Impact-resistant series resonance system for fault detection and searching and working method of impact-resistant series resonance system

Abstract

The invention discloses an impact-resistant series resonance system for fault detection and a working method thereof, and belongs to the technical field of power cable fault detection.The system comprises a power supply module, a variable-frequency power source, a tuning boosting module and a measurement control system, the aluminum electrolytic capacitor bank provides direct current for the variable-frequency power supply after the external power is cut off; the variable-frequency power supply inverts direct current into alternating current and outputs original alternating current voltage; the tuning boost module comprises a test transformer and a reactor. The test transformer performs first boosting on the original alternating current voltage to generate excitation voltage; the reactor and the cable to be detected form a series resonance circuit, and resonance voltage is generated on the cable to be detected; the measurement control system monitors the voltage signal of the voltage divider in real time and controls the output of the variable frequency power supply so as to realize fault positioning. According to the invention, the impact of fault breakdown instant pulse current on the system can be improved, the stability and convenience of the system are high, and the applicability is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of power cable fault detection, and particularly relates to an impact-resistant series resonance system for fault location and its working method. Background Art

[0002] As an important power transmission device, the safe and reliable operation of power cables is related to the safety of the power system. During the actual operation of cables, due to reasons such as external force damage and insulation deterioration, different types of faults may occur, such as high-resistance, low-resistance, and short-circuit faults. For high-resistance faults, the currently commonly used fault location method is to apply a high voltage to the cable to be measured, causing the fault point to discharge, collect the discharge pulse signal, and locate the fault point according to the propagation law of the discharge pulse signal in the cable.

[0003] However, the currently commonly used fault location method has the following defects: First, when using the above method to locate high-resistance cable faults, an extremely high pulse current will be generated at the moment of fault breakdown, requiring the power supply to provide a huge instantaneous pulse power at the moment of fault breakdown. This instantaneous pulse power far exceeds the power that can be provided by commonly used 220V or 380V mains electricity, resulting in the tripping of the power supply, the failure of fault location, and even serious power supply faults. Second, when measuring and locating faults in cables of different lengths and different voltage levels, different power supply capacities are required. If a large-capacity capacitor is used, it will result in a huge volume and mass, which is not conducive to the convenience of the equipment. If a small-capacity capacitor is used, the applicable range is small, and it is difficult to meet the requirements of long-distance cable fault location. Third, different from equipment such as transformers and switches, cable lines vary greatly in length according to factors such as the line route, ranging from hundreds of meters to dozens of kilometers. This means that if a large-capacity reactor is used, although it can cover cables of different lengths, its volume and mass will be extremely large, seriously affecting the convenience of transportation and being not conducive to the rapid development of cable fault location. Therefore, in summary, in the current cable fault location methods, the instantaneous pulse power impact may cause the power supply to trip, the voltage distribution in the reactor is uneven, and the applicability to cables with variable lengths is not high. Summary of the Invention

[0004] The invention provides an impact-resistant series resonance system for fault location and its working method, aiming to solve the problems in the current cable fault location methods, such as the instantaneous pulse power impact may cause the power supply to trip, the voltage distribution in the reactor is uneven, and the applicability to cables with variable lengths is not high.

[0005] To achieve the above object, the invention adopts the following technical solutions: The invention provides an impact-resistant series resonance system for fault location, including a power supply module, a frequency conversion power supply, a tuning and boosting module, and a measurement and control system, wherein: The power supply module includes an aluminum electrolytic capacitor bank, which is used to provide direct current for the variable-frequency power supply after disconnecting the external power supply; The variable-frequency power supply is used to invert direct current into alternating current and output the original alternating voltage; The tuning and boosting module is connected to the variable-frequency power supply and the cable under test. The tuning and boosting module includes a test transformer and a reactor; the test transformer is used to boost the original alternating voltage for the first time to generate an excitation voltage; the reactor and the cable under test form a series resonance circuit and generate a resonance voltage on the cable under test; The measurement and control system includes a voltage divider and measurement control software. The cable under test includes a conductor end and a metal shield end of the cable under test. The high-voltage side of the voltage divider is connected to the conductor end of the cable under test and the high-voltage end of the reactor, and the grounding side is connected to the metal shield end of the cable under test and the grounding end of the test transformer; The measurement and control system is used to monitor the voltage signal of the voltage divider in real time, and control the output frequency and amplitude of the variable-frequency power supply through the measurement control software to increase the excitation voltage until the fault point of the cable under test breaks down and generates a discharge signal, thereby realizing fault location.

[0006] In some embodiments, the aluminum electrolytic capacitor bank includes a number of parallel aluminum electrolytic capacitors. The rated working voltage of each aluminum electrolytic capacitor is 350 - 500 Vdc, and the capacitance is 1500 - 22000 μF.

[0007] In some embodiments, the frequency range of the output voltage of the variable-frequency power supply is 20 - 300 Hz.

[0008] In some embodiments, the variable-frequency power supply is integrated with a protection system module, which is used to cut off the variable-frequency power supply after the fault point of the cable under test breaks down.

[0009] In some embodiments, the reactor is used to adjust the inductance value and withstand voltage value to adapt to different voltage levels and the specifications of the cable under test; among them, the reactor includes: A single reactor module, a reactor group formed by two series-connected reactor modules, multiple parallel reactor modules, or multiple parallel reactor groups.

[0010] Further, the output voltage of each reactor module does not exceed 50 kV, and each reactor module can support the fault detection of a cable under test with a capacitance of less than 1 μF.

[0011] Further, each reactor module is composed of multiple stages of coils connected in series.

[0012] Further, by adjusting the spacing and inductance value between the stages of coils inside the reactor module, the ratio of the voltage borne by each stage of coil to the inductance value is made consistent to uniformize the internal electric field of the reactor module.

[0013] In some embodiments, when the cable under test is connected, the measurement control software gradually increases the excitation voltage by using the step-up voltage method when controlling the variable-frequency power supply.

[0014] The present invention also provides a working method for an impact-resistant series resonance system for fault location, including the following steps: S1. After the power supply module is connected to an external power supply to charge the aluminum electrolytic capacitor bank to the rated voltage, the external power supply is disconnected, and the aluminum electrolytic capacitor bank provides direct current for the variable-frequency power supply; S2. The variable-frequency power supply converts the direct current into alternating current and outputs the original alternating voltage; S3. The test transformer boosts the original alternating voltage for the first time to generate the excitation voltage; the reactor and the cable under test form a series resonance circuit, and a resonance voltage is generated on the cable under test; S4. The measurement and control system monitors the voltage signal of the voltage divider in real time, and controls the output frequency and amplitude of the variable-frequency power supply through the measurement control software to increase the excitation voltage until the fault point of the cable under test breaks down and generates a discharge signal, thereby realizing fault location.

[0015] Compared with the prior art, an impact-resistant series resonance system for fault location and its working method of the present invention have the following beneficial effects: The impact-resistant series resonance system for fault location of the present invention uses an aluminum electrolytic capacitor bank to replace the commercial power used in the current series resonance system, improves the impact of the pulse current on the power supply at the moment of fault breakdown during cable fault location, and provides instant high-power support for the entire loop system. At the same time, it provides a stable and low-harmonic component high-quality power supply for the loop system. The present invention provides an impact-resistant, highly stable, wide application range, and highly convenient impact-resistant series resonance system for power cable fault location, providing technical support for the rapid and convenient location of cable faults.

[0016] On the other hand, in view of the fact that the current variable-frequency power supply uses AC power supply, the present invention adopts a variable-frequency power supply with DC power supply on the basis of the power supply of the aluminum electrolytic capacitor bank. At the same time, in view of the problem that the lengths of the cables under test are different and the transportation of large-capacity reactors is inconvenient, the present invention modularly designs the reactor based on the modular idea, splits the giant reactor into multiple reactor modules, significantly improves the portability of the equipment, and adjusts the overall inductance value and withstand voltage value of the reactor by connecting in series and / or in parallel multiple reactor modules, so as to meet the test requirements of cables under test with different voltage levels, various lengths, and specifications, and improve the overall practicability of the system. Moreover, the present invention also addresses the problem of voltage distribution inside the reactor. By adjusting the spacing and inductance value between the coils at all levels inside the reactor module, the ratio of the voltage borne by each coil to the inductance value tends to be consistent, making the electric field inside the reactor uniform, and further improving the convenience and accuracy of cable fault location. Brief Description of the Drawings

[0017] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0018] Figure 1 It is a schematic diagram of the architecture of an impact-resistant series resonance system for fault location according to the present invention; Figure 2 It is a schematic diagram of the voltage distribution before and after the optimization of the reactor parameters in an impact-resistant series resonance system for fault location according to the present invention.

[0019] Reference numerals: 1. Aluminum electrolytic capacitor bank; 2. Frequency conversion power supply; 3. Test transformer; 4. Reactor; 5. Divider; 6. Measurement and control system; 7. Conductor end of the cable to be tested; 8. Metal shielding end of the cable to be tested; 9. Power supply module; 10. Tuning and boosting module. Detailed Embodiments

[0020] In order to make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated in the accompanying drawings herein can be arranged and designed in various different configurations.

[0021] 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 claimed present invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0022] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0023] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0024] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0025] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they 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 directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] How to provide a power supply guarantee with shock resistance, high stability, wide application range, and high convenience for the rapid and convenient detection of cable faults, thereby improving the efficiency and accuracy of the detection of the cable to be tested, is an urgent problem to be solved in the current cable fault detection.

[0027] Based on this, as Figure 1 shown, the present invention provides an impact-resistant series resonance system for fault detection, including a power supply module 9, a variable frequency power supply 2, a tuning and boosting module 10, and a measurement and control system 6, wherein: The power supply module 9 includes an aluminum electrolytic capacitor bank 1, and the aluminum electrolytic capacitor bank 1 is used to provide direct current for the variable frequency power supply 2 after disconnecting the external power supply; The variable frequency power supply 2 is used to invert direct current into alternating current and output the original alternating voltage; The tuning and boosting module 10 is connected to the variable frequency power supply 2 and the cable to be tested. The tuning and boosting module 10 includes a test transformer 3 and a reactor 4; the test transformer 3 is used to perform the first voltage boost on the original alternating voltage to generate an excitation voltage; the reactor 4 and the cable to be tested form a series resonance circuit and generate a resonance voltage on the cable to be tested; The measurement and control system 6 includes a voltage divider 5 and measurement and control software. The cable under test includes a conductor end 7 of the cable under test and a metal shield end 8 of the cable under test. The high-voltage side of the voltage divider 5 is connected to the conductor end 7 of the cable under test and the high-voltage end of the reactor 4, and the grounding side is connected to the metal shield end 8 of the cable under test and the grounding end of the test transformer; The measurement and control system is used to monitor the voltage signal of the voltage divider in real time, and control the output frequency and amplitude of the variable-frequency power supply through the measurement and control software to increase the excitation voltage until the fault point of the cable under test breaks down and generates a discharge signal, thereby realizing fault location.

[0028] As Figure 1 shown, the anti-shock series resonance system of the present invention mainly provides power for the detection of high-resistance faults in cables when the mains power is not connected, and solves problems such as instantaneous pulse power shock, uneven voltage distribution inside the reactor 4, and strong applicability required due to the variable length of the cable under test during the fault detection process. Compared with the existing series resonance boosting technology, the present invention utilizes the characteristics of the aluminum electrolytic capacitor bank 1 with a large specific power (about 600 W / kg), a high rated working voltage (350 - 500 Vdc), and a wide tolerance range (1500 - 22000 ) to design a power supply module 9 with high stability power supply, low harmonic components, strong instantaneous output, and modular design. The 220V (380V) mains power is rectified and first charges the aluminum electrolytic capacitor bank 1. After the aluminum electrolytic capacitor bank 1 is fully charged, S1 is disconnected, and the aluminum electrolytic capacitor bank 1 provides power guarantee for the entire loop system. At the moment when the cable under test breaks down, the required instantaneous large pulse power is provided by the aluminum electrolytic capacitor bank 1, which solves the problem of power supply tripping and even faults caused by instantaneous pulse power, and at the same time provides a stable and high-quality power supply with low harmonic components for the loop system.

[0029] In some embodiments, when the present invention conducts fault detection on cables under test with different voltage levels and different lengths, different power supply capacities are required. The aluminum electrolytic capacitor bank 1 adopts a modular design, and achieves the purpose of high convenience and wide applicability through parallel connection according to the voltage level and length of the cable under test.

[0030] Furthermore, the reactor 4 of the present invention is used to adjust the inductance value and withstand voltage value to adapt to different voltage levels and the specifications of the cable under test; the reactor 4 includes: a single reactor module, a reactor group formed by connecting two reactor modules in series, multiple parallel reactor modules, or multiple parallel reactor groups. In view of the different lengths and voltage levels of the cable under test, and comprehensively considering factors such as the quality of the reactor 4 and the capacity of the cable under test, the reactor 4 is formed by combining an appropriate number and connection method of reactor modules, which can make the designed reactor 4 easy to transport, have a wide coverage range, and be able to adapt to the fault detection of cables under test with different lengths. In actual working conditions, as an option, each reactor module can meet the fault detection of different cables below 1 μF (5 km), and the output voltage of each reactor module does not exceed 50 kV.

[0031] In some embodiments, specifically: For the cable under test with a low voltage level, the breakdown voltage of its fault point is relatively low, and the rated voltage of a single reactor module can meet the requirement; for the cable under test with a high voltage level, the breakdown voltage of its fault point is relatively high, and the rated voltage of a single reactor module is difficult to meet. By stacking two reactor modules together and then connecting them in series to form a reactor group, the rated voltage is increased to meet the requirement of fault detection for the cable under test with a high voltage level.

[0032] For the short cable under test, the rated current of a single reactor module or a single reactor group can meet the requirement of fault detection for the short cable under test; For the long cable under test, when the rated current of a single reactor module or a single reactor group is difficult to meet, multiple reactor modules or multiple reactor groups can be connected in parallel to increase the rated current to meet the requirement of fault detection for the long cable under test.

[0033] In some embodiments, the variable-frequency power supply 2 of the present invention has the function of converting the DC input of the aluminum electrolytic capacitor bank 1 into an AC output. The variable-frequency power supply 2 is equipped with a protection system module, which can quickly cut off the variable-frequency power supply 2 after the breakdown of a high-resistance fault point, thereby protecting the system; the frequency range of the output voltage of the variable-frequency power supply 2 is 20 - 300 Hz.

[0034] The present invention is based on the power supply module 9 with the aluminum electrolytic capacitor bank 1 as the core. During the charging stage, the fast-switching switch S1 is closed, and the 220V or 380V mains is rectified and then used to charge the aluminum electrolytic capacitor bank 1; after the charging is completed, the fast-switching switch S1 is disconnected to isolate the mains, and the voltage output of the entire loop system is carried out in a passive state, which is the key to the low system noise; the aluminum electrolytic capacitor bank 1 can work in parallel according to the different lengths of the cable under test to ensure the convenience of its transportation.

[0035] The present invention adjusts the spacing and inductance value between the coils at all levels inside the reactor module, and according to the design objectives that the combined height is less than the maximum height, the inductance value is close to the preset value, the resistance value is close to the preset value, the inter-turn field strength is less than the corona inception field strength, and the temperature rise and loss are lower than the maximum value, it is adjusted so that the inductance values and spacings of the coils at all levels inside the reactor module are not the same, making the ratio of the voltage borne by each level of coil to the inductance value tend to be consistent. The voltage distributions at all levels inside the reactor 4 before and after adjustment are as Figure 2 shown.

[0036] The present invention also provides a working method for an impact-resistant series resonance system for fault location, including the following steps: S1. First, the power supply module 9 is connected to the commercial power AC (Alternating Current) 220V (380V), the fast on-off switch S1 is closed, and the commercial power AC 220V (380V) is rectified to charge the aluminum electrolytic capacitor bank 1; after the aluminum electrolytic capacitor bank 1 is charged to the rated voltage, the fast on-off switch S1 is disconnected to isolate the commercial power, and the aluminum electrolytic capacitor bank 1 provides direct current for the variable frequency power supply 2; S2. The variable frequency power supply 2 converts the direct current into alternating current and outputs the original AC voltage; S3. The test transformer 3 boosts the original AC voltage for the first time to generate an excitation voltage; the reactor 4 and the cable to be tested form a series resonance circuit, and a resonance voltage is generated on the cable to be tested; S4. The measurement and control system 6 monitors the voltage signal of the voltage divider 5 in real time, and controls the output frequency and amplitude of the variable frequency power supply 2 through the measurement control software, and boosts the excitation voltage until the fault point of the cable to be tested breaks down and generates a discharge signal, thereby realizing fault location. The present invention uses an impact-resistant series resonance system for fault location to perform the fault location work on the cable to be tested, so as to improve the convenience and accuracy of fault location, and the impact-resistant series resonance system of the present invention is applicable to cables to be tested with different lengths.

[0037] The following further details an impact-resistant series resonance system for fault location and its working method according to the present invention through specific embodiments.

[0038] Based on the modular aluminum electrolytic capacitor bank 1 of the present invention, a power supply module 9 with high-stability power supply, low harmonic components, and strong instantaneous output is formed to supply power to the variable frequency power supply 2; The variable frequency power supply 2 with a DC power supply as the input is used to convert the DC power supply provided by the aluminum electrolytic capacitor bank 1 into AC power supplies with different amplitudes and different frequencies as required; The test transformer 3 is used to boost the AC voltage with a lower amplitude output by the variable frequency power supply 2 to a higher amplitude variable frequency voltage; A reactor 4 is used to form a series resonance circuit with the cable under test to achieve the purpose of generating a high voltage on the cable under test; A measurement and control system 6 based on a voltage divider 5 and measurement control software is used to measure the voltage on the cable under test and provide data for the measurement and control system 6; The measurement and control system 6 realizes the operation control and measurement of the entire loop.

[0039] The specific circuit connection of the anti-shock type series resonance system for fault location of the present invention is that the commercial power AC220V (380V) is rectified and then connected to the positive and negative poles of the charging end of the aluminum electrolytic capacitor bank 1 respectively. The positive and negative poles of the output end of the aluminum electrolytic capacitor bank 1 are connected to the positive and negative poles of the input end of the frequency conversion power supply 2 respectively. The output end of the frequency conversion power supply 2 is connected to the first end and the last end of the low-voltage winding of the test transformer 3 respectively. The first end of the high-voltage winding of the test transformer 3 is connected to the low-voltage end of the reactor 4. The high-voltage end of the reactor 4 is connected to the conductor end 7 of the cable under test and the high-voltage side of the voltage divider 5. The metal shielding end 8 of the cable under test, the grounding terminal of the voltage divider 5 and the last end of the high-voltage winding of the test transformer 3 are grounded together.

[0040] As Figure 1 shown, the specific working process of the anti-shock type series resonance system of the present invention is as follows: First, close the fast switching switch S1, and the commercial power AC220V (380V) is rectified and charged to the aluminum electrolytic capacitor bank 1; after the aluminum electrolytic capacitor bank 1 is charged to the rated voltage, disconnect the fast switching switch S1, and the aluminum electrolytic capacitor bank 1 supplies power to the frequency conversion power supply 2; the frequency conversion power supply 2 converts the DC voltage provided by the aluminum electrolytic capacitor bank 1 into an AC power supply through an inverter circuit, and then converts it into a voltage with a corresponding frequency and amplitude through the frequency conversion power supply 2 for output; the measurement and control system 6 controls the frequency conversion power supply 2 to output a lower amplitude excitation voltage, and then adjusts the output voltage frequency in the range of 20Hz - 300Hz to search for the loop resonance frequency. The power supply frequency when the voltage divider 5 feeds back the highest voltage value is the loop resonance frequency. At this loop resonance frequency, the measurement and control system 6 controls the frequency conversion power supply 2 to gradually increase the excitation voltage by the step-up method until the fault point of the cable under test breaks down and generates a discharge signal for fault location of the cable under test. To improve the overall convenience of the system, the aluminum electrolytic capacitor bank 1 adopts a modular design, and multiple aluminum electrolytic capacitors are connected in parallel to provide power supply for fault location of cables under test with different lengths and different voltage levels. The rated working voltage of each aluminum electrolytic capacitor is 2500V, and the capacitance is 5mF.

[0041] The reactor 4 of the present invention adopts a modular design. The mass of each reactor module is 30 kg, the inductance value is 10 H, the rated working voltage is 25 kV, and the height is 40 cm. Two reactor modules connected in series can complete the fault detection of a 5-km long 110-kV cable. According to the length and voltage level of the cable to be measured, the fault detection of different cables to be measured can be completed by series-parallel connection, and the maximum output voltage is 50 kV.

[0042] In summary, the anti-shock series resonance system for fault detection of the present invention can improve the problem that when using a series resonance circuit to carry out fault detection of a cable to be measured, the instantaneous power of the circuit is extremely large at the moment of fault breakdown, which impacts the power supply and causes damage to the power supply. The present invention can solve the problem that the voltage distribution on each coil is uneven due to different magnetic fluxes passing through the windings at different heights in the vertical axis of the current reactor. It reduces the excessive potential gradient during the operation of the reactor, makes the voltage distribution tend to be balanced, improves the voltage distribution, reduces the maximum field strength, and achieves the purpose of reducing corona loss, preventing leakage tracking and erosion. Through modular design, the present invention realizes the light weight of the equipment, ensures the convenience during the fault detection of the cable to be measured. At the same time, through the series-parallel connection of each module, it realizes the full coverage of cables to be measured with different voltage levels and different lengths, has a certain applicability, and is suitable for popularization and use.

[0043] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Any person skilled in the art can smoothly implement the present invention according to the description in the specification and the above. Slight changes, modifications and equivalent variations made by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. An impact-resistant series resonance system for fault location, characterized in that, It includes a power supply module (9), a variable-frequency power supply (2), a tuned step-up module (10), and a measurement and control system (6), where: The power supply module (9) includes an aluminum electrolytic capacitor bank (1), and the aluminum electrolytic capacitor bank (1) is used to provide direct current for the variable-frequency power supply (2) after disconnecting the external power supply; The variable-frequency power supply (2) is used to invert direct current into alternating current and output the original alternating voltage; The tuned step-up module (10) is connected to the variable-frequency power supply (2) and the cable under test. The tuned step-up module (10) includes a test transformer (3) and a reactor (4); the test transformer (3) is used to perform the first step-up of the original alternating voltage to generate an excitation voltage; the reactor (4) forms a series resonance circuit with the cable under test and generates a resonance voltage on the cable under test; The measurement and control system (6) includes a voltage divider (5) and measurement and control software. The cable under test includes a conductor end (7) of the cable under test and a metal shield end (8) of the cable under test. The high-voltage side of the voltage divider (5) is connected to the conductor end (7) of the cable under test and the high-voltage end of the reactor (4), and the grounding side is connected to the metal shield end (8) of the cable under test and the grounding end of the test transformer (3); The measurement and control system (6) is used to monitor the voltage signal of the voltage divider (5) in real time, and control the output frequency and amplitude of the variable-frequency power supply (2) through the measurement and control software to increase the excitation voltage until the fault point of the cable under test breaks down and generates a discharge signal, thereby realizing fault location.

2. The anti-shock type series resonance system for fault location according to claim 1, characterized in that, The aluminum electrolytic capacitor bank (1) includes a number of parallel aluminum electrolytic capacitors. The rated working voltage of each aluminum electrolytic capacitor is 350 - 500 Vdc, and the capacitance is 1500 - 22000 μF.

3. The anti-shock type series resonance system for fault location according to claim 1, wherein The frequency range of the output voltage of the variable-frequency power supply (2) is 20 - 300 Hz.

4. The impact-resistant series resonance system for fault location according to claim 1, characterized in that, The variable-frequency power supply (2) is integrated with a protection system module, and the protection system module is used to cut off the variable-frequency power supply (2) after the fault point of the cable under test breaks down.

5. The impact-resistant series resonance system for fault location according to claim 1, characterized in that, The reactor (4) is used to adjust the inductance value and withstand voltage value to adapt to different voltage levels and the specifications of the cable under test; where, the reactor (4) includes: A single reactor module, a reactor bank formed by connecting two reactor modules in series, a number of parallel reactor modules, or a number of parallel reactor banks.

6. The impact-resistant series resonance system for fault location according to claim 5, wherein The output voltage of each reactor module does not exceed 50 kV, and each reactor module can support the fault detection of a cable under test with a capacitance of less than 1 μF.

7. The impact-resistant series resonance system for fault location according to claim 6, characterized in that, The interior of each reactor module is composed of multiple levels of coils connected in series.

8. The impact-resistant series resonance system for fault location according to claim 7, wherein By adjusting the spacing and inductance value between the levels of coils inside the reactor module, the ratio of the voltage borne by each level of coil to the inductance value is made consistent to homogenize the internal electric field of the reactor module.

9. The impact-resistant series resonance system for fault location according to claim 1, characterized in that In the case where the cable under test is connected, when the measurement and control software controls the variable-frequency power supply (2), the excitation voltage is gradually increased using the step-up method.

10. A working method of the impact-resistant series resonance system for fault location according to any one of claims 1-9, characterized in that, It includes the following steps: S1. After the power supply module (9) is connected to the external power supply to charge the aluminum electrolytic capacitor bank (1) to the rated voltage, the external power supply is disconnected, and the aluminum electrolytic capacitor bank (1) provides direct current for the variable-frequency power supply (2); S2. The variable-frequency power supply (2) inverts direct current into alternating current and outputs the original alternating voltage; S3. The test transformer (3) boosts the original AC voltage for the first time to generate an excitation voltage; the reactor (4) forms a series resonance circuit with the cable under test and generates a resonance voltage on the cable under test. S4. The measurement and control system (6) monitors the voltage signal of the voltage divider (5) in real time, and controls the output frequency and amplitude of the variable frequency power supply (2) through measurement control software to increase the excitation voltage until the fault point of the cable under test breaks down and generates a discharge signal, thereby achieving fault location.

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