A method, device and electronic equipment for measuring the insulation resistance of high-voltage cable outer sheath

Abstract

The present invention discloses a method, device, and electronic device for measuring the insulation resistance of a high-voltage cable outer sheath. The method comprises: while the high-voltage cable is in operation, measuring the voltage and current at both ends of the aluminum sheath of each cross-connected segment of the high-voltage cable to obtain corresponding voltage and current phasors, respectively; and calculating the voltage and current phasors using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath. This method allows the insulation state of the high-voltage cable outer sheath to be determined without stopping the high-voltage cable, and the insulation resistance value of the high-voltage cable outer sheath at the corresponding time.

Description

Technical Field

[0001] The present invention relates to the field of high voltage and insulation technology, and in particular to a method, device and electronic equipment for measuring the insulation resistance of a high voltage cable outer sheath. Background Art

[0002] The current electricity economy and people's electricity demand are constantly rising, leading to a growing concern for the power system. Power cables are a vital part of the power system's transmission and distribution of electrical energy. The outer sheath of the power cable is the first line of defense for protecting the power cable, and its integrity is crucial to the cable's service life.

[0003] With the increasing complexity of my country's cable-laying environment and the rapid development of high-speed railways and urban subways, an increasing number of high-voltage cross-linked polyethylene cables are being laid within railway bridges and cable tunnels. Older cables are inevitably subject to various types of damage. High-voltage cables laid in cable tunnels, railway bridges, and other environments are often subjected to long-term vibrations of specific frequencies, leading to fatigue damage, cracking of the cable sheath, and cracking and deformation of the metal sheath. Furthermore, with economic development, construction workers often carry out road reconstruction, which can easily cause cable deformation during installation, making the cable sheath structure more susceptible to damage. This can lead to increased current circulating around the cable's metal sheath, reducing the transmission capacity of the cable line, and even corroding the metal sheath, compromising the cable's primary insulation, leading to insulation breakdown and accidents.

[0004] High-voltage cables primarily refer to power cables with a rated voltage of 110kV and above. These cables are primarily constructed of a conductor, a three-layer co-extruded insulation system, a buffer water-blocking layer, a sealed metal sheath, and an outer sheath. The outer sheath also has a semi-conductive layer on its surface. Typically, they are laid in a cross-connected pattern. When the insulation of the cable's outer sheath is damaged and grounded, a large current flows through it, creating an imbalance in the induced voltage across the sheath. The induced voltages across the three sheath sections in the cross-connected system cannot be fully offset, and the induced current in the metal sheath will vary significantly. Damage to cable sheaths caused by power grid construction, such as cable laying, is common, and most of this damage is structural. Currently, data on cable sheath structural damage is scarce.

[0005] Because the insulation performance of the high-voltage power cable outer sheath directly affects the safe and economical operation and service life of the cable line, the outer sheath electrical insulation performance is tested and required during the cable's factory test, arrival inspection, handover test, and periodic preventive test. The factory test is a test performed by the manufacturer on all manufactured lengths of cable to verify whether the specified requirements are met. It is also called a routine test. Regarding the electrical insulation properties of the cable outer sheath, the standards have consistent provisions and require that the cable outer sheath should be able to withstand a DC voltage of 25kV for 1 minute without breakdown when the product leaves the factory. This test is usually performed in the manufacturer using a DC withstand voltage tester and is performed on 100% of the cables leaving the factory. It can ensure the electrical properties of the outer sheath of the delivered cable.

[0006] The traditional method of measuring the insulation resistance of the high-voltage cable outer sheath is usually to use a megohmmeter to measure it when the high-voltage cable is out of service. The outer sheath insulation resistance value of the high-voltage cable in operation can only be measured with a megohmmeter when it stops running. However, in actual engineering, this method has a certain delay, that is, this method cannot be used to measure the high-voltage cable in operation, because there is a circulating current flowing through the outer sheath of the cable when the cable is running, causing interference. When the outer sheath of the high-voltage cable is damaged or other faults occur, it cannot be discovered in time to stop the damage. Offline measurement can only be performed when the high-voltage cable fails. When using a megohmmeter to measure the insulation resistance of the high-voltage cable sheath, due to test time limitations, the measured value is not equal to the voltage and current that the sheath withstands when the cable is running, so the megohmmeter measurement value cannot fully reflect the insulation status of the high-voltage cable sheath. Summary of the Invention

[0007] The present invention provides a method, device and electronic equipment for measuring the insulation resistance of a high-voltage cable outer sheath, so as to solve the problem that when a fault such as damage occurs in the high-voltage cable outer sheath, the damage cannot be discovered and stopped in time, and only offline measurement can be performed, and the insulation status of the high-voltage cable sheath is inaccurately reflected.

[0008] According to one aspect of the present invention, a method for measuring the insulation resistance of a high-voltage cable outer sheath is provided, the method comprising:

[0009] When the high-voltage cable is in operation, voltage and current are measured at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable to obtain corresponding voltage phasors and current phasors respectively;

[0010] The voltage phasor and the current phasor are operated according to Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath.

[0011] Optionally, the high-voltage cable aluminum sheath circulating current includes: leakage current flowing from the cable core of the high-voltage cable through the cross-linked polyethylene insulation layer to the aluminum sheath, current generated by the induced voltage induced on the aluminum sheath by the cable core of this phase under the action of the magnetic field, and current generated by the voltage induced on the aluminum sheath of this phase by the cable core of other phases acting on the aluminum sheath of the cable.

[0012] Optionally, measuring the current at both ends of the aluminum sheath of each cross-connected section of the high-voltage cable to obtain the corresponding current phasor includes:

[0013] According to the following formula, the sheath current of the high-voltage cable aluminum sheath is induced by the inductor coil to the current transformer for effective value and phase acquisition to obtain the corresponding current phasor, specifically:

[0014] I1=[I 11 I 12 I 13 ]

[0015] I2=[I 21 I 22 I 23 ]

[0016] I3=[I 31 I 32 I 33 ]

[0017] I4=[I 41 I 42 I 43 ]

[0018] Wherein, [I1 I2 I3 I4] is the current phasor;

[0019] [I 11 I 12 I 13 I 21 I 22 I 23 I 31 I 32 I 33 I 41 I 42 I 43 ] is the measured current at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable.

[0020] Optionally, the voltage of the aluminum sheath of the high-voltage cable to the ground includes: the voltage generated by the magnetic field of the current phase cable core acting on the aluminum sheath, the induced voltage generated by the other phase cable cores acting on the aluminum sheath of the current phase, and the voltage generated by the leakage current flowing from the cable core to the aluminum sheath through the cross-linked polyethylene insulation layer.

[0021] Optionally, measuring the voltage at both ends of the aluminum sheath of each cross-connected section of the high-voltage cable to obtain the corresponding voltage phasor includes:

[0022] According to the following formula, the voltage between the aluminum sheath of the high-voltage cable and the ground is measured by voltage transformer for effective value and phase acquisition. The voltage is measured at the first direct grounding box, the second direct grounding box, the first cross-connection box, and the second cross-connection box to obtain the corresponding voltage phasor, which is specifically:

[0023] U1=[U 11 U 12 U 13 ]

[0024] U2=[U 21 U 22 U 23 ]

[0025] U3=[U 31 U 32 U 33 ]

[0026] U4=[U 41 U 42 U 43 ]

[0027] Wherein, [U1 U2 U3 U4] is the voltage phasor;

[0028] [U 11 U 12 U 13 U 21 U 22 U 23 U 31 U 32 U 33 U 41 U 42 U 43 ] is the measured voltage across the aluminum sheath of each cross-connection section of the high-voltage cable.

[0029] Optionally, before calculating the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, the method further includes:

[0030] The insulation resistance of the outer sheath of the nine-section high-voltage cable is defined as three diagonal arrays according to the order of the cross-connected segments from the power supply end to the load end. The value of the main diagonal line of each diagonal array corresponds to the insulation resistance of the outer sheath of the cross-connected segment, specifically:

[0031] R1=diag[R 11R 12 R 13 ]

[0032] R2=diag[R 21 R 22 R 23 ]

[0033] R3=diag[R 31 R 32 R 33 ]

[0034] Among them, [R1 R2 R3] is the outer sheath insulation resistance value of each cross-connected section on the high-voltage cable

[0035] [R 11 R 12 R 13 R 21 R 22 R 23 R 31 R 32 R 33 ] is the calculated resistance of the aluminum sheath of each cross-connection section in the high-voltage cable cross-connection section.

[0036] Optionally, the voltage phasor and the current phasor are operated using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, including:

[0037] The insulation resistance value of the high-voltage cable outer sheath is obtained by calculating the voltage phasor and the current phasor using the following formula, specifically:

[0038] (1 / 2)*(U1+U2)=(I1-I2)diag[R 11 R 12 R 13 ]

[0039] (1 / 2)*(U2+U3)=(I3-I2)diag[R 21 R 22 R 23 ].

[0040] (1 / 2)*(U3+U4)=(I4-I3)diag[R 31 R 32 R 33 ]

[0041] According to another aspect of the present invention, a device for measuring the insulation resistance of a high-voltage cable outer sheath is provided, the device comprising:

[0042] The current and voltage measurement module is used to perform voltage and current measurements at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable when the high-voltage cable is in operation, and obtain corresponding voltage phasors and current phasors respectively;

[0043] The outer sheath insulation resistance measurement module is used to perform operations on the voltage phasor and the current phasor through Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath.

[0044] According to another aspect of the present invention, an electronic device is provided, comprising:

[0045] at least one processor; and

[0046] a memory communicatively connected to the at least one processor; wherein,

[0047] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the high-voltage cable outer sheath insulation resistance measuring method according to any embodiment of the present invention.

[0048] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the high-voltage cable outer sheath insulation resistance measurement method according to any embodiment of the present invention when executed.

[0049] The technical solution of the embodiment of the present invention measures the voltage and current at both ends of the aluminum sheath of each cross-interconnected section of the high-voltage cable while the high-voltage cable is in operation, obtaining corresponding voltage phasors and current phasors respectively; and calculating the voltage phasors and current phasors using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath. This solves the problem that when the high-voltage cable outer sheath is damaged, the damage cannot be detected and stopped in time, and only offline measurement can be performed, and the insulation state of the high-voltage cable sheath is inaccurately reflected. It is possible to judge the insulation state of the high-voltage cable outer sheath without stopping the high-voltage cable and obtain the insulation resistance value of the high-voltage cable outer sheath at the corresponding time.

[0050] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 This is a flow chart of a method for measuring the insulation resistance of a high-voltage cable outer sheath provided in accordance with the first embodiment of the present invention;

[0053] Figure 2 Schematic diagram of the generation cause and distribution principle of leakage current flowing from the cable core of a high-voltage cable to the aluminum sheath through the cross-linked polyethylene insulation layer according to an embodiment of the present invention;

[0054] Figure 3 is a schematic diagram of a high-voltage cable cross-connection structure applicable to an embodiment of the present invention;

[0055] Figure 4 is a schematic diagram of the components of the induced voltage on the aluminum sheath of a high-voltage cable applicable to an embodiment of the present invention;

[0056] Figure 5 Schematic diagram of the voltage to ground and sheath current components of the aluminum sheath of a high-voltage cable applicable to an embodiment of the present invention;

[0057] Figure 6 This is a structural diagram of a device for measuring the insulation resistance of a high-voltage cable outer sheath provided according to a second embodiment of the present invention;

[0058] Figure 7 The present invention is a schematic structural diagram of an electronic device for implementing the method for measuring the insulation resistance of a high-voltage cable outer sheath according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0060] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0061] Example 1

[0062] Figure 1 A flowchart of a method for measuring the insulation resistance of a high-voltage cable outer sheath is provided for the first embodiment of the present invention. This embodiment is applicable to the case where the insulation resistance of a high-voltage cable outer sheath is measured without stopping the high-voltage cable. The method for measuring the insulation resistance of a high-voltage cable outer sheath can be performed by a high-voltage cable outer sheath insulation resistance measuring device. The high-voltage cable outer sheath insulation resistance measuring device can be implemented in the form of hardware and / or software. The high-voltage cable outer sheath insulation resistance measuring device can be configured in an electronic device of a high-voltage power system. Figure 1 As shown, the method for measuring the insulation resistance of the high-voltage cable outer sheath includes:

[0063] S110. When the high-voltage cable is in operation, voltage and current are measured at both ends of the aluminum sheath of each cross-interconnected section of the high-voltage cable to obtain corresponding voltage phasors and current phasors, respectively.

[0064] Among them, voltage measurement and current measurement can be achieved through voltage transformer and current transformer respectively.

[0065] The mutual inductance coil, a measuring tool for the current transformer, should be placed on the cable aluminum sheath lead-out wires of the first direct grounding box, the second direct grounding box, the first cross-connection box, and the second cross-connection box. The cable aluminum sheath current is the vector sum of the currents on the aluminum sheath, and the current on the cable aluminum sheath is the industrial frequency AC current. The mutual inductance principle between inductors is used to induce the sheath current of the high-voltage cable aluminum sheath through the inductance coil to the current transformer for effective value and phase acquisition to obtain the corresponding current phasor.

[0066] Voltage measurement uses a voltage transformer, whose principle is a mutual inductance transformer. The voltage between the aluminum sheath of the high-voltage cable and the ground is measured and collected in effective value and phase through the voltage transformer. The measurement is performed at the first direct grounding box, the second direct grounding box, the first cross-connection box, and the second cross-connection box to obtain the corresponding voltage phasor.

[0067] On the basis of the above, see Figure 2 In the current measurement step, the high-voltage cable aluminum sheath circulating current includes: the leakage current I flowing from the cable core of the high-voltage cable through the cross-linked polyethylene insulation layer to the aluminum sheath, the current I generated by the induced voltage induced on the aluminum sheath under the action of the magnetic field of the cable core of the phase acting on the cable aluminum sheath L The voltage induced by other phase cable cores on the aluminum sheath of the phase acts on the aluminum sheath of the cable to generate the current I R .

[0068] Among them, the leakage current I of the high-voltage cable core flows through the cross-linked polyethylene insulation layer to the aluminum sheath. Since the equivalent conductance of cross-linked polyethylene is much smaller than the equivalent susceptance, Y C , so the leakage current is mainly capacitive current; the induced voltage induced on the aluminum sheath under the action of the magnetic field of the cable core acts on the current I generated on the cable aluminum sheath L The purpose of cross-connection is to offset the current generated by this part of the voltage; the voltage induced by other phase cable cores on the aluminum sheath of the phase acts on the aluminum sheath of the cable to generate the current I R Based on the above, the current in the aluminum sheath of the high-voltage cable to be measured is the vector sum of the three currents on the sheath.

[0069] Since the current in the aluminum sheath of the high-voltage cable is an AC current at industrial frequency, it is necessary to measure not only the effective value of the current but also the phase of the current in order to facilitate calculation. Figure 3 The schematic diagram of the high-voltage cable cross-connection system is shown. According to the following formula, the sheath current of the high-voltage cable aluminum sheath is induced by the inductor coil to the current transformer for effective value and phase acquisition to obtain the corresponding current phasor. The twelve measured current phasors are divided into three groups from the power end to the load end according to different cross-connection sections, specifically:

[0070] I1=[I 11 I 12 I 13 ]

[0071] I2=[I 21 I 22 I 23 ]

[0072] I3=[I 31 I 32 I 33 ]

[0073] I4=[I 41 I 42 I 43 ]

[0074] Wherein, [I1 I2 I3 I4] is the current phasor;

[0075] [I 11 I 12 I 13 I 21 I 22 I 23 I 31 I 32 I 33 I 41 I 42 I 43 ] is the measured current at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable.

[0076] Depend on Figure 3 As shown, I 11 is the current flowing into the first end of the cable aluminum sheath A1 from the first direct grounding box, I 12 is the current flowing into the first end of the cable aluminum sheath B1 from the first direct grounding box, I 13 I is the current flowing into the first end of the cable aluminum sheath C1 from the first direct grounding box; 21 is the current flowing from the second end of the cable aluminum sheath A1 to the first end of the first cross-connection box, I 22 is the current flowing from the second end of the cable aluminum sheath B1 to the first end of the first cross-connection box, I 23 I is the current flowing from the second end of the cable aluminum sheath C1 to the first end of the first cross-connection box; 23 is the current flowing from the second end of the first cross-connection box into the first end of the cable aluminum sheath A2, I 21 is the current flowing from the second end of the first cross-connection box into the first end of the cable aluminum sheath B2, I 22 I is the current flowing from the second end of the first cross-connection box into the first end of the cable aluminum sheath C2; 31 is the current flowing from the second end of the cable aluminum sheath A2 to the first end of the second cross-connection box, I 32 is the current flowing from the second end of the cable aluminum sheath B2 into the first end of the second cross-connection box, I 33 I is the current flowing from the second end of the cable aluminum sheath C2 to the first end of the second cross-connection box; 33 is the current flowing from the second end of the second cross-connection box into the first end of the cable aluminum sheath A3, I 31 is the current flowing from the second end of the second cross-connection box into the first end of the cable aluminum sheath B3, I 32 I is the current flowing from the second end of the second cross-connection box into the first end of the cable aluminum sheath C3; 41 I is the current flowing from the second end of the cable aluminum sheath A3 into the second directly grounded box, 42is the current flowing from the second end of the cable aluminum sheath B3 into the second directly grounded box, I 43 This is the current flowing into the second directly grounded box from the second end of the cable aluminum sheath C3.

[0077] On the basis of the above, see Figure 4 and Figure 5 In the current measurement step, at the grounding box, connect the voltage transformer measuring coil to the ground wire and lead the ground wire out of the cable aluminum sheath. The effective value and phase of the voltage are measured by the mutual inductance transformation principle. The grounding resistance value at this location can be measured by a grounding resistance measuring instrument, and the voltage phasor value at this location is calculated from the grounding resistance value and the grounding current at this location.

[0078] Specifically, the voltage between the high-voltage cable's aluminum sheath and ground consists of the voltage generated by the magnetic field of the cable core acting on the aluminum sheath, the induced voltage generated by the magnetic field of the cable core of the other phase acting on the aluminum sheath of the cable core, and the voltage caused by leakage current flowing from the cable core through the cross-linked polyethylene insulation layer to the aluminum sheath. Based on the above, the voltage between the high-voltage cable's aluminum sheath and ground to be measured is the vector sum of these three voltage components.

[0079] At the cross-connection box, a voltage transformer is connected to the cable's aluminum sheath lead wire and the ground wire. The voltage across the aluminum sheath at that end is measured. Each cross-connection segment has two voltage values. Considering the sheath line loss, the average voltage across the cable's aluminum sheath is used as the calculated voltage. The twelve measured voltage phasors are divided into three groups based on the order of the cross-connection segments at the power and load ends. These are defined as voltage row vectors, specifically:

[0080] U1=[U 11 U 12 U 13 ]

[0081] U2=[U 21 U 22 U 23 ]

[0082] U3=[U 31 U 32 U 33 ]

[0083] U4=[U 41 U 42 U 43 ]

[0084] Wherein, [U1 U2 U3 U4] is the voltage phasor;

[0085] [U 11 U 12 U 13 U 21 U 22 U23 U 31 U 32 U 33 U 41 U 42 U 43 ] is the measured voltage across the aluminum sheath of each cross-connection section of the high-voltage cable.

[0086] S120. Calculate the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath.

[0087] In the step of solving the insulation resistance of the high-voltage cable outer sheath in this embodiment, the matrix operation relationship between the voltage phasor, the current phasor, and the insulation resistance is shown in the following formula. The nine-segment high-voltage cable outer sheath insulation resistance is defined as three diagonal matrices in the order of the cross-connected segments from the power end to the load end. The value of the main diagonal line of each diagonal matrix corresponds to the outer sheath insulation resistance of the cross-connected segment, specifically:

[0088] R1=diag[R 11 R 12 R 13 ]

[0089] R2=diag[R 21 R 22 R 23 ]

[0090] R3=diag[R 31 R 32 R 33 ]

[0091] ∑I=0

[0092] U=R*I

[0093] Where [R1 R2 R3] is the outer sheath insulation resistance value of each cross-connection section on the high-voltage cable;

[0094] [R 11 R 12 R 13 R 21 R 22 R 23 R 31 R 32 R 33 ] is the calculated resistance of the aluminum sheath of each cross-connection section in the high-voltage cable cross-connection section.

[0095] The voltage of the high-voltage cable outer sheath insulation resistance is defined as the average voltage of the cross-connected section. According to Kirchhoff's current law, the current difference between the two ends of the aluminum sheath of each cable section is the cable outer sheath leakage current. According to Ohm's law, the relationship between the current phasor, voltage phasor and cable outer sheath insulation resistance is obtained as follows:

[0096] (1 / 2)*(U1+U2)=(I1-I2)diag[R 11 R 12 R 13 ]

[0097] (1 / 2)*(U2+U3)=(U3-I2)diag[R 21 R 22 R 23 ]

[0098] (1 / 2)*(U3+U4)=(I4-I3)diag[R 31 R 32 R 33 ]

[0099] When the insulation state of the high-voltage cable outer sheath is normal, the insulation resistance value of the high-voltage cable outer sheath is very large, and the leakage current flowing through the high-voltage cable outer sheath is very small. When a ground fault occurs in the high-voltage cable outer sheath, the insulation resistance value of the high-voltage cable outer sheath will drop significantly. The high-voltage cable outer sheath insulation resistance measurement method provided by this embodiment can obtain the cable outer sheath insulation resistance value at the corresponding time.

[0100] The technical solution of the embodiment of the present invention measures the voltage and current at both ends of the aluminum sheath of each cross-interconnected section of the high-voltage cable while the high-voltage cable is in operation, obtaining corresponding voltage phasors and current phasors respectively; and calculating the voltage phasors and current phasors using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath. This solves the problem that when the high-voltage cable outer sheath is damaged, the damage cannot be detected and stopped in time, and only offline measurement can be performed, and the insulation state of the high-voltage cable sheath is inaccurately reflected. It is possible to judge the insulation state of the high-voltage cable outer sheath without stopping the high-voltage cable and obtain the insulation resistance value of the high-voltage cable outer sheath at the corresponding time.

[0101] Example 2

[0102] Figure 6 This is a schematic diagram of the structure of a high-voltage cable outer sheath insulation resistance measuring device provided by the third embodiment of the present invention. Figure 6 As shown, the high-voltage cable outer sheath insulation resistance measuring device includes:

[0103] The current and voltage measurement module 610 is used to perform voltage and current measurements at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable when the high-voltage cable is in operation, and obtain corresponding voltage phasors and current phasors respectively;

[0104] The outer sheath insulation resistance measurement module 620 is configured to calculate the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath.

[0105] Optionally, the high-voltage cable aluminum sheath circulating current includes: leakage current flowing from the cable core of the high-voltage cable through the cross-linked polyethylene insulation layer to the aluminum sheath, current generated by the induced voltage induced on the aluminum sheath by the cable core of this phase under the action of the magnetic field, and current generated by the voltage induced on the aluminum sheath of this phase by the cable core of other phases acting on the aluminum sheath of the cable.

[0106] Optionally, measuring the current at both ends of the aluminum sheath of each cross-connected section of the high-voltage cable to obtain the corresponding current phasor includes:

[0107] According to the following formula, the sheath current of the high-voltage cable aluminum sheath is induced by the inductor coil to the current transformer for effective value and phase acquisition to obtain the corresponding current phasor, specifically:

[0108] I1=[I 11 I 12 I 13 ]

[0109] I2=[I 21 I 22 I 23 ]

[0110] I3=[I 31 I 32 I 33 ]

[0111] I4=[I 41 I 42 I 43 ]

[0112] Wherein, [I1 I2 I3 I4] is the current phasor;

[0113] [I 11 I 12 I 13 I 21 I 22 I 23 I 31 I 32 I 33 I41 I 42 I 43 ] is the measured current at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable.

[0114] Optionally, the voltage of the aluminum sheath of the high-voltage cable to the ground includes: the voltage generated by the magnetic field of the current phase cable core acting on the aluminum sheath, the induced voltage generated by the other phase cable cores acting on the aluminum sheath of the current phase, and the voltage generated by the leakage current flowing from the cable core to the aluminum sheath through the cross-linked polyethylene insulation layer.

[0115] Optionally, measuring the voltage at both ends of the aluminum sheath of each cross-connected section of the high-voltage cable to obtain the corresponding voltage phasor includes:

[0116] According to the following formula, the voltage between the aluminum sheath of the high-voltage cable and the ground is measured by voltage transformer for effective value and phase acquisition. The voltage is measured at the first direct grounding box, the second direct grounding box, the first cross-connection box, and the second cross-connection box to obtain the corresponding voltage phasor, which is specifically:

[0117] U1=[U 11 U 12 U 13 ]

[0118] U2=[U 21 U 22 U 23 ]

[0119] U3=[U 31 U 32 U 33 ]

[0120] U4=[U 41 U 42 U 43 ]

[0121] Wherein, [U1 U2 U3 U4] is the voltage phasor;

[0122] [U 11 U 12 U 13 U 21 U 22 U 23 U 31 U 32 U 33 U 41 U 42 U 43 ] is the measured voltage across the aluminum sheath of each cross-connection section of the high-voltage cable.

[0123] Optionally, before calculating the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, the method further includes:

[0124] The insulation resistance of the outer sheath of the nine-section high-voltage cable is defined as three diagonal arrays according to the order of the cross-connected segments from the power supply end to the load end. The value of the main diagonal line of each diagonal array corresponds to the insulation resistance of the outer sheath of the cross-connected segment, specifically:

[0125] R1=diag[R 11 R 12 R 13 ]

[0126] R2=diag[R 21 R 22 R 23 ]

[0127] R3=diag[R 31 R 32 R 33 ]

[0128] Among them, [R1 R2 R3] is the outer sheath insulation resistance value of each cross-connected section on the high-voltage cable

[0129] [R 11 R 12 R 13 R 21 R 22 R 23 R 31 R 32 R 33 ] is the calculated resistance of the aluminum sheath of each cross-connection section in the high-voltage cable cross-connection section.

[0130] Optionally, the voltage phasor and the current phasor are operated using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, including:

[0131] The insulation resistance value of the high-voltage cable outer sheath is obtained by calculating the voltage phasor and the current phasor using the following formula, specifically:

[0132] (1 / 2)*(U1+U2)=(I1-I2)diag[R 11 R 12 R 13 ]

[0133] (1 / 2)*(U2+U3)=(I3-I2)diag[R 21 R 22 R 23 ].

[0134] (1 / 2)*(U3+U4)=(I4-I3)diag[R 31 R 32 R 33 ]

[0135] The high-voltage cable outer sheath insulation resistance measuring device provided in the embodiment of the present invention can execute the high-voltage cable outer sheath insulation resistance measuring method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects for executing the high-voltage cable outer sheath insulation resistance measuring method.

[0136] Example 3

[0137] Figure 7 A schematic diagram of the structure of an electronic device 10 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0138] like Figure 7 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., which is communicatively connected to the at least one processor 11. The memory stores a computer program that can be executed by the at least one processor. The processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 into the random access memory (RAM) 13. Various programs and data required for the operation of the electronic device 10 can also be stored in the RAM 13. The processor 11, ROM 12, and RAM 13 are connected to each other via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0139] Multiple components in the electronic device 10 are connected to the I / O interface 15, including an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a magnetic disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0140] The processor 11 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various specialized artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as the method for measuring the insulation resistance of the high-voltage cable outer sheath.

[0141] In some embodiments, the high-voltage cable outer sheath insulation resistance measuring method can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the high-voltage cable outer sheath insulation resistance measuring method described above can be performed. Alternatively, in other embodiments, the processor 11 can be configured to execute the high-voltage cable outer sheath insulation resistance measuring method in any other appropriate manner (for example, by means of firmware).

[0142] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0143] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0144] In the context of the present invention, computer-readable storage media can be tangible media that can contain or store a computer program for use with an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. Computer-readable storage media can include but are not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, computer-readable storage media can be machine-readable signal media. More specific examples of machine-readable storage media can include electrical connections based on one or more lines, portable computer disks, hard disks, random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memory), optical fibers, portable compact disk read-only memories (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0145] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0146] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0147] A computing system may include clients and servers. The clients and servers are typically remote from each other and typically interact via a communication network. This client-server relationship arises through computer programs running on the respective computers, creating a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a hosting product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosting and VPS services.

[0148] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present invention can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved. This is not limited herein.

[0149] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for measuring the insulation resistance of a high-voltage cable outer sheath, characterized in that: include: When the high-voltage cable is in operation, voltage and current are measured at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable to obtain corresponding voltage phasors and current phasors respectively; Calculating the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath; The voltage measurement is performed on both ends of the aluminum sheath of each cross-connection section of the high-voltage cable to obtain the corresponding voltage phasor, including: According to the following formula, the voltage between the aluminum sheath of the high-voltage cable and the ground is measured by voltage transformer for effective value and phase acquisition. The voltage is measured at the first direct grounding box, the second direct grounding box, the first cross-connection box, and the second cross-connection box to obtain the corresponding voltage phasor, which is specifically: U1=[U 11 U 12 U 13 ] U2=[U 21 U 22 U 23 ] U3=[U 31 YOU 32 YOU 33 ] U4=[U 41 And 42 And 43 ] Wherein, [U1 U2 U3 U4] is the voltage phasor; [U 11 U 12 U 13 U 21 U 22 U 23 U 31 U 32 U 33 U 41 U 42 U 43 ] is the measured voltage across the aluminum sheath of each cross-connection section of the high-voltage cable.

2. The method for measuring the insulation resistance of the high-voltage cable outer sheath according to claim 1, characterized in that: The high-voltage cable aluminum sheath circulating current includes: leakage current flowing from the cable core of the high-voltage cable through the cross-linked polyethylene insulation layer to the aluminum sheath, current generated by the induced voltage induced on the aluminum sheath by the cable core under the action of the magnetic field of the same phase and acting on the cable aluminum sheath, and current generated by the voltage induced on the aluminum sheath of the other phase cable core and acting on the cable aluminum sheath.

3. The method for measuring the insulation resistance of the high-voltage cable outer sheath according to claim 2, characterized in that: The current is measured at both ends of the aluminum sheath of each cross-connected section of the high-voltage cable to obtain the corresponding current phasor, including: According to the following formula, the sheath current of the high-voltage cable aluminum sheath is induced by the inductor coil to the current transformer for effective value and phase acquisition to obtain the corresponding current phasor, specifically: I1=[I 11 I 12 I 13 ] I2=[I 21 I 22 I 23 ] I3=[I 31 I 32 I 33 ] I4=[I 41 I 42 I 43 ] Wherein, [I1 I2 I3 I4] is the current phasor; [I 11 I 12 I 13 I 21 I 22 I 23 I 31 I 32 I 33 I 41 I 42 I 43 ] is the measured current at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable.

4. The method for measuring the insulation resistance of the high-voltage cable outer sheath according to claim 3, characterized in that: The voltage of the aluminum sheath of the high-voltage cable to the ground includes: the voltage generated by the magnetic field of the cable core of this phase acting on the aluminum sheath, the induced voltage generated by the cable cores of other phases acting on the aluminum sheath of this phase, and the voltage generated by the leakage current flowing from the cable core to the aluminum sheath through the cross-linked polyethylene insulation layer.

5. The method for measuring the insulation resistance of the high-voltage cable outer sheath according to claim 1, characterized in that: Before calculating the voltage phasor and the current phasor using Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, the method further includes: The insulation resistance of the outer sheath of the nine-section high-voltage cable is defined as three diagonal arrays according to the order of the cross-connected segments from the power supply end to the load end. The value of the main diagonal line of each diagonal array corresponds to the insulation resistance of the outer sheath of the cross-connected segment, specifically: R1=diag[R 11 R 12 R 13 ] R2=diag[R 21 R 22 R 23 ] R3=diag[R 31 R 32 R 33 ] Where [R1 R2 R3] is the outer sheath insulation resistance value of each cross-connection section on the high-voltage cable; [R 11 R 12 R 13 R 21 R 22 R 23 R 31 R 32 R 33 ] is the calculated resistance of the aluminum sheath of each cross-connection section in the high-voltage cable cross-connection section.

6. The method for measuring the insulation resistance of the high-voltage cable outer sheath according to claim 5, characterized in that: The voltage phasor and the current phasor are operated by Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath, including: The insulation resistance value of the high-voltage cable outer sheath is obtained by calculating the voltage phasor and the current phasor using the following formula, specifically:

7. A device for measuring the insulation resistance of a high-voltage cable outer sheath, controlled by the method for measuring the insulation resistance of a high-voltage cable outer sheath according to any one of claims 1 to 6, characterized in that: include: The current and voltage measurement module is used to perform voltage and current measurements at both ends of the aluminum sheath of each cross-connection section of the high-voltage cable when the high-voltage cable is in operation, and obtain corresponding voltage phasors and current phasors respectively; The outer sheath insulation resistance measurement module is used to perform operations on the voltage phasor and the current phasor through Kirchhoff's law and Ohm's law to obtain the insulation resistance value of the high-voltage cable outer sheath.

8. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor. The computer program is executed by the at least one processor to enable the at least one processor to perform the high-voltage cable outer sheath insulation resistance measuring method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the high-voltage cable outer sheath insulation resistance measurement method according to any one of claims 1 to 6 when executed.

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