A multi-loop power distribution cable overlapping state electromagnetic distribution characteristic simulation device and method

Abstract

The application discloses a kind of multi-loop power distribution cable overlapping state electromagnetic distribution characteristic simulation device and method, including power frequency power supply, phase modulation unit, flow unit, high-frequency signal coupling unit, multiple cable sections, multiple cable overlapping units, control unit and electromagnetic signal measurement unit, modular design is adopted, only by changing the position of cable connection plug can simultaneously simulate the overlapping state of multiple different cables, and different current loads and high-frequency signals can be applied simultaneously, the real simulation of cable group in cable channel can be realized.

Description

Technical Field

[0001] This invention belongs to the field of power distribution cable testing technology, specifically relating to an electromagnetic distribution simulation device and method for multi-circuit power distribution cables in overlapping states. Background Technology

[0002] Medium-voltage distribution cables are critical equipment in urban power distribution networks and industrial power transmission networks. However, due to on-site installation issues and harsh laying environments, the insulation of distribution cables may gradually deteriorate during operation, eventually leading to insulation breakdown and accidents. To ensure the safe and reliable operation of cables, workers often use live or de-energized methods to test or inspect the cables. When testing while energized, the detection signal is often affected by electromagnetic interference from the surrounding space (other operating cables in the cable trench); when testing while de-energized, according to safety regulations, it is necessary to first determine whether the cable is energized. This determination often uses high-frequency electromagnetic pulse coupling signals, which are also susceptible to surrounding electromagnetic interference, potentially leading to misjudgments and personal safety accidents.

[0003] However, the environment in cable trenches is very complex, and power distribution cables of different circuits overlap with each other. If the electromagnetic signals in cable trenches in such a complex environment are not simulated and analyzed, and the electromagnetic interference characteristics under the condition of multiple overlapping cables are not understood, it will cause great interference to the on-site detection. Summary of the Invention

[0004] This invention provides a device and method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, which can simultaneously simulate the overlapping states of multiple different cables and realize the realistic simulation of cable groups in cable trenches.

[0005] To achieve the above objectives, the present invention provides a simulation device for electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, comprising a phase modulation unit, a current boosting unit, a high-frequency signal coupling unit, a cable, and an electromagnetic signal measurement unit. The cable comprises n cable segments connected by the cable overlapping units. The input end of the phase modulation unit is used to connect to the power frequency power supply, and the output end is connected to the primary side of the current boosting unit. The secondary side of the current boosting unit is connected to the beginning of the cable through the high-frequency signal coupling unit, and the end of the cable is connected to the secondary side of the current boosting unit. The cable comprises n cable segments and overlapping units connecting the n cable segments, and an electromagnetic signal measurement unit is installed on each cable segment.

[0006] Furthermore, the current boosting unit includes a three-phase through-core transformer, three-phase metal conductor rods, insulating support components, an electromagnetic shielding enclosure, a first end wire core plug, and a second end wire core plug. The three-phase through-core transformer, three-phase metal conductor rods, and insulating support components are all housed within the electromagnetic shielding enclosure.

[0007] Both ends of the metal guide rod are respectively equipped with a first end core plug and a second end core plug for connecting the two ends of the cable. The first end core plug and the second end core plug pass through the side wall of the electromagnetic shielding box. The metal guide rod passes through the first insulating support, the second insulating support and the third insulating support. A through-type transformer is installed on each of the three phase metal guide rods.

[0008] Furthermore, the first insulating support, the second insulating support, and the third insulating support are located at the beginning, middle, and end of the metal guide rod, respectively, and provide support for the metal guide rod.

[0009] Furthermore, the high-frequency signal coupling unit includes a high-frequency signal generating unit, capacitive coupling sensors, and a coaxial metal shield. The coaxial metal shield covers the metal guide rod of the current boosting unit, and capacitive coupling sensors are installed inside the coaxial metal shield. All three phase capacitive coupling sensors are connected to the high-frequency signal generating unit. The three-phase high-frequency signal generating unit is used to generate high-frequency electromagnetic signals that simulate the cable trench environment.

[0010] Furthermore, the cable overlapping unit includes an insulation panel, which has a multi-layer structure. Each layer is provided with a sliding guide rail, and a rotatable disc is installed on the sliding guide rail. The rotatable disc includes a base and a turntable rotatably mounted on the base. Both ends of the rotatable disc have connectors. The rotatable disc can rotate the connector on a plane. The connector includes a three-phase core plug, a metal coaxial shielding structure, and a rubber layer arranged sequentially from the inside to the outside.

[0011] Furthermore, the insulating panel is equipped with a locking mechanism for securing the position of the rotatable disc surface.

[0012] Furthermore, the wire core plug is made of metal, and the turntable is made of insulating material.

[0013] A method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, based on the aforementioned apparatus, includes the following steps:

[0014] S1. Let m be the total number of power distribution cable loops in the simulated cable trench. The first three phases of the cable segment of each loop are stripped and separated, and the three-phase conductors are connected to the high-frequency signal coupling unit. The last three phases of the cable segment n of each loop are stripped and separated, and the three-phase conductors are connected to the secondary side of the current boosting unit.

[0015] S2. Connect each cable segment of each circuit through the cable overlap unit. The positions of the cable segments on both sides of the cable overlap unit are changed according to the test requirements.

[0016] S3. The phase adjustment unit converts the three-phase power frequency voltage with a phase difference of 120° into m sets of three-phase voltages with different initial phases φ, and connects the phase-adjusted voltages to m A, B, and C three-phase through-core transformers in the current boosting unit respectively.

[0017] The high-frequency signal coupling unit generates the required high-frequency signal, and the generated signal is coupled to the cable core through the capacitive coupling sensor 16;

[0018] S4. Each cable segment has a different cable overlap pattern, and each loop cable carries a different amount of current and different types of high-frequency signals. In each cable segment, electromagnetic signal detection devices such as Rogowski coils, capacitive couplers, UHF sensors and / or ground wave sensors are used to measure signals at different locations or locations required by actual needs.

[0019] Furthermore, during cable voltage testing, no current boosting signal was applied to one of the cables. Instead, a pulse signal was applied to that cable circuit using a path meter, while the other circuits experienced normal current boosting. High-order harmonic signals, random noise signals, and / or partial discharge signals were coupled into the other circuits. The overlap of the cable segments was changed using overlapping units, and the characteristics of the applied signals in other phases were used. High-frequency CT was used to detect the signal characteristics of the circuits without applied current boosting signals.

[0020] Furthermore, during partial discharge interference testing, the overlapping state of different cables is changed using an overlapping unit, different discharge signal types are set, and different noise interference is set through a high-frequency signal coupling unit. Then, an ultra-high frequency sensor is used to measure the partial discharge signal.

[0021] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0022] The simulation device of this invention includes a current boosting unit, a high-frequency signal coupling unit, cable segments, cable overlap units, and an electromagnetic signal measurement unit. The current boosting unit provides different current loads to different cable simulation circuits. The high-frequency signal coupling unit generates high-frequency electromagnetic signals that may occur in the cable trench. The cable segments and cable overlap units simulate the cable overlap state. The modular design allows for the simulation of multiple different cable overlap states simply by changing the position of the cable connectors. It can also simultaneously apply different current loads and high-frequency signals, making it relatively easy to achieve a realistic simulation of cable groups in cable trenches.

[0023] Furthermore, the overlapping unit of the present invention includes an insulating panel, which has a multi-layer structure. Each layer is provided with a rotatable disk that can slide horizontally and rotate. Different cable overlapping forms can be conveniently and quickly simulated by sliding and rotating the rotatable disk. It is easy to operate and highly practical.

[0024] Furthermore, an electromagnetic shielding enclosure is installed outside the current boosting unit and the high-frequency signal coupling unit. The electromagnetic shielding enclosure can shield the signal of the electromagnetic coupling unit inside the enclosure, so that the electromagnetic signal is coupled into the cable only through the electromagnetic coupling unit, avoiding interference at the measurement unit caused by electromagnetic signals propagating through space to each cable segment.

[0025] Furthermore, the rotatable disc of the present invention is similar to the cable body structure, which can basically restore the cable body structure. This makes the impact of adding overlapping units, high-frequency signal coupling units, current boosting units and other structures on the distribution of electromagnetic signals in the cable less, and the obtained measurement data more accurate. Attached Figure Description

[0026] Figure 1 A schematic diagram of the electromagnetic distribution characteristics simulation device for the overlapping state of multi-circuit power distribution cables provided by the present invention;

[0027] Figure 2 This is a schematic diagram showing the connection method between the phase adjustment unit, the current boosting unit, and the cable.

[0028] Figure 3 A schematic diagram of the current boosting unit and high-frequency signal coupling unit;

[0029] Figure 4 This is the front view of the cable overlap unit;

[0030] Figure 5 Left view of the cable overlap unit;

[0031] In the attached diagram: 1. Cable body; 21. First core plug; 22. Second core plug; 3. Metal guide rod; 41. First insulating support; 42. Second insulating support; 43. Third insulating support; 5. Electromagnetic shielding box; 6. Coaxial metal shield; 7. Base; 8. Turntable; 9. Sliding guide rail; 10. Locking device; 11. Three-phase conductor; 12. Core plug; 13. Rubber layer; 14. Insulating panel; 15. Coaxial metal shielding structure; 16. Capacitive coupling sensor. Detailed Implementation

[0032] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0033] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0034] This invention discloses a device for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables. A schematic diagram of the device is shown below. Figure 1 As shown, it mainly consists of a power frequency power supply, a phase modulation unit, a current boosting unit, a high-frequency signal coupling unit, cables, a control unit, and an electromagnetic signal measurement unit. The cable includes n cable segments connected by cable overlap units.

[0035] The power frequency power supply is connected to the input terminal of the phase modulation unit. The output terminal of the phase modulation unit is connected to the primary side of the current boosting unit. The secondary side of the current boosting unit is connected to the cable start end via a high-frequency signal coupling unit. The cable end is connected to the secondary side of the current boosting unit. The cable consists of n cable segments and overlapping units connecting the n cable segments. An electromagnetic signal measurement unit is installed on each cable segment. Both the current boosting unit and the high-frequency signal coupling unit are connected to the control unit. The power frequency power supply is a three-phase voltage regulator, whose function is to generate a three-phase voltage with a fixed phase difference of 120°.

[0036] The function of the phase adjustment unit is to adjust the initial phase of the three-phase voltage acting on the current boosting unit in each group, so that the initial phase of the cable in each circuit is different.

[0037] The current boosting unit consists of 3×m through-core transformers with different turns ratios. The primary winding of each through-core transformer has N turns, and the secondary winding consists of cable conductors passing through the transformer core. It has the function of boosting current for m three-phase circuits. In the current boosting unit, the through-core transformers for boosting the three phases of the same cable have the same number of turns, while the through-core transformers for boosting the three phases of different cables have different numbers of turns. This simulates the situation where the load on the same cable in a distribution cable is basically balanced, while the loads on surrounding cables are different.

[0038] The cable segment consists of n cable segments connected end to end, and each phase of each circuit cable is connected end to end.

[0039] The connection method between the phase adjustment unit, the current boosting unit and the cable is as follows: Figure 2 The power frequency power supply generates three-phase voltage (each with a phase difference of 120°), which is then processed by a phase adjustment unit to generate three-phase voltages with initial phases of φ1, φ2...φm. Each phase of the three-phase voltage acts on a through-core transformer, and the conductor of each phase of the cable passes through the core of the through-core transformer.

[0040] like Figure 3 As shown, the current boosting unit mainly consists of a through-hole transformer T m1 Through-core transformer T m2 Through-core transformer T m2 The system consists of a three-phase metal conductor rod 3, insulating support components, an electromagnetic shielding enclosure 5, three-phase first-end conductor plugs 21, and three-phase second-end conductor plugs 22. The through-type transformer, metal conductor rod 3, and insulating support components are all housed within the electromagnetic shielding enclosure 5. The cable body 1 is stripped into three separate conductors outside the electromagnetic shielding enclosure 5 and connected to the conductor plugs 12 on the enclosure 5. The metal conductor rod 3 is directly connected to both ends of the cable.

[0041] The metal guide rod 3 has a first end core plug 21 and a second end core plug 22 at both ends. The first end core plug 21 and the second end core plug 22 pass through the left and right side walls of the electromagnetic shielding box 5 and are connected to the cable body 1. The metal guide rod 3 passes through the first insulating support 41, the second insulating support 42 and the third insulating support 43. The first insulating support 41, the second insulating support 42 and the third insulating support 43 are located at the beginning, middle and end of the metal guide rod 3, respectively. The insulating support provides support for the metal guide rod 3. A through-core transformer is installed on the three-phase metal guide rod 3 at the position between the first insulating support 41 and the second insulating support 42.

[0042] The high-frequency signal coupling unit mainly consists of a high-frequency signal generating unit, capacitive coupling sensors 16, and a coaxial metal shield 6. In the high-frequency signal coupling unit, the coaxial metal shield 6 is shielded by a layer of insulating material with the same thickness as the cable insulation, and a metal guide rod 3 is coaxially wrapped around this portion. Capacitive coupling sensors 16 are installed in the middle of the coaxial metal shield 6, and all three phases of the capacitive coupling sensors 16 are connected to the high-frequency signal generating unit. The three-phase high-frequency signal generating unit can generate high-frequency electromagnetic signals that may occur in the cable trench, such as partial discharge and higher harmonics.

[0043] The phase modulation unit and the high-frequency signal coupling unit are controlled by a control unit. The control unit can control the phase deviation value generated by the phase modulation unit, control the on / off state of the high-frequency signal, and select the type of high-frequency signal generated.

[0044] The cable segment consists of m cycles of three-phase cables.

[0045] The electromagnetic signal measurement unit, according to the measurement requirements of the cable segment, installs different types and quantities of sensors at different locations, including but not limited to Rogowski coils, capacitive couplers, and ultra-high frequency sensors.

[0046] Reference Figure 4 and Figure 5 The cable overlapping unit consists of an insulating panel 14, a sliding guide rail 9 and a locking lock 10, a rotatable disc surface and a locking lock 10, a three-phase core plug 12, a metal coaxial shielding structure 15, and a rubber layer 13 coaxial covering structure.

[0047] The insulating panel 14 has a multi-layer structure, with each layer consisting of a sliding guide rail 9 and a rotatable disc surface slidably mounted on the sliding guide rail 9. In the embodiment, the number of layers generally does not exceed 5, and the number of rotatable disc surfaces in each layer generally does not exceed 3. The rotatable disc surface can move freely within the layer via the sliding guide rail 9 and can be fixed at a designated position by a locking lock 10, which can be implemented using screws and screw holes. The rotatable disc surface includes a base 7 and a turntable 8 rotatably mounted on the base 7. The turntable 8 is provided with three metal wire core plugs 12 and is made of insulating material.

[0048] The rotatable disc has cylindrical connectors at both ends. The rotatable disc allows the cylindrical connectors to rotate at a certain angle on a plane and can be fixed at that angle by a locking lock 10, which can be implemented using screws and screw holes. The cylindrical connectors mainly consist of three-phase core plugs 12, a metal coaxial shielding structure 15, and a rubber layer 13 coaxial covering structure. The core plugs 12 at both ends of the insulating panel 14 are conductive, and the metal shielding is also conductive. Different cable segments of the same cable are connected to the cylindrical connectors at both ends of the insulating panel 14. The three-phase conductors 11 at the cable's front end are stripped into independent three phases, while retaining their copper shielding layer, and are connected to the three-phase core plugs 12 respectively. The cable body 1 is covered by the rubber layer 13 for a certain distance, connecting the metal coaxial shielding to the steel armor in the cable body 1. Each core plug 12 has a coaxial metal shielding structure 6.

[0049] This invention discloses a method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, comprising the following steps:

[0050] S1. The total number of power distribution cable circuits in the simulated cable trench is m. The first three phases of the cable segment 1 of each circuit are stripped and separated, and the three-phase conductor 11 is connected to the second end core plug 22. The last three phases of the cable segment n of each circuit are stripped and separated, and the three-phase conductor 11 is connected to the first end core plug 21.

[0051] S2. Connect each cable segment of each circuit through the cylindrical connectors on the cable overlap unit. The positions of the cable segments on both sides of the cable overlap unit can be changed according to the test requirements. Different cylindrical connectors can be inserted on the other side, or the positions of each connector can be slid on the guide rail to change their horizontal position. The local cable twisting state can also be changed through the rotatable disc surface.

[0052] S3. Use power frequency power to generate a three-phase power frequency voltage with a phase difference of 120°.

[0053] The control unit controls the phase adjustment unit to convert the three-phase power frequency voltage with a phase difference of 120° into m sets of three-phase voltages with different initial phases φ. The phase-adjusted voltages are then connected to m A, B, and C three-phase through-core transformers in the current boosting unit.

[0054] The control unit controls the high-frequency signal coupling unit to generate the required high-frequency signal, such as partial discharge signal, higher harmonics, random interference signal, etc. The generated signal is coupled to the cable core through capacitive coupling sensor 16.

[0055] S4. Each cable segment has different cable overlap patterns, and each loop cable carries different currents and different types of high-frequency signals. Within each cable segment, electromagnetic signal detection devices such as Rogowski coils, capacitive couplers, UHF sensors, and / or ground wave sensors are used to measure signals at different locations or locations required by actual needs.

[0056] The device of the present invention has a wide range of applications, as exemplified below:

[0057] Application Scenario 1: Used for research on cable voltage testing technology

[0058] The detection of voltage in power distribution cables has always been a pressing issue in the field. Currently, the common method is to use a cable path meter on the substation side to couple a high-frequency pulse signal onto a non-energized cable, and then measure this signal on-site using a high-frequency CT to determine if the cable is energized. However, cable trenches in the field contain numerous operating cables with significant electromagnetic interference signals. Therefore, extensive simulations of the complex conditions in cable trenches are needed in the laboratory to reduce misjudgments in field applications.

[0059] This invention simulates a scenario where no current-boosting signal is applied to one of the cable circuits; instead, a pulse signal is applied to that circuit using a path meter. Meanwhile, other circuits receive normal current boosting, and high-order harmonic signals, random noise signals, and partial discharge signals are coupled into these circuits. By continuously changing the overlap of cable segments and the characteristics of the applied signals to other phases, a high-frequency CT is used to detect the signal characteristics of the de-energized circuit (the circuit without a current-boosting signal).

[0060] Application Scenario 2: Partial Discharge Interference Test

[0061] During on-site partial discharge detection of power distribution cables, noise interference is the biggest factor affecting the sensitivity of partial discharge detection and the accuracy of defect location. Since partial discharge is a high-frequency electromagnetic signal, it exhibits multi-conductor coupling characteristics in overlapping cables, thus requiring extensive testing to obtain the true characteristics of partial discharge in cable trenches. The device of this invention allows for easy modification of the overlapping state of different cables, setting different discharge signal types, and incorporating different noise interference through a high-frequency signal coupling unit. Then, an ultra-high frequency sensor is used to measure the partial discharge signal.

[0062] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A device for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, characterized in that, It includes a phase modulation unit, a current boosting unit, a high-frequency signal coupling unit, a cable, and an electromagnetic signal measurement unit. The cable includes n cable segments connected by cable overlapping units. The input end of the phase modulation unit is used to connect to the power frequency power supply, and the output end is connected to the primary side of the current boosting unit. The secondary side of the current boosting unit is connected to the beginning of the cable through a high-frequency signal coupling unit, and the end of the cable is connected to the secondary side of the current boosting unit. The cable includes n cable segments and a cable overlapping unit connecting the n cable segments. An electromagnetic signal measurement unit is installed on each cable segment. The cable overlapping unit includes an insulating panel (14), which has a multi-layer structure. Each layer is provided with a sliding guide rail (9). A rotatable disc is installed on the sliding guide rail (9). The rotatable disc includes a base (7) and a turntable (8) rotatably mounted on the base (7). Both ends of the rotatable disc have connectors. The rotatable disc can rotate the connector on a plane. The connector includes a three-phase core plug (12), a metal coaxial shielding structure (15), and a rubber layer (13) arranged sequentially from the inside to the outside.

2. The electromagnetic distribution characteristic simulation device for the overlapping state of multi-circuit power distribution cables according to claim 1, characterized in that, The current boosting unit includes a three-phase through-core transformer, a three-phase metal guide rod (3), an insulating support, an electromagnetic shielding box (5), a first end wire core plug (21), and a second end wire core plug (22). The three-phase through-core transformer, the three-phase metal guide rod (3), and the insulating support are all installed in the electromagnetic shielding box (5). The metal guide rod (3) is provided with a first end core plug (21) and a second end core plug (22) for connecting the two ends of the cable. The first end core plug (21) and the second end core plug (22) pass through the side wall of the electromagnetic shielding box (5). The metal guide rod (3) passes through the first insulating support (41), the second insulating support (42) and the third insulating support (43). A through-core transformer is installed on each of the three phase metal guide rods (3).

3. The electromagnetic distribution characteristic simulation device for the overlapping state of multi-circuit power distribution cables according to claim 2, characterized in that, The first insulating support (41), the second insulating support (42) and the third insulating support (43) are located at the beginning, middle and end of the metal guide rod (3) respectively, and play a supporting role for the metal guide rod (3).

4. The electromagnetic distribution characteristic simulation device for the overlapping state of multi-circuit power distribution cables according to claim 1, characterized in that, The high-frequency signal coupling unit includes a high-frequency signal generating unit, a capacitive coupling sensor (16), and a coaxial metal shield (6). The coaxial metal shield (6) covers the metal guide rod (3) of the current boosting unit. The capacitive coupling sensor (16) is installed inside the coaxial metal shield (6). All three phase capacitive coupling sensors (16) are connected to the high-frequency signal generating unit. The high-frequency signal generating unit is used to generate high-frequency electromagnetic signals that simulate the field conditions of the cable trench.

5. The electromagnetic distribution characteristic simulation device for the overlapping state of multi-circuit power distribution cables according to claim 1, characterized in that, The insulating panel (14) is equipped with a locking lock (10) for fixing the position of the rotatable disc surface.

6. The electromagnetic distribution characteristic simulation device for the overlapping state of multi-circuit power distribution cables according to claim 1, characterized in that, The core plug (12) is made of metal, and the turntable (8) is made of insulating material.

7. A method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables, based on the device described in claim 1, characterized in that, Includes the following steps: S1. Let the total number of power distribution cable circuits in the simulated cable trench be m. Separate the three phases at the beginning of cable segment 1 of each circuit, connect the three-phase conductor (11) to the high-frequency signal coupling unit, separate the three phases at the end of cable segment n of each circuit, and connect the three-phase conductor (11) to the secondary side of the current boosting unit. S2. Connect each cable segment of each circuit through the cable overlap unit. The positions of the cable segments on both sides of the cable overlap unit are changed according to the test requirements. S3. The phase adjustment unit converts the three-phase power frequency voltage with a phase difference of 120° into m sets of three-phase voltages with different initial phases φ, and connects the phase-adjusted voltages to m A, B, and C three-phase through-core transformers in the current boosting unit respectively. The high-frequency signal coupling unit generates the required high-frequency signal, and the generated signal is coupled to the cable core through the capacitive coupling sensor (16); S4. Each cable segment has a different cable overlap pattern, and each loop cable carries a different current and different types of high-frequency signals; in each cable segment, signal measurements are performed at different locations or locations required by actual needs through Rogowski coils, capacitive couplers, UHF sensors and / or ground wave sensors.

8. The method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables according to claim 7, characterized in that, When conducting cable voltage testing, no current boosting signal is applied to one of the cables. Only a pulse signal is applied to the cable of that circuit using a path meter. The other circuits are subjected to normal current boosting. High-order harmonic signals, random noise signals, and / or partial discharge signals are coupled into the other circuits. The cable overlap unit is used to change the overlap of the cable segment and the characteristics of the signals applied to other phases. The signal characteristics of the circuit without a current boosting signal are detected by a high-frequency CT.

9. The method for simulating the electromagnetic distribution characteristics of overlapping multi-circuit power distribution cables according to claim 7, characterized in that, When conducting partial discharge interference tests, the overlapping state of different cables is changed using a cable overlap unit, different discharge signal types are set, and different noise interferences are set through a high-frequency signal coupling unit. Then, an ultra-high frequency sensor is used to measure the partial discharge signal.

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