Measurement method and device for obtaining cable broadband impedance spectrum based on digital lock-in amplifier, electronic equipment and storage medium

Abstract

The invention discloses a measurement method and device for obtaining a cable broadband impedance spectrum based on a digital lock-in amplifier, electronic equipment and a storage medium. The method comprises the following steps: determining a frequency list of a broadband impedance spectrum of a to-be-measured cable; measuring time domain voltages in different connection states by using a test device comprising a connector, a pulse generation assembly and a voltage acquisition assembly; analyzing the frequency component of the time domain voltage by using a digital lock-in amplifier; and calculating the impedance spectrum of the to-be-measured cable according to the analysis result. The invention further provides a correction method for solving the influence of the internal cable and the external connection cable. The broadband impedance spectrum of the cable is obtained through pure voltage measurement, only simple test equipment is needed, expensive professional equipment is not needed, and the test cost is remarkably reduced; and meanwhile, the digital lock-in amplifier can be used for randomly assigning an analyzed frequency point, so that the measurement flexibility is improved, the method is suitable for various field test environments, and an economical and efficient technical solution is provided for cable state monitoring.

Description

Technical Field

[0001] The present disclosure relates to the field of electrical engineering, and particularly to a measurement method, device, electronic device, and storage medium for obtaining a broadband impedance spectrum of a cable based on a digital lock-in amplifier. Background Art

[0002] Power cables are important devices for transmitting electrical energy in a power system, and their safe and stable operation is directly related to the reliability of the power system. With the continuous expansion of the scale of the power system and the extension of the service life of cables, the probability of cable failures gradually increases. Traditional cable fault detection methods mainly detect and locate faults after they occur, while the frequency domain reflectometry (FDR) as an emerging detection technology can identify weak defects in cables before the faults develop into serious ones, thus avoiding potential major losses.

[0003] The core of the frequency domain reflectometry is to obtain the broadband impedance spectrum of the cable, especially the beginning-end impedance spectrum (BIS) of the cable. By analyzing the impedance spectrum characteristics of the cable, various abnormal conditions in the cable, such as potential defects like insulation aging, water trees, and partial discharges, can be identified. Compared with the time domain reflectometry, the frequency domain reflectometry has higher sensitivity and better resolution in detecting weak faults.

[0004] Currently, the mainstream devices for obtaining the broadband impedance spectrum of cables are mainly impedance analyzers (IAs) and vector network analyzers (VNAs). These professional devices use sweep frequency technology to measure the impedance or reflection coefficient of the cable at different frequency points, thereby obtaining the impedance spectrum of the cable. However, these devices have the following obvious deficiencies:

[0005] I. High cost

[0006] Impedance analyzers and vector network analyzers are expensive, often costing hundreds of thousands of yuan or even more, which makes it difficult to popularize and apply them in large-scale cable condition monitoring;

[0007] II. Harsh test requirements

[0008] These devices have high requirements for the test environment and the state of the system under test, require professional personnel to operate, and often require the cable to be disconnected or out of service, which is difficult to achieve in actual operation and maintenance processes;

[0009] III. Poor portability

[0010] Professional test devices are usually large in size and heavy in weight, which are not convenient for on-site carrying and operation, especially in some narrow or complex test environments;

[0011] IV. Frequency point limitations

[0012] When using FFT (Fast Fourier Transform) analysis, the frequency points are restricted by the time window and the sampling rate, resulting in the "granularity" problem and reducing the flexibility of spectrum analysis.

[0013] In addition, during the actual measurement process, the influence of internal cables and external connection cables is also a difficult problem to solve. The existence of these connection cables will introduce additional impedance and signal reflection, interfering with the accuracy of measurement results, and the existing technology lacks effective correction methods to eliminate these influences.

[0014] Therefore, it is urgent to develop a cable broadband impedance spectrum measurement method with low cost, easy operation, and low test requirements, which can ensure measurement accuracy and provide technical support for power cable condition monitoring and fault warning. Summary of the Invention

[0015] The present disclosure proposes a measurement scheme for obtaining the cable broadband impedance spectrum by a digital lock-in amplifier, which can obtain the cable broadband impedance spectrum through a pure voltage measurement method, effectively reduce the test cost, simplify the test equipment, and improve the flexibility of the selection of measurement frequency points.

[0016] According to an embodiment of the present disclosure, a measurement method for obtaining the cable broadband impedance spectrum based on a digital lock-in amplifier is proposed, including:

[0017] Determine the frequency list [f 1 :delta_f:f 2 of the cable broadband impedance spectrum to be measured, where f 1 and f 2 are the lower and upper frequency limits respectively, and delta_f is the frequency step;

[0018] Measure the time-domain voltage when the test device is in different connection states. The test device includes a connector with at least three ports, a pulse generation component for generating an excitation signal, and a voltage acquisition component for measuring the time-domain voltage. The first port of the connector is connected to the pulse generation component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable to be measured. Among them, when the third port is disconnected, the measured time-domain voltage is U N , and when the third port is connected to the cable to be measured, the measured time-domain voltage is U L ;

[0019] Using the frequency list, use the digital lock-in amplifier analysis algorithm to analyze the frequency components of the time-domain voltage measured when the test device is in different connection states, and obtain the analysis results DLIA(U N ) and DLIA(U L );

[0020] According to the analysis results DLIA(U N) and DLIA(U L ) to calculate the impedance spectrum Z of the cable under test c .

[0021] In some embodiments, when the third port is directly connected to the cable under test and there is no connecting cable inside the test device, calculate the impedance spectrum Z of the cable under test c including:

[0022] Calculate the impedance spectrum Zc of the cable under test according to the following formula:

[0023] Z c = Z g / [DLIA(U N ) / DLIA(U L ) - 1],

[0024] where Z g is the internal resistance of the pulse generating component.

[0025] In some embodiments, when there is a connecting cable inside the test device, the method further includes:

[0026] Obtain the frequency transfer characteristics of the internal connecting cable:

[0027]

[0028] where U 1 , U 2 represent the voltages at the head and end of the internal connecting cable respectively, and I 1 , I 2 represent the currents at the head and end of the internal connecting cable respectively;

[0029] When the internal connecting cable is between the pulse generating component and the connector, calculating the impedance spectrum Zc of the cable under test includes:

[0030] Calculate the impedance spectrum Z of the cable under test according to the following formula c :

[0031] Z c = (B + D * Z g ) / {[A + C * Z g * [DLIA(U N ) / DLIA(U L ) - 1]},

[0032] where Z g is the internal resistance of the pulse generating component.

[0033] In some embodiments, when the internal connecting cable is between the voltage acquisition component and the connector, calculate the impedance spectrum Z of the cable under test cIncluding:

[0034] Calculate the impedance spectrum Zc of the cable under test according to the following formula:

[0035] Z c = (A * Z g ) / {[A + C * Z g * [DLIA(U N )] / DLIA(U L ) - 1}},

[0036] where Z g is the internal resistance of the pulse generating component.

[0037] In some embodiments, when the cable under test is connected to the third port through an external connection cable, the method further includes:

[0038] Measure the time-domain voltage U lo when the external connection cable is connected to the third port and the end of the external connection cable is kept open;

[0039] Measure the time-domain voltage U ls when the external connection cable is connected to the third port and the end of the external connection cable is kept short-circuited;

[0040] Use the frequency list and the digital lock-in amplifier analysis algorithm to analyze the frequency components of the time-domain voltage U lo and the time-domain voltage U ls to obtain the analysis results DLIA(U lo ) and DLIA(U ls );

[0041] Calculating the impedance spectrum Z c of the cable under test includes:

[0042] Calculate the system impedance spectrum Z o when the end of the external connection cable is open according to the following formula:

[0043] Z o = Z g / [DLIA(U N ) / DLIA(U lo ) - 1];

[0044] Calculate the system impedance spectrum Z s when the end of the external connection cable is short-circuited according to the following formula:

[0045] Z s = Z g / [DLIA(U N ) / DLIA(U ls ) - 1];

[0046] Calculate the system impedance spectrum \(Z\) when the end of the external connection cable is connected to the cable system under test according to the following formula: t :

[0047] Z t =Z g / [DLIA(U N ) / DLIA(U L ) - 1];

[0048] Calculate the impedance spectrum \(Z\) of the cable under test according to the following formula: c :

[0049] Z c =Z o *(Z t - Z s ) / (Z o - Z t ),

[0050] where \(Z\) g is the internal resistance of the pulse generating component.

[0051] In some embodiments, using a frequency list, the frequency components of the time-domain voltage are analyzed using a digital lock-in amplifier analysis algorithm, including:

[0052] For the \(k\)-th frequency \(\omega\) k in the frequency list, select \(\cos(\omega\) k t)\) as the first reference signal, multiply it with the input time-domain voltage and obtain the \(X\) component through low-pass filtering;

[0053] Select \(\sin(\omega\) k t)\) as the second reference signal, multiply it with the input time-domain voltage and obtain the \(Y\) component through low-pass filtering;

[0054] According to the \(X\) and / or \(Y\) components, obtain the analysis result corresponding to the frequency \(\omega\) k .

[0055] According to an embodiment of the present disclosure, a measurement device for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier is also proposed, including:

[0056] A frequency list determination unit for determining the frequency list \([f 1 :\Delta f:f 2 \) of the broadband impedance spectrum of the cable under test, where \(f 1 \) and \(f 2 \) are the lower and upper frequency limits respectively, and \(\Delta f\) is the frequency step size;

[0057] ​​​​​A voltage measurement unit for measuring the time-domain voltage of the test device in different connection states. The test device includes a connector with at least three ports, a pulse generation component for generating an excitation signal, and a voltage acquisition component for measuring the time-domain voltage. The first port of the connector is connected to the pulse generation component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable under test. When the third port is disconnected, the measured time-domain voltage is U N , and when the third port is connected to the cable under test, the measured time-domain voltage is U L ;

[0058] A digital lock-in amplifier analysis unit for using a frequency list and analyzing the frequency components of the time-domain voltage measured by the test device in different connection states using a digital lock-in amplifier analysis algorithm to obtain analysis results DLIA(U N ) and DLIA(U L );

[0059] A broadband impedance spectrum calculation unit for calculating the impedance spectrum Z N ) and DLIA(U L ) of the cable under test according to the analysis results DLIA(U c .

[0060] In some embodiments, when the third port is directly connected to the cable under test and there is no internal connection cable in the test device, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z c of the cable under test according to the following formula:

[0061] Z c = Z g / [DLIA(U N ) / DLIA(U L ) - 1],

[0062] where Z g is the internal resistance of the pulse generation component.

[0063] In some embodiments, when there is an internal connection cable in the test device, the device further includes an internal cable frequency transfer characteristic acquisition unit for acquiring the frequency transfer characteristics of the internal connection cable:

[0064]

[0065] where U 1 , U 2 respectively represent the voltages at the head and tail of the internal connection cable, and I 1 , I 2 respectively represent the currents at the head and tail of the internal connection cable;

[0066] When the internal connection cable is located between the pulse generating component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z of the cable under test according to the following formula c :

[0067] Z c =(B + D * Z g ) / {[A + C * Z g * [DLIA(U N ) / DLIA(U L ) - 1]},

[0068] where Z g is the internal resistance of the pulse generating component.

[0069] In some embodiments, when the internal connection cable is located between the voltage acquisition component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z of the cable under test according to the following formula c :

[0070] Z c =(A * Z g ) / {[A + C * Z g * [DLIA(U N )] / DLIA(U L ) - 1}},

[0071] where Z g is the internal resistance of the pulse generating component.

[0072] In some embodiments, when the cable under test is connected to the third port through an external connection cable,

[0073] the voltage measurement unit is further configured to:

[0074] measure the time-domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is kept open lo and measure the time-domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is kept short-circuited ls ;

[0075] the digital lock-in amplifier analysis unit is further configured to use a frequency list and analyze the frequency components of the time-domain voltage U lo and the time-domain voltage U ls using the digital lock-in amplifier analysis algorithm to obtain the analysis results DLIA(U lo ) and DLIA(U ls );

[0076] the broadband impedance spectrum calculation unit is further configured to:

[0077] calculate the impedance spectrum Z of the cable under testc including:

[0078] Calculate the system impedance spectrum Z when the external connection cable end is open circuit according to the following formula o :

[0079] Z o =Z g / [DLIA(U N ) / DLIA(U lo )-1];

[0080] Calculate the system impedance spectrum Z when the external connection cable end is short circuit according to the following formula s :

[0081] Z s =Z g / [DLIA(U N ) / DLIA(U ls )-1];

[0082] Calculate the system impedance spectrum Z when the external connection cable end is connected to the cable system under test according to the following formula t :

[0083] Z t =Z g / [DLIA(U N ) / DLIA(U L )-1];

[0084] Calculate the impedance spectrum Z of the cable under test according to the following formula c :

[0085] Z c =Z o *(Z t -Z s ) / (Z o -Z t ),

[0086] wherein, Z g is the internal resistance of the pulse generating component.

[0087] According to an embodiment of the present disclosure, an electronic device is provided, the device includes a memory and a processor, the memory is used to store computer instructions that can be run on the processor, and the processor is used to implement the method described in any one of the above when executing the computer instructions.

[0088] According to an embodiment of the present disclosure, a computer-readable storage medium is provided, on which a computer program is stored, and the program implements the method described in any one of the above when executed by a processor.

[0089] The measurement scheme for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier proposed in this disclosure realizes the acquisition of the broadband impedance spectrum of the cable through pure voltage measurement. By using the digital lock-in amplifier algorithm, the frequency points for analysis can be arbitrarily specified, breaking through the limitations of traditional FFT analysis and providing more flexible frequency point selection. Moreover, the test device consists only of a pulse generation component, a connector, and a voltage acquisition component, with a simple structure and a significant reduction in cost, without relying on expensive professional equipment. At the same time, this scheme has low requirements for the state of the system to be measured, is easy to operate efficiently, and has strong adaptability.

[0090] Regarding the possible problems in actual measurement, this disclosure also proposes corresponding correction algorithms. For the influence of the internal cable, an accurate mathematical model is established by obtaining its transfer characteristic matrix; for the external connection cable, the "three-impedance method" correction technology is innovatively proposed, which can achieve accurate correction without prior knowledge of the cable parameters.

[0091] Practical application verification shows that the measurement results of this scheme can meet the actual application requirements, providing a new technical path for cable condition monitoring that is low-cost, flexible, convenient, and easy to operate.

[0092] Other features and advantages of the technical solution proposed in this disclosure are described in detail below. Brief Description of the Drawings

[0093] The accompanying drawings here are incorporated into the specification and form a part of this specification, showing the embodiments consistent with this specification and used together with the specification to explain the principles of this specification.

[0094] Figure 1 Shows a flowchart of a measurement method for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier according to an embodiment of this disclosure.

[0095] Figure 2 Shows a schematic diagram of a test circuit according to an exemplary embodiment of this disclosure.

[0096] Figure 3 Shows a schematic diagram of the time-domain voltage U when the third port is disconnected in the measurement according to an exemplary embodiment of this disclosure. N and the time-domain voltage U when the third port is connected to the cable under test. L of the schematic diagram.

[0097] Figure 4 Shows a comparison schematic diagram of the broadband characteristic impedance spectrum of the cable obtained according to an exemplary embodiment of this disclosure and the impedance spectrum measured by an impedance analyzer.

[0098] Figure 5 Shows a schematic diagram of a test circuit according to an exemplary embodiment of this disclosure.

[0099] Figure 6 The schematic diagram of a test circuit according to an exemplary embodiment of the present disclosure is shown.

[0100] Figure 7 It is a schematic structural diagram of an electronic device shown in at least one embodiment of the present disclosure. Detailed implementation manners

[0101] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present disclosure. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0102] Embodiments of the present disclosure can be applied to a computer system / server, which can operate together with many other general-purpose or special-purpose computing system environments or configurations. Examples of well-known computing systems, environments, and / or configurations suitable for use with a computer system / server include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, minicomputer systems, mainframe computer systems, and distributed cloud computing technology environments including any of the above systems, and so on.

[0103] The computer system / server can be described in the general context of computer system-executable instructions (such as program modules) executed by the computer system. Generally, program modules can include routines, programs, object programs, components, logics, data structures, etc., which perform specific tasks or implement specific abstract data types. The computer system / server can be implemented in a distributed cloud computing environment, where tasks are executed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0104] Figure 1 The flowchart of a measurement method for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier according to an embodiment of the present disclosure is shown. As Figure 1 shown, the method includes steps 1 to 4.

[0105] Step 1, determine the frequency list [f 1 :delta_f:f 2 of the broadband impedance spectrum of the cable to be measured, where f 1 , f 2 are the lower frequency limit and the upper frequency limit respectively, and delta_f is the frequency step.

[0106] The frequency list refers to a series of discrete frequency points to be analyzed, and these frequency points constitute the abscissa of the cable impedance spectrum.

[0107] Lower frequency limit f 1 and upper frequency limit f 2 are usually determined according to the characteristics of the cable to be measured and the target application. In the detection of power cables, the low-frequency band corresponds to the characteristics of the cable at a relatively long distance, and the high-frequency band corresponds to the characteristics of the proximal end of the cable. The frequency step delta_f refers to the interval between adjacent frequency points and determines the frequency resolution. A smaller frequency step can provide finer spectral details, but it will increase the computational amount and measurement time.

[0108] In practical applications, the frequency list can be determined according to the cable type and length, fault type, measurement accuracy requirements, measurement efficiency, etc. For example, for a typical power cable with a length of 80 meters, a frequency range of 1 MHz to 30 MHz can be selected, which has a good effect on identifying common cable faults.

[0109] In particular, the digital lock-in amplifier algorithm adopted in the subsequent embodiments of the present invention can process any arbitrarily specified analyzed frequency points and is not affected by the time window and sampling rate limitations in FFT analysis. Therefore, when determining the frequency list of the broadband impedance spectrum of the cable to be measured in step 1, the frequency points of interest can be flexibly selected, thereby improving the measurement efficiency and pertinence.

[0110] Step 2, measure the time-domain voltage when the test device is in different connection states. The test device includes a connector with at least three ports, a pulse generating component for generating an excitation signal, and a voltage acquisition component for measuring the time-domain voltage. The first port of the connector is connected to the pulse generating component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable to be measured. When the third port is disconnected, the measured time-domain voltage is U N , and when the third port is connected to the cable to be measured, the measured time-domain voltage is U L .

[0111] The test device may include a pulse generating component, a connector, and a voltage acquisition component, and the connector with at least three ports connects the components together. In some embodiments, a T-shaped connector can be used, and its three ports are respectively connected to the pulse generating component, the voltage acquisition component, and the cable to be measured.

[0112] The pulse generating component is used to generate an excitation signal, and its internal resistance is Z gThe pulse generation component can be a signal generator, a pulse source, or other devices that can generate the required excitation signal. During measurement, the pulse generation component can be used to generate a pulsed square wave with a repetition rate of f, a pulse width of w, and an amplitude of V0. Moreover, when measuring the time-domain voltage in various connection states, the settings of the pulse generation component are kept unchanged to generate the same excitation signal.

[0113] The voltage acquisition component is used to measure voltage signals, and its internal resistance is usually at the MΩ level to ensure that the measurement has the least impact on the circuit. The actually used voltage acquisition component can be an oscilloscope, a data acquisition card, or a dedicated voltage measurement device.

[0114] The time-domain voltage refers to the voltage signal that varies with time and is the basic observable quantity in this embodiment.

[0115] Connect the pulse generation component to the first port of the connector, connect the voltage acquisition component to the second port of the T-shaped connector, and keep the third port of the T-shaped connector disconnected (open circuit state). The time-domain voltage measured by the voltage acquisition component in this connection state is U. N 。

[0116] Connect the pulse generation component to the first port of the T-shaped connector, connect the voltage acquisition component to the second port of the T-shaped connector, and connect the cable under test to the third port of the T-shaped connector. The far end of the cable under test is usually kept in an open circuit state. The time-domain voltage measured by the voltage acquisition component in this connection state is U. L 。

[0117] Step 3: Using the frequency list, analyze the frequency components of the time-domain voltage measured when the test device is in different connection states by using the digital lock-in amplifier analysis algorithm to obtain the analysis results DLIA(U N ) and DLIA(U L ).

[0118] This embodiment uses the digital lock-in amplifier algorithm to analyze the frequency components of the time-domain voltage. First, the basic principle of the digital lock-in amplifier is introduced below.

[0119] The Digital Lock-In Amplifier (DLIA) is a high-precision measurement device used to extract weak signals of specific frequencies from a complex signal environment. It generates orthogonal reference signals for phase locking and digital processing, and can accurately measure the amplitude and phase of signals in a high-noise background. The dual-channel DLIA has two independent input channels and can simultaneously measure the orthogonal components (such as X and Y components) of the input signal, which is particularly suitable for application scenarios that require synchronous processing of multiple signal sources or complex vector analysis, such as precision optical measurement, material property research, and signal processing of high-sensitivity sensors.

[0120] For the input signal Vin(t), when using the first reference signal cos(wt), it can be obtained by multiplying through a multiplier as follows:

[0121] Vmix1(t) = V w / 2 * [cos(phi) + cos(2wt + phi)] + delta,

[0122] where Vmix1 is the signal after multiplication, V w is the amplitude of the w-frequency component in Vin(t), phi is the phase of the w-frequency component, and delta is the noise term generated by the multiplication of the multiplier. By performing low-pass filtering on the Vmix1(t) signal, the low-frequency quantity V w / 2 * cos(phi) can be obtained, denoted as X.

[0123] Similarly, for the input signal Vin(t), when using the second reference signal sin(wt), after passing through a multiplier and a low-pass filter, the low-frequency quantity V w / 2 * sin(phi) can be obtained, denoted as Y.

[0124] The output result of the digital lock-in amplifier is usually a complex result X + jY, where j is the imaginary unit.

[0125] Based on the complex result X + jY output by the digital lock-in amplifier, the amplitude Z and phase theta of the w-frequency component in Vin(t) can be extracted:

[0126] Z = sqrt(X^2 + Y^2), theta = arctan(Y / X).

[0127] The above is the basic principle of the digital lock-in amplifier algorithm.

[0128] In this embodiment, the real part X, the imaginary part Y, or the amplitude Z can be used as the analysis result.

[0129] The greatest advantage of the digital lock-in amplifier in extracting frequency components lies in its anti-interference ability and the ability for the user to determine the frequency list by themselves.

[0130] According to some embodiments of this embodiment, for the k-th frequency w k in the frequency list, select cos(w k t) as the first reference signal, multiply it with the input time-domain voltage U N and obtain the X component through low-pass filtering; select sin(w k t) as the second reference signal, multiply it with the input time-domain voltage U N and obtain the Y component through low-pass filtering; based on the X and / or Y components, obtain the frequency w kThe corresponding analysis results.

[0131] Traverse each frequency in the frequency list, and analyze the time-domain voltage U N respectively to obtain an analysis result sequence, which is the analysis result DLIA(U N ) corresponding to the time-domain voltage U N .

[0132] Use the digital lock-in amplifier analysis algorithm to analyze the time-domain voltage U L . The process is similar to the above process of analyzing the time-domain voltage U N . Similarly, use this frequency list to analyze the frequency components of the time-domain voltage U L to obtain the sequence DLIA(U L ).

[0133] In some examples, the real part (i.e., the X component) output by the digital lock-in amplifier algorithm can be used as the analysis result for subsequent processing; in some other examples, the imaginary part (i.e., the Y component) output by the digital lock-in amplifier algorithm can be used as the analysis result; in some other embodiments, the amplitude Z extracted based on the real part X and the imaginary part Y can be used as the analysis result. When analyzing each time-domain voltage signal, the same result selection criterion should be adopted. For example, if when analyzing the time-domain voltage U N , the X component is used as the analysis result DLIA(U N ), then when analyzing the time-domain voltage U L , the X component is also used as the analysis result DLIA(U L ). When analyzing the time-domain voltages measured under various connection states, the same result selection criterion should be adopted.

[0134] Step 4, according to the analysis results DLIA(U N ) and DLIA(U L ), calculate the impedance spectrum Z c of the cable to be measured.

[0135] The impedance spectrum Z N calculated according to the analysis results DLIA(U L ) and DLIA(U c ) can comprehensively reflect the electrical characteristics of the cable in a wide frequency range and provide detailed information for cable condition assessment, etc.

[0136] The measurement method for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier proposed in this embodiment significantly reduces the complexity and cost of the measurement system by only measuring the time-domain voltage signal and analyzing the frequency-domain components in combination with the digital lock-in amplifier algorithm, avoiding the expensive impedance analyzer and complex current measurement link in the traditional method. This method is easy to operate, the test device has a simple structure, and at the same time, it can flexibly specify the analysis frequency points, breaking through the "granularity" limitation of the traditional FFT analysis, improving the flexibility and applicability of the spectrum analysis, and providing an economical and efficient technical solution for cable condition monitoring and fault warning.

[0137] Figure 2 FIG. shows a schematic diagram of a test circuit according to an exemplary embodiment of the present disclosure. As Figure 2 shown, the test device includes a pulse generation component, a T-shaped connector, and a voltage acquisition component.

[0138] The pulse generation component is connected to one port of the T-shaped connector, the voltage acquisition component is connected to the other port of the T-shaped connector, and the third port of the T-shaped connector is used to connect / disconnect the cable under test at the connection point. When the cable under test is connected to this connection point, the far end of the cable under test remains open. GND represents the ground point to ensure the stability of the reference potential of the measurement device.

[0139] As Figure 2 shown in the test circuit, the impedance spectrum Z of the cable under test can be calculated according to the following formula c :

[0140] Z c =Z g / [DLIA(U N ) / DLIA(U L ) - 1],

[0141] where Z g is the internal resistance of the pulse generation component.

[0142] Based on the transmission line theory, by calculating the ratio DLIA(U N ) / DLIA(U L ) of the analysis results of the digital lock-in amplifier and combining with the internal resistance characteristic Z g of the pulse generation component, the impedance value of the cable under test at each frequency point can be accurately calculated.

[0143] To verify the effectiveness and accuracy of this embodiment, the inventor conducted on-site test experiments. The test object was a 80m-long power cable, and the test frequency range was set to 1 - 30 MHz.

[0144] Figure 3 FIG. shows the time-domain voltage U when the third port is disconnected measured according to an exemplary embodiment of the present disclosureN and the time-domain voltage U when connecting the cable under test to the third port L Schematic diagram.

[0145] Figure 4 Shows a comparison of the cable impedance spectra measured according to this embodiment and using a precision impedance analyzer TH285-030 respectively. From Figure 4 It can be seen that the results measured by the two methods are highly consistent, which fully proves that the cable broadband impedance spectrum measurement method provided according to this embodiment has high feasibility and economic advantages.

[0146] In an actual measurement environment, the components of the test device may not be directly connected and need to be connected through internal cables. The existence of these internal connection cables will introduce additional transmission line effects and affect the measurement accuracy. To solve this problem, the present disclosure proposes the following correction method to eliminate the interference of the internal cables on the measurement results, ensure the accuracy of the impedance spectrum measurement, and at the same time maintain the flexibility and applicability of the test system.

[0147] Figure 5 Shows a schematic diagram of a test circuit according to an exemplary embodiment of the present disclosure. As Figure 5 shown, the test device includes a pulse generation component, a T-shaped connector, and a voltage acquisition component, which is basically the same as the basic composition of Embodiment 1. The difference is that in Figure 5 the shown test circuit, there are connection cables inside the test device.

[0148] As Figure 5 shown, the internal cables usually may have two forms of existence in the test system: internal cable 1 is located between the voltage acquisition component and the T-shaped connector; internal cable 2 is located between the pulse generation component and the T-shaped connector. Usually only one internal cable exists in the test device, and these two forms represent two possible cases of the internal cable connection.

[0149] Since the existence of the internal connection cables will affect the measurement accuracy, the frequency transfer characteristics of the internal cables can be obtained first according to the following formula:[[]]END]]

[0150]

[0151] where U 1 and U 2 represent the voltages at the head and end of the internal connection cable respectively, and I 1 and I 2 represent the currents at the head and end of the internal connection cable respectively. These parameters can be measured and obtained by a network vector analyzer, or calculated using the precise structural parameters and electrical parameters of the internal cable.

[0152] When the internal connecting cable is located between the pulse generating assembly and the connector (such as Figure 5 When the internal cable 2 is shown in the figure, the impedance spectrum Z of the cable to be tested can be calculated according to the following formula c :

[0153] Z c =(B+D*Z g ) / {[A+C*Z g ]*[DLIA(U N ) / DLIA(U L )-1]},

[0154] Among them, Z g is the internal resistance of the pulse generating component.

[0155] When the internal connecting cable is located between the voltage collection component and the connector (such as Figure 5 When the internal cable 1 is shown in the figure, the impedance spectrum Z of the cable to be tested can be calculated according to the following formula c :

[0156] Z c =(A*Z g ) / {[A+C*Z g ]*[DLIA(U N )] / DLIA(U L )-1}},

[0157] Among them, Z g is the internal resistance of the pulse generating component.

[0158] According to the correction method of the above embodiment, on the one hand, the simple characteristic of only measuring the time domain voltage is maintained, and on the other hand, the error problem that may be introduced by the internal cable in the actual measurement is solved through the transfer matrix correction, making the measurement system more flexible and applicable to a wider range. This is particularly important for scenarios where the test equipment components cannot be directly connected, which greatly enhances the practical application value of the method.

[0159] In some test scenarios, the T-shaped connector may not be able to directly connect to the cable system to be tested. There is a certain spatial distance between the test device and the system to be tested, and an external connection cable is required for connection. The existence of the external connection cable will affect the accuracy of the measurement results. To solve this problem, the present disclosure also proposes a "three-impedance method" correction method, which can eliminate the influence of the transfer characteristic parameters of the external connection cable on the measurement results without obtaining the transfer characteristic parameters of the external connection cable in advance, further enhancing the versatility and practicality of the method.

[0160] Figure 6 FIG. 2 shows a schematic diagram of a test loop according to an exemplary embodiment of the present disclosure. Figure 6As shown, the test device includes a pulse generation component, a T-shaped connector, and a voltage acquisition component, which is basically the same as the Figure 2 shown test circuit. The difference is that Figure 6 in the shown test circuit, when the cable under test is connected to the test device, it is connected to the connection point through an external connection cable. The external connection cable enables the test device to be connected to the cable under test, solving the problem that the test device cannot be directly connected to the cable under test.

[0161] When there is an external connection cable, in order to make the finally calculated impedance spectrum Z c have high reliability, in addition to measuring the time-domain voltage U N and U L , it is also necessary to measure the time-domain voltage when the external connection cable is connected to the third port and its end is open / short-circuited. The measurement process includes:

[0162] First, disconnect the Figure 6 connection point in, measure the time-domain voltage when the test device disconnects the cable under test, and record it as U N ;

[0163] Connect the external connection cable and keep the end of the connection cable open, measure the time-domain voltage at this time, and record it as U lo ;

[0164] Connect the external connection cable and keep the end of the connection cable short-circuited, measure the time-domain voltage at this time, and record it as U ls ;

[0165] Connect the external connection cable and connect the end of the connection cable to the cable system under test, measure the time-domain voltage at this time, and record it as U L .

[0166] Using the same frequency list, use the digital lock-in amplifier analysis algorithm to analyze the frequency components of U N , U lo , U ls and U L respectively, and correspondingly obtain DLIA(U N ), DLIA(U lo ), DLIA(U ls ) and DLIA(U L );

[0167] The impedance spectrum Z c of the cable under test can be calculated according to the "three-impedance method", and the calculation process is as follows:

[0168] Calculate the system impedance spectrum Z o when the end of the external connection cable is open according to the following formula:

[0169] Z o =Zg / [DLIA(U N ) / DLIA(U lo )-1];

[0170] Calculate the system impedance spectrum Z when the external connection cable is short - circuited at the end according to the following formula s :

[0171] Z s =Z g / [DLIA(U N ) / DLIA(U ls )-1];

[0172] Calculate the system impedance spectrum Z when the external connection cable is connected to the cable system under test at the end according to the following formula t :

[0173] Z t =Z g / [DLIA(U N ) / DLIA(U L )-1];

[0174] Calculate the impedance spectrum Z of the cable under test according to the following formula c :

[0175] Z c =Z o *(Z t -Z s ) / (Z o -Z t ),

[0176] where Z g is the internal resistance of the pulse - generating component.

[0177] The "three - impedance method" correction technology proposed in this embodiment does not require prior acquisition of the transfer characteristic parameters of the external connection cable. By measuring the voltage responses in three different states (open - circuit, short - circuit, connected to the cable under test), a complete mathematical model can be established to achieve precise correction of the influence of the external connection cable. This method has strong applicability, can adapt to external connection cables of different models and lengths, further reduces the test cost and complexity, and maintains the flexibility and accuracy of measurement in various complex test environments.

[0178] The "three - impedance method" is completely calibrated based on measurement data, and the operation is more convenient, especially suitable for the situation where accurate cable parameters cannot be obtained under on - site test conditions. This correction method further expands the application scope of the present disclosure, can cope with more complex and changeable test environments, and provides a more flexible and practical technical solution for cable condition monitoring.

[0179] The present disclosure also provides a measuring device for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier, including:

[0180] A frequency list determination unit for determining the frequency list [f 1 :delta_f:f 2 of the broadband impedance spectrum of the cable to be measured, where f 1 and f 2 are the lower and upper frequency limits respectively, and delta_f is the frequency step;

[0181] A voltage measurement unit for measuring the time-domain voltage when the test device is in different connection states. The test device includes a connector with at least three ports, a pulse generation component for generating an excitation signal, and a voltage acquisition component for measuring the time-domain voltage. The first port of the connector is connected to the pulse generation component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable to be measured. When the third port is disconnected, the measured time-domain voltage is U N , and when the third port is connected to the cable to be measured, the measured time-domain voltage is U L ;

[0182] A digital lock-in amplifier analysis unit for using the frequency list and analyzing the frequency components of the time-domain voltage measured when the test device is in different connection states by using a digital lock-in amplifier analysis algorithm to obtain the analysis results DLIA(U N ) and DLIA(U L );

[0183] A broadband impedance spectrum calculation unit for calculating the impedance spectrum Z N of the cable to be measured according to the analysis results DLIA(U L ); c .

[0184] In some embodiments, when the third port is directly connected to the cable to be measured and there is no connecting cable inside the test device, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z c of the cable to be measured according to the following formula:

[0185] Z c = Z g / [DLIA(U N ) / DLIA(U L ) - 1],

[0186] where Z g is the internal resistance of the pulse generation component.

[0187] In some embodiments, when there is a connection cable inside the test device, the device further includes an internal cable frequency transfer characteristic acquisition unit for acquiring the frequency transfer characteristics of the internal connection cable:

[0188]

[0189] where U 1 and U 2 represent the voltages at the head and tail ends of the internal connection cable respectively, and I 1 and I 2 represent the currents at the head and tail ends of the internal connection cable respectively;

[0190] When the internal connection cable is located between the pulse generating component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z c of the cable under test according to the following formula:

[0191] Z c = (B + D * Z g ) / {[A + C * Z g * [DLIA(U N ) / DLIA(U L ) - 1]},

[0192] where Z g is the internal resistance of the pulse generating component.

[0193] In some embodiments, when the internal connection cable is located between the voltage acquisition component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z c of the cable under test according to the following formula:

[0194] Z c = (A * Z g ) / {[A + C * Z g * [DLIA(U N )] / DLIA(U L ) - 1}},

[0195] where Z g is the internal resistance of the pulse generating component.

[0196] In some embodiments, when the cable under test is connected to the third port through an external connection cable,

[0197] the voltage measurement unit is further configured to:

[0198] Measure the time-domain voltage U lo when the external connection cable is connected to the third port and the end of the external connection cable is kept open.and measuring the time-domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is kept short-circuited ls ;

[0199] The digital lock-in amplifier analysis unit is further configured to use the frequency list and analyze the time-domain voltage U using the digital lock-in amplifier analysis algorithm lo and the time-domain voltage U ls to obtain the analysis results DLIA(U lo ) and DLIA(U ls ;

[0200] The broadband impedance spectrum calculation unit is further configured to:

[0201] calculate the impedance spectrum Z of the cable under test c including:

[0202] calculate the system impedance spectrum Z when the end of the external connection cable is open-circuited according to the following formula o :

[0203] Z o =Z g / [DLIA(U N ) / DLIA(U lo ) - 1];

[0204] calculate the system impedance spectrum Z when the end of the external connection cable is short-circuited according to the following formula s :

[0205] Z s =Z g / [DLIA(U N ) / DLIA(U ls ) - 1];

[0206] calculate the system impedance spectrum Z when the end of the external connection cable is connected to the cable under test system according to the following formula t :

[0207] Z t =Z g / [DLIA(U N ) / DLIA(U L ) - 1];

[0208] calculate the impedance spectrum Z of the cable under test according to the following formula c :

[0209] Z c =Z o *(Z t - Z s ) / (Z o - Z t ),

[0210] where Z g is the internal resistance of the pulse generating component.

[0211] For other details and features of this embodiment, please refer to the relevant descriptions above.

[0212] Figure 7 An electronic device provided by at least one embodiment of the present disclosure, the device includes a memory and a processor, the memory is used to store computer instructions that can run on the processor, and the processor is used to implement the measurement method for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier described in any embodiment or implementation manner of the present disclosure when executing the computer instructions.

[0213] At least one embodiment of the present disclosure also provides a computer-readable storage medium, on which a computer program is stored, and the program implements the measurement method for obtaining the broadband impedance spectrum of a cable based on a digital lock-in amplifier described in any embodiment or implementation manner of the present disclosure when executed by a processor.

[0214] Those skilled in the art should understand that one or more embodiments of this specification can be provided as a method, a system, or a computer program product. Therefore, one or more embodiments of this specification can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, one or more embodiments of this specification can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memory, CD-ROM, optical memory, etc.) that contain computer-usable program code.

[0215] The various embodiments in this specification are all described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the embodiment of the data processing device, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment.

[0216] The specific embodiments of this specification are described above. Other embodiments are within the scope of the appended claims. In some cases, the acts or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired results. Additionally, the processes depicted in the figures do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain implementations, multitasking and parallel processing are also possible or may be advantageous.

[0217] Although this specification contains many specific implementation details, these should not be construed as limiting the scope of any invention or the scope of what is claimed, but rather as mainly for describing the features of specific embodiments of a particular invention. Certain features described in multiple embodiments within this specification can also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment can also be implemented separately in multiple embodiments or in any suitable sub-combination. Additionally, although features may function in certain combinations as described above and were even initially claimed as such, one or more features from a claimed combination can in some cases be removed from that combination, and the claimed combination can be directed to a sub-combination or a variation of a sub-combination.

[0218] Similarly, although operations are depicted in the drawings in a particular order, this should not be construed as requiring that those operations be performed in the particular order shown or sequentially, or that all illustrated operations be performed to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Additionally, the separation of the various system modules and components in the above embodiments should not be construed as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0219] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the acts recited in the claims can be performed in a different order and still achieve the desired result. Additionally, the processes depicted in the drawings are not necessarily in the particular order or sequential order shown to achieve the desired result. In some implementations, multitasking and parallel processing may be advantageous.

[0220] The above description is only the preferred embodiments of one or more embodiments of this specification and is not intended to limit one or more embodiments of this specification. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of one or more embodiments of this specification shall be included within the scope protected by one or more embodiments of this specification.

Claims

1. A measurement method for obtaining a broadband impedance spectrum of a cable based on a digital lock-in amplifier, characterized in that: include: Determine the frequency list [f1:delta_f:f2] of the broadband impedance spectrum of the cable to be tested, where f1 and f2 are the lower and upper limits of the frequency respectively, and delta_f is the frequency step size; The time domain voltage of the test device is measured when it is in different connection states. The test device includes a connector with at least three ports, a pulse generating component for generating an excitation signal, and a voltage acquisition component for measuring the time domain voltage. The first port of the connector is connected to the pulse generating component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable to be tested. When the third port is disconnected, the measured time domain voltage is U N When the third port is connected to the cable to be tested, the measured time domain voltage is U L ; Using the frequency list, the digital lock-in amplifier analysis algorithm is used to analyze the frequency components of the time domain voltage measured when the test device is in different connection states, and the analysis results DLIA (U N ) and DLIA(U L ); According to the analysis results DLIA (U N ) and DLIA(U L ), calculate the impedance spectrum Z of the cable to be tested c .

2. The method according to claim 1, characterized in that When the third port is directly connected to the cable under test and there is no connecting cable inside the test device, calculate the impedance spectrum Z of the cable under test c include: Calculate the impedance spectrum Zc of the cable under test according to the following formula: Z c =Z g / [DLIA(U N ) / DLIA(U L )-1], Among them, Z g is the internal resistance of the pulse generating component.

3. The method according to claim 1, characterized in that When there is a connecting cable inside the test device, the method further includes: Get the frequency transfer characteristics of the internal connecting cable: Among them, U1 and U2 represent the voltage at the beginning and end of the internal connection cable respectively, and I1 and I2 represent the current at the beginning and end of the internal connection cable respectively; When the internal connecting cable is located between the pulse generating component and the connector, calculating the impedance spectrum Zc of the cable to be tested includes: Calculate the impedance spectrum Z of the cable under test according to the following formula: c : Z c =(B+D*Z g ) / {[A+C*Z g ]*[DLIA(U N ) / DLIA(U L )-1]}, Among them, Z g is the internal resistance of the pulse generating component.

4. The method according to claim 3, characterized in that When the internal connecting cable is located between the voltage collection component and the connector, the impedance spectrum Z of the cable to be tested is calculated. c include: Calculate the impedance spectrum Zc of the cable under test according to the following formula: Z c =(A*Z g ) / {[A+C*Z g ]*[DLIA(U N )] / DLIA(U L )-1}}, Among them, Z g is the internal resistance of the pulse generating component.

5. The method according to claim 1, characterized in that When the cable to be tested is connected to the third port through an external connection cable, the method further includes: Measure the time domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is kept open lo ; Measure the time domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is short-circuited ls ; Using the frequency list, the time domain voltage U is analyzed using the digital lock-in amplifier analysis algorithm lo and the time domain voltage U ls The frequency components of the analysis result DLIA(U lo ) and DLIA(U ls ); Calculate the impedance spectrum Z of the cable under test c include: Calculate the system impedance spectrum Z when the end of the external connection cable is open according to the following formula o : Z o =Z g / [DLIA(U N ) / DLIA(U lo )-1]; Calculate the system impedance spectrum Z when the end of the external connection cable is short-circuited according to the following formula s : Z s =Z g / [DLIA(U N ) / DLIA(U ls )-1]; Calculate the system impedance spectrum Z when the end of the external connection cable is connected to the cable system to be tested according to the following formula t : Z t =Z g / [DLIA(U N ) / DLIA(U L )-1]; Calculate the impedance spectrum Z of the cable under test according to the following formula: c : WITH c =Z o *(WITH t -WITH s ) / (WITH o -WITH t ), Among them, Z g is the internal resistance of the pulse generating component.

6. The method according to claim 1, characterized in that Using the frequency list, the digital lock-in amplifier analysis algorithm is used to analyze the frequency content of the time domain voltage, including: For the kth frequency w in the frequency list k , select cos(w k t) as the first reference signal, multiplied by the input time domain voltage and obtained by low-pass filtering; Select sin(w k t) as the second reference signal, multiplied with the input time domain voltage and obtained by low-pass filtering the Y component; Based on the X and / or Y components, we get the frequency w k The corresponding analysis results.

7. A measuring device for obtaining broadband impedance spectrum of a cable based on a digital lock-in amplifier, characterized in that: include: The frequency list determination unit is used to determine the frequency list [f1:delta_f:f2] of the broadband impedance spectrum of the cable to be tested, where f1 and f2 are the lower and upper limits of the frequency respectively, and delta_f is the frequency step size; A voltage measuring unit is used to measure the time domain voltage when the test device is in different connection states, the test device includes a connector with at least three ports, a pulse generating component for generating an excitation signal, and a voltage acquisition component for measuring the time domain voltage, the first port of the connector is connected to the pulse generating component, the second port is connected to the voltage acquisition component, and the third port is used to connect or disconnect the cable to be tested, wherein when the third port is disconnected, the measured time domain voltage is U N When the third port is connected to the cable to be tested, the measured time domain voltage is U L ; The digital lock-in amplifier analysis unit is used to analyze the frequency components of the time domain voltage measured when the test device is in different connection states using the digital lock-in amplifier analysis algorithm using the frequency list to obtain the analysis result DLIA (U N ) and DLIA(U L ); Broadband impedance spectrum calculation unit, used to calculate the impedance spectrum according to the analysis results DLIA (U N ) and DLIA(U L ), calculate the impedance spectrum Z of the cable to be tested c .

8. The device according to claim 7, characterized in that When the third port is directly connected to the cable to be tested and there is no connecting cable inside the test device, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z of the cable to be tested according to the following formula: c : Z c =Z g / [DLIA(U N ) / DLIA(U L )-1], Among them, Z g is the internal resistance of the pulse generating component.

9. The device according to claim 7, characterized in that When there is a connecting cable inside the test device, the device further comprises an internal cable frequency transfer characteristic acquisition unit, which is used to acquire the frequency transfer characteristic of the internal connecting cable: Among them, U1 and U2 represent the voltage at the beginning and end of the internal connection cable respectively, and I1 and I2 represent the current at the beginning and end of the internal connection cable respectively; When the internal connection cable is located between the pulse generating component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z of the cable to be tested according to the following formula: c : Z c =(B+D*Z g ) / {[A+C*Z g ]*[DLIA(U N ) / DLIA(U L )-1]}, Among them, Z g is the internal resistance of the pulse generating component.

10. The device according to claim 9, characterized in that When the internal connection cable is located between the voltage collection component and the connector, the broadband impedance spectrum calculation unit calculates the impedance spectrum Z of the cable to be tested according to the following formula: c : Z c =(A*Z g ) / {[A+C*Z g ]*[DLIA(U N )] / DLIA(U L )-1}}, Among them, Z g is the internal resistance of the pulse generating component.

11. The device according to claim 7, characterized in that When the cable under test is connected to the third port through an external connecting cable, The voltage measuring unit is also used for: Measure the time domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is kept open lo And measure the time domain voltage U when the external connection cable is connected to the third port and the end of the external connection cable is short-circuited ls ; The digital lock-in amplifier analysis unit is also used to analyze the time domain voltage U using the frequency list and the digital lock-in amplifier analysis algorithm. lo and the time domain voltage U ls The frequency components of the analysis result DLIA(U lo ) and DLIA(U ls ); The broadband impedance spectrum calculation unit is also used for: Calculate the impedance spectrum Z of the cable under test c include: Calculate the system impedance spectrum Z when the end of the external connection cable is open according to the following formula o : Z o =Z g / [DLIA(U N ) / DLIA(U lo )-1]; Calculate the system impedance spectrum Z when the end of the external connection cable is short-circuited according to the following formula s : Z s =Z g / [DLIA(U N ) / DLIA(U ls )-1]; Calculate the system impedance spectrum Z when the end of the external connection cable is connected to the cable system to be tested according to the following formula t : Z t =Z g / [DLIA(U N ) / DLIA(U L )-1]; Calculate the impedance spectrum Z of the cable under test according to the following formula: c : WITH c =Z o *(WITH t -WITH s ) / (WITH o -WITH t ), Among them, Z g is the internal resistance of the pulse generating component.

12. An electronic device, characterized in that: The device comprises a memory and a processor, wherein the memory is used to store computer instructions executable on the processor, and the processor is used to implement the method according to any one of claims 1 to 6 when executing the computer instructions.

13. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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