Multi-circuit high-voltage cable fault calculation method and device, electronic equipment and medium

Abstract

The application discloses a kind of multi-loop high-voltage cable fault calculation method, device, electronic equipment and medium.The multi-loop high-voltage cable fault calculation method includes: when the asymmetric ground short circuit of high-voltage cable metal sheath occurs, asymmetric ground short circuit is converted into target symmetric three-phase short circuit by symmetric component method, and the asymmetric ground short circuit includes single-phase ground short circuit and two-phase ground short circuit;Based on the principle of multi-loop high-voltage cable metal sheath circulating current calculation, the target symmetric three-phase short circuit is calculated, the insulation state of high-voltage cable is determined, to calculate the corresponding multi-loop high-voltage cable fault according to the insulation state.This embodiment studies the insulation state of high-voltage cable line, anticipates high-voltage cable insulation state and takes corresponding measures, which is beneficial to the safety and reliability of high-voltage cable transmission line.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable, in particular to a multi-loop high-voltage cable fault calculation method and device, electronic equipment and medium. BACKGROUND

[0002] With the acceleration of urbanization construction, the available land resources in the transmission, transformation and distribution engineering construction are becoming more and more nervous. Due to the large land occupation and the difficulty in obtaining the path corridor, the overhead line is not so suitable in the urban power distribution network. The cable can be classified according to the different insulation materials, which can be divided into oil-immersed paper insulated cable, rubber insulated cable, plastic insulated cable and air-filled cable. At present, the commonly used one is XLPE cable (crosslinked polyethylene cable). Although the electrical performance of the XLPE cable is superior, due to the limitation of the manufacturing process, there will be air gap, impurities, protruding burrs and other defects in the insulation layer during production. Under the long-term effect of strong electric field, combined with the comprehensive effect of heat effect, mechanical stress, chemical corrosion and other external factors, the aging phenomena such as electrical treeing and water treeing will occur in the insulation, which will eventually lead to insulation breakdown and cause safety accidents and economic losses.

[0003] The high-voltage cable generally adopts a single-core structure, and the metal sheath of the high-voltage cable selects an aluminum sheath. When the core flows through an alternating current, a certain induced voltage will be formed on the metal sheath of the high-voltage cable. When the high-voltage cable insulation is aged and broken down to form a loop with the ground, the induced voltage will generate a sheath induced circulating current in the loop. The circulating current will cause cable loss and heat, thereby causing the local temperature of the high-voltage cable insulation to rise, accelerating the insulation aging speed, and greatly threatening the safe operation of the high-voltage cable line and greatly shortening the normal service life of the cable line. The over-standard grounding circulating current (the circulating current value is greater than 50A or exceeds 20% of the load current or the maximum value / minimum value between phases is greater than 3) not only affects the cable carrying capacity and service life, but also causes serious heat caused by the circulating current to burn the grounding wire or grounding box, and if the defect is not timely repaired, it may cause a serious power grid accident. SUMMARY

[0004] The present application provides a multi-loop high-voltage cable fault calculation method, device, electronic equipment and medium to solve the problems of safety operation hidden danger of high-voltage cable and shortening of service life of high-voltage cable.

[0005] According to an aspect of the present application, a multi-loop high-voltage cable fault calculation method is provided, which comprises:

[0006] When an asymmetric ground short circuit occurs in a high-voltage cable metal sheath, the asymmetric ground short circuit, including a single-phase ground short circuit and a two-phase ground short circuit, is converted into a target symmetric three-phase short circuit through a symmetric component method;

[0007] The target symmetric three-phase short circuit is calculated based on a multi-loop high-voltage cable metal sheath circulating current calculation principle, and an insulation state of the high-voltage cable is determined, so that a corresponding multi-loop high-voltage cable fault is calculated according to the insulation state.

[0008] Optionally, the multi-loop high-voltage cable metal sheath circulating current calculation principle is specifically represented by the following formula:

[0009] I s1 (R+jX)+(I s1 +I s2 +I s3 )(R1+R2+R3)+U′1=U1

[0010] I s2 (R+jX)+(I s1 +I s2 +I s3 )(R1+R2+R3)+U′2=U2

[0011] I s3 (R+jX)+(I s1 +I s2 +I s3 )(R1+R2+R3)+U′3=U3

[0012] I s4 (R+jX)+(I s4 +I s5 +I s6 )(R1+R2+R3)+U′4=U4

[0013] I s5 (R+jX)+(I s4 +I s5 +I s6 )(R1+R2+R3)+U′5=U5

[0014] I s6 (R+jX)+(I s4 +I s5 +I s6 )(R1+R2+R3)+U′6=U6

[0015] I s7 (R+jX)+(I s7 +I s8 +I s9)(R1+R2+R3)+U'7=U7

[0016] I s8 (R+jX)+(I s7 +I s8 +I s9 )(R1+R2+R3)+U'8=U8

[0017] I s9 (R+jX)+(I s7 +I s8 +I s9 )(R1+R2+R3)+U'9=U9

[0018] wherein, I s1 -I s9 are three-phase high-voltage cable metal sheath loop currents respectively; R1 is a first grounding resistance; R2 is a second grounding resistance; (R+jX) is a metal sheath self-impedance; R3 is a ground leakage resistance; U1-U9 are induced voltages generated by the conductor current on the sheath; U'1-U'9 are induced voltages generated by other phase sheath loop currents and ground loop currents on the sheath respectively.

[0019] Optionally, the multi-loop high-voltage cable metal sheath loop current calculation principle calculates the target symmetrical three-phase short circuit, comprising:

[0020] obtaining the first grounding resistance, the second grounding resistance, the ground leakage resistance, and the metal sheath self-impedance, and according to the measured induced voltages generated by the conductor current on the sheath and the induced voltages generated by other phase sheath loop currents and ground loop currents on the sheath respectively;

[0021] The multi-loop high-voltage cable metal sheath loop current calculation principle calculates the target symmetrical three-phase short circuit according to the first grounding resistance, the second grounding resistance, the ground leakage resistance, the metal sheath self-impedance, the induced voltages generated by the conductor current on the sheath, and the induced voltages generated by other phase sheath loop currents and ground loop currents on the sheath respectively, to obtain the three-phase high-voltage cable metal sheath loop current.

[0022] Optionally, the multi-loop high-voltage cable metal sheath loop current calculation principle calculates the target symmetrical three-phase short circuit, comprising:

[0023] obtaining the three-phase high-voltage cable metal sheath loop current, the induced voltages generated by the conductor current on the sheath, and the induced voltages generated by other phase sheath loop currents and ground loop currents on the sheath respectively;

[0024] Based on the principle of the metal sheath loop current calculation of the multi-circuit high-voltage cable, the target symmetrical three-phase short circuit is calculated according to the induced voltage on the sheath generated by the metal sheath loop current and the current of the conductor of the three-phase high-voltage cable, and the induced voltage on the sheath generated by the loop current of the sheath of other phases and the earth loop current, to obtain the first grounding resistance, the second grounding resistance, the earth leakage resistance and the self-impedance of the metal sheath.

[0025] Optionally, the multi-circuit high-voltage cable fault calculation method further comprises:

[0026] The equivalent resistance of the metal sheath of the high-voltage cable is calculated according to the first grounding resistance, the second grounding resistance, the earth leakage resistance and the self-impedance of the metal sheath.

[0027] Optionally, the equivalent resistance of the metal sheath of the high-voltage cable is calculated by the following formula, specifically:

[0028] R eq =R+R1+R2+R3

[0029] Wherein, R eq is the equivalent resistance of the metal sheath of the high-voltage cable.

[0030] Optionally, the multi-circuit high-voltage cable fault calculation method further comprises:

[0031] The insulation resistance of the outer sheath of the multi-circuit high-voltage cable is calculated according to the following formula, specifically:

[0032]

[0033] Wherein, R is the insulation resistance of the outer sheath of the multi-circuit high-voltage cable; p i is the volume resistivity of the outer sheath material; L is the length of the high-voltage cable; D i is the outer diameter of the outer sheath of the high-voltage cable; and D c is the inner diameter of the outer sheath of the high-voltage cable.

[0034] According to another aspect of the present application, a multi-circuit high-voltage cable fault calculation device is provided, which comprises:

[0035] The circuit conversion module is configured to convert the asymmetric grounding short circuit into a target symmetrical three-phase short circuit by the symmetrical component method when the metal sheath of the high-voltage cable occurs asymmetric grounding short circuit, and the asymmetric grounding short circuit includes single-phase grounding short circuit and two-phase grounding short circuit.

[0036] The fault calculation module is configured to calculate the target symmetrical three-phase short circuit based on the principle of the metal sheath loop current calculation of the multi-circuit high-voltage cable, determine the insulation state of the high-voltage cable, and calculate the corresponding multi-circuit high-voltage cable fault according to the insulation state.

[0037] According to another aspect of the present application, there is provided an electronic device, comprising:

[0038] at least one processor; and

[0039] a memory connected with the at least one processor; wherein,

[0040] 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 to enable the at least one processor to perform the multi-loop high-voltage cable fault calculation method according to any one of the embodiments of the present application.

[0041] According to another aspect of the present application, there is provided a computer readable storage medium storing computer instructions for enabling a processor to implement the multi-loop high-voltage cable fault calculation method according to any one of the embodiments of the present application when executed by the processor.

[0042] The technical scheme of the embodiments of the present application, when the high-voltage cable metal sheath occurs asymmetric grounding short circuit, the asymmetric grounding short circuit is converted into target symmetric three-phase short circuit by the symmetric component method, the asymmetric grounding short circuit includes single-phase grounding short circuit and two-phase grounding short circuit; the target symmetric three-phase short circuit is calculated based on the multi-loop high-voltage cable metal sheath circulating current calculation principle, the insulation state of the high-voltage cable is determined, and the corresponding multi-loop high-voltage cable fault is calculated according to the insulation state. The problem of the safety operation hidden danger of the high-voltage cable and the shortening of the service life of the high-voltage cable is solved. The insulation state of the high-voltage cable line is researched, the insulation state of the high-voltage cable is predicted in advance, and corresponding measures are taken, which is beneficial to the safety and reliability of the cable transmission line.

[0043] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0045] Figure 1 is a flow chart of a multi-loop high-voltage cable fault calculation method provided according to the first embodiment of the present application;

[0046] Figure 2is a three-phase cross-connection two-end grounding equivalent circuit diagram of a high-voltage cable outer sheath according to an embodiment of the present application;

[0047] Figure 3 is a first loop schematic diagram of a three-loop high-voltage cable metal sheath according to an embodiment of the present application;

[0048] Figure 4 is a second loop schematic diagram of a three-loop high-voltage cable metal sheath according to an embodiment of the present application;

[0049] Figure 5 is a third loop schematic diagram of a three-loop high-voltage cable metal sheath according to an embodiment of the present application;

[0050] Figure 6 is a principle diagram of a three-phase short-circuit grounding of a high-voltage cable metal sheath according to an embodiment of the present application;

[0051] Figure 7 is a principle diagram of a two-phase short-circuit grounding of a high-voltage cable metal sheath according to an embodiment of the present application;

[0052] Figure 8 is a principle diagram of a single-phase short-circuit grounding of a high-voltage cable metal sheath according to an embodiment of the present application;

[0053] Figure 9 is a principle diagram of a high-voltage cable sheath according to an embodiment of the present application;

[0054] Figure 10 is a structure schematic diagram of a multi-loop high-voltage cable fault calculation device according to an embodiment of the present application;

[0055] Figure 11 is a structure schematic diagram of an electronic device for implementing a multi-loop high-voltage cable fault calculation method according to an embodiment of the present application. DETAILED DESCRIPTION

[0056] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0057] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0058] Example 1

[0059] Figure 1 This is a flowchart of a multi-circuit high-voltage cable fault calculation method provided in Embodiment 1 of the present invention. This embodiment is applicable to the calculation of faults in multi-circuit high-voltage cables. This multi-circuit high-voltage cable fault calculation method can be executed by a multi-circuit high-voltage cable fault calculation device, which can be implemented in hardware and / or software and can be configured in electronic equipment of a power system. Figure 1 As shown, the fault calculation method for multi-circuit high-voltage cables includes:

[0060] S110. When an asymmetrical grounding short circuit occurs in the metal sheath of a high-voltage cable, the asymmetrical grounding short circuit is converted into a target symmetrical three-phase short circuit by means of the symmetrical component method. The asymmetrical grounding short circuit includes a single-phase grounding short circuit and a two-phase grounding short circuit.

[0061] In simple terms, an asymmetrical short-circuit includes single-phase to ground faults, two-phase to ground faults, and two-phase-to-phase short circuits. Three-phase to ground faults are considered symmetrical short circuits, but short circuits where the three phases to ground occur at different points are also considered asymmetrical. In terms of actual probability, 90% of short circuits in power systems are asymmetrical short circuits, and 90% of these are single-phase to ground faults. Therefore, power system short-circuit faults generally refer to single-phase short-circuit faults. In this embodiment, the asymmetrical short-circuit mainly involves single-phase to ground faults and two-phase to ground faults.

[0062] The method of symmetrical components is a fundamental method in electrical engineering for analyzing the asymmetrical operating state of symmetrical systems. It is widely used in calculating electrical quantities in three-phase AC systems where parameters are symmetrical but operating conditions are asymmetrical. When a power system experiences asymmetrical faults such as single-phase-to-ground short circuits, two-phase short circuits, two-phase-to-ground short circuits, single-phase open circuits, and two-phase open circuits, the three-phase impedances are different, the three-phase voltages and currents are unequal, and the phase differences between phases are also unequal. For such three-phase systems, it is not possible to analyze only one phase; the method of symmetrical components is typically used. The asymmetrical voltage and current quantities generated after an asymmetrical fault in a power system can be decomposed into three sequence networks using the method of symmetrical components. Within each sequence network, the voltage and current are analyzed symmetrically, and then synthesized into the actual ABC quantities, greatly simplifying the calculation of asymmetrical faults.

[0063] High-voltage cables may experience sheath damage during operation, leading to variations in grounding resistance and grounding points. In such cases, conventional and simple calculation formulas are insufficient to reflect the actual situation. It is necessary to consider the entire cable network, taking into account grounding resistance, node voltage distribution, and inter-loop mutual inductance, to obtain the distribution characteristics of sheath circulating current and induced voltage. A brief analysis using a single-loop model is provided below, primarily categorized into symmetrical and asymmetrical short circuits. Figures 6-8 As shown.

[0064] Cable metal sheaths exhibit varying grounding resistances under different grounding methods and at different grounding points, primarily falling into three categories as shown in the diagram above. When a three-phase ground fault occurs in the cable metal sheath, the circuit can be divided into several separate networks at the short-circuit point for calculation. However, when an asymmetrical ground fault occurs in the high-voltage cable metal sheath, i.e., a single-phase or two-phase ground fault, the simple calculation model is insufficient. In such cases, the symmetrical component method is introduced to transform the asymmetry of the fault point into symmetry when calculating asymmetrical ground faults. This transforms the three-phase circuit, whose symmetry has been disrupted by the short circuit, into a symmetrical circuit, thus obtaining the target symmetrical three-phase short circuit. Then, calculations are performed using a single-phase circuit.

[0065] S120. Based on the principle of circulating current calculation of the metal sheath of multi-circuit high-voltage cables, the target symmetrical three-phase short circuit is calculated to determine the insulation state of the high-voltage cable, so as to calculate the corresponding multi-circuit high-voltage cable fault according to the insulation state.

[0066] In this embodiment, most lines are generally laid in three-phase parallel configuration. Due to the asymmetrical position of the three phases, even if the segments are evenly divided, the sum of the induced voltages in each segment is not zero, and a circulating current will flow through the metal sheath of the high-voltage cable. When a single-phase or two-phase ground fault occurs in the metal sheath of the high-voltage cable, the symmetrical component method is used to convert the single-phase or two-phase ground fault into a target symmetrical three-phase short circuit. Therefore, an equivalent circuit for the circulating current in the sheath under the three-phase cross-connection with direct grounding at both ends is established. Specifically, the equivalent circuit for the three-phase cross-connection with grounding at both ends of the high-voltage cable outer sheath is as follows: Figure 2 As shown.

[0067] In actual power system operation, multiple circuit cables are often laid in the same channel. High-voltage cables often use multiple circuit cables laid in parallel, which makes the sheath circulating current problem more complex. This analysis uses a three-circuit cable as a prototype. The schematic diagram of the circulating current principle of the first, second, and third circuits of a three-circuit high-voltage cable is shown below. Figures 3-5 As shown.

[0068] Based on the above, the calculation principle of circulating current in the metal sheath of multi-circuit high-voltage cables is specifically expressed by the following formula:

[0069] I s1 (R+jX)+(I s1 +I s2 +I s3 (R1+R2+R3)+U′1=U1

[0070] I s2 (R+jX)+(I s1 +I s2 +I s3 (R1+R2+R3)+U′2=U2

[0071] I s3 (R+jX)+(I 51 +I s2 +I s3 (R1+R2+R3)+U′3=U3

[0072] I s4 (R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′4=U4

[0073] I s5 (R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′5=U5

[0074] I s6(R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′6=U6

[0075] I s7 (R+jX)+(I s7 +I s8 +I s9 (R1+R2+R3)+U′7=U7

[0076] I s8 (R+jX)+(I s7 +I s8 +I s9 (R1+R2+R3)+U′8=U8

[0077] I s9 (R+jX)+(I s7 +I s8 +I s9 (R1+R2+R3)+U′9=U9

[0078] Among them, I s1 -I s9 R1 is the circulating current in the metal sheath of the three-phase high-voltage cable; R2 is the first grounding resistance; (R+jX) is the self-impedance of the metal sheath; R3 is the leakage resistance of the ground; U1-U9 are the induced voltages generated on the sheath by the conductor current; U′1-U′9 are the induced voltages generated on the sheath by the circulating current in the sheath of the other phases and the circulating current in the ground, respectively.

[0079] Furthermore, the first grounding resistance, the second grounding resistance, the large ground drain resistance, and the metal sheath self-impedance are obtained. Based on the measured induced voltage generated on the sheath by the conductor current and the induced voltages generated on the sheath by the other phase sheath circulating current and the ground circulating current, the circulating current of the three-phase high-voltage cable metal sheath is calculated for the target symmetrical three-phase short circuit according to the first grounding resistance, the second grounding resistance, the large ground drain resistance, the metal sheath self-impedance, the induced voltage generated on the sheath by the conductor current, and the induced voltages generated on the sheath by the other phase sheath circulating current and the ground circulating current.

[0080] The induced voltages generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltages generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground, are obtained. Based on the calculation principle of circulating current in the metal sheath of multi-circuit high-voltage cables, the induced voltages generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltages generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground, are calculated for the target symmetrical three-phase short circuit to obtain the first grounding resistance, the second grounding resistance, the ground leakage resistance, and the self-impedance of the metal sheath.

[0081] Based on the above, the equivalent resistance of the high-voltage cable's metal sheath is calculated using the first grounding resistance, the second grounding resistance, the large ground leakage resistance, and the self-impedance of the metal sheath. Specifically, the equivalent resistance of the high-voltage cable's metal sheath can be calculated using the following formula:

[0082] R eq =R + R1 + R2 + R3

[0083] Among them, R eq This is the equivalent resistance of the metal sheath of a high-voltage cable.

[0084] Based on the above embodiments, the insulation resistance of the metal sheath of high-voltage cables is also an indicator for measuring the insulation level of a component or power system. It is related to various factors, including materials (volume resistivity), structural shape, and environmental conditions such as temperature and humidity. The main materials for the outer sheath of high-voltage power cables are polyvinyl chloride, polyethylene, and flame-retardant polyolefin. For single-core high-voltage power cables, the insulation resistance of the outer sheath of multi-circuit high-voltage cables can be calculated using the following formula:

[0085]

[0086] Where R is the insulation resistance (Ω·m) of the outer sheath of the multi-circuit high-voltage cable; ρ i D is the volume resistivity of the outer sheath material; L is the length of the high-voltage cable (m); i D is the outer diameter of the high-voltage cable's outer sheath. c This refers to the inner diameter of the outer sheath of the high-voltage cable.

[0087] As shown in the formula for calculating the insulation resistance of the outer sheath of a multi-circuit high-voltage cable, the insulation resistance of the outer sheath is directly proportional to the volume resistivity of the material and inversely proportional to the length of the outer sheath of the tested multi-circuit high-voltage cable. The higher the volume resistivity of the material, the greater the insulation resistance. For multi-circuit high-voltage cables with the same material and structure, the longer the length, the smaller the insulation resistance; theoretically, when the length is infinitely long, the insulation resistance approaches zero. For multi-circuit high-voltage cable lines of variable length, the test results of the outer sheath insulation resistance cannot usually be directly used as an evaluation parameter.

[0088] The relationship between the conductor and sheath of a high-voltage cable can be viewed as a hollow transformer. The conductor of the high-voltage cable is equivalent to the primary winding of the transformer, and the metal sheath is equivalent to the secondary winding. When the two ends of the metal sheath of the high-voltage cable are grounded, when an alternating current flows through the conductor of the high-voltage cable, an induced voltage will be generated on the metal sheath, and a circulating current will be generated on the sheath. The circuit diagram is shown below. Figure 9 As shown, where I s1 -I s3 R1 is the circulating current in the metal sheath of the three-phase high-voltage cable; R2 is the circulating current flowing to the ground; R1 is the first grounding resistance; R2 is the second grounding resistance; (R+jX) is the self-impedance of the metal sheath; R3 is the leakage resistance of the ground; U1-U3 are the induced voltages generated on the sheath by the conductor current; U′1-U′3 are the induced voltages generated on the sheath by the circulating currents in the other phases and the ground current, respectively.

[0089] The technical solution of this invention, when an asymmetrical ground fault occurs in the metal sheath of a high-voltage cable, converts the asymmetrical ground fault into a target symmetrical three-phase short circuit using the symmetrical component method. The asymmetrical ground fault includes single-phase and two-phase ground faults. Based on the principle of circulating current calculation for the metal sheath of multi-circuit high-voltage cables, the target symmetrical three-phase short circuit is calculated to determine the insulation state of the high-voltage cable, and the corresponding multi-circuit high-voltage cable fault is calculated based on the insulation state. This solves the problem of potential safety hazards in high-voltage cables and the shortened service life of high-voltage cables. By studying the insulation state of high-voltage cable lines, predicting the insulation state in advance, and taking corresponding measures, it is beneficial to the safety and reliability of cable transmission lines.

[0090] Example 2

[0091] Figure 10 This is a schematic diagram of a multi-circuit high-voltage cable fault calculation device provided in Embodiment 3 of the present invention. Figure 10 As shown, the multi-circuit high-voltage cable fault calculation device includes:

[0092] The circuit conversion module 1010 is used to convert an asymmetrical grounding short circuit into a target symmetrical three-phase short circuit by means of the symmetrical component method when an asymmetrical grounding short circuit occurs in the metal sheath of a high-voltage cable. The asymmetrical grounding short circuit includes a single-phase grounding short circuit and a two-phase grounding short circuit.

[0093] The fault calculation module 1020 is used to perform calculations on the target symmetrical three-phase short circuit based on the circulating current calculation principle of the metal sheath of multi-circuit high-voltage cables, determine the insulation state of the high-voltage cable, and calculate the corresponding multi-circuit high-voltage cable fault based on the insulation state.

[0094] Optionally, the calculation principle of circulating current in the metal sheath of the multi-circuit high-voltage cable is specifically expressed by the following formula:

[0095] I s1 (R+jX)+(I s1 +I s2 +I s3 (R1+R2+R3)+U′1=U1

[0096] I s2 (R+jX)+(I s1 +I s2 +I s3 (R1+R2+R3)+U′2=U2

[0097] I s3 (R+jX)+(I 51 +I s2 +I s3 (R1+R2+R3)+U′3=U3

[0098] I s4 (R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′4=U4

[0099] I s5 (R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′5=U5

[0100] I s6 (R+jX)+(I s4 +I s5 +I s6 (R1+R2+R3)+U′6=U6

[0101] I s7 (R+jX)+(I s7 +I s8 +I s9 (R1+R2+R3)+U′7=U7

[0102] I s8 (R+jX)+(I s7 +I s8 +I s9 (R1+R2+R3)+U′8=U8

[0103] I s9 (R+jX)+(I s7 +I s8 +Is9 (R1+R2+R3)+U′9=U9

[0104] Among them, I s1 -I s9 R1 is the circulating current in the metal sheath of the three-phase high-voltage cable; R2 is the first grounding resistance; (R+jX) is the self-impedance of the metal sheath; R3 is the leakage resistance of the ground; U1-U9 are the induced voltages generated on the sheath by the conductor current; U′1-U′9 are the induced voltages generated on the sheath by the circulating current in the sheath of the other phases and the circulating current in the ground, respectively.

[0105] Optionally, the calculation of the target symmetrical three-phase short circuit based on the circulating current calculation principle of multi-circuit high-voltage cable metal sheath includes:

[0106] Obtain the first grounding resistance, the second grounding resistance, the large ground drain resistance, and the self-impedance of the metal sheath. Based on the measured induced voltage generated on the sheath by the current in the conductor and the induced voltage generated on the sheath by the circulating current in the other phases of the sheath and the circulating current in the ground, respectively.

[0107] Based on the calculation principle of circulating current in the metal sheath of multi-circuit high-voltage cables, the circulating current in the metal sheath of the three-phase high-voltage cable is calculated by considering the first grounding resistance, the second grounding resistance, the large ground leakage resistance, the self-impedance of the metal sheath, the induced voltage generated on the sheath by the current in the conductor, and the induced voltage generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground.

[0108] Optionally, the calculation of the target symmetrical three-phase short circuit based on the circulating current calculation principle of multi-circuit high-voltage cable metal sheath includes:

[0109] The induced voltages generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltages generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground, are obtained.

[0110] Based on the calculation principle of circulating current in the metal sheath of multi-circuit high-voltage cables, the induced voltage generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltage generated on the sheath by the circulating current in the other phases and the circulating current in the ground, the first grounding resistance, the second grounding resistance, the ground leakage resistance, and the self-impedance of the metal sheath are calculated for the target symmetrical three-phase short circuit.

[0111] Optionally, the multi-circuit high-voltage cable fault calculation device further includes:

[0112] The equivalent resistance of the high-voltage cable metal sheath is calculated based on the first grounding resistance, the second grounding resistance, the large ground leakage resistance, and the self-impedance of the metal sheath.

[0113] Optionally, the equivalent resistance of the high-voltage cable's metallic sheath can be calculated using the following formula:

[0114] R eq =R + R1 + R2 + R3

[0115] Among them, R eq This is the equivalent resistance of the metal sheath of a high-voltage cable.

[0116] Optionally, the multi-circuit high-voltage cable fault calculation device further includes:

[0117] The insulation resistance of the outer sheath of a multi-circuit high-voltage cable is calculated using the following formula:

[0118]

[0119] Where R is the insulation resistance of the outer sheath of the multi-circuit high-voltage cable; ρ i D is the volume resistivity of the outer sheath material; L is the length of the high-voltage cable; i D is the outer diameter of the high-voltage cable outer sheath. c This refers to the inner diameter of the outer sheath of the high-voltage cable.

[0120] The multi-circuit high-voltage cable fault calculation device provided in this embodiment of the invention can execute the multi-circuit high-voltage cable fault calculation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the multi-circuit high-voltage cable fault calculation method.

[0121] Example 3

[0122] Figure 11 A schematic diagram of an electronic device 10 that can be used to implement embodiments 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 processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0123] like Figure 11As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 may also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0124] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0125] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the multi-loop high-voltage cable fault calculation method.

[0126] In some embodiments, the multi-loop high-voltage cable fault calculation method can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the multi-loop high-voltage cable fault calculation method described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the multi-loop high-voltage cable fault calculation method by any other suitable means (e.g., by means of firmware).

[0127] Various embodiments of the systems and techniques described above 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), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0128] Computer programs used to implement 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 executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0129] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0130] 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 provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, 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 sound input, voice input, or tactile input).

[0131] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0132] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0133] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0134] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for calculating faults in multi-circuit high-voltage cables, characterized in that, include: When an asymmetrical grounding short circuit occurs in the metal sheath of a high-voltage cable, the asymmetrical grounding short circuit is converted into a target symmetrical three-phase short circuit by the symmetrical component method. The asymmetrical grounding short circuit includes a single-phase grounding short circuit and a two-phase grounding short circuit. The target symmetrical three-phase short circuit is calculated based on the circulating current calculation principle of the metal sheath of multi-circuit high-voltage cable to determine the insulation state of the high-voltage cable, and the corresponding multi-circuit high-voltage cable fault is calculated based on the insulation state. The calculation of the target symmetrical three-phase short circuit based on the circulating current calculation principle of multi-circuit high-voltage cable metal sheath includes: The induced voltages generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltages generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground, are obtained. Based on the calculation principle of circulating current in the metal sheath of multi-circuit high-voltage cables, the induced voltage generated on the sheath by the circulating current in the metal sheath of the three-phase high-voltage cable and the current in the conductor, as well as the induced voltage generated on the sheath by the circulating current in the sheath of other phases and the circulating current in the ground, the first grounding resistance, the second grounding resistance, the ground leakage resistance, and the self-impedance of the metal sheath are calculated for the target symmetrical three-phase short circuit. The multi-circuit high-voltage cable fault calculation method also includes: The equivalent resistance of the high-voltage cable metal sheath is calculated based on the first grounding resistance, the second grounding resistance, the large ground leakage resistance, and the self-impedance of the metal sheath. The calculation principle for circulating current in the metal sheath of multi-circuit high-voltage cables is specifically expressed by the following formula: in, - These are respectively the circulating current of the metal sheath of three-phase high-voltage cables; The first grounding resistance; This is the second grounding resistance; The metal sheath has self-impedance; The leakage resistance of the ground; - The induced voltage on the sheath is the current in the conductor. - The induced voltages generated on the sheath by the sheath circulating current and the ground circulating current of other phases, respectively.

2. The multi-circuit high-voltage cable fault calculation method according to claim 1, characterized in that, The equivalent resistance of the metal sheath of the high-voltage cable is calculated using the following formula: in, This is the equivalent resistance of the metal sheath of a high-voltage cable.

3. A multi-circuit high-voltage cable fault calculation device, used to execute the multi-circuit high-voltage cable fault calculation method as described in any one of claims 1-2, characterized in that, include: The circuit conversion module is used to convert an asymmetrical ground fault into a target symmetrical three-phase short circuit when an asymmetrical ground fault occurs in the metal sheath of a high-voltage cable using the symmetrical component method. The asymmetrical ground fault includes a single-phase ground fault and a two-phase ground fault. When an asymmetrical ground fault occurs in the metal sheath of a high-voltage cable, the three-phase impedances are not the same, the three-phase voltages and currents are not equal, and the phase differences between phases are not equal. The fault calculation module is used to perform calculations on the target symmetrical three-phase short circuit based on the circulating current calculation principle of the metal sheath of multi-circuit high-voltage cables, determine the insulation state of the high-voltage cable, and calculate the corresponding multi-circuit high-voltage cable fault based on the insulation state.

4. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the multi-circuit high-voltage cable fault calculation method according to any one of claims 1-2.

5. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that are used to cause a processor to execute the multi-circuit high-voltage cable fault calculation method according to any one of claims 1-2.

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