Distribution cable insulation state detection system

Abstract

A distribution cable insulation state detection system relates to the technical field of electrical engineering and comprises a central control module, an FDS first insulation detection module, an FDS second insulation detection module and an insulation state comprehensive judgment module. The central control module is used for controlling the starting and closing of the FDS first insulation detection module or the FDS second insulation detection module, and is used for receiving an output result of the insulation state comprehensive judgment module; the FDS first insulation detection module is used for receiving voltage of an external power supply and carrying out insulation detection on a cable to be detected; the FDS second insulation detection module is used for receiving the voltage of the primary side power supply and carrying out insulation detection on the cable to be detected; the insulation state comprehensive judgment module is used for receiving insulation detection results of the FDS first insulation detection module and the FDS second insulation detection module, analyzing the insulation state of the cable to be detected and outputting the corresponding insulation state to the central control module; accurate and convenient cable insulation performance detection can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical engineering, and in particular to a distribution cable insulation state detection system. Background Art

[0002] The medium and low voltage electrical systems of nuclear power plants have been fully covered by cables, but cable failures still account for a high proportion of power equipment failures each year. Affected by the temperature and moisture in the operating environment of nuclear power plants, the cable insulation medium will inevitably experience thermal aging and moisture, and will also experience radiation aging due to the influence of radiation, so it is necessary to regularly evaluate and test the insulation performance of the cable.

[0003] Traditional evaluation and testing methods for cable insulation are generally divided into two categories. The first method requires sampling and testing of cable insulation or is destructive, such as indentation modulus test and withstand voltage test. The second method requires untying the cable lugs, which is complicated to operate and has high maintenance time cost, such as partial discharge test or ultra-low frequency dielectric loss test.

[0004] Among them, the first type of method is destructive to the cable. For nuclear power plants, safe operation is of great importance. The safety of the cable repaired after being damaged is bound to be reduced, so it is not suitable for medium and low voltage electrical systems during operation. The frequency domain dielectric spectrum test (FDS) in the second type of method is an insulation medium test and evaluation method based on the dielectric response method. It will not have a destructive effect on the cable insulation, and can effectively identify insulation aging, water tree defects, etc., and plays an important role in the insulation detection of the cable. However, when using the external FDS equipment for testing alone, the lines to be tested need to be shut down and disassembled one by one before further testing can be carried out, resulting in increased testing costs and reduced efficiency. When the high-frequency overvoltage of the line itself is used as the excitation for FDS testing alone, due to the uncontrollable frequency component, the test results cannot fully reflect the actual effect of the cable insulation, and the high-frequency overvoltage caused by multiple closing operations will also cause a certain degree of damage to the insulation medium.

[0005] Publication No.: CN110208662B discloses a Chinese patent for a superconducting cable PPLP insulation detection method and system based on dielectric spectrum. Based on the dielectric spectrum principle, the method uses a detection method of applying AC voltages of different frequencies to the PPLP to calculate the insulation performance of the PPLP. However, when applying AC voltages of different frequencies to the PPLP, this method will also perform multiple closing operations, so there will still be high-frequency overvoltages caused by multiple closings, causing a certain degree of damage to the insulating medium.

[0006] Therefore, we propose a cable insulation detection system that can achieve accurate and convenient detection. Summary of the invention

[0007] The object of the present invention is to provide a distribution cable insulation status detection system, which can achieve accurate and convenient detection.

[0008] The present invention is achieved through the following technical solutions:

[0009] A distribution cable insulation state detection system, comprising a central control module, an FDS first insulation detection module, an FDS second insulation detection module and an insulation state comprehensive judgment module;

[0010] The central control module is used to control the start and stop of the FDS first insulation detection module or the FDS second insulation detection module, and is used to receive the output result of the insulation status comprehensive judgment module;

[0011] The FDS first insulation detection module is used to receive the voltage of the external power supply and perform insulation detection on the cable to be tested;

[0012] The second insulation detection module of FDS is used to receive the voltage of the primary power supply and perform insulation detection on the cable to be tested;

[0013] The insulation status comprehensive judgment module is used to receive the insulation detection results of the FDS first insulation detection module and the FDS second insulation detection module, analyze the insulation status of the cable to be tested, and output the corresponding insulation status to the central control module.

[0014] Furthermore, the output voltage of the external power supply is 200V, and the output frequency is 1mHz-1kHz.

[0015] Furthermore, the FDS first insulation detection module and the FDS second insulation detection module both include a signal generator, a current sensor, a voltage sensor, a data acquisition and processing unit, a communication interface, and a control logic unit; the signal generator is used to generate a test signal within a specific frequency range according to an external power supply or a primary power supply, and apply it to the cable to be tested;

[0016] The current sensor and the voltage sensor are used to monitor the current and voltage changes of the cable under test when a test signal is applied to the cable under test;

[0017] The data acquisition and processing unit is used to receive data from the current sensor and the voltage sensor, and calculate the data to obtain a test result set;

[0018] The communication interface is used to output the parameters acquired by the data acquisition and processing unit to the insulation status comprehensive judgment module;

[0019] The control logic unit is used to receive control instructions from the central control module, and control the signal generator, current sensor, voltage sensor, data acquisition and processing unit and communication interface to perform corresponding operations.

[0020] Furthermore, the FDS first insulation detection module and the FDS second insulation detection module also include a protection circuit, which is composed of an overvoltage protection unit and a short-circuit protection unit, and is used to prevent the signal generator, the data acquisition and processing unit, and the communication interface from being damaged by overvoltage and short circuit.

[0021] Further, the overvoltage protection unit includes a transient voltage suppression diode, a metal oxide varistor and a gas discharge tube, wherein the power input end of the transient voltage suppression diode is electrically connected to an external power supply or a primary power supply, and the power output end of the transient voltage suppression diode is electrically connected to a signal generator;

[0022] The metal oxide varistor is installed at the signal input end of the data acquisition and processing unit;

[0023] The gas discharge tube is installed at the signal input end of the communication interface.

[0024] Further, the short-circuit protection unit includes a current limiter and a fast-blow fuse, wherein the current limiter is installed at the signal input end of the data acquisition and processing unit;

[0025] The power input end of the fast-blow fuse is electrically connected to an external power supply or a primary-side power supply, and the power output end of the fast-blow fuse is electrically connected to a signal generator.

[0026] Furthermore, the control logic unit is set as a circuit breaker, the control input end of the circuit breaker is electrically connected to the central control module, and the control output end of the circuit breaker is electrically connected to the signal generator, current sensor, voltage sensor, data acquisition and processing unit and communication interface respectively.

[0027] Furthermore, the test result set of the first insulation detection module of the FDS is: A = [a1, a2, ..., a n ]

[0028] Among them, a n Indicates the test result of the first insulation detection module of the nth cable to be tested. According to the test result of FDS, if a n =0, indicating that the insulation state is abnormal. If a n =1, it means the insulation is in good condition; n represents the number of cables actually installed to be tested.

[0029] Furthermore, the test result set of the second insulation detection module of the FDS is: B = [b1, b2, ..., b n ]

[0030] Among them, b n Indicates the test result of the second insulation detection module of the nth cable to be tested. According to the test result of FDS, if b n =0, indicating that the insulation state is abnormal. If b n =1, it means the insulation is in good condition; n represents the number of cables actually installed to be tested.

[0031] Furthermore, the insulation status comprehensive judgment module analyzes the insulation status of the cable as follows:

[0032] C=A+B=[c1,c2,···,c n ];

[0033] Among them, c n Indicates the insulation status judgment result of the nth cable to be tested. If c n =0, indicating that the cable under test is close to a fault. If c n =1, indicating that the insulation performance of the tested cable has a certain risk of failure. n =2, indicating that the insulation performance of the cable under test is faulty.

[0034] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0035] The present invention discloses a distribution cable insulation state detection system, which uses two insulation detection modules to detect the insulation performance of the cable to be tested in turn, and then uses the insulation state comprehensive judgment module to make a comprehensive judgment, thereby improving the detection accuracy of the insulation performance of the cable to be tested;

[0036] Since both the FDS first insulation detection module and the FDS second insulation detection module can be directly connected to the cable to be tested to detect the insulation performance of the cable to be tested, the convenience of insulation detection can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a system structure of the present invention;

[0038] Figure 2 It is a structural schematic diagram of the first insulation detection module of the FDS of the present invention.

[0039] Figure numerals: 1. Central control module; 2. FDS first insulation detection module; 21. Signal generator; 22. Current sensor; 23. Voltage sensor; 24. Data acquisition and processing unit; 25. Communication interface; 26. Control logic unit; 3. FDS second insulation detection module; 4. Insulation status comprehensive judgment module; 5. External power supply; 6. Primary side power supply; 7. Cable to be tested. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0043] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0044] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Example 1

[0046] As attached Figure 1 A distribution cable insulation state detection system shown includes a central control module 1, an FDS first insulation detection module 2, an FDS second insulation detection module 3 and an insulation state comprehensive judgment module 4;

[0047] The central control module 1 is used to control the start and stop of the FDS first insulation detection module 2 or the FDS second insulation detection module 3, and to receive the output result of the insulation state comprehensive judgment module 4;

[0048] The FDS first insulation detection module 2 is used to receive the voltage of the external power supply 5 and perform insulation detection on the cable to be tested 7;

[0049] The FDS second insulation detection module 3 is used to receive the voltage of the primary power supply 6 and perform insulation detection on the cable to be tested 7;

[0050] For the FDS first insulation detection module 2 and the FDS second insulation detection module 3, both are insulation detections based on the frequency domain dielectric spectrum test FDS. Therefore, in the process of conducting insulation performance test on the cable 7 to be tested, it is not necessary to destroy the integrity of the cable 7 to be tested. It is only necessary to connect the two insulation detection modules to the modules to be tested. It should be noted that the wiring terminals of the first FDS insulation detection module and the second FDS insulation detection module are both electrically connected to the cable 7 to be tested, and the power supply end of the first FDS insulation detection module is electrically connected to the external power supply 5, and the power supply end of the second FDS insulation detection module is electrically connected to the primary side power supply 6 in the medium and low voltage electrical system of the nuclear power plant; that is, the voltages generated by the two power supplies are respectively input into the cable 7 to be tested through the corresponding FDS insulation detection modules, and then the two FDS insulation detection modules respectively obtain corresponding insulation performance test results, and then the insulation status comprehensive judgment module 4 is used to accurately judge the insulation performance of the cable 7 to be tested.

[0051] The insulation status comprehensive judgment module 4 is used to receive the insulation detection results of the FDS first insulation detection module 2 and the FDS second insulation detection module 3, analyze the insulation status of the cable to be tested 7, and output the corresponding insulation status to the central control module 1.

[0052] In particular, the output voltage of the external power supply 5 is 200V, and the output frequency is 1mHz-1kHz; wherein the voltage of 200V is sufficient to perform effective insulation detection on most distribution cables without causing damage to the cables. This voltage value is usually higher than the normal operating voltage, but is still within a safe range, and can effectively test the insulation performance of the cable; in addition, the frequency range of 1mHz to 1kHz is a relatively wide frequency band, and different insulation defects may show different responses to test signals of different frequencies. By changing the frequency within this range, the aging and defects of the cable insulation material can be more comprehensively evaluated, thereby improving the detection accuracy;.

[0053] Example 2

[0054] As attached Figure 2As shown, the FDS first insulation detection module 2 and the FDS second insulation detection module 3 each include a signal generator 21, a current sensor 22, a voltage sensor 23, a data acquisition and processing unit 24, a communication interface 25 and a control logic unit 26; the signal generator 21 is used to generate a test signal within a specific frequency range according to the external power supply 5 or the primary side power supply 6, and apply it to the cable 7 to be tested;

[0055] The current sensor 22 and the voltage sensor 23 are used to monitor the current and voltage changes of the cable 7 under test, that is, the current change I(t) and the voltage change V(t) when the test signal is applied to the cable 7 under test;

[0056] The data acquisition and processing unit 24 is used to receive data from the current sensor 22 and the voltage sensor 23, and calculate the data to obtain a test result set;

[0057] The data acquisition and processing unit 24 integrates an algorithm for frequency domain dielectric spectrum testing. Based on the voltage and current data obtained by the electrical parameter measurement acquisition module, an algorithm program is used to calculate and obtain dielectric loss parameters such as dielectric loss tangent and complex capacitance in the frequency range from low frequency 1mHz to high frequency 10kHz.

[0058] The specific calculation process of the frequency domain dielectric spectrum test algorithm is as follows:

[0059] a. Synchronize the current change I(t) and the voltage change V(t), and filter the current change I(t) and the voltage change V(t);

[0060] b. For each frequency point f, calculate the complex impedance Z(f) according to Ohm's law:

[0061]

[0062] Where V(f) and I(f) are the complex values ​​of the voltage and current after Fourier transformation, respectively;

[0063] c. Assuming the cable is a coaxial structure, use the following formula to calculate the complex capacitance C * (f):

[0064]

[0065] Where ω = 2πf, is the angular frequency;

[0066] d. Restore the capacitance C * (f) is decomposed into its real part C'(f) and imaginary part C''(f):

[0067] C * (f) = C'(f) - jC''(f);

[0068] e. The dielectric loss tangent tanδ(f) is defined by the ratio of the imaginary part to the real part of the complex capacitance:

[0069]

[0070] f. Extract key indicators characterizing insulation conditions from the curve features of C'(f), C''(f) and tanδ(f), such as maximum value, minimum value, average value, median, slope change, and specific frequency response characteristics in the frequency domain, to form a frequency domain dielectric spectrum data set;

[0071] g. By setting corresponding thresholds for each indicator in the frequency domain dielectric spectrum data set, and using two different thresholds for the first insulation detection module 2 of FDS and the second insulation detection module 3 of FDS;

[0072] h. According to the rules, if all the characteristics of the first cable are within the normal range, then a1 = 1,

[0073] b1=1;

[0074] If the average of the dielectric loss tangent value of the second cable exceeds the threshold range of the FDS first insulation detection module 2 and the FDS second insulation detection module 3, then a2=0, b2=0;

[0075] If a certain feature of the third cable exceeds the threshold requirement of the first insulation detection module 2 of the FDS, then a3=0, but does not exceed the threshold requirement of the second insulation detection module 3 of the FDS, then b3=1.

[0076] The communication interface 25 is used to output the parameters obtained by the data acquisition and processing unit 24 to the insulation state comprehensive judgment module 4.

[0077] The control logic unit 26 is used to receive control instructions from the central control module 1 and control the signal generator 21, the current sensor 22, the voltage sensor 23, the data acquisition and processing unit 24 and the communication interface 25 to perform corresponding operations.

[0078] In particular, the control logic unit 26 is set as a circuit breaker, the control input end of the circuit breaker is electrically connected to the central control module 1, and the control output end of the circuit breaker is electrically connected to the signal generator 21, the current sensor 22, the voltage sensor 23, the data acquisition and processing unit 24 and the communication interface 25 respectively;

[0079] Since the circuit breaker has the characteristics of rapid response and quick action, the control of each unit in the two insulation detection modules can be simply and quickly achieved through the circuit breaker.

[0080] Example 3

[0081] The FDS first insulation detection module 2 and the FDS second insulation detection module 3 also include a protection circuit, which is composed of an overvoltage protection unit and a short-circuit protection unit, and is used to prevent the signal generator 21, the data acquisition and processing unit 24, and the communication interface 25 from being damaged by overvoltage and short circuit, thereby improving the safety of the entire system when performing insulation performance testing.

[0082] Specifically, the overvoltage protection unit includes a transient voltage suppression diode, a metal oxide varistor and a gas discharge tube, wherein the power input end of the transient voltage suppression diode is electrically connected to the external power supply 5 or the primary side power supply 6, and the power output end of the transient voltage suppression diode is electrically connected to the signal generator 21; the diode is a special silicon PN junction diode, which is designed to respond quickly and conduct under instantaneous high voltage conditions, and discharge the excess voltage to the ground line, and has the characteristics of fast response speed in nanoseconds, low capacitance and bidirectional protection;

[0083] The metal oxide varistor is installed at the signal input end of the data acquisition and processing unit 24. The varistor is a nonlinear resistor that exhibits high impedance under normal operating conditions. When the voltage exceeds its threshold, its impedance drops rapidly, allowing a large current to pass through to absorb energy. It can withstand a large pulse current and is suitable for handling large energy events such as lightning surges.

[0084] The gas discharge tube is installed at the signal input end of the communication interface 25. The discharge tube consists of two or more electrodes and is encapsulated in a sealed container filled with inert gas. When the voltage between the two ends reaches a certain level, the gas is ionized to form a conductive path, which can handle very high peak currents, but the response time is relatively slow.

[0085] The short-circuit protection unit includes a current limiter and a fast-blow fuse, wherein the current limiter is installed at the signal input end of the data acquisition and processing unit 24, and the current limiter includes components such as a thermistor and a magnetic latching relay, which can automatically reduce the output current or completely shut down the power supply when an abnormally large current is detected, which can effectively limit the short-circuit current and prevent the device from being damaged due to overheating;

[0086] The power input end of the fast-blow fuse is electrically connected to the external power supply 5 or the primary power supply 6, and the power output end of the fast-blow fuse is electrically connected to the signal generator 21. The fuse has the characteristics of fast response speed and can quickly cut off the current when a short circuit occurs to protect downstream components from damage.

[0087] Example 4

[0088] Combined with this insulation status detection system, the following steps are used for detection:

[0089] Step 1, the central control module 1 enables the FDS first insulation detection module 2, locks the FDS second insulation detection module 3, and the FDS first insulation detection module 2 uses an external power supply 5 to perform the first FDS test on the cable to be tested 7 at the installation site to obtain a test result set A, as shown in the following formula:

[0090] A=[a1,a2,…,a n ];

[0091] In the formula, a n represents the test result of the first insulation detection module 2 of the nth cable 7 to be tested. According to the test result of FDS, if a n =0, indicating that the insulation state is abnormal. If a n =1, it indicates that the insulation condition is good; n indicates the number of cables 7 to be tested that are actually installed.

[0092] Step 2, the central control module 1 locks the FDS first insulation detection module 2, enables the FDS second insulation detection module 3, and the FDS second insulation detection module 3 connects the electrical system primary power supply 6 and the cable to be tested 7 through the built-in circuit breaker, and the generated high-frequency closing overvoltage is used as the FDS power supply, thereby performing the second FDS test and obtaining the test result set B, as shown in the following formula:

[0093] B=[b1,b2,…,b n ];

[0094] Where b n Indicates the test result of the second insulation detection module 3 of the nth cable 7 to be tested. If b n =0, indicating that the insulation state is abnormal. If b n =1, it indicates that the insulation condition is good; n indicates the number of cables 7 to be tested that are actually installed.

[0095] Step 3, the FDS first insulation detection module 2 and the FDS second insulation detection module 3 output the test result sets A and B to the insulation state comprehensive judgment module 4 respectively.

[0096] Step 4, the insulation status comprehensive judgment module 4 adds the test result set A and the test result set B to obtain a comprehensive judgment result set C, as shown in the following formula:

[0097] C=A+B=[c1,c2,···,c n ];

[0098] In the formula, c n The comprehensive judgment result of the nth cable 7 to be tested is shown in Table 1.

[0099] Table 1 Correspondence table of comprehensive judgment results

[0100]

[0101] Step 5: The insulation status comprehensive judgment module will generate the comprehensive judgment result c n Feedback to the central control module, the central control module according to c n The corresponding action is performed on the nth cable according to the numerical value, as shown in Table 2.

[0102] Table 2 Central control module actions based on cn values

[0103]

[0104]

[0105] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A distribution cable insulation status detection system, characterized in that: It comprises a central control module (1), an FDS first insulation detection module (2), an FDS second insulation detection module (3) and an insulation state comprehensive judgment module (4); The central control module (1) is used to control the start and stop of the FDS first insulation detection module (2) or the FDS second insulation detection module (3), and is used to receive the output result of the insulation state comprehensive judgment module (4); The FDS first insulation detection module (2) is used to receive the voltage of the external power supply (5) and perform insulation detection on the cable to be tested (7); The FDS second insulation detection module (3) is used to receive the voltage of the primary side power supply (6) and perform insulation detection on the cable to be tested (7); The insulation state comprehensive judgment module (4) is used to receive the insulation detection results of the FDS first insulation detection module (2) and the FDS second insulation detection module (3), analyze the insulation state of the cable to be tested (7), and output the corresponding insulation state to the central control module (1).

2. The distribution cable insulation status detection system according to claim 1, characterized in that: The output voltage of the external power supply (5) is 200V, and the output frequency is 1mHz-1kHz.

3. The distribution cable insulation status detection system according to claim 1, characterized in that: The FDS first insulation detection module (2) and the FDS second insulation detection module (3) both comprise a signal generator (21), a current sensor (22), a voltage sensor (23), a data acquisition and processing unit (24), a communication interface (25) and a control logic unit (26); the signal generator (21) is used to generate a test signal within a specific frequency range according to an external power supply (5) or a primary power supply (6), and apply the test signal to the cable to be tested (7); The current sensor (22) and the voltage sensor (23) are used to monitor the current and voltage changes of the cable (7) to be tested when a test signal is applied to the cable (7) to be tested; The data acquisition and processing unit (24) is used to receive data from the current sensor (22) and the voltage sensor (23), and to calculate the data to obtain a test result set; The communication interface (25) is used to output the parameters acquired by the data acquisition and processing unit (24) to the insulation state comprehensive judgment module (4); The control logic unit (26) is used to receive control instructions from the central control module (1), and control the signal generator (21), the current sensor (22), the voltage sensor (23), the data acquisition and processing unit (24) and the communication interface (25) to perform corresponding operations.

4. The distribution cable insulation status detection system according to claim 3, characterized in that: The FDS first insulation detection module (2) and the FDS second insulation detection module (3) further include a protection circuit, which is composed of an overvoltage protection unit and a short circuit protection unit, and is used to prevent the signal generator (21), the data acquisition and processing unit (24), and the communication interface (25) from being damaged by overvoltage and short circuit.

5. The distribution cable insulation status detection system according to claim 4, characterized in that: The overvoltage protection unit comprises a transient voltage suppression diode, a metal oxide varistor and a gas discharge tube, wherein the power input end of the transient voltage suppression diode is electrically connected to an external power supply (5) or a primary power supply (6), and the power output end of the transient voltage suppression diode is electrically connected to a signal generator (21); The metal oxide varistor is installed at the signal input end of the data acquisition and processing unit (24); The gas discharge tube is installed at the signal input end of the communication interface (25).

6. The distribution cable insulation status detection system according to claim 4, characterized in that: The short-circuit protection unit comprises a current limiter and a fast-blow fuse, wherein the current limiter is installed at the signal input end of the data acquisition and processing unit (24); The power input end of the fast-blow fuse is electrically connected to an external power source (5) or a primary power source (6), and the power output end of the fast-blow fuse is electrically connected to a signal generator (21).

7. The distribution cable insulation status detection system according to claim 5, characterized in that: The control logic unit (26) is set as a circuit breaker, the control input end of the circuit breaker is electrically connected to the central control module (1), and the control output end of the circuit breaker is electrically connected to the signal generator (21), the current sensor (22), the voltage sensor (23), the data acquisition and processing unit (24) and the communication interface (25).

8. The distribution cable insulation status detection system according to claim 1, characterized in that: The test result set of the FDS first insulation detection module (2) is: A = [a1, a2, ..., a n ] Among them, a n represents the test result of the first insulation detection module (2) of the nth cable (7) to be tested. According to the test result of FDS, if a n =0, indicating that the insulation state is abnormal. If a n =1, it indicates that the insulation condition is good; n indicates the number of cables (7) actually installed to be tested.

9. The distribution cable insulation status detection system according to claim 8, characterized in that: The test result set of the FDS second insulation detection module (3) is: B = [b1, b2, ..., b n ] Among them, b n represents the test result of the second insulation detection module (3) of the nth cable (7) to be tested. According to the test result of FDS, if b n =0, indicating that the insulation state is abnormal. If b n =1, it indicates that the insulation condition is good; n indicates the number of cables (7) actually installed to be tested.

10. The distribution cable insulation status detection system according to claim 9, characterized in that: The insulation state comprehensive judgment module (4) analyzes the insulation state of the cable as follows: C=A+B=[c1,c2,···,c n ]; Among them, c n represents the insulation status judgment result of the nth tested cable (7). If c n = 0, indicating that the cable under test (7) is close to a fault. If c n =1, indicating that the insulation performance of the tested cable (7) has a certain risk of failure. n =2, indicating that the insulation performance of the tested cable (7) is faulty.

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