Cable characteristic parameter evaluation method and device based on pulse injection and measurement system

Abstract

The invention provides a cable characteristic parameter evaluation method and device based on pulse injection and a measurement system, and relates to the technical field of power equipment detection. The method is applied to a measurement system. The measuring system comprises a partial discharge calibration instrument, a matching resistor, a measuring resistor, a connecting cable and a connector. The method comprises the following steps: during a cable oscillation wave test period, carrying out connection cable short circuit calibration measurement on a measurement system, and obtaining a first reflection pulse signal generated at the short circuit tail end of a connection cable; performing open-circuit measurement on the to-be-measured cable on the measurement system to obtain a second reflection pulse signal generated by the connector and a third reflection pulse signal generated by the open-circuit tail end of the to-be-measured cable; and according to the first reflection pulse signal, the second reflection pulse signal and the third reflection pulse signal, determining a characteristic parameter estimation value of the to-be-detected cable. According to the invention, the characteristic parameters of the to-be-tested cable can be accurately evaluated during a cable oscillation wave test period, and then the positioning precision of the partial discharge point and the accuracy of discharge capacity evaluation can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of power equipment detection, and in particular to a method, device and measurement system for evaluating cable characteristic parameters based on pulse injection. Background Art

[0002] With the widespread use of cables in urban power transmission and distribution lines, the demand for cable testing is increasing. Oscillation wave testing technology is a reliable and effective testing technology that can effectively detect and locate discharge defects on cable lines.

[0003] However, in oscillatory wave testing, empirical parameters are often used to locate partial discharge points and estimate the discharge volume at defect points. Localization of partial discharge points relies on the arrival time difference of the discharge pulse and wave velocity assessment, while assessment of the discharge volume at defect points relies on the intensity of the partial discharge pulse. However, wave velocity is often estimated based on typical wave velocity or distance, which introduces significant errors in locating partial discharge points. Furthermore, assessment of the discharge volume at defect points cannot be accurately determined due to the attenuation of partial discharge pulses during propagation.

[0004] To accurately locate the discharge point and assess the discharge amount at that point, the cable's characteristic parameters are key factors. In related technologies, measuring cable characteristic parameters often requires a sophisticated vector network analyzer, the production of cable samples, and the rigorous design of the necessary connection accessories. This process is cumbersome, costly, and potentially inaccurate, leading to large errors in locating partial discharge points and assessing discharge amounts. Summary of the Invention

[0005] The embodiments of the present application provide a method, device and measurement system for evaluating cable characteristic parameters based on pulse injection to solve the problem that the existing cable characteristic parameter measurement process is cumbersome, costly and may have poor accuracy, which in turn leads to large errors in localizing local discharge points and evaluating discharge amounts.

[0006] In a first aspect, an embodiment of the present application provides a method for evaluating cable characteristic parameters based on pulse injection, which is applied to a measurement system; the measurement system includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is respectively connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, and the connecting cable is further used to connect to the cable to be tested through the connector; the method for evaluating cable characteristic parameters based on pulse injection includes:

[0007] During the cable oscillation wave test, performing a connection cable short-circuit calibration measurement on the measurement system to obtain a first reflected pulse signal generated by the short-circuited end of the connection cable;

[0008] Performing an open-circuit measurement of the cable to be tested on the measurement system to obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open-circuit end of the cable to be tested;

[0009] An estimated value of a characteristic parameter of the cable to be tested is determined according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

[0010] In a possible implementation, determining the estimated value of the characteristic parameter of the cable to be tested according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal includes:

[0011] Performing time-frequency transformation on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal, respectively, to obtain corresponding first pulse spectrum, second pulse spectrum, and third pulse spectrum;

[0012] Based on the functional relationship between the first pulse spectrum, the second pulse spectrum, the third pulse spectrum and the characteristic parameters of the cable to be tested, an estimated value of the characteristic parameter of the cable to be tested is determined.

[0013] In a possible implementation, the characteristic parameters of the cable to be tested include the characteristic impedance Z of the cable to be tested. c and the propagation coefficient γ of the cable under test c ;

[0014] The functional relationship includes:

[0015]

[0016] Among them, V os is the first pulse spectrum; V oD is the second pulse spectrum; V oE is the third pulse spectrum; e is a natural constant; l c is the length of the cable to be tested; Z2 is the characteristic impedance of the connecting cable.

[0017] In a possible implementation, the characteristic parameters of the cable under test include the propagation coefficient γ of the cable under test. c ; Among them, γ c =α c +jβ c , α c is the attenuation constant of the cable under test, β c is the phase constant of the cable to be tested, j is an imaginary unit;

[0018] After determining the estimated value of the characteristic parameter of the cable to be tested, the method further includes:

[0019] based on and β c =k β ·ω, to α c and β c Fitting is performed to obtain a final estimated value of the attenuation constant of the cable to be tested and a final estimated value of the phase constant of the cable to be tested; wherein, k α is the fitting coefficient of the decay constant, k β is the fitting coefficient of the phase constant, and ω is the frequency.

[0020] In a possible implementation, when performing a connection cable short-circuit calibration measurement on the measurement system, the connection cable and the cable to be tested are disconnected, and an end of the connection cable is short-circuited;

[0021] When performing open-circuit measurement of the cable to be tested on the measurement system, the connecting cable and the cable to be tested are connected via the connector, and the end of the cable to be tested is open-circuited;

[0022] When performing a short-circuit calibration measurement on the connection cable of the measurement system and when performing an open-circuit measurement on the cable to be measured of the measurement system, the partial discharge calibrator injects the same incident pulse signal.

[0023] In a possible implementation, the resistance value of the matching resistor and the resistance value of the measuring resistor are both equal to the characteristic impedance of the connecting cable;

[0024] The connecting cable is a standard signal cable, and characteristic parameters of the connecting cable are known.

[0025] In a possible implementation, the measurement system further includes a T-shaped connector;

[0026] The matching resistor is connected between the output end of the partial discharge calibrator and the first end of the T-shaped connector, the connecting cable is connected between the second end of the T-shaped connector and the first end of the connector, the measuring resistor is connected between the third end of the T-shaped connector and the ground potential, and the second end of the connector is used to connect the cable to be tested.

[0027] In a possible implementation, the partial discharge calibrator is used to output an incident pulse signal having a rising edge and a falling edge; the rising edge and the falling edge are both less than or equal to 60 ns, and the pulse width of the incident pulse signal is less than or equal to 100 ns.

[0028] In a second aspect, an embodiment of the present application provides a pulse injection-based cable characteristic parameter evaluation device, which is applied to a measurement system; the measurement system includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is respectively connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, and the connecting cable is further used to connect to the cable to be tested through the connector; the pulse injection-based cable characteristic parameter evaluation device includes:

[0029] a short-circuit calibration measurement module, configured to perform a connection cable short-circuit calibration measurement on the measurement system during a cable oscillation wave test, and obtain a first reflected pulse signal generated by a short-circuit end of the connection cable;

[0030] an open circuit measurement module, configured to perform an open circuit measurement of the cable to be tested on the measurement system, and obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open circuit end of the cable to be tested;

[0031] An evaluation module is configured to determine an estimated value of a characteristic parameter of the cable to be tested based on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

[0032] In a third aspect, an embodiment of the present application provides a measurement system, comprising a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, respectively, and the connecting cable is further used to connect to a cable to be tested through the connector;

[0033] The measurement system is used to evaluate the characteristic parameters of the cable to be measured by adopting the cable characteristic parameter evaluation method based on pulse injection in the first aspect or any possible implementation of the first aspect.

[0034] In a fourth aspect, an embodiment of the present application provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the cable characteristic parameter evaluation method based on pulse injection as described in the first aspect or any possible implementation of the first aspect.

[0035] In an embodiment of the present application, a partial discharge calibrator during a cable oscillation wave test is used as the main equipment. By connecting a simple external measurement circuit, there is no need for a precise vector network analyzer, the preparation of cable samples to be tested, and the strict design of connection accessories required for measurement. That is, there is no need for complex measurement equipment and processes, which facilitates the evaluation of characteristic parameters of the cable to be tested during the existing cable oscillation wave test. Moreover, through the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal, it is possible to accurately evaluate the characteristic parameters of the cable to be tested without increasing the cost and workload, thereby significantly improving the accuracy of local discharge point positioning and the accuracy of discharge amount evaluation during the cable oscillation wave test. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the structure of the measurement system provided in an embodiment of the present application;

[0037] Figure 2 This is a flow chart of an implementation method for evaluating cable characteristic parameters based on pulse injection provided in an embodiment of the present application;

[0038] Figure 3 is a schematic diagram of a first reflected pulse signal provided in an embodiment of the present application;

[0039] Figure 4 is a schematic diagram of a third reflected pulse signal of a second reflected pulse signal provided in an embodiment of the present application;

[0040] Figure 5 Schematic diagram of the final estimated values and corresponding reference values of characteristic parameters of the cable to be tested provided by an embodiment of the present application;

[0041] Figure 6 1 is a schematic structural diagram of a cable characteristic parameter evaluation device based on pulse injection provided in an embodiment of the present application;

[0042] Figure 7 Schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0044] Figure 1 This is a schematic diagram of the structure of the measurement system provided in the embodiment of the present application. Figure 1 As shown, the measurement system includes a partial discharge calibrator V s , matching resistor R s , measure resistance R m , connecting cable 11 and connector D; matching resistor R s Partial discharge calibrator V s , connecting cable 11 and measuring resistor Rm The connecting cable 11 is also used to connect to the cable to be tested 12 through the connector D.

[0045] Specifically, see Figure 1 , Partial Discharge Calibrator V s The positive electrode and matching resistor R s The first end is connected to the partial discharge calibrator V s The negative pole is grounded. Matching resistor R s The second end of the connecting cable 11 and the measuring resistor R m Connect the first end and measure the resistance R m The second end of the connecting cable 11 is used to connect to the cable under test 12 through the connector D, that is, the first end 4 of the connector D is used to connect to the connecting cable 11, and the second end 5 of the connector D is used to connect to the cable under test 12.

[0046] Among them, the partial discharge calibrator V s The positive electrode can also be called the partial discharge calibrator V s the second end of the connecting cable 11 may also be referred to as the end of the connecting cable 11; the end 6 of the cable to be tested 12 away from the connector D is called the end of the cable to be tested 12.

[0047] The measurement system can measure the pulse response of the cable under test.

[0048] In some possible implementations, see Figure 1 , the measuring system may further include a T-connector T.

[0049] The first end 1 of the T-connector T is connected to the matching resistor R s The second end of the T-type connector T is connected to the first end of the connecting cable 11, and the third end 3 of the T-type connector T is connected to the measuring resistor R m The first end.

[0050] exist Figure 1 In the equation, Z2, γ2 and l2 are the characteristic impedance, propagation coefficient and length of the connecting cable 11 respectively. These three parameters of the connecting cable 11 are all known parameters. c , γ c and l c They are the characteristic impedance, propagation coefficient and length of the cable 12 to be tested. The length of the cable 12 to be tested can be measured. The characteristic impedance and propagation coefficient of the cable 12 to be tested are characteristic parameters to be evaluated for the cable 12 to be tested.

[0051] Partial Discharge Calibrator V s It is a pulse signal source, a device used to generate pulses, used to stimulate the reflected signal of the cable, and is the core signal source of the measurement system.

[0052] Matching resistor R s Connect in series with the partial discharge calibrator V s and T-connector T, used to achieve impedance matching to ensure the partial discharge calibrator V s The injected incident pulse signal can be effectively transmitted to the connecting cable 11. Matching resistor R s The resistance value can be equal to the characteristic impedance of the connecting cable 11.

[0053] Measuring resistance R m Connected in series between the T-connector T and the ground potential, it is used to measure the reflected signal, ensure system impedance matching, and improve the accuracy of signal acquisition. m The resistance value can be equal to the characteristic impedance of the connecting cable 11.

[0054] T-type connector T is used to connect the matching resistor R s , measure resistance R m The interface device of the connecting cable 11 constructs the physical connection path of the measurement system and distributes the signal flow direction.

[0055] The connector D is used to connect to the cable to be tested 12 to achieve a physical connection between the connecting cable 11 and the cable to be tested 12, thereby forming a complete measurement loop.

[0056] The connecting cable 11 may be a standard signal cable. The characteristic impedance of the connecting cable 11 is its inherent impedance characteristic. The propagation coefficient of the connecting cable 11 is used to describe the attenuation and phase change of the signal when propagating in the connecting cable 11 .

[0057] The cable to be tested 12 is a power cable whose characteristic parameters need to be estimated, and may also be referred to as a tested cable.

[0058] exist Figure 1 In, V + It can be understood as a partial discharge calibrator V s The injected incident pulse voltage signal, V - It can be understood as the reflected pulse voltage signal, V o To measure the resistance R m The voltage across both ends.

[0059] The above embodiment introduces the structure of the measurement system. The following will continue to introduce the implementation process of the cable characteristic parameter evaluation method based on pulse injection.

[0060] See also Figure 2 , which shows a flow chart of the implementation of the cable characteristic parameter evaluation method based on pulse injection provided by an embodiment of the present application, which is detailed as follows:

[0061] The cable characteristic parameter evaluation method based on pulse injection is applied to a measurement system; the measurement system includes a partial discharge calibrator V s , matching resistor R s , measure resistance R m , connecting cable 11 and connector D; matching resistor R s Partial discharge calibrator V s , connecting cable 11 and measuring resistor R m The connecting cable 11 is further used to connect to the cable to be tested 12 through the connector D. The cable characteristic parameter evaluation method based on pulse injection may include:

[0062] In S201 , during the cable oscillation wave test, a connection cable short-circuit calibration measurement is performed on the measurement system to obtain a first reflected pulse signal generated by the short-circuited end of the connection cable.

[0063] The method provided in the embodiment of the present application is applied during a cable oscillatory wave test, and more specifically, during a partial discharge calibration process during the cable oscillatory wave test, wherein the characteristic parameters of the cable under test are evaluated using a partial discharge calibrator used in the process.

[0064] Before officially measuring the cable under test, the measurement system must be calibrated. This involves short-circuiting the connecting cable. During this calibration, the end of the connecting cable (i.e., the second end of the connecting cable) is short-circuited. The partial discharge calibrator injects an incident pulse signal, which generates a reflected pulse signal at the short-circuited end of the connecting cable. This reflected pulse signal is called the first reflected pulse signal, and this first reflected pulse signal is captured.

[0065] See also Figure 3 , the first reflected pulse signal is Figure 3 v in os (t).

[0066] In S202, an open-circuit measurement of the cable to be tested is performed on the measurement system to obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open-circuit end of the cable to be tested.

[0067] After the calibration measurement, the measurement system performs an open-circuit measurement of the cable under test. At this point, the end of the cable under test remains open. The PD calibrator injects an incident pulse signal. Since the length of the connecting cable is known, the reflected pulse from the connector (the second reflected pulse signal) is extracted. Simultaneously, the reflected signal from the open-circuit end of the cable under test (the third reflected pulse signal) is extracted.

[0068] See also Figure 4 , the second reflected pulse signal is Figure 4 v in oD(t), the third reflected pulse signal is Figure 4 v in oE (t).

[0069] In S203, an estimated value of a characteristic parameter of the cable to be tested is determined according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

[0070] The first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal obtained through the aforementioned steps in the embodiment of the present application can accurately evaluate the characteristic parameters of the cable to be tested and obtain estimated values of the characteristic parameters of the cable to be tested.

[0071] The embodiment of the present application uses a partial discharge calibrator during cable oscillation wave testing as the main equipment. By connecting a simple external measurement circuit, there is no need for a sophisticated vector network analyzer, the production of cable samples to be tested, and the strict design of the connection accessories required for the measurement. That is, there is no need for complex measurement equipment and processes, which facilitates the evaluation of the characteristic parameters of the cable to be tested during the existing cable oscillation wave test. Moreover, through the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal, it is possible to accurately evaluate the characteristic parameters of the cable to be tested without increasing cost and workload, thereby providing accurate information required for localizing the local discharge point and evaluating the discharge amount during the cable oscillation wave test, reducing the errors in localizing the local discharge point and evaluating the discharge amount caused by empirical parameters, and significantly improving the accuracy of localizing the local discharge point and evaluating the discharge amount during the cable oscillation wave test.

[0072] The above embodiment introduces the overall implementation process of the cable characteristic parameter evaluation method based on pulse injection. The steps are detailed below.

[0073] In some embodiments, the above S203 may include:

[0074] Performing time-frequency transformation on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal to obtain corresponding first pulse spectrum, second pulse spectrum, and third pulse spectrum;

[0075] Based on the functional relationship between the first pulse spectrum, the second pulse spectrum, the third pulse spectrum and the characteristic parameters of the cable to be tested, an estimated value of the characteristic parameter of the cable to be tested is determined.

[0076] In the embodiment of the present application, a first reflected pulse signal is subjected to time-frequency transformation to obtain a first pulse spectrum; a second reflected pulse signal is subjected to time-frequency transformation to obtain a second pulse spectrum; and a third reflected pulse signal is subjected to time-frequency transformation to obtain a third pulse spectrum. The time-frequency transformation may be a Fourier transform or other transformation method capable of converting the time domain into the frequency domain, and is not specifically limited here.

[0077] There is a certain functional relationship between the first pulse spectrum, the second pulse spectrum, and the third pulse spectrum and the characteristic parameters of the cable under test. Substituting the first pulse spectrum, the second pulse spectrum, and the third pulse spectrum into the functional relationship, the values of the characteristic parameters of the cable under test obtained by calculating are the estimated values of the characteristic parameters of the cable under test.

[0078] In some embodiments, the characteristic parameters of the cable under test include the characteristic impedance Z of the cable under test. c and the propagation coefficient γ of the cable under test c ;

[0079] The above functional relationships include:

[0080]

[0081] Among them, V os is the first pulse spectrum; V oD is the second pulse spectrum; V oE is the third pulse spectrum; e is a natural constant; l c is the length of the cable to be tested; Z2 is the characteristic impedance of the connecting cable.

[0082] The characteristic impedance of the cable under test reflects its electrical properties and is a key parameter for locating partial discharge points and assessing discharge volume. The propagation coefficient of the cable under test describes the propagation characteristics of the signal in the cable under test. It is used to analyze the signal attenuation and propagation speed in the cable under test and directly affects the waveform and amplitude of the partial discharge pulse.

[0083] In this functional relationship, the first pulse spectrum, the second pulse spectrum, the third pulse spectrum, the length of the cable to be tested, and the characteristic impedance of the connecting cable are all known quantities. Therefore, through the above functional relationship, the characteristic impedance Z of the cable to be tested can be obtained. c and the propagation coefficient γ of the cable under test c estimated value.

[0084] The estimation of the characteristic parameters of the cable under test in the aforementioned embodiment can be considered a preliminary estimate of the characteristic parameters of the cable under test. The characteristic impedance is essentially constant across the entire frequency range. However, because the denominator in the above functional relationship may be zero at certain frequencies, the estimated propagation coefficient of the cable under test at certain frequencies may be a singular value (e.g., a meaningless value or an outlier). Therefore, it is necessary to eliminate these singular values. The following details how to eliminate these singular values.

[0085] In some embodiments, the characteristic parameters of the cable under test include the propagation coefficient γ of the cable under test. c ; Among them, γ c =α c +jβ c, α c is the attenuation constant of the cable to be tested, β c is the phase constant of the cable to be tested, j is the imaginary unit;

[0086] After S203, the pulse injection-based cable characteristic parameter evaluation method further includes:

[0087] based on and β c =k β ·ω, to α c and β c Fitting is performed to obtain the final estimated value of the attenuation constant of the cable under test and the final estimated value of the phase constant of the cable under test; wherein, k α is the fitting coefficient of the decay constant, k β is the fitting coefficient of the phase constant, and ω is the frequency.

[0088] In the embodiment of the present application, by fitting the attenuation constant and phase constant of the cable under test, a final estimated value of the attenuation constant and phase constant of the cable under test can be obtained. Since the characteristic impedance is essentially a constant value across the entire frequency range, no fitting is required, and the estimated value of the characteristic impedance of the cable under test serves as the final estimated value.

[0089] The characteristic parameters of the cable to be tested in the embodiment of the present application include the attenuation constant of the cable to be tested, the phase constant of the cable to be tested, and the characteristic impedance of the cable to be tested.

[0090] The fitting method may be polynomial fitting or any other commonly used fitting method, which is not specifically limited here.

[0091] See also Figure 5 , which shows the final estimated value of the attenuation constant of the cable under test, the final estimated value of the phase constant of the cable under test, and the final estimated value of the characteristic impedance of the cable under test. The final estimated value corresponding to each characteristic parameter can also be called the frequency domain characteristic curve corresponding to each characteristic parameter.

[0092] Figure 5 In addition to the final estimated values of each characteristic parameter of the cable under test, the corresponding reference values are also given. Figure 5 It can be seen that the final estimated values of the characteristic parameters of the cable to be tested are basically consistent with the corresponding reference values, that is, the final estimated values of the characteristic parameters of the cable to be tested determined in the embodiment of the present application are highly accurate.

[0093] In some possible implementations, after obtaining the final estimated value of the attenuation constant of the cable under test and the final estimated value of the phase constant of the cable under test, the following steps may be further included:

[0094] Based on the final estimated value of the attenuation constant of the cable under test, the final estimated value of the phase constant of the cable under test and the final estimated value of the characteristic impedance of the cable under test, the partial discharge point is located and the discharge amount of the partial discharge point is evaluated.

[0095] In some embodiments, when performing a connection cable short-circuit calibration measurement on a measurement system, the connection cable and the cable to be measured are disconnected, and an end of the connection cable is short-circuited;

[0096] When performing open-circuit measurement of the cable under test on the measurement system, the connecting cable and the cable under test are connected through a connector, and the end of the cable under test is open-circuited;

[0097] When performing short-circuit calibration measurements on the measurement system and when performing open-circuit measurements on the cables under test, the partial discharge calibrator injects the same incident pulse signal.

[0098] In an embodiment of the present application, when performing a connection cable short-circuit calibration measurement on the measurement system, the connection cable and the cable to be tested are disconnected, that is, the measurement system is not connected to the cable to be tested, and the end of the connection cable is short-circuited.

[0099] When performing open-circuit measurement of the cable under test on the measurement system, the cable under test is connected to the measurement system through the connector, and the end of the cable under test is open-circuited. At this time, the end of the connecting cable is no longer short-circuited.

[0100] When performing short-circuit calibration measurements on the measurement system and when performing open-circuit measurements on the cable to be tested, the partial discharge calibrator injects the same incident pulse signal, that is, for the same incident pulse signal, it obtains the corresponding first reflected pulse signal, second reflected pulse signal and third reflected pulse signal.

[0101] In some embodiments, the resistance of the matching resistor and the resistance of the measuring resistor are both equal to the characteristic impedance of the connecting cable;

[0102] The connecting cable is a standard signal cable, and the characteristic parameters of the connecting cable are known.

[0103] The connecting cable is a standard signal cable, and its characteristic parameters, such as characteristic impedance and propagation coefficient, are known. The term "known" here can be understood as parameters that are known without requiring measurement using any equipment, or can be directly measured using a vector network analyzer or other related equipment.

[0104] The characteristic impedance of the connecting cable is known, so when setting the matching resistor and the measuring resistor, they can be set according to the characteristic impedance of the connecting cable.

[0105] In some embodiments, the measurement system further comprises a T-connector;

[0106] The matching resistor is connected between the output end of the partial discharge calibrator and the first end of the T-type connector, the connecting cable is connected between the second end of the T-type connector and the first end of the connector, the measuring resistor is connected between the third end of the T-type connector and the ground potential, and the second end of the connector is used to connect the cable to be tested.

[0107] For the relevant description of the embodiments of the present application, please refer to the relevant description of the measurement system in the aforementioned embodiments, which will not be repeated here.

[0108] In some embodiments, the partial discharge calibrator is used to output an incident pulse signal having a rising edge and a falling edge; the rising edge and the falling edge are both less than or equal to 60ns, and the pulse width of the incident pulse signal is less than or equal to 100ns.

[0109] The rising edge and falling edge are both steep rising edge and steep falling edge.

[0110] For example, the rising edge and the falling edge may both be 20 ns, 30 ns, 40 ns, 50 ns, or 60 ns, etc., and the pulse width of the incident pulse signal may be 100 ns, 90 ns, 80 ns, 70 ns, or 60 ns, etc. In one possible application scenario, the rising edge and the falling edge may both be 20 ns, and the pulse width of the incident pulse signal may be 100 ns.

[0111] The pulse injection-based cable characteristic parameter assessment method provided in the embodiments of this application can evaluate the characteristic parameters of the cable under test during oscillatory wave testing. It provides key calculation parameters for locating partial discharge points and evaluating the discharge volume during oscillatory wave testing. This method can effectively improve the accuracy of locating partial discharge points and evaluating the partial discharge volume during oscillatory wave testing, thereby improving the overall performance of the oscillatory wave testing system and possessing significant industrial application value and promising prospects.

[0112] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0113] The following are device embodiments of the present application. For details not fully described therein, please refer to the corresponding method embodiments described above.

[0114] Figure 6 The following is a schematic diagram of the structure of a cable characteristic parameter evaluation device based on pulse injection provided in an embodiment of the present application. For ease of explanation, only the parts related to the embodiment of the present application are shown, which are detailed as follows:

[0115] The pulse injection-based cable characteristic parameter evaluation device is applied to the measurement system, which includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable and the measuring resistor respectively, and the connecting cable is also used to connect to the cable to be tested through the connector. Figure 6 As shown, the pulse injection-based cable characteristic parameter evaluation device 60 includes: a short-circuit calibration measurement module 61 , an open-circuit measurement module 62 and an evaluation module 63 .

[0116] The short-circuit calibration measurement module 61 is used to perform a short-circuit calibration measurement of the connection cable on the measurement system during the cable oscillation wave test, and obtain a first reflected pulse signal generated by the short-circuit end of the connection cable;

[0117] An open circuit measurement module 62 is configured to perform an open circuit measurement of the cable under test on the measurement system, and obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open circuit end of the cable under test;

[0118] The evaluation module 63 is configured to determine an estimated value of a characteristic parameter of the cable to be tested according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

[0119] In a possible implementation, the evaluation module 63 is specifically configured to:

[0120] Performing time-frequency transformation on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal to obtain corresponding first pulse spectrum, second pulse spectrum, and third pulse spectrum;

[0121] Based on the functional relationship between the first pulse spectrum, the second pulse spectrum, the third pulse spectrum and the characteristic parameters of the cable to be tested, an estimated value of the characteristic parameter of the cable to be tested is determined.

[0122] In a possible implementation, the characteristic parameters of the cable to be tested include the characteristic impedance Z of the cable to be tested. c and the propagation coefficient γ of the cable under test c ;

[0123] The above functional relationships include:

[0124]

[0125] Among them, V os is the first pulse spectrum; V oD is the second pulse spectrum; V oE is the third pulse spectrum; e is a natural constant; l c is the length of the cable to be tested; Z2 is the characteristic impedance of the connecting cable.

[0126] In a possible implementation, the characteristic parameters of the cable under test include the propagation coefficient γ of the cable under test. c ; Among them, γ c =α c +jβ c , α c is the attenuation constant of the cable to be tested, β c is the phase constant of the cable to be tested, j is the imaginary unit;

[0127] The evaluation module 63 is further configured to: after determining the estimated value of the characteristic parameter of the cable to be tested, and β c =k β ·ω, to α c and β c Perform fitting to obtain the final estimated value of the attenuation constant of the cable under test and the final estimated value of the phase constant of the cable under test; where k α is the fitting coefficient of the decay constant, k β is the fitting coefficient of the phase constant, and ω is the frequency.

[0128] In a possible implementation, when performing a connection cable short-circuit calibration measurement on a measurement system, the connection cable and the cable to be measured are disconnected, and an end of the connection cable is short-circuited;

[0129] When performing open-circuit measurement of the cable under test on the measurement system, the connecting cable and the cable under test are connected through a connector, and the end of the cable under test is open-circuited;

[0130] When performing short-circuit calibration measurements on the measurement system and when performing open-circuit measurements on the cables under test, the partial discharge calibrator injects the same incident pulse signal.

[0131] In a possible implementation, the resistance value of the matching resistor and the resistance value of the measuring resistor are both equal to the characteristic impedance of the connecting cable;

[0132] The connecting cable is a standard signal cable, and the characteristic parameters of the connecting cable are known.

[0133] In one possible implementation, the measurement system further includes a T-connector;

[0134] The matching resistor is connected between the output end of the partial discharge calibrator and the first end of the T-type connector, the connecting cable is connected between the second end of the T-type connector and the first end of the connector, the measuring resistor is connected between the third end of the T-type connector and the ground potential, and the second end of the connector is used to connect the cable to be tested.

[0135] In a possible implementation, the partial discharge calibrator is used to output an incident pulse signal having a rising edge and a falling edge; the rising edge and the falling edge are both less than or equal to 60 ns, and the pulse width of the incident pulse signal is less than or equal to 100 ns.

[0136] Figure 7 Schematic diagram of an electronic device provided in an embodiment of the present application. Figure 7 As shown, the electronic device 7 of this embodiment includes a processor 70 and a memory 71. Memory 71 stores a computer program 72. When the processor 70 executes computer program 72, it implements the steps of the aforementioned embodiments of the pulse injection-based cable characteristic parameter assessment method. Alternatively, when the processor 70 executes computer program 72, it implements the functions of the various modules / units in the aforementioned device embodiments.

[0137] Exemplarily, the computer program 72 may be divided into one or more modules / units, which are stored in the memory 71 and executed by the processor 70 to implement the present application. The one or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 72 in the electronic device 7.

[0138] The electronic device 7 may include, but is not limited to, a processor 70 and a memory 71. Those skilled in the art will appreciate that Figure 7 It is only an example of the electronic device 7 and does not constitute a limitation of the electronic device 7. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 7 may also include input and output devices, network access devices, buses, etc.

[0139] For the sake of convenience and brevity, the division of the above functional modules / units is only used as an example. In actual applications, the above functions can be assigned to different functional modules / units as needed. The above modules / units can be implemented in the form of hardware, software, or a combination of hardware and software.

[0140] The embodiment of the present application further provides a measurement system, comprising a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, respectively; the connecting cable is further used to connect to a cable to be measured through the connector;

[0141] The measurement system is used to evaluate the characteristic parameters of the cable to be measured by using any of the above cable characteristic parameter evaluation methods based on pulse injection.

[0142] In some possible implementations, the measurement system may further include the electronic device described above, which is configured to execute any of the above methods for evaluating cable characteristic parameters based on pulse injection to evaluate characteristic parameters of the cable to be measured.

[0143] For the description of the measurement system, reference can be made to the relevant description in the aforementioned embodiment, which will not be repeated here.

[0144] In the above embodiments, the descriptions of each embodiment have their own focus. For parts not described or recorded in detail in one embodiment, please refer to the relevant descriptions of other embodiments. Unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other. The technical features of different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0145] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A method for evaluating cable characteristic parameters based on pulse injection, characterized in that: Applicable to a measurement system; the measurement system includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, respectively, and the connecting cable is further used to connect to a cable to be measured through the connector; the method includes: During the cable oscillation wave test, performing a connection cable short-circuit calibration measurement on the measurement system to obtain a first reflected pulse signal generated by the short-circuited end of the connection cable; Performing an open-circuit measurement of the cable to be tested on the measurement system to obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open-circuit end of the cable to be tested; An estimated value of a characteristic parameter of the cable to be tested is determined according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

2. The cable characteristic parameter evaluation method based on pulse injection according to claim 1 is characterized in that: Determining the estimated value of the characteristic parameter of the cable to be tested according to the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal includes: performing time-frequency transformation on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal, respectively, to obtain corresponding first pulse spectrum, second pulse spectrum, and third pulse spectrum; Based on the functional relationship between the first pulse spectrum, the second pulse spectrum, the third pulse spectrum and the characteristic parameters of the cable to be tested, an estimated value of the characteristic parameter of the cable to be tested is determined.

3. The cable characteristic parameter evaluation method based on pulse injection according to claim 2, characterized in that: The characteristic parameters of the cable to be tested include the characteristic impedance Z of the cable to be tested c and the propagation coefficient γ of the cable under test c ; The functional relationship includes: Among them, V os is the first pulse spectrum; V oD is the second pulse spectrum; V oE is the third pulse spectrum; e is a natural constant; l c is the length of the cable to be tested; Z2 is the characteristic impedance of the connecting cable.

4. The cable characteristic parameter evaluation method based on pulse injection according to claim 1 is characterized in that: The characteristic parameters of the cable under test include the propagation coefficient γ of the cable under test c ; Among them, γ c =α c +jβ c , α c is the attenuation constant of the cable under test, β c is the phase constant of the cable to be tested, j is an imaginary unit; After determining the estimated value of the characteristic parameter of the cable to be tested, the method further includes: based on and β c =k β ·ω, to α c and β c Fitting is performed to obtain a final estimated value of the attenuation constant of the cable to be tested and a final estimated value of the phase constant of the cable to be tested; wherein, k α is the fitting coefficient of the decay constant, k β is the fitting coefficient of the phase constant, and ω is the frequency.

5. The cable characteristic parameter evaluation method based on pulse injection according to any one of claims 1 to 4, characterized in that: When performing a connection cable short-circuit calibration measurement on the measurement system, the connection cable and the cable to be tested are disconnected, and the end of the connection cable is short-circuited; When performing open-circuit measurement of the cable to be tested on the measurement system, the connecting cable and the cable to be tested are connected via the connector, and the end of the cable to be tested is open-circuited; When performing a short-circuit calibration measurement on the connection cable of the measurement system and when performing an open-circuit measurement on the cable to be measured of the measurement system, the partial discharge calibrator injects the same incident pulse signal.

6. The cable characteristic parameter evaluation method based on pulse injection according to any one of claims 1 to 4, characterized in that: The resistance value of the matching resistor and the resistance value of the measuring resistor are both equal to the characteristic impedance of the connecting cable; The connecting cable is a standard signal cable, and characteristic parameters of the connecting cable are known.

7. The method for evaluating cable characteristic parameters based on pulse injection according to any one of claims 1 to 4, characterized in that: The measurement system further includes a T-connector; The matching resistor is connected between the output end of the partial discharge calibrator and the first end of the T-shaped connector, the connecting cable is connected between the second end of the T-shaped connector and the first end of the connector, the measuring resistor is connected between the third end of the T-shaped connector and the ground potential, and the second end of the connector is used to connect the cable to be tested.

8. The cable characteristic parameter evaluation method based on pulse injection according to any one of claims 1 to 4, characterized in that: The partial discharge calibrator is used to output an incident pulse signal with a rising edge and a falling edge; the rising edge and the falling edge are both less than or equal to 60ns, and the pulse width of the incident pulse signal is less than or equal to 100ns.

9. A device for evaluating cable characteristic parameters based on pulse injection, characterized in that: Applicable to a measurement system; the measurement system includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable, and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable, and the measuring resistor, respectively, and the connecting cable is further used to connect to a cable to be measured through the connector; the device includes: a short-circuit calibration measurement module, configured to perform a connection cable short-circuit calibration measurement on the measurement system during a cable oscillation wave test, and obtain a first reflected pulse signal generated by a short-circuit end of the connection cable; an open circuit measurement module, configured to perform an open circuit measurement of the cable to be tested on the measurement system, and obtain a second reflected pulse signal generated by the connector and a third reflected pulse signal generated by the open circuit end of the cable to be tested; An evaluation module is configured to determine an estimated value of a characteristic parameter of the cable to be tested based on the first reflected pulse signal, the second reflected pulse signal, and the third reflected pulse signal.

10. A measurement system, characterized in that: It includes a partial discharge calibrator, a matching resistor, a measuring resistor, a connecting cable and a connector; the matching resistor is connected to the partial discharge calibrator, the connecting cable and the measuring resistor respectively, and the connecting cable is also used to connect to the cable to be tested through the connector; The measurement system is used to evaluate characteristic parameters of a cable to be measured by using the cable characteristic parameter evaluation method based on pulse injection according to any one of claims 1 to 8.

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