system has very high requirements for the performance of CVT voltage measurement, especially measurements related to protection, control and its automation system, however, the existing CVT measurement performance assessment methods are mostly focused on the static performance, dynamic performance, stability and reliability of traditional CVT, and harmonic response performance, and lack a broadband measurement performance assessment method for 500kV CVT. Therefore, it is urgent to establish a measurement performance assessment method for 500kV CVT to evaluate its measurement performance in a complex operating environment, which can systematically clarify its performance when operating in an actual power grid, help identify potential sources of error and design defects, and take effective measures to improve measurement accuracy. Summary of the invention

[0005] The purpose of the present invention is to provide a test method and device for effectively testing the measurement performance of a capacitive voltage transformer in a wide-band environment and assessing the wide-band measurement performance of the capacitive voltage transformer.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A test method for evaluating the broadband measurement performance of a capacitive voltage transformer comprises the following steps:

[0008] Frequency response test:

[0009] 101) collecting a sinusoidal voltage signal of set frequency and amplitude as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a first output voltage signal output after the sinusoidal voltage signal is input into the capacitive voltage transformer (5) to be tested;

[0010] 102) Repeat step 101) multiple times to obtain sinusoidal voltage signals at different frequency points and corresponding first output voltage signals;

[0011] 103) Based on the sinusoidal voltage signal and the corresponding first output voltage signal, analysis and processing are performed to output an amplitude response characteristic curve, a phase response characteristic curve and a frequency domain waveform to obtain gain characteristics and phase characteristics at each frequency point;

[0012] Square wave signal transmission test:

[0013] 201) collecting a periodic square wave voltage signal with a fixed frequency and constant amplitude as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a second output voltage signal output after the square wave voltage signal is input into the capacitive voltage transformer (5) to be tested;

[0014] 202) Based on the square wave voltage signal and the second output voltage signal, time domain analysis and frequency domain analysis are performed to obtain the transient response capability of the capacitive voltage transformer (5) to rapid voltage changes and the broadband measurement accuracy;

[0015] Operation / lightning impulse transmission test:

[0016] 301) collecting a transient operation / lightning impulse wave voltage signal as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a third output voltage signal output after the operation / lightning impulse wave voltage signal is input into the capacitive voltage transformer (5) to be tested;

[0017] 302) Based on the operation / lightning impulse wave voltage signal and the third output voltage signal, analysis and processing are performed to obtain the response capability of the capacitive voltage transformer (5) to transient overvoltage and the broadband measurement accuracy;

[0018] The broadband measurement performance of the capacitive voltage transformer (5) to be tested is obtained based on the frequency response test results, the square wave signal transmission test results and the operation / lightning impulse transmission test results.

[0019] Furthermore, in the frequency response test, the step of obtaining the gain characteristics and phase characteristics at each frequency point includes:

[0020] Calculate the ratio of the amplitude of the sine wave voltage signal to the amplitude of the first output voltage signal at each frequency point f as the gain, and mark the gain point at each frequency point f;

[0021] Calculate the difference between the phase of the sinusoidal voltage signal and the phase of the first output voltage signal at each frequency point f as the phase difference, and mark the phase difference point at each frequency point f;

[0022] Connect all gain points and phase difference points to draw amplitude response characteristic curve and phase response characteristic curve;

[0023] Converting the time domain voltage waveform of the sinusoidal voltage signal into a frequency domain waveform;

[0024] By comparing the amplitude / phase response characteristic curve with the frequency domain waveform, the gain characteristics and phase characteristics at each frequency point can be clarified.

[0025] Furthermore, the fast Fourier transform method is used to convert the time domain voltage waveform into a frequency domain waveform, where the conversion expression is:

[0026]

[0027] Where X(f) is the frequency domain at frequency point f, and x(t) is the time domain signal.

[0028] Furthermore, in the operation / lightning impulse transmission test, the steps of analyzing and processing include:

[0029] Compare the characteristic parameters of the time domain waveform of the operation / lightning impulse wave voltage signal and the time domain waveform of the third output voltage signal to obtain the distortion condition of the capacitive voltage transformer to be tested;

[0030] The time domain waveform of the operation / lightning impulse wave voltage signal and the time domain waveform of the third output voltage signal are both converted into frequency domain waveforms, and the frequency domain waveforms are compared to obtain the loss or attenuation of the high frequency part.

[0031] Furthermore, the characteristic parameters include the wavefront time, wave tail time, peak value and steepness of the operation / lightning impulse wave voltage signal input waveform and the response waveform.

[0032] Furthermore, it also includes:

[0033] Before steps 103), 202), and 302), the sinusoidal wave voltage signal, the square wave voltage signal, and the operation / lightning impulse wave voltage signal are transformed according to the transformation ratio of the capacitive voltage transformer to be tested.

[0034] The present invention also provides a test device based on the above-mentioned test method for assessing the broadband measurement performance of a capacitive voltage transformer, comprising a signal generator, a standard voltage divider, an oscilloscope and a PC terminal.

[0035] The signal generator is connected to the standard voltage divider and the capacitive voltage transformer to be tested respectively, and the signal generator is used to transmit the generated multiple input voltage signals to the standard voltage divider and the capacitive voltage transformer to be tested respectively. The standard voltage divider and the capacitive voltage transformer to be tested are both connected to the oscilloscope, and the standard voltage divider is used to transmit the input voltage signal to the oscilloscope after transformation according to the transformation ratio, and the capacitive voltage transformer to be tested is used to transmit the measured output voltage signal to the oscilloscope. The oscilloscope is connected to the PC end, and the PC end is used to perform data processing and comparative analysis on the input voltage signal and the output voltage signal after transformation according to the transformation ratio, so as to obtain the attenuation or phase distortion characteristics of the capacitive voltage transformer to be tested at different frequency points.

[0036] Furthermore, the signal generator includes a sweep signal generating device, a square wave signal generating device and an impulse signal generating device to respectively generate a sine wave signal, a square wave signal and an operation / lightning impulse wave voltage signal, and respectively perform the frequency response test, the square wave signal transmission test and the operation / lightning impulse transmission test.

[0037] Furthermore, the oscilloscope is provided with two channels, namely CH1 and CH2, the CH1 is connected to the standard voltage divider, and the CH2 is connected to the capacitive voltage transformer to be tested.

[0038] Furthermore, the test device is suitable for assessing capacitive voltage transformers to be tested of 500 kV and above.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention generates a variety of voltage signals through a signal generator and transmits them to a capacitive voltage transformer and a standard voltage divider. The original input voltage and output voltage are recorded by an oscilloscope and analyzed and processed by a PC to obtain the response capability of the capacitive voltage transformer under different voltage signals, thereby effectively testing the measurement performance of the capacitive voltage transformer in a wide-band environment.

[0041] (2) The frequency response test of the present invention evaluates the response capability of the capacitive voltage transformer under steady-state conditions by analyzing the frequency response characteristics within the entire wide frequency range. The square wave signal transmission test evaluates the transient response capability of the capacitive voltage transformer to rapid voltage changes by analyzing whether the output voltage waveform is distorted or offset. The operation / lightning impulse transmission test evaluates the anti-interference capability and measurement accuracy of the CVT to high-frequency impulse wave voltage signals by recording the output voltage waveform under transient high-frequency voltage conditions and analyzing key parameters such as wavefront time, wave tail time, peak value and steepness.

[0042] (3) The present invention comprehensively evaluates the broadband measurement performance of the capacitor voltage transformer by conducting frequency response tests, square wave signal transmission tests, and operation / lightning impulse transmission tests, and evaluates the response capability of the capacitor voltage transformer from different test angles, thereby better reflecting the actual application capability of the equipment in complex power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the test method flow of the present invention;

[0044] Figure 2 It is a circuit diagram of the test device of the present invention;

[0045] Figure 3 The basic structure of the 500kV CVT of the present invention;

[0046] Figure 4 The sine wave voltage signal test results of the present invention;

[0047] Figure 5 The frequency domain waveform-amplitude of the sinusoidal voltage signal of the present invention;

[0048] Figure 6 The frequency domain waveform-phase of the sinusoidal voltage signal of the present invention;

[0049] Figure 7The high-frequency square wave voltage signal simulation waveform of the present invention;

[0050] Figure 8 The operating impact test waveform of the present invention;

[0051] Fig. 9 This is the lightning impulse test waveform of the present invention. DETAILED DESCRIPTION

[0052] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0053] This embodiment provides a test method for evaluating the broadband measurement performance of a capacitor voltage transformer, which is used to test the broadband measurement performance of a capacitor voltage transformer 5 to be tested, wherein the frequency range is 10 Hz to 10 7 Hz. This test method is based on the test device, such as Figure 2 As shown, the device includes: a signal generator 1, a standard voltage divider 2, an oscilloscope 3 and a PC terminal 4. The signal generator 1 includes a sweep signal generating device 11, a square wave signal generating device 12 and an impulse signal generating device 13. In combination with the test device, the steps of the test method include:

[0054] (1) The test device of the present application is applicable to core-type or coreless capacitor voltage transformers (CVTs) with a rated voltage level of 500 kV and above. In this embodiment, a 500 kV CVT is used as the capacitor voltage transformer 5 to be tested. First, it is clear that the basic structure and working principle of the 500 kV CVT are the basis for proposing a broadband measurement performance assessment method. Its basic structure is as follows: Figure 3 As shown, it consists of four parts: a capacitor voltage divider, a compensating reactor, an intermediate transformer, and a damper, each of which has different functions. The core part of CVT is the capacitor, which is usually composed of multiple capacitor units connected in series, in parallel, or in series and parallel, and is used to distribute the source input high voltage signal to the medium voltage capacitor C2 and the transient capacitor C3 in proportion, so as to meet the needs of voltage reduction and measurement. The compensating reactor L and the capacitor form a low-pass filter to adjust the overall frequency characteristics, which can effectively suppress high-frequency signals and harmonic components, thereby improving the measurement accuracy of low-frequency voltage signals. The voltage signal distributed by the medium-voltage capacitor is adjusted by the compensating reactor and transmitted to the intermediate transformer T, which not only plays the role of voltage conversion, but also provides safe electrical isolation to ensure the accuracy and reliability of voltage measurement and protection in the power system. Due to the electrical characteristics of capacitors and other components, oscillations or overshoots may occur during circuit operation, affecting the stability and accuracy of the voltage signal. For this reason, a damper R is introduced. DThis situation is improved by consuming energy to slow down the oscillation and ensure stable operation of the CVT. Figure 3 a and n are the secondary winding lead terminals, d a ,d n For R D Lead-out terminal; U is the 500kV CVT source input high voltage signal, U C3 The transient capacitor C3 outputs a voltage signal.

[0055] (2) It is an important prerequisite for conducting the test to clearly define the test circuits for the frequency response test, square wave signal transmission test, and operation / lightning impulse transmission test. Figure 2 As shown, first, the signal generator 1 in the figure can generate sinusoidal voltage signals, square wave voltage signals and operation / lightning impulse wave voltage signals at different frequencies required for the test; secondly, the high-voltage signal generated by the signal generator 1 will be respectively transmitted to the standard voltage divider 2 and the capacitive voltage transformer 5 to be tested, wherein the standard voltage divider 2 transforms the high-voltage signal source voltage generated by the signal generator 1 in the figure according to the transformation ratio; finally, the standard voltage divider 2 and the transient capacitance measurement output voltage signal are respectively transmitted to two channels (CH1, CH2) of the oscilloscope 3 via shielded coaxial cables to record the voltage waveform for subsequent data processing and comparative analysis on the PC end 4.

[0056] (3) Conducting a 500kV CVT frequency response test is the root of the broadband measurement performance assessment method. The frequency response test is to input a sine wave voltage signal at different frequencies to the CVT, test the gain and phase changes of the output signal, and evaluate the measurement performance and steady-state response capability of the CVT at various frequencies. The process of conducting a frequency response test on a CVT includes the following three points:

[0057] 1) Before the test, prepare the 500kV CVT to be tested, the sweep signal generator 11, the standard voltage divider 2, the oscilloscope 3 and the PC terminal 4. Record the temperature, humidity and atmospheric pressure of the test on the day to ensure that the test environment is dry and reduce external electromagnetic interference to improve the test accuracy.

[0058] 2) Generate a sinusoidal voltage signal of known frequency and amplitude to the 500kV CVT through the frequency sweep signal generating device 11, and transmit it to the standard voltage divider 2 at the same time; use the two channels CH1 and CH2 of the oscilloscope to receive it, and after 55 times of input and output at different frequency points, record the input voltage signal and output voltage signal at different frequency points.

[0059] 3) PC terminal 4 performs data analysis on the acquired signal data. The ratio of the output voltage signal amplitude to the input voltage signal amplitude at each frequency point f is the gain (Gain(f)), and the difference between the output voltage signal phase and the input voltage signal phase is the phase difference (Phase Shift(f)). The corresponding gain values ​​and phase difference values ​​are marked at different f points, and then all points are connected to form an amplitude response characteristic curve and a phase response characteristic curve. If there are obvious gain changes (such as peaks or troughs) and phase shifts in certain frequency ranges, it indicates that the measurement work of CVT in this frequency band is unstable; if there are no obvious gain changes and phase shifts, it means that the transmission characteristics of CVT in this frequency band are good and the measurement work is stable.

[0060] 4) Take the case of applying a 50Hz 400V sine wave voltage signal to a 500kV CVT for analysis. Figure 4 The figure shows the time domain voltage waveform obtained according to the above test process. In order to clarify the energy distribution of the signal in each frequency component, the time domain signal x(t) is converted to the frequency domain X(f) using Fast Fourier Transform (FFT). The formula is:

[0061]

[0062] Therefore, the FFT analysis method is used to Figure 4 The time domain waveform is converted into a frequency domain waveform, such as Figure 5 and Figure 6 As shown, the gain characteristics and phase characteristics at each frequency point are respectively shown.

[0063] (4) Carrying out a 500kV CVT square wave signal transmission test is an important task to assess the broadband measurement performance of CVT. The square wave test verifies the CVT's ability to respond to rapid voltage changes by applying a square wave signal of a certain frequency and amplitude. The process of conducting a square wave signal transmission test on a CVT includes the following two points:

[0064] 1) Before the test, prepare the 500kV CVT to be tested, square wave signal generating equipment 12, standard voltage divider 2, oscilloscope 3, PC terminal 4, etc. Record the temperature, humidity, and atmospheric pressure of the test on the day to ensure that the test environment is dry and reduce external electromagnetic interference to improve the test accuracy.

[0065] 2) Generate a periodic waveform with a fixed frequency and constant amplitude to the 500kV CVT via the square wave signal generating device 12, and transmit it to the standard voltage divider 2 at the same time; use the two channels CH1 and CH2 of the oscilloscope 3 to receive and record the input voltage signal and the output voltage signal.

[0066] Set the square wave signal generating device 12, where the frequency is set to 10 5 , the high level is set to 500kV, the low level is set to 0V, taking this as an example of a 500kV CVT source input square wave voltage signal, and using PC terminal 4 for analysis, such as Figure 7 As shown, it is the simulated voltage signal obtained according to the above test process. Ideally, the transient capacitor C3 can convert the source input signal into an output voltage signal at a certain ratio. However, due to factors such as CVT design and insulation aging, the square wave input introduces odd harmonics, which may cause waveform distortion, especially attenuation and phase lag of the high-frequency part. The following are the assessment and analysis steps:

[0067] Observe the time domain waveform: The response waveform of the square wave will have clear rising and falling edges, and at different voltages

[0068] If the rising and falling edges of the output waveform become slow or smooth or the symmetry between the rising and falling edges is broken, it indicates that the signal has been distorted; if the flat top and trough fluctuate or are clipped, it also indicates that the signal is distorted or deformed.

[0069] Frequency domain analysis (FFT): The spectrum of a square wave contains the fundamental frequency and all its odd harmonics.

[0070] The input signal is obviously different, and some of the high-order harmonics are significantly weakened or lost, indicating that the waveform is distorted.

[0071] Therefore, conducting square wave tests on CVT can determine whether there is significant distortion, etc., and assess its transient response capability to rapid voltage changes and measurement accuracy.

[0072] (5) Carrying out 500kV CVT operation / lightning impulse transmission test is a test technology to further evaluate the broadband measurement performance of CVT after the square wave signal transmission test. The operation / lightning impulse transmission test simulates the operation overvoltage or lightning overvoltage phenomenon in the power system by applying a transient, high-amplitude voltage impulse signal to evaluate the transient high-frequency response capability and measurement accuracy of the CVT. The process of conducting impulse signal transmission test on CVT includes the following two points:

[0073] 1) Before the test, prepare the 500kV CVT to be tested, the impulse signal generating device 13, the standard voltage divider 2, the oscilloscope 3, the PC terminal 4, etc. Record the temperature, humidity, and atmospheric pressure of the test on that day to ensure that the test environment is dry and reduce external electromagnetic interference to improve the test accuracy.

[0074] 2) Set the impulse signal generating device 13 to generate the amplitude and waveform of the operation / lightning impulse wave voltage signal, and transmit it to the standard voltage divider 2 at the same time; use the two channels CH1 and CH2 of the oscilloscope 3 to receive, and record the output voltage signal and the input voltage signal waveform data.

[0075] The test voltage signal obtained according to the above test process is as follows Figure 8 and Fig. 9 The figure shows the test results of applying positive operating shock wave voltage signal and negative lightning shock wave voltage signal to 500kV CVT. Ideally, transient capacitor C3 can convert the source input signal into output voltage signal at a certain ratio. However, due to factors such as the initial design of CVT, the introduction of transient high-frequency signal may cause high-frequency response waveform distortion and transient distortion. The following are the assessment and analysis steps of PC terminal 4:

[0076] Observe the time domain waveform and compare the parameters: Operation / lightning impulse waves usually have high amplitude and transient characteristics. If the CVT cannot correctly measure the output waveform in a short time, it will cause the waveform to be delayed, burred, distorted or even oscillated. If the above situation occurs, it indicates that the waveform has transient distortion or high-frequency response distortion. In addition, the operation / lightning impulse wave has important characteristic parameters such as wavefront time, wave tail time, peak value and steepness. By comparing the characteristic parameter values ​​of the output waveform and the input waveform, it is also possible to assess whether the 500kV CVT is distorted.

[0077] Frequency domain analysis (FFT): Operation / lightning impulse wave voltage signals usually contain a large number of high-frequency components. If the output spectrum is significantly different from the input signal, and the display of the high-frequency part is lost or attenuated, it indicates that the waveform is distorted.

[0078] Therefore, conducting operation impulse test and lightning impulse test on CVT in sequence will help to evaluate the response ability of CVT to transient high-frequency voltage, and determine whether there is transient distortion, waveform distortion, etc.

[0079] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0080] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A test method for evaluating the broadband measurement performance of a capacitive voltage transformer, characterized in that: The following steps are involved: Frequency response test: 101) collecting a sinusoidal voltage signal of set frequency and amplitude as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a first output voltage signal output after the sinusoidal voltage signal is input into the capacitive voltage transformer (5) to be tested; 102) Repeat step 101) multiple times to obtain sinusoidal voltage signals at different frequency points and corresponding first output voltage signals; 103) Based on the sinusoidal voltage signal and the corresponding first output voltage signal, analysis and processing are performed to output an amplitude response characteristic curve, a phase response characteristic curve and a frequency domain waveform to obtain gain characteristics and phase characteristics at each frequency point; Square wave signal transmission test: 201) collecting a periodic square wave voltage signal with a fixed frequency and constant amplitude as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a second output voltage signal output after the square wave voltage signal is input into the capacitive voltage transformer (5) to be tested; 202) Based on the square wave voltage signal and the second output voltage signal, time domain analysis and frequency domain analysis are performed to obtain the transient response capability of the capacitive voltage transformer (5) to rapid voltage changes and the broadband measurement accuracy; Operation / lightning impulse transmission test: 301) collecting a transient operation / lightning impulse wave voltage signal as an input signal of the capacitive voltage transformer (5) to be tested, and simultaneously collecting a third output voltage signal output after the operation / lightning impulse wave voltage signal is input into the capacitive voltage transformer (5) to be tested; 302) Based on the operation / lightning impulse wave voltage signal and the third output voltage signal, analysis and processing are performed to obtain the response capability of the capacitive voltage transformer (5) to transient overvoltage and the broadband measurement accuracy; The broadband measurement performance of the capacitive voltage transformer (5) to be tested is obtained based on the frequency response test results, the square wave signal transmission test results and the operation / lightning impulse transmission test results.

2. A test method for assessing the broadband measurement performance of a capacitive voltage transformer according to claim 1, characterized in that: In the frequency response test, the step of obtaining the gain characteristics and phase characteristics at each frequency point includes: Calculate the ratio of the amplitude of the sine wave voltage signal to the amplitude of the first output voltage signal at each frequency point f as the gain, and mark the gain point at each frequency point f; Calculate the difference between the phase of the sinusoidal voltage signal and the phase of the first output voltage signal at each frequency point f as the phase difference, and mark the phase difference point at each frequency point f; Connect all gain points and phase difference points to draw amplitude response characteristic curve and phase response characteristic curve; Converting the time domain voltage waveform of the sinusoidal voltage signal into a frequency domain waveform; By comparing the amplitude / phase response characteristic curve with the frequency domain waveform, the gain characteristics and phase characteristics at each frequency point can be clarified.

3. A test method for assessing the broadband measurement performance of a capacitive voltage transformer according to claim 2, characterized in that: The time domain voltage waveform is converted into a frequency domain waveform using the fast Fourier transform method, where the conversion expression is: Where X(f) is the frequency domain at frequency point f, and x(t) is the time domain signal.

4. A test method for assessing the broadband measurement performance of a capacitive voltage transformer according to claim 1, characterized in that: In the operation / lightning impulse transmission test, the analysis and processing steps include: Comparing characteristic parameters of the time domain waveform of the operation / lightning impulse wave voltage signal and the time domain waveform of the third output voltage signal to obtain the distortion condition of the capacitive voltage transformer (5) to be tested; The time domain waveform of the operation / lightning impulse wave voltage signal and the time domain waveform of the third output voltage signal are both converted into frequency domain waveforms, and the frequency domain waveforms are compared to obtain the loss or attenuation of the high frequency part.

5. A test method for assessing the broadband measurement performance of a capacitive voltage transformer according to claim 4, characterized in that: The characteristic parameters include the wavefront time, wave tail time, peak value and steepness of the operation / lightning impulse wave voltage signal input waveform and the response waveform.

6. A test method for assessing the broadband measurement performance of a capacitive voltage transformer according to claim 1, characterized in that: Also includes: Before steps 103), 202), and 302), the sinusoidal voltage signal, the square wave voltage signal, and the operation / lightning impulse wave voltage signal are transformed according to the transformation ratio of the capacitive voltage transformer (5) to be tested.

7. A test device for evaluating the broadband measurement performance of a capacitive voltage transformer based on the test method according to any one of claims 1 to 6, comprising a signal generator (1), a standard voltage divider (2), an oscilloscope (3) and a PC terminal (4), The signal generator (1) is connected to the standard voltage divider (2) and the capacitive voltage transformer (5) to be tested respectively. The signal generator (1) is used to transmit the generated multiple input voltage signals to the standard voltage divider (2) and the capacitive voltage transformer (5) to be tested respectively. The standard voltage divider (2) and the capacitive voltage transformer (5) to be tested are both connected to the oscilloscope (3). The standard voltage divider (2) is used to transmit the input voltage signal to the oscilloscope (3) after transformation according to the transformation ratio. The capacitive voltage transformer (5) to be tested is used to transmit the measured output voltage signal to the oscilloscope (3). The oscilloscope (3) is connected to a PC terminal (4). The PC terminal (4) is used to perform data processing and comparative analysis on the input voltage signal and the output voltage signal after transformation according to the transformation ratio, so as to obtain the attenuation or phase distortion characteristics of the capacitive voltage transformer (5) to be tested at different frequency points.

8. The test device according to claim 7, characterized in that: The signal generator (1) comprises a sweep signal generating device (11), a square wave signal generating device (12) and an impulse signal generating device (13) to respectively generate a sine wave signal, a square wave signal and an operation / lightning impulse wave voltage signal, and respectively carry out the frequency response test, the square wave signal transmission test and the operation / lightning impulse transmission test.

9. The test device according to claim 7, characterized in that: The oscilloscope (3) is provided with two channels, namely CH1 and CH2, wherein the CH1 is connected to the standard voltage divider (2), and the CH2 is connected to the capacitive voltage transformer (5) to be tested.

10. The test device according to claim 7, characterized in that: The test device is suitable for testing capacitive voltage transformers (5) of 500 kV and above.

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