CN115184720A - Device and method for electrified diagnosis of defects of cable cross-connection grounding system - Google Patents

Abstract

The invention discloses a device and a method for electrified diagnosis of defects of a cable cross-connection grounding system, wherein the device comprises a data acquisition module, a synchronous time synchronization module and a calculation judgment module; the data acquisition module is used for acquiring the load current of a cable line, the three-phase grounding circulation current and the grounding resistance of the head end and the tail end of the metal sheath; the synchronous time synchronization module is used for realizing synchronous acquisition of cable line load current and three-phase grounding circulation current; and the calculation and judgment module is used for performing circulation calculation according to the acquired load current of the cable line, the three-phase grounding circulation and the grounding resistance at the head end and the tail end of the metal sheath, matching the circulation calculation result with the acquired circulation value, and pre-judging the reason and the position of the defect according to the matching result. The invention can complete the prejudgment of the defect reason and the defect position before power failure, realize purposeful power failure maintenance after power failure, shorten the power failure time, reduce the defect removal difficulty and improve the power supply reliability.

Description

Device and method for electrified diagnosis of defects of cable cross-connection grounding system

Technical Field

The invention relates to the technical field of power transmission equipment, in particular to a device and a method for electrified diagnosis of defects of a cable cross-connection grounding system.

Background

With the acceleration of urban development process, overhead lines are gradually replaced by cables, and long-distance cable lines are more and more. At present, single-core cables are mostly adopted for 110kV and above-ground cables, and metal sheath cross interconnection grounding modes are mostly adopted for long-distance single-core transmission cables. The cross interconnection grounding system has the possibility of system defects during installation, maintenance or operation, such as wiring errors of inconsistent connection modes of two insulating joint grounding columns in a cross interconnection unit and inner and outer cores of a coaxial cable, failure of cross interconnection transposition and the like, and the wiring errors can cause the defect operation of a cable line if the wiring errors cannot be diagnosed and eliminated in time.

Circulation abnormality is generally caused by defects of the cross-connection grounding system, but due to the fact that defects of the cable cross-connection grounding system have a plurality of possible situations, defect historical circulation data of a certain cable line cannot guide defect judgment of other lines. Therefore, how to determine the defect type and position according to the circulating current abnormal signal is a research difficulty in the field.

In the operation and the maintenance of the transmission cable, the traditional method for processing the abnormal defects of the grounding circulation is to adopt a scheduled power failure maintenance means to carry out a coaxial grounding cable inner core and outer core conduction test, a segmented cable outer sheath voltage withstand test and the like. The method needs to be powered off for a long time, wastes a large amount of manpower and material resources, cannot quickly confirm the defect reasons and positions, and even causes misjudgment of the defect reasons. Due to the limitation of the power failure time, part of the cable lines have to operate with defects, further resulting in increased circulating current loss, reduced current-carrying capacity, insulation aging and even major insulation failure.

Through retrieval, china special for 2021, 10 months and 15 days of publication No. CN113504487A discloses a method for detecting the connection state of a high-voltage cable cross-connection grounding system, which comprises the following steps: s1: connecting a test lead of a connection state detection device of the high-voltage cable cross-connection grounding system with any two-phase copper bar test positions of three-phase cables A, B and C in an Nth group of protection grounding boxes of a cross-connection section respectively, and S2: the voltage between the two copper bars of the Nth group of protection grounding boxes is obtained through the voltage measuring unit, and the current between the two copper bars of the Nth group of protection grounding boxes is obtained through the current measuring unit; calculating the resistance value and the reactance value of each phase of the three sections of metal sheaths through a data processing unit; s4: and judging whether the cable metal sheath has a connection defect or not according to the resistance value of each phase of the three sections of metal sheaths and the resistance ratio of the same section of the three-phase metal sheath. Although the patent application can detect the electrical connection state of the high-voltage cable cross interconnection metal sheath in a charged and power-off manner under the condition that a cross interconnection grounding system is not disassembled, the defect reason cannot be pre-judged.

Therefore, the invention provides a device which can complete prejudgment on the defect reason and the defect position before power failure, realize targeted power failure maintenance after power failure, shorten the power failure time, reduce the defect removal difficulty and improve the power supply reliability.

Disclosure of Invention

To overcome the above-mentioned deficiencies of the prior art, the present invention provides an apparatus and a method for diagnosing the defects of the cable cross-connection grounding system with electricity, so as to solve at least one of the above-mentioned technical problems.

According to one aspect of the present disclosure, a device for diagnosing defects of a cable cross-connection grounding system in a live manner is provided, which includes a data acquisition module, a synchronous timing module and a calculation and judgment module; the data acquisition module is used for acquiring the load current of a cable line, the three-phase grounding circulation current and the grounding resistance of the head end and the tail end of the metal sheath; the synchronous time synchronization module is used for realizing synchronous acquisition of cable line load current and three-phase grounding circulation current; and the calculation and judgment module is used for performing circulation calculation according to the acquired load current of the cable line, the three-phase grounding circulation and the grounding resistance at the head end and the tail end of the metal sheath, matching the circulation calculation result with the acquired circulation value, and prejudging the reasons and positions causing the defects according to the matching result.

According to the technical scheme, the load current of the cable line, the three-phase grounding circulation and the grounding resistance of the head end and the tail end of the metal sheath are acquired through the data acquisition module, the acquired load current and the three-phase grounding circulation are guaranteed to be data at the same moment through the synchronous time synchronization module, circulation calculation and logic judgment are carried out through the calculation and judgment module, and finally the defect reason and position are pre-judged. The technical scheme is used as a portable electrified diagnosis device, is applied to the installation or maintenance stage, can realize the judgment of defect reasons and the positioning of defect positions in an electrified state, and completes the conversion from power failure diagnosis to electrified diagnosis.

As a further technical scheme, the data acquisition module comprises three load ammeters for respectively acquiring three-phase load currents of the cable line; the three clamp-shaped ammeters are used for respectively collecting three-phase grounding circulation currents; and the grounding resistance tester is used for collecting the grounding resistance of the two direct grounding boxes.

As a further technical scheme, the load ammeter and the clamp ammeter are respectively connected with the synchronous time synchronization module, and the load ammeter, the clamp ammeter and the ground resistance tester are respectively connected with the calculation judgment module in a bluetooth manner. Six meters of the data acquisition module are ensured to be acquired simultaneously through the synchronous time synchronization module, and data acquired by seven meters are transmitted to the calculation judgment module in a Bluetooth mode to be displayed and further processed.

As a further technical scheme, the calculation and judgment module comprises a collected data display unit for displaying the measured values of the load current of the cable line, the three-phase grounding circulating current and the grounding resistance sent by the data collection module; the parameter input unit is used for inputting the inner and outer radiuses of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable; the calculation unit is used for performing circulation calculation by combining a circulation calculation model according to the measured value input by the data acquisition module and each parameter input by the parameter input unit; the judging unit is used for matching the circulation calculation result of the calculating unit with the circulation measurement value input by the data acquisition module and prejudging the defect reason and position according to the matching result; and the output unit is used for outputting the defect reason and the defect position and simultaneously outputting a schematic diagram of the defect cross interconnection unit and a circulating current calculated value under the current defect.

As a further technical solution, the calculation and judgment module is configured in a handheld terminal, and the handheld terminal is connected with the data acquisition module through bluetooth.

Further, the inner radius and the outer radius of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable can be obtained by looking up the standing book information or field measurement.

As a further technical solution, the calculation and judgment module further includes a storage unit, which is used for constructing and storing a circulating current calculation model of the cable cross-connection grounding system.

As a further technical solution, the circulating current calculation model is used for calculating circulating current values of the cable cross-connection grounding system in 2 normal states and 46 defect states, respectively.

Specifically, the calculation and judgment module is composed of a hardware part and a software part, the hardware part is a handheld terminal, the software part comprises 48 sub-calculation programs, circulation calculation can be performed on 2 normal conditions and 46 common defect conditions respectively, namely 48 condition simulations are performed on the cross interconnection unit, circulation values in each condition are calculated respectively and then matched with the circulation values acquired before, the defect generation is judged according to which condition causes the defect, the defect reason and the position are displayed on the output unit finally, a defect cross interconnection unit schematic diagram is given, and a circulation calculation value under the defect condition is given.

According to an aspect of the present specification, there is provided a method for diagnosing a defective electrified diagnosis device of a cable cross-connection grounding system, including:

synchronously collecting line load current and three-phase grounding circulation of a cross interconnection unit with abnormal circulation defects, and simultaneously collecting grounding resistances of two direct grounding boxes;

acquiring the inner radius and the outer radius of a metal sheath of a cable, the length of each section of cable and the phase distance of each section of cable;

according to the acquired data and the acquired parameters, circulation calculation is carried out by combining a circulation calculation model;

and matching the calculated circulation value with the circulation value synchronously acquired on site, and prejudging the defect reason and position according to the matching result.

As a further technical solution, the method further comprises:

constructing a loop calculation model of

Wherein, I _S1 、I _S2 And I _S3 Respectively representing induced circulating currents of three circuits of the cross-connected unit, L ₁ 、L ₂ 、L ₃ Respectively representing the lengths, Z, of three sections of cable lines ₁ 、Z ₂ 、Z ₃ Are all an impedance matrix, X ₁ 、X ₂ 、X ₃ Are all inductive reactance matrices, I _A 、I _B 、I _C Respectively representing load currents of three phases A, B and C, R _d Representing a ground resistance matrix;

changing Z ₁ 、Z ₂ 、Z ₃ 、X ₁ 、X ₂ 、X ₃ 、R _d The arrangement mode of the medium elements is used for respectively calculating the circulating current values of the cable cross-connection grounding system in 2 normal states and 46 defect states;

and matching the actual measured value of the circular current with the calculation results of 48 conditions to realize the prejudgment of the defect reasons and the defect positions.

Compared with the prior art, the invention has the beneficial effects that:

according to the invention, the prejudgment on the defect reason and position is completed before power failure through the circulation calculation model, so that targeted power failure maintenance can be realized after power failure, the power failure time is shortened, the difficulty in defect removal diagnosis is reduced, the power supply reliability is improved, the conversion from power failure diagnosis to live diagnosis is realized, the user operation is simple, the technical threshold is low, and the operation and maintenance personnel can conveniently use the system.

Drawings

Fig. 1 is a schematic diagram of a cable cross-connect grounding system defect live diagnosis apparatus according to an embodiment of the present invention.

Fig. 2 is a flowchart of a method for diagnosing a defective live diagnosis apparatus of a cable cross-connection grounding system according to an embodiment of the present invention.

Fig. 3 is a schematic equivalent circuit diagram of a cable cross-connect grounding system in a normal state according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of an equivalent circuit of a cable cross-connect grounding system in a defect state according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating a software interface of a calculation determination module according to an embodiment of the present invention.

Fig. 6 is a schematic diagram of a cross-connect unit according to an embodiment of the invention.

Fig. 7 (a) is a schematic view illustrating a first copper bar connection manner of the cross-connect box according to an embodiment of the present invention.

Fig. 7 (b) is a schematic view of a second cross-connecting box copper bar connection method according to an embodiment of the present invention.

FIG. 8 is a drawing showing a J-shaped cross-connecting box copper bar connection mode according to a second embodiment of the present invention _1A And J _2B Schematic diagram when reverse.

FIG. 9 is a drawing showing a J-shaped cross-connecting box copper bar connection mode according to a second embodiment of the present invention _1A And J _2B And (5) connecting the equivalent circuit diagram in the reverse direction.

Detailed Description

The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a cable cross-connection grounding system defect live diagnosis device, which is composed of a data acquisition module, a synchronous time setting module and a calculation judgment module as shown in figure 1. The data acquisition module can acquire the load current of a cable line, the three-phase grounding circulation and the grounding resistance of the head end and the tail end of the metal sheath, and the synchronous time synchronization module is used for ensuring that the acquired load current and the three-phase grounding circulation are data at the same time. And the calculation and judgment module can finally judge the defect reason and position through theoretical calculation and logic judgment.

The calculation judging module comprises a hardware part and a software part, wherein the hardware part is a handheld terminal and is light and portable, and the software part is written by java language and comprises a parameter input unit, a collected data display unit, an output unit, a calculating unit and a judging unit.

The parameter input unit is used for inputting the inner and outer radiuses of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable; the acquisition data display unit is used for displaying the measured values of the load current, the three-phase grounding circulation and the grounding resistance of the cable circuit sent by the data acquisition module; the calculation unit is used for performing circulation calculation by combining a circulation calculation model according to the measured value input by the data acquisition module and each parameter input by the parameter input unit; the judging unit is used for matching the circulation calculation result of the calculating unit with the circulation measurement value input by the data acquisition module and prejudging the defect reason and position according to the matching result; and the output unit is used for outputting the defect reason and the defect position and simultaneously outputting a schematic diagram of the defect cross interconnection unit and a circulating current calculated value under the current defect.

The data acquisition module comprises three load ammeters, three clamp ammeters and one grounding resistance tester, and is used for respectively measuring the load current, the three-phase circulating current and the grounding resistance at two direct grounding boxes. And the synchronous time synchronization module ensures that the three load ammeters and the three clamp-shaped ammeters are simultaneously acquired. The data collected by the data collection module is transmitted to a collected data display unit of the calculation and judgment module through the Bluetooth function and is displayed on the interface.

And the inside and outside radiuses of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable are obtained by looking up the ledger information or field measurement, and are input into a data input unit of the calculation and judgment module.

The calculation judgment module comprises a hardware part and a software part, wherein the hardware part is a handheld terminal, and the software part comprises 48 sub-calculation programs and can respectively perform circulation calculation on 2 normal conditions and 46 common defect conditions. And performing 48 condition simulations on the cross interconnection unit, respectively calculating a circulation value under each condition, matching the circulation value with the circulation value acquired before, judging which condition causes the generation of the defect, finally displaying the defect reason and position on an output unit, and providing a schematic diagram of the defect cross interconnection unit and a calculated value of circulation under the defect condition.

In another aspect, the present invention provides a method for diagnosing a defect live diagnosis apparatus of a cable cross-connect grounding system, where one cable cross-connect unit of the cable cross-connect grounding system includes four grounding boxes, i.e., two direct connection boxes and two cross-connect boxes. When the abnormal circulating current defect of one cross interconnection unit is found, the load current and the three-phase grounding circulating current of the line are acquired on site at each grounding box through a load ammeter and a clamp ammeter of a data acquisition module, and the grounding resistance of two direct grounding boxes is acquired by using a grounding resistance tester.

As shown in fig. 2, the diagnosis method includes:

step 1, data acquisition.

The synchronous time synchronization module simultaneously sends acquisition instructions to the three load ammeters and the three clamp-shaped ammeters to realize synchronous acquisition. Because the grounding loop current and the load current are in a direct proportional relation, three-phase loop current values collected at the last three grounding boxes can be converted into loop current data under the same load condition as the first grounding box according to the load current proportion. And the data acquired on site is transmitted to the calculation and judgment module through Bluetooth.

And the inside and outside radiuses of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable are obtained by looking up the ledger information or field measurement, and are input into a data input unit of the calculation and judgment module.

And 2, according to the input parameters, the acquired load current, the grounding circulation and the grounding resistance, software in the calculation and judgment module can simulate 48 conditions and respectively calculate the circulation value, wherein the conditions comprise two normal conditions and 46 defect conditions, wherein the two defects comprise two types of defects of cross interconnection transposition failure and reverse connection (commonly called as 'cavel' reverse connection) of an insulating joint grounding column and an inner core and an outer core of a coaxial grounding cable, namely the conditions of 4 types of cross interconnection transposition failure, 12 types of 1 group of 'cavels' reverse connection and 30 types of 2 groups of 'cavels' reverse connection simultaneously, and the conditions cover all common cross interconnection wiring error types.

And 3, outputting a judgment result, including the defect reason and position, the schematic diagram of the defect cross interconnection unit and a circulation calculation value under the defect condition, as shown in fig. 3.

As an embodiment, the circulation calculation model is described by taking a correct case and a defective case as an example.

(1) In a normal case, the equivalent circuit is shown in fig. 4.

Induced voltage U of metal sheath layer of each cross interconnection section _Ai 、U _Bi 、U _Ci (i =1,2,3) consists of two parts, i.e. under normal operating conditions, U _Ai ＝E _SAi +E _TAi ,U _Bi ＝E _SBi +E _TBi ,U _Ci ＝E _SCi +E _TCi 。

Z _SAi 、Z _SBi 、Z _SCi (i =1,2, 3) is the self-impedance (Ω), R, of the metal sheath of each cross-connect segment _e Is earth leakage resistance (omega), R ₁ 、R ₂ The grounding resistance (omega) is directly grounded at two ends of the metal sheath; e _SAi 、E _SBi 、E _SCi Induced voltage (V) caused by each section of core current; e _TAi 、E _TBi 、E _TCi (i =1,2, 3) is the induced voltage (V) generated on the two adjacent metal sheaths except the sheath itself by the current in each metal sheath (i =1,2, 3) and the earth return current. I.C. A _S1 、I _S2 、I _S3 Three loops of induced circulation (A) respectively.

Three loops of a normal cross interconnection section are respectively as follows: a first loop A1-B2-C3, a second loop B1-C2-A3, and a second loop C1-A2-B3.

The calculation model is as follows:

Z ₁ 、Z ₂ 、Z ₃ and R _d Are all matrices:

wherein, I _S1 、I _S2 And I _S3 Respectively representing induced loops (A), L of three loops of a cross-connected unit ₁ 、L ₂ 、L ₃ Respectively representing the lengths, Z, of three sections of cable lines ₁ 、Z ₂ 、Z ₃ Are an impedance matrix, X ₁ 、X ₂ 、X ₃ Are all an inductive reactance matrix, Z _ABi And Z _ACi Respectively impedance between the metal sheath of the B phase and the metal sheath of the C phase and the metal sheath of the A phase (omega/m), Z _BAi And Z _BCi The mutual impedance (omega/m), Z between the A-phase metal sheath and the C-phase metal sheath and the B-phase metal sheath respectively _CAi And Z _CBi The mutual impedance (omega/m) and R between the A-phase metal sheath and the B-phase metal sheath and the C-phase metal sheath are respectively _d A matrix of resistances to ground is represented,

R＝R ₁ +R ₂ +R _e

R _e ＝R _g ×(L ₁ +L ₂ +L ₃ )

R _g ＝π ² f×10 ^-7

in the formula:

f is the current transmission frequency (Hz), R ₁ 、R ₂ The grounding resistance (omega) and R at the direct grounding of the two ends of the metal sheath _g Denotes the ground resistance per unit length, R _e Represents earth leakage resistance (Ω/m).

In the formula:

a is the resistivity (omega. M) of the metal sheath, r ₁ And r ₂ Respectively the inner and outer radius (mm) of the metal sheath, L _i For the length (m), D of i-section (i =1,2, 3) cabling _e Indicating the depth of earth leakage current, r _s Representing the geometric mean radius of the metal sheath.

ρ is the earth resistivity.

r _s ＝r ₂ ×e ^-0.25

X ₁ 、X ₂ And X ₃ Are all matrices:

in the formula:

where j is a complex number calculation factor, ω is an angular velocity, and ω =2 π f. S _ABi 、S _BCi And S _CAi The distance between the ith cable core A, the ith cable core B and the ith cable core C is mm. X _AASi 、X _ABSi 、X _ACSi Mutual inductance reactance (omega/m) and mutual inductance X between phase A core, phase B core and phase C core of the ith section of cable and the phase A metal sheath _BASi 、X _BBSi 、X _BCSi Mutual inductance reactance (omega/m) and mutual inductance X between the phase core A, the phase core B and the phase core C of the ith section of cable and the phase metal sheath B of the ith section of cable respectively _CASi 、X _CBSi 、X _CCSi Mutual inductance (omega/m) between the phase core and the phase C metal sheath of the ith section of cable A, B and C respectively.

According to the model, the circulation value of the normal cross-interconnected system can be calculated in a programming mode.

(2) The second group of insulated joints A has the defect that the inner core and the outer core of the phase are reversely connected, and the equivalent circuit is shown in figure 5. The three loops of the cross interconnection section are respectively as follows: a first loop A1-B2-C3, a second loop B1-C2-A2-C1, and a second loop A3-B3. The calculation model is as follows:

in the formula:

only the change of Z compared to the normal case is required ₁ 、Z ₂ 、Z ₃ 、R _d 、X ₁ 、X ₂ And X ₃ The elements in these 7 matrices are arranged in the same way, and the calculation formula of the elements is the same as that of the normal cross-connect grounding system. Therefore, the matrix calculation model can be listed for other 46 cases respectively, and only the arrangement of the elements in 7 matrices needs to be changed, while the calculation formula of the elements is not changed.

(3) Description of six particular cases

As shown in FIG. 6, in one cross-connection unit, six insulated terminals are connected to two cross-connection boxes, and the three insulated terminals connected to the No. 2 cross-connection box are respectively numbered J according to the phase _1A 、J _1B And J _1C Three insulation joints connected with the 3# cross interconnection box are respectively numbered J according to the phase _2A 、J _2B And J _2C 。

There are two ways of cross-connecting the copper bars of the box as shown in fig. 7 (a) - (b).

In the first connection, J, as shown in FIG. 7 (a) _1A And J _2C Simultaneously reverse connection, J _1B And J _2A Are simultaneously connected inversely and J _1C And J _2B In the case of simultaneous reverse connection, the cross-connected cells form four loops, and thus the matrix changes accordingly. In a second connection, J _1A And J _2B Simultaneously reverse connection, J _1B And J _2C Simultaneous reverse and J _1C And J _2A A similar result would be the case with reverse. In a second arrangement J _1A And J _2B Meanwhile, the case of reversing is described as an example.

A schematic diagram of the cross-connect cell in this case is shown in fig. 8.

The cross-interconnect unit is known to be divided into four loops: a first loop A1-C1, a second loop B1-C2-A3, a third loop A2-B2, and a fourth loop B3-C3. The equivalent circuit diagram in this case is shown in fig. 9.

Constructing a loop calculation model of

In the formula:

in other five cases, only Z needs to be changed ₁ 、Z ₂ 、Z ₃ 、R _d 、X ₁ 、X ₂ And X ₃ The elements in these 7 matrices are arranged in the same way and the calculation formula for the elements is the same as for a normal cross-interconnect grounding system.

After the matrix calculation model is determined, the loop calculation subprogram of 48 cases is completed by using java language. The judgment of the defect cause and position is realized by matching the actual measured value of the loop current with the calculation results of 48 cases.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims (9)

1. The electrified diagnosis device for the defects of the cable cross-connection grounding system is characterized by comprising a data acquisition module, a synchronous time setting module and a calculation judgment module; the data acquisition module is used for acquiring the load current of a cable line, the three-phase grounding circulation current and the grounding resistance of the head end and the tail end of the metal sheath; the synchronous time synchronization module is used for realizing synchronous acquisition of cable line load current and three-phase grounding circulation; and the calculation and judgment module is used for performing circulation calculation according to the acquired load current of the cable line, the three-phase grounding circulation and the grounding resistance at the head end and the tail end of the metal sheath, matching the circulation calculation result with the acquired circulation value, and pre-judging the reason and the position of the defect according to the matching result.

2. The apparatus for diagnosing defects of a cross-cable interconnection grounding system of claim 1, wherein the data acquisition module comprises three load ammeters for respectively acquiring three phase load currents of the cable lines; the three clamp-shaped ammeters are used for respectively collecting three-phase grounding circulation currents; and the grounding resistance tester is used for acquiring grounding resistances at the two direct grounding boxes.

3. The apparatus according to claim 2, wherein the load ammeter and the clamp ammeter are respectively connected to the synchronous timing module, and the load ammeter, the clamp ammeter and the ground resistance tester are respectively connected to the calculation and judgment module via bluetooth.

4. The apparatus for diagnosing the defect of the cable cross-connection grounding system according to claim 1, wherein the calculation and judgment module comprises a data acquisition and display unit for displaying the measured values of the load current, the three-phase grounding loop current and the grounding resistance of the cable line sent by the data acquisition module; the parameter input unit is used for inputting the inner and outer radiuses of the metal sheath of the cable, the length of each section of cable and the phase distance of each section of cable; the calculation unit is used for performing circulation calculation by combining a circulation calculation model according to the measured value input by the data acquisition module and each parameter input by the parameter input unit; the judging unit is used for matching the circulation calculation result of the calculating unit with the circulation measurement value input by the data acquisition module and prejudging the defect reason and position according to the matching result; and the output unit is used for outputting the defect reason and the defect position and simultaneously outputting a schematic diagram of the defect cross interconnection unit and a circulating current calculated value under the current defect.

5. The apparatus for diagnosing defects of a cross-cable grounding system of claim 4, wherein the calculating and determining module is disposed in a handheld terminal, and the handheld terminal is connected to the data collecting module via bluetooth.

6. The apparatus for electrified diagnosis of defects in a cable cross-connection grounding system according to claim 4, wherein the calculation and judgment module further comprises a storage unit for constructing and storing a circular current calculation model of the cable cross-connection grounding system.

7. The apparatus for diagnosing defects of a cross-cable interconnection grounding system according to claim 6, wherein the circulating current calculation model is used for calculating circulating current values of the cross-cable interconnection grounding system under 2 normal states and 46 defect states, respectively.

8. The diagnosis method of the electrified diagnosis device for the defects of the cable cross-connection grounding system is characterized by comprising the following steps:

synchronously collecting line load current and three-phase grounding circulation of a cross interconnection unit with circulation abnormal defects, and simultaneously collecting grounding resistances of two direct grounding boxes;

acquiring the inner radius and the outer radius of a metal sheath of a cable, the length of each section of cable and the phase distance of each section of cable;

performing circulation calculation by combining a circulation calculation model according to the acquired data and the acquired parameters;

and matching the calculated circulation value with a circulation value synchronously acquired on site, and prejudging the defect reason and position according to the matching result.

9. The method for diagnosing the defect electrified diagnosis device of the cable cross-connection grounding system according to claim 8, further comprising:

constructing a loop calculation model of

Wherein, I _S1 、I _S2 And I _S3 Respectively representing induced circulating currents of three circuits of the cross-connected unit, L ₁ 、L ₂ 、L ₃ Respectively representing the lengths, Z, of three sections of cable lines ₁ 、Z ₂ 、Z ₃ Are all an impedance matrix, X ₁ 、X ₂ 、X ₃ Are all inductive reactance matrices, I _A 、I _B 、I _C Respectively representing load currents of three phases A, B and C, R _d Representing a ground resistance matrix;

changing Z ₁ 、Z ₂ 、Z ₃ 、X ₁ 、X ₂ 、X ₃ 、R _d The arrangement mode of the medium elements is used for respectively calculating the circulating current values of the cable cross-connection grounding system in 2 normal states and 46 defect states;

and matching the measured value of the loop current with the calculation results of 48 conditions to realize the prejudgment of the defect reason and the defect position.

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