A device and method for detecting defects in a high-voltage cable cross-transposition grounding system

Abstract

The present invention discloses a device and method for detecting defects in a cross-transposed grounding system of a high-voltage cable. A certain protective grounding box of the cross-transposed grounding system is selected, and a signal excitation coupler is connected to the coaxial cables of phases A, B, and C of the protective grounding box respectively. A stable signal of a certain F1 frequency that distinguishes the power frequency or field interference is selected, and the effective value and phase of the current of the coaxial cables of phases A, B, and C in the protective grounding box are respectively tested when the coupling injection frequency is the stable signal of F1; the resistance and inductance parameters of each branch of the cable line cross-transposed grounding system are calculated and obtained according to the measured data. When any resistance of each branch of the cable cross-interconnected grounding system is greater than or equal to 0.3Ω or the ratio between the two branches exceeds 1.2, the cable cross-transposed grounding system connection defect is determined. The detection of defects in the cross-transposed grounding system of a high-voltage cable based on the device of the present invention is simple and convenient to operate, highly efficient, and has good application prospects.

Description

Technical Field

[0001] The invention relates to a device and a method for detecting defects in a high-voltage cable cross-transposition grounding system, belonging to the technical field of power transmission and transformation equipment. Background Art

[0002] At present, the connection defects of the cable cross-transposition grounding system can easily cause the metal suspension discharge inside the cable aluminum sheath or cable accessories, thus causing cable failure. Due to the long length of the cable cross-interconnection section, the cable metal sheath in the interconnection section is connected to the accessory tail pipe and the grounding box copper busbar, and the electrical connection is complicated. The traditional detection method can only be used when the line is out of service and the cross-transposition system is disassembled for testing, which is time-poor and has limitations. Summary of the invention

[0003] In order to overcome the deficiencies in the prior art, the present invention provides a device and method for detecting defects in a high-voltage cable cross-transposition grounding system, which can detect the electrical connection status of the cable cross-transposition grounding system with or without power, and is simple, convenient and efficient to operate.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] The present invention provides a device for detecting defects in a high-voltage cable cross-transposition grounding system, comprising an AC power supply, a signal acquisition device, an input current test device, a signal excitation coupler, an output current test device and a test sensor;

[0006] The AC power supply is connected to the signal excitation coupler, and the AC power supply is used to provide the signal excitation coupler with an AC power supply that distinguishes between power frequency and field interference frequency;

[0007] The signal excitation coupler is installed on the cross-transposed grounding lead coaxial cable, and the signal excitation coupler is used to couple the stable current signal into the cable cross-transposed grounding system;

[0008] The AC power supply is connected to the input current testing equipment, and the input current testing equipment is used to test the effective value and phase of the current output by the AC power supply;

[0009] The output current test equipment is connected to the test sensor, the test sensor is installed on the cross-transposed grounding lead coaxial cable, and the output current test equipment is used to test the effective value and phase of the current response under the excitation frequency of the coaxial cable of the cross-transposed grounding system;

[0010] The input current test equipment and the output current test equipment are both connected to the signal acquisition equipment, and the signal acquisition equipment is used to sample the current information output by the input current test equipment and the output current test equipment.

[0011] Furthermore, the input current testing equipment is an AC measuring device.

[0012] The present invention also provides a method for detecting defects in a high-voltage cable cross-transposition grounding system, comprising:

[0013] Use AC power to select a stable current signal of F1 frequency that distinguishes power frequency and field interference;

[0014] The F1 frequency current stabilization signal is coupled and injected into the A-phase, B-phase and C-phase coaxial cables of a certain protective grounding box of the cross-transposed grounding system through a signal excitation coupler;

[0015] Under the condition that the F1 frequency current stable signal is injected into the coaxial cables of phases A, B and C, the input current test equipment is used to test the effective value and phase of the output current of the AC power supply, and the output current test equipment is used to test the effective value and phase of the current of the coaxial cables of phases A, B and C of the cross-transposed grounding system;

[0016] Calculate the resistance of each branch of the cross-transposition system based on the test data;

[0017] Defects in the high-voltage cable cross-transposed grounding system are determined based on the calculated resistance.

[0018] Furthermore, the input current test equipment is used to test the effective value and phase of the AC power supply output current, and the induced voltage of the cross-transposed grounding system is calculated according to the following formula:

[0019] U1i∠αi=k1*F1*Ii*[cosαi+j*sinαi]=Pi+j*Qi;

[0020] αi=βi+θi;

[0021] Among them, U1i∠αi is the induced voltage of the cross-transposed grounding system under phase αi, αi is the induced phase, Ii and βi are the effective value and phase of the output current of the AC power supply, Pi is the real part of the complex number U1i, Qi is the real part of the complex number U1i, k1 is the proportionality coefficient, θi is the phase difference, i=1,2,3 represents the i-th coupling injection;

[0022] U1i and αi are calculated based on the test data, and then Pi and Qi are obtained.

[0023] Furthermore, the output current test equipment is used to test the effective value and phase of the current response of the coaxial cable of phases A, B and C of the cross-transposed grounding system, and the current and phase of the internal lead of the coaxial cable are calculated according to the following method:

[0024] When the A phase coaxial cable couples and injects a stable current signal of frequency F1, the current and phase of the internal lead of the coaxial cable are calculated using the following formula:

[0025]

[0026] Among them, IA_1, IB_1 and IC_1 are the effective values ​​of the currents of the coaxial cables of phases A, B and C measured when the current stable signal of the frequency F1 is injected into the coaxial cable of phase A, γA_1, γB_1 and γC_1 are the current phases of the coaxial cables of phases A, B and C measured, IAB_1, IBC_1 and ICA_1 are the A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the coaxial cable when the current stable signal of the frequency F1 is injected into the coaxial cable of phase A, γAB_1, γBC_1 and γCA_1 are the phases of the A1-B2 lead current, B1-C2 lead current and C1-A3 lead current, X1j, j=1, 2, 3 are the real parts of the complex numbers of IAB_1, IBC_1 and ICA_1, respectively, and Y1j are the imaginary parts of the complex numbers of IAB_1, IBC_1 and ICA_1, respectively;

[0027] When the B phase coaxial cable couples and injects a stable current signal of frequency F1, the current and phase of the internal lead of the coaxial cable are calculated using the following formula:

[0028]

[0029] Among them, IA_2, IB_2 and IC_2 are the effective values ​​of the currents of the coaxial cables of phases A, B and C measured when the current stable signal of the frequency F1 is injected into the coaxial cable of phase B, γA_2, γB_2 and γC_2 are the current phases of the coaxial cables of phases A, B and C measured, IAB_2, IBC_2 and ICA_2 are the A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the coaxial cable when the current stable signal of the frequency F1 is injected into the coaxial cable of phase B, γAB_2, γBC_2 and γCA_2 are the A1-B2 lead current phase, B1-C2 lead current phase and C1-A3 lead current phase, X2j, j = 1, 2, 3 are the real parts of the complex numbers of IAB_2, IBC_2 and ICA_2, respectively, and Y2j are the imaginary parts of the complex numbers of IAB_2, IBC_2 and ICA_2, respectively;

[0030] When the C phase coaxial cable couples and injects a stable current signal with a frequency of F1, the following formula is used to calculate the current and phase of the internal lead of the coaxial cable:

[0031]

[0032] Among them, IA_3, IB_3 and IC_3 are the effective values ​​of the current responses of phase A, phase B and phase C coaxial cables measured when the current stabilization signal of frequency F1 is injected into the coaxial cable coupling of phase C, γA_3, γB_3 and γC_3 are the current phases of phase A, phase B and phase C coaxial cables measured, IAB_3, IBC_3 and ICA_3 are the A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the coaxial cable when the current stabilization signal of frequency F1 is injected into the coaxial cable coupling of phase C, γAB_3, γBC_3 and γCA_3 are the A1-B2 lead current phase, B1-C2 lead current phase and C1-A3 lead current phase, X3j, j=1, 2, 3 are the real parts of the complex numbers of IAB_3, IBC_3 and ICA_3, respectively, and Y3j are the imaginary parts of the complex numbers of IAB_3, IBC_3 and ICA_3, respectively.

[0033] Furthermore, the resistance of each branch of the cross-transposition system is calculated using the following formula:

[0034]

[0035] Among them, R1, R2 and R3 are the A1-B2-C3 branch resistance, B1-C2-A3 branch resistance and C1-A2-B3 branch resistance of the cross-transposed grounding system respectively; X1, X2 and X3 are the A1-B2-C3 branch inductance, B1-C2-A3 branch inductance and C1-A2-B3 branch inductance of the cross-transposed grounding system respectively.

[0036] Furthermore, if any one of the following two conditions is met, the high-voltage cable cross-transposition grounding system defect is determined:

[0037] A. In the cable cross-connected grounding system, at least one branch resistance of each branch is greater than or equal to 0.3Ω;

[0038] B. Among the pairwise ratios of the branch resistances in the cable cross-connected grounding system, at least one exceeds 1.2.

[0039] The beneficial effects of the present invention are:

[0040] The present invention selects a certain protective grounding box of the cross-transposed grounding system, and uses a signal excitation coupler to couple a certain stable signal of F1 frequency that distinguishes power frequency or field interference into the cross-transposed grounding system; based on the effective current value and phase of the response of the coaxial cables A, B, and C, and the input current effective value and phase simultaneous equations, the resistance and inductance parameters of each branch of the cable line cross-transposed grounding system are calculated and obtained, and when any resistance of each branch of the cable cross-interconnected grounding system is greater than or equal to 0.3Ω or the ratio between the two exceeds 1.2, the cable cross-transposed grounding system connection defect is determined. The present invention is simple and convenient to operate, and has high efficiency, which fills the gap in the technical field and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the cross-transposition grounding system for cable lines;

[0042] Figure 2 A structural diagram of a device for detecting defects in a high-voltage cable cross-transposition grounding system provided by an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the same-coaxial test of the cable grounding system A in an embodiment of the present invention;

[0044] Figure 4 1 is an equivalent circuit diagram of the A-phase coaxial cable test in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The present invention is further described below. The following examples are only used to more clearly illustrate the technical solution of the present invention, and are not intended to limit the protection scope of the present invention.

[0046] The cable adopts cross-transposition grounding mode, and the transposition sections A1-B2-C3, A2-B3-C1, and A3-B1-C2 are interconnected, and there are coaxial cables A, B, and C at the grounding box, such as Figure 1 .

[0047] An embodiment of the present invention provides a device for detecting defects in a high voltage cable cross-transposition grounding system. Figure 2 , including: AC power supply, signal acquisition equipment, voltage testing equipment, input current testing equipment, signal excitation coupler, output current testing equipment and test sensor.

[0048] Specifically, the AC power supply is connected to the signal excitation coupler to provide the signal excitation coupler with an AC power supply that distinguishes between the power frequency and the on-site interference frequency;

[0049] The AC power supply is also connected to an input current test device, which is used to test the effective value and phase of the current output by the AC power supply;

[0050] The signal excitation coupler is installed on the cross-transposed grounding lead coaxial cable, and injects the stable signal coupling into the cable cross-transposed grounding system by electromagnetic induction;

[0051] The output current test equipment is connected to the test sensor, and the test sensor is installed on the cross-transposed grounding lead coaxial cable. The output current test equipment is used to test the effective value and phase of the current at the excitation frequency of the coaxial cable of the cross-transposed grounding system through the test sensor;

[0052] The input current test equipment and the output current test equipment are both connected to the signal acquisition equipment, and the signal acquisition equipment is used to sample and compare the phase parameters of the AC power input current and the coupled induced current of the cross-transposed grounding system.

[0053] The voltage test equipment is used to observe the voltage injected by the coupling coil.

[0054] As a preferred implementation, the AC power supply output signal is an AC signal with adjustable frequency.

[0055] As a preferred implementation, the input current testing device is an AC measuring device that can test the effective value and phase parameters of the current at different frequencies.

[0056] As a preferred implementation, the output current testing device can test the effective value and phase parameters of the current at different frequencies through a testing sensor.

[0057] Another embodiment of the present invention provides a method for detecting defects in a high-voltage cable cross-transposition grounding system, comprising:

[0058] Use AC power to select a stable current signal of F1 frequency that distinguishes power frequency and field interference;

[0059] The F1 frequency current stabilization signal is coupled and injected into the A-phase, B-phase and C-phase coaxial cables of a certain protective grounding box of the cross-transposed grounding system through a signal excitation coupler;

[0060] Under the condition that the F1 frequency current stable signal is injected into the coaxial cables of phases A, B and C, the input current test equipment is used to test the effective value and phase of the output current of the AC power supply, and the output current test equipment is used to test the effective value and phase of the current of the coaxial cables of phases A, B and C of the cross-transposed grounding system;

[0061] Calculate the resistance of each branch of the cross-transposition system based on the test data;

[0062] Defects in the high-voltage cable cross-transposed grounding system are determined based on the calculated resistance.

[0063] As a preferred implementation, a method for detecting defects in a high-voltage cable cross-transposition grounding system specifically comprises the following steps:

[0064] (1) Select a protective grounding box of the cross-transposed grounding system, connect the signal excitation coupler to the coaxial cables of phase A, phase B, and phase C of the protective grounding box respectively, use the AC power supply to select a stable current signal of F1 frequency that distinguishes the power frequency and field interference, couple and inject it into the cross-transposed grounding system, and test the effective value Ii and phase βi of the output current of the AC power supply through the input current test equipment. Let the effective value of the induced voltage of the cross-transposed grounding system be U1i and the phase be αi, and the following relationship exists:

[0065] U1i∠αi=k1*F1*Ii*[cosαi+j*sinαi]=Pi+j*Qi;

[0066] αi=βi+θi;

[0067] Based on the test results, U1i and αi are calculated, and then Pi and Qi are obtained.

[0068] Among them, Ii is in A, U1i is in mV, αi and βi are in degrees, Pi is the real part of the complex number U1i, Qi is the real part of the complex number U1i, k1 is the proportionality coefficient, which is generally set manually during coupling injection and is dimensionless, θi is the phase difference, and i=1, 2, 3 represents the i-th coupling injection measurement.

[0069] (2) Use the output current test equipment to test the signal excitation coupler to couple the coaxial cables in the protective grounding boxes A, B, and C respectively. When the injection frequency is F1, the current stable signal is injected. The positive direction of the test current is the direction of the nearest grounding box side, and the current and phase of the internal lead of the coaxial cable are calculated. Specifically:

[0070] When the coaxial cable of phase A couples and injects a stable signal with a frequency of F1, the effective value of the current of the coaxial cable of phase A is IA_1, and the phase is γA_1; the effective value of the coaxial cable of phase B is IB_1, and the phase is γB_1; the effective value of the coaxial cable of phase C is IC_1, and the phase is γC_1;

[0071] The current of the A1-B2 lead inside the coaxial cable is IAB_1, the phase is γAB_1, the current of the B1-C2 lead is IBC_1, the phase is γBC_1, the current of the C1-A3 lead is ICA_1, and the phase current is γCA_1, then the following relationship exists:

[0072]

[0073] Among them, the units of IA_1, IB_1, IC_1, IAB_1, IBC_1, and ICA_1 are A, and the units of γA_1, γB_1, and γC_1 are degrees; X1j, j=1, 2, and 3 are the real parts of the complex numbers of IAB_1, IBC_1, and ICA_1, respectively, and Y1j, j=1, 2, and 3 are the imaginary parts of the complex numbers of IAB_1, IBC_1, and ICA_1, respectively.

[0074] Based on the above relationship and test data, the A1-B2 lead current IAB_1 and phase γAB_1, B1-C2 lead current IBC_1 and phase γBC_1, C1-A3 lead current ICA_1 and phase current γCA_1 inside the coaxial cable are solved when the A phase coaxial cable is coupled with a stable signal with an injection frequency of F1, and then X1j and Y1j are obtained.

[0075] Similarly, when the coaxial cable of phase B couples and injects a stable signal with a frequency of F1, the effective value of the coaxial cable of phase A is IA_2, the phase is γA_2, the effective value of the coaxial cable of phase B is IB_2, the phase is γB_2, and the effective value of the coaxial cable of phase C is IC_2, the phase is γC_2;

[0076] The A1-B2 lead current inside the coaxial cable is IAB_2, the phase is γAB_2, the IBC_2 lead current is IBC_2, the phase is γBC_2, the ICA_2 lead current is ICA_2, the phase is γCA_2, then there is the following relationship:

[0077]

[0078]

[0079] Among them, the units of IA_2, IB_2, IC_2, IAB_2, IBC_2, and ICA_2 are A, and the units of γA_2, γB_2, and γC_2 are degrees; X2j, j=1, 2, and 3 are the real parts of the complex numbers IAB_2, IBC_2, and ICA_2, respectively, and Y2j, j=1, 2, and 3 are the imaginary parts of the complex numbers IAB_2, IBC_2, and ICA_2, respectively.

[0080] Based on the above relationship and test data, the A1-B2 lead current IAB_2 and phase γAB_2, B1-C2 lead current IBC_2 and phase γBC_2, C1-A3 lead current ICA_2 and phase current γCA_2 inside the coaxial cable are solved when the B phase coaxial cable is coupled with a stable signal with an injection frequency of F1, and then X2j and Y2j are obtained.

[0081] Similarly, when the coaxial cable of phase C couples and injects a stable signal with a frequency of F1, the effective value of the coaxial cable of phase A is IA_3, the phase is γA_3, the effective value of the coaxial cable of phase B is IB_3, the phase is γB_3, and the effective value of the coaxial cable of phase C is IC_3, the phase is γC_3;

[0082] The A1-B2 lead current inside the coaxial cable is IAB_3, the phase is γAB_3, the B1-C2 lead current is, the phase is IBC_3, the phase is γBC_3, the C1-A3 lead current is, the phase is ICA_3, the phase is γCA_3, then:

[0083]

[0084] Among them, the units of IA_3, IB_3, IC_3, IAB_3, IBC_3, and ICA_3 are A, and the units of γA_3, γB_3, and γC_3 are degrees; X3j, j=1, 2, and 3 are the real parts of the complex numbers IAB_3, IBC_3, and ICA_3 respectively, and Y3j, j=1, 2, and 3 are the imaginary parts of the complex numbers IAB_3, IBC_3, and ICA_3 respectively.

[0085] Based on the above relationship and test data, the A1-B2 lead current IAB_3 and phase γAB_3, B1-C2 lead current IBC_3 and phase γBC_3, C1-A3 lead current ICA_3 and phase current γCA_3 inside the coaxial cable are solved when the C phase coaxial cable is coupled with a stable signal with an injection frequency of F1, and then X3j and Y3j are obtained.

[0086] Those skilled in the art should know that during field testing, the coaxial cable is fixed, and the excitation coupler and the test sensor are both openable and closable, clamping and holding the coaxial cable like pliers to inject current and test current.

[0087] (3) According to the simultaneous equations of electromagnetic induction cable and ohmic cable assembly, the resistance and inductance parameters of each branch of the cable line cross-transposition system are calculated, which are as follows:

[0088]

[0089]

[0090] in,

[0091] ZA1-B2-C3=R1+jX1;

[0092] ZB1-C2-A3=R2+jX2;

[0093] ZC1-A2-B3=R3+jX3;

[0094] R1 is the resistance of the A1-B2-C3 branch of the cross-transposed grounding system, mΩ; X1 is the inductive reactance of the A1-B2-C3 branch of the cross-transposed grounding system at frequency F1, mΩ; ZA1-B2-C3 is the impedance of the A1-B2-C3 branch;

[0095] R2 is the resistance of the cross-transposed grounding system B1-C2-A3 branch, mΩ; X2 is the inductive reactance of the cross-transposed grounding system B1-C2-A3 branch at frequency F1, mΩ; ZB1-C2-A3 is the impedance of the B1-C2-A3 branch;

[0096] R3 is the resistance of the C1-A2-B3 branch of the cross-transposed grounding system, mΩ; X3 is the inductive reactance of the C1-A2-B3 branch of the cross-transposed grounding system at frequency F1, mΩ; ZC1-A2-B3 is the impedance of the C1-A2-B3 branch.

[0097] Calculate the inductance of each branch as:

[0098] L1=X1 / (2*π*F1)

[0099] L2=X2 / (2*π*F1)

[0100] L3=X2 / (2*π*F1)

[0101] L1 is the inductance of the A1-B2-C3 branch of the cross-transposed grounding system;

[0102] L2 is the inductance of the B1-C2-A3 branch of the cross-transposed grounding system;

[0103] L3 is the inductance of the C1-A2-B3 branch of the cross-transposed grounding system.

[0104] (4) When any resistance of each branch of the cable cross-connected grounding system is greater than or equal to 0.3Ω or the ratio between the two branches exceeds 1.2, the cable cross-connected grounding system is determined to be defective.

[0105] Example 1

[0106] In this embodiment, the first protective grounding box of the cross-transposed grounding system is selected, such as Figure 3 As shown, the signal excitation coupler is connected to the coaxial cable of phase A of the protective grounding box, and a stable current signal of a certain F1 frequency that is different from the power frequency or field interference is selected by AC power supply, coupled and injected into the cross-transposed grounding system, and the output current test equipment is used to test the effective value and phase of the current response of the coaxial cables of phases A, B, and C. Similarly, the same protective grounding box is selected for the test, and the signal excitation coupler is connected to the coaxial cable of phase B and C of the protective grounding box respectively, and the effective value and phase of the current response of the coaxial cables of phases A, B, and C are obtained by testing. Based on the test results, the current and phase of the internal lead of the coaxial cable are calculated.

[0107] The equivalent circuit diagram of the same phase A coaxial cable injected with AC signal is as follows Figure 4 As shown, according to the simultaneous equations of the resistance, current and voltage parameters of the electromagnetic induction cable and the ohmic cable assembly, the resistance and inductance parameters of each branch of the cable line cross-transposition system are calculated and obtained. When any resistance of each branch of the cable cross-interconnected grounding system is greater than or equal to 0.3Ω or the ratio between the two branches exceeds 1.2, the connection defect of the cable cross-transposition grounding system is determined. The operation is simple, convenient and efficient, which fills the gap in this technical field and has good application prospects.

[0108] Example 2

[0109] Take the initial phase of the exciting coaxial cable test current signal as 0, the output current frequency of the AC current source as 70Hz, and inject the coaxial cable in phase A of the first group of cable cross-connection boxes. The test data of the coaxial cables in phases A, B, and C are as follows:

[0110] I1=5A, β1=-173.7°; IA_1=0.919, γA_1=0°; IB_1=1.712, γB_1=-139.99°; IC_1=1.168,

[0111] γC_1=70.37°.

[0112] When the coaxial cable of the first cross-connection box B is injected, the test data of the coaxial cables of A, B, and C are as follows:

[0113] I2=5A, β2=-173.77°; IA_2=0.931, γA_2=0°; IB_2=1.736, γB_2=-140.01°; IC_2=1.185,

[0114] γC_2=70.32°.

[0115] When the coaxial cable of the first cross-connection box C is injected, the test data of the coaxial cables of A, B, and C are as follows:

[0116] I3=5A, β3=-264.08; IA_3=0.001, γA_3=0°; IB_3=2.488, γB_3=-244.07°; IC_3=2.487,

[0117] γC_3=-64.10°.

[0118] Calculate the induced voltage parameters of the cross-transposed grounding system based on the above test data:

[0119] Take k1=1.6, θi=90°, i=1, 2, 3.

[0120] but,

[0121] α1=-83.70°; α2=-83.77°; α3=-174.08°.

[0122] U1∠α1=1.6*70*I1*[cosα1+j*sinα1]=P1+j*Qi=242.631+j*(-2197.446)(mV);

[0123] U2∠α2=1.6*70*I1*[cosα2+j*sinα2]=P2+j*Q2=243.032+j*(-2226.777)(mV);

[0124] U3∠α3=1.6*70*I1*[cosα2+j*sinα2]=P3+j*Q3=-2199.025+j*(-227.870)(mV);

[0125] but:

[0126] P1=242.631, Q1=-2197.446; P2=243.032, Q2=-2226.777; P3=-2199.025, Q3=-227.870.

[0127] Calculate the coaxial cable core current parameters:

[0128]

[0129] Among them, X1j, j = 1, 2, 3 are the real parts of the complex numbers IAB_1, IBC_1, ICA_1 respectively, and Y1j, j = 1, 2, 3 are the imaginary parts of the complex numbers IAB_1, IBC_1, ICA_1 respectively.

[0130] The solution is X11=-0.392, Y11=-1.100; X12=1.311, Y12=1.100; X13=-0.919, Y13=0.

[0131] Similarly, find:

[0132] X21=-0.399, Y21=-1.116; X22=1.330, Y22=1.116; X23=-0.931, Y23=0; wherein X2j, j=1, 2, 3 are the real parts of the complex numbers IAB_2, IBC_2, ICA_2 respectively, and Y2j, j=1, 2, 3 are the imaginary parts of the complex numbers IAB_2, IBC_2, ICA_2 respectively.

[0133] X31 = -1.087, Y31 = 2.237; X32 = 1.088, Y32 = -2.237; X33 = -0.001, Y33 = 0. Among them, X3j, j = 1, 2, 3 are the real parts of IAB_3, IBC_3, ICA_3 complex numbers respectively, and Y3j, j = 1, 2, 3 are the imaginary parts of IAB_3, IBC_3, ICA_3 complex numbers respectively.

[0134] Finally, according to the simultaneous equations of electromagnetic induction cable and ohmic cable assembly, the resistance and inductance parameters of each branch of the cable line cross-transposition system are calculated, which are as follows:

[0135]

[0136]

[0137] Calculate the inductance of each branch as:

[0138] L1=X1 / (2*π*F1)=411.234 / (2*π*70)=0.935mH;

[0139] L2=X2 / (2*π*F1)=418.272 / (2*π*70)=0.951mH;

[0140] L3=X2 / (2*π*F1)=416.952 / (2*π*70)=0.948mH;

[0141] L1 is the inductance of the A1-B2-C3 branch of the cross-transposed grounding system;

[0142] L2 is the inductance of the B1-C2-A3 branch of the cross-transposed grounding system;

[0143] L3 is the inductance of the C1-A2-B3 branch of the cross-transposed grounding system.

[0144] According to the cross-grounding system A1-B2-C3 branch resistance R1 = 1200mΩ greater than 300mΩ, it is judged to be a defect.

[0145] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0146] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0147] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0148] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A device for detecting defects in a high-voltage cable cross-transposition grounding system, characterized in that: Including AC power supply, signal acquisition equipment, input current test equipment, signal excitation coupler, output current test equipment and test sensor; The AC power supply is connected to the signal excitation coupler, and the AC power supply is used to provide the signal excitation coupler with an AC current that distinguishes between the power frequency and the on-site interference frequency; The signal excitation coupler is installed on the grounding lead coaxial cable at the protective grounding box of the high-voltage cable cross-transposition grounding system, and the signal excitation coupler is used to couple the AC current provided by the AC power source, which distinguishes between the power frequency and the on-site interference frequency, and inject it into the grounding lead coaxial cable at the protective grounding box of the high-voltage cable cross-transposition grounding system; The AC power supply is connected to the input current testing equipment, the input current testing equipment is connected to the signal excitation coupler, and the input current testing equipment is used to test the effective value and phase of the current output by the AC power supply; The output current test equipment is connected to the test sensor, and the test sensor is installed on the grounding lead coaxial cable at the protective grounding box of the high-voltage cable cross-transposition grounding system. The output current test equipment is used to test the effective value and phase of the current of the grounding lead coaxial cable at the protective grounding box of the high-voltage cable cross-transposition grounding system under the excitation frequency; The input current test equipment and the output current test equipment are both connected to the signal acquisition device, and the signal acquisition device is used to sample the current information output by the input current test equipment and the output current test equipment.

2. A device for detecting defects in a high-voltage cable cross-transposition grounding system according to claim 1, characterized in that: The input current testing equipment is an AC measuring equipment.

3. A method for detecting defects in a high-voltage cable cross-transposition grounding system, characterized in that: The method is implemented by using the device for detecting defects in a high-voltage cable cross-transposition grounding system according to any one of claims 1 or 2, and the method comprises: Use AC power to select a stable current signal of F1 frequency that distinguishes power frequency and field interference; The F1 frequency current stabilization signal is coupled and injected into the A-phase, B-phase and C-phase grounding lead coaxial cables of a certain protective grounding box of the high-voltage cable cross-transposed grounding system through a signal excitation coupler; Under the condition that the A-phase, B-phase and C-phase grounding lead coaxial cables are coupled and injected with the F1 frequency current stable signal, the input current test equipment is used to test the effective value and phase of the output current of the AC power supply, and the output current test equipment is used to test the effective value and phase of the current of the A-phase, B-phase and C-phase grounding lead coaxial cables at the protective grounding box of the high-voltage cable cross-transposed grounding system; Calculate the resistance of each branch of the high-voltage cable cross-transposed grounding system based on test data, including: The input current test equipment is used to test the effective value and phase of the AC power output current, and the induced voltage of the high-voltage cable cross-transposed grounding system is calculated according to the following formula: U1i∠αi=k1*F1*Ii*[cosαi+j*sinαi]=Pi+j*Qi; αi=βi+θi; Among them, U1i∠αi is the induced voltage of the high-voltage cable cross-transposed grounding system under phase αi, αi is the induced phase, Ii and βi are the effective value and phase of the AC power supply output current, Pi is the real part of the complex number U1i, Qi is the real part of the complex number U1i, k1 is the proportionality coefficient, θi is the phase difference, i=1,2,3 represents the i-th coupling injection; Calculate U1i and αi according to the test data, and then get Pi and Qi; The output current test equipment is used to test the effective value and phase of the current of the A-phase, B-phase and C-phase grounding lead coaxial cables at the protective grounding box of the high-voltage cable cross-transposed grounding system. The current and phase of the inner lead of the grounding lead coaxial cable are calculated as follows: When the A-phase grounding lead coaxial cable is coupled and injected with a stable current signal of the F1 frequency, the current and phase of the inner lead of the grounding lead coaxial cable are calculated using the following formula: Among them, IA_1, IB_1 and IC_1 are the measured current effective values ​​of the grounding lead coaxial cables of phases A, B and C when the A phase grounding lead coaxial cable is coupled and injected with the F1 frequency current stable signal, γA_1, γB_1 and γC_1 are the measured current phases of the grounding lead coaxial cables of phases A, B and C, IAB_1, IBC_1 and ICA_1 are the measured current phases of the grounding lead coaxial cables of phases A, B and C, respectively, when the A phase grounding lead coaxial cable is coupled and injected with the F1 frequency current stable signal. A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the ground lead coaxial cable, γAB_1, γBC_1 and γCA_1 are the phases of A1-B2 lead current, B1-C2 lead current and C1-A3 lead current respectively, X1j, j=1, 2, 3 are the real parts of IAB_1, IBC_1, ICA_1 complex numbers respectively, and Y1j are the imaginary parts of IAB_1, IBC_1, ICA_1 complex numbers respectively; When the B-phase grounding lead coaxial cable couples and injects a stable current signal of frequency F1, the current and phase of the inner lead of the grounding lead coaxial cable are calculated using the following formula: Among them, IA_2, IB_2 and IC_2 are the measured current effective values ​​of the grounding lead coaxial cables of phases A, B and C when the B-phase grounding lead coaxial cable is coupled and injected with the F1 frequency current stable signal, γA_2, γB_2 and γC_2 are the measured current phases of the grounding lead coaxial cables of phases A, B and C, and IAB_2, IBC_2 and ICA_2 are the measured current effective values ​​of the grounding lead coaxial cables of phases B when the F1 frequency current stable signal is injected into the grounding lead coaxial cable. A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the ground lead coaxial cable, γAB_2, γBC_2 and γCA_2 are the phases of A1-B2 lead current, B1-C2 lead current and C1-A3 lead current respectively, X2j, j=1, 2, 3 are the real parts of IAB_2, IBC_2, ICA_2 complex numbers respectively, Y2j are the imaginary parts of IAB_2, IBC_2, ICA_2 complex numbers respectively; When the C-phase grounding lead coaxial cable couples and injects a stable current signal of frequency F1, the current and phase of the inner lead of the grounding lead coaxial cable are calculated using the following formula: Among them, IA_3, IB_3 and IC_3 are the measured current effective values ​​of the grounded lead coaxial cables of phases A, B and C when the C phase grounded lead coaxial cable is coupled and injected with the F1 frequency current stable signal, γA_3, γB_3 and γC_3 are the measured current phases of the grounded lead coaxial cables of phases A, B and C, and IAB_3, IBC_3 and ICA_3 are the measured current effective values ​​of the grounded lead coaxial cables of phases C when the C phase grounded lead coaxial cable is coupled and injected with the F1 frequency current stable signal. A1-B2 lead current, B1-C2 lead current and C1-A3 lead current inside the ground lead coaxial cable, γAB_3, γBC_3 and γCA_3 are the phases of A1-B2 lead current, B1-C2 lead current and C1-A3 lead current respectively, X3j, j=1, 2, 3 are the real parts of IAB_3, IBC_3, ICA_3 complex numbers respectively, Y3j are the imaginary parts of IAB_3, IBC_3, ICA_3 complex numbers respectively; The following formula is used to calculate the resistance of each branch of the high-voltage cable cross-transposed grounding system: Among them, R1, R2 and R3 are the A1-B2-C3 branch resistance, B1-C2-A3 branch resistance and C1-A2-B3 branch resistance of the high-voltage cable cross-transposition grounding system respectively; X1, X2 and X3 are the A1-B2-C3 branch inductance, B1-C2-A3 branch inductance and C1-A2-B3 branch inductance of the high-voltage cable cross-transposition grounding system respectively; Defects in the high-voltage cable cross-transposed grounding system are determined based on the calculated resistance.

4. A method for detecting defects in a high-voltage cable cross-transposition grounding system according to claim 3, characterized in that: If any of the following two conditions are met, the high-voltage cable cross-transposition grounding system is determined to be defective: A. In the high-voltage cable cross-transposition grounding system, at least one branch resistance of each branch is greater than or equal to 0.3Ω; B. Among the pairwise ratios of the branch resistances in the high-voltage cable cross-transposition grounding system, at least one exceeds 1.2.

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