Cross-connection cable sheath ring current calculation method and device, electronic equipment and medium

Abstract

The application discloses a cross-interconnected cable sheath loop current calculation method and device, electronic equipment and medium. The cross-interconnected cable sheath loop current calculation method considers the influence of the leakage current in the core when calculating the cross-interconnected cable metal sheath loop current, more accurately obtains the sheath loop current on each cross-interconnected section, is more in line with the actual operation condition, and is convenient for monitoring and protecting the cable. To obtain the continuous distribution of the sheath current along the sheath loop, the pi type equivalent circuit microelement between the core and the sheath is divided, and then the distributed equivalent circuit is obtained to make similar calculation, so that the distribution of the sheath loop current on each cross-interconnected section is more accurately obtained, and the cable is convenient for laying, monitoring and protecting.

Description

Technical Field

[0001] This invention relates to the field of circulating current calculation technology for the metal sheath of multi-circuit high-voltage cables, and particularly to a method, apparatus, electronic device, and medium for calculating circulating current in the sheath of cross-connected cables. Background Technology

[0002] Figure 1 This is a schematic diagram of an existing single-core cable. (See attached diagram) Figure 1 A single-core cable consists of a conductor, a semiconductor shield, main insulation, an insulating shield, a metal sheath, and an outer sheath. Single-core cables using cross-linked polyethylene as the main insulation have a unit insulation resistance of up to several hundred GΩ / km. The resistive component of the leakage current is less than 1mA / km, while the capacitive component can reach several A / km. The current flowing from the conductor through the main insulation to the metal sheath is called the leakage current. Therefore, the leakage current is mainly capacitive and cannot be ignored when calculating the sheath circulating current.

[0003] According to the law of electromagnetic induction, the alternating magnetic field generated by the current when the high-voltage cable is running will link with the metal sheath to generate an induced voltage. If there is a closed loop in the metal sheath, an induced current will be generated. The total induced current in the sheath loop is generated by the load current in the cable core, the leakage current in the core, and the sheath circulating current in other sheath loops. Among them, the current in the metal sheath of the cross-connected cable is the sum of the induced current and the leakage current. Summary of the Invention

[0004] This invention provides a method, apparatus, electronic device, and medium for calculating the circulating current of a cross-connected cable sheath, in order to solve the problems of not considering the influence of leakage current when calculating the induced voltage generated by the conductor current, and not considering the distribution of the circulating current in the sheath circuit when calculating the circulating current in the sheath.

[0005] According to one aspect of the present invention, a method for calculating the circulating current of a cross-connect cable sheath is provided, the method comprising:

[0006] Obtain the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Calculate the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature.

[0007] The leakage current between the conductor sheaths is calculated based on the length of each segment of the cross-connected cable using a π-type equivalent circuit. The leakage current is then superimposed with the three-phase load current to obtain the three-phase conductor current of the cross-connected cable.

[0008] The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable is calculated based on the phase spacing, using the current values ​​of the three-phase cable core current and the three-phase sheath circulating current.

[0009] The induced current value on the metal sheath is calculated based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit.

[0010] The leakage current between the core sheaths is divided into components, and the actual circulating current value of each three-phase sheath of the current cross-connected cable is obtained by superimposing the componentized leakage current with the induced current value on the metal sheath.

[0011] Optionally, the step of calculating the metal sheath resistance, metal sheath self-inductance, and ground equivalent resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total length of the cable, the sheath resistivity, and the sheath operating temperature includes:

[0012] The resistance of the metal sheath, the self-inductance of the metal sheath, and the equivalent resistance of the ground of the current cross-connection cable are calculated according to the following formulas (I), (II), and (III):

[0013]

[0014]

[0015] R e =π 2 f×10 -7 Formula L (III)

[0016] Where R is the resistance of the metal sheath; X is the self-inductance of the metal sheath; R e ρ is the equivalent resistance of the earth; α is the sheath resistivity; T is the sheath resistance temperature coefficient; r1 is the inner radius of the sheath; r2 is the outer radius of the sheath; L is the total length of the cable; ω is the angular frequency; D e R represents the geodetic depth. av denoted as the geometric mean radius of the sheath; f is the frequency.

[0017] Optionally, the step of calculating the leakage current between the conductor sheaths using a π-type equivalent circuit based on the length of each segment of the cross-connecting cable, and then superimposing the leakage current with the three-phase load current to obtain the three-phase conductor current of the cross-connecting cable, includes:

[0018] The leakage current between the conductor sheaths is calculated using the following formulas (iv) and (v):

[0019] I Lji≈jωC / 2×U j ×L i Formula (IV)

[0020]

[0021] Among them, I Lij L is the i-th leakage current in the π-type equivalent circuit of the j-phase conductor sheath; C is the capacitance between the metal sheath and the conductor per unit length of the cable; L i U is the length of the i-th crossover cable segment; j ε is the system voltage on phase j conductor under normal operating conditions; r ε is the relative permittivity; ε0 is the vacuum permittivity; D c δ represents the diameter of the cable core; δ represents the thickness of the cable insulation.

[0022] The three-phase core currents of the cross-connecting cable are obtained according to the following formula:

[0023]

[0024]

[0025]

[0026] Among them, I Ai (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase A cable; I Bi (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase B cable; I Ci (i = 1, 2, 3) represents the core current on the i-th cross-connecting cable of phase C cable.

[0027] Optionally, the step of calculating the induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable based on the phase spacing, using the current values ​​of the three-phase cable core current and the three-phase sheath circulating current, includes:

[0028] The induced electromotive force generated by the three-phase cable core current and the three-phase sheath circulating current in each phase and segment of the current cross-connection cable is calculated according to the following formula:

[0029]

[0030]

[0031]

[0032] Among them, E jiLet S be the induced voltage generated by the conductor current on the i-th segment of the j-phase sheath; GMR is the geometric mean radius of the metal sheath; S jj This refers to the phase spacing;

[0033]

[0034]

[0035]

[0036] Among them, E′ ji I represents the induced voltage generated by the sheath current of other phases on the i-th cross-interconnection segment in the j-phase sheath circuit; SA I SB I SC These are the induced currents in the three-phase sheathing circuit;

[0037] The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current is calculated according to the following formula:

[0038]

[0039]

[0040] Among them, U SA U SB U SC U′ is the total induced voltage generated by the conductor current in each sheath circuit; SA 、U′ SB 、U′ SC L1, L2, and L3 represent the total induced voltage generated by the sheath current of other phases in each sheath circuit; L1, L2, and L3 are the lengths of each segment of the cross-connecting cable.

[0041] Optionally, the step of calculating the induced current value on the metal sheath based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated in each phase and segment of the sheath circuit includes:

[0042] The induced current value on the metal sheath is calculated using the following formula:

[0043]

[0044] Among them, I SA I SB I SC R1 and R2 are the induced current values ​​on the metal sheath; R1 and R2 are the grounding resistances at both ends of the metal sheath.

[0045] Optionally, the step of dividing the leakage current between the core sheaths includes:

[0046] The leakage current between the core sheaths can be divided into components according to the following formula:

[0047]

[0048] Among them, I LjiL I LjiR This represents the left and right components of the i-th leakage current in the j-phase conductor sheath in a π-type equivalent circuit.

[0049] Optionally, the actual circulating current value of each three-phase sheath of the current cross-connecting cable is obtained by superimposing the leakage current after componentization with the induced current value on the metal sheath.

[0050] The actual values ​​of the three-phase sheath circulating current in each section of the current cross-connected cable are obtained according to the following formula:

[0051]

[0052]

[0053]

[0054] Among them, I SA1 I SA2 I SA3 This indicates the circulating current in the sheath of phase A, specifically in sections 1, 2, and 3 of the sheath circuit; I SB1 I SB2 I SB3 This indicates the circulating current in the sheath on sections 1, 2, and 3 of the B-phase sheath circuit; I SC1 I SC2 I SC3 This indicates the circulating current in the sheath on the first, second, and third sections of the C-phase sheath circuit.

[0055] According to another aspect of the present invention, a cross-connect cable sheath circulating current calculation device is provided, the cross-connect cable sheath circulating current calculation device comprising:

[0056] The information acquisition module is used to acquire the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature, the module calculates the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable.

[0057] The three-phase conductor current determination module is used to calculate the leakage current between conductor sheaths based on the length of each segment of the cross-interconnected cable using a π-type equivalent circuit, and then superimpose the leakage current with the three-phase load current to obtain the three-phase conductor current of the cross-interconnected cable.

[0058] An induced electromotive force generation module is used to perform calculations based on the phase spacing to generate induced electromotive forces in each phase and segment of the sheath circuit of the current cross-connected cable, which are generated by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current.

[0059] The induced current value determination module is used to calculate the induced current value on the metal sheath based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit.

[0060] The three-phase sheath circulating current actual value determination module is used to perform the following: the leakage current between the core sheaths is divided into components, and the actual value of the three-phase sheath circulating current of each segment of the current cross-connected cable is obtained by superimposing the componentized leakage current with the induced current value on the metal sheath.

[0061] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0062] At least one processor; and

[0063] A memory communicatively connected to the at least one processor; wherein,

[0064] The memory stores a computer program that can be executed by the at least one processor, which enables the at least one processor to perform the cross-connected cable sheath circulating current calculation method according to any embodiment of the present invention.

[0065] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the cross-connected cable sheath circulating current calculation method according to any embodiment of the present invention.

[0066] The technical solution of this invention obtains the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connecting cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connecting cable. Based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature, the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connecting cable are calculated. A π-type equivalent circuit is used to calculate the leakage current between the core sheaths based on the length of each segment of the cross-connecting cable, and the leakage current is then... The current is superimposed on the three-phase load current to obtain the three-phase core current of the cross-connected cable; the induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current is calculated based on the phase spacing; the induced current value on the metal sheath is calculated based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated in each phase and segment of the sheath circuit; the leakage current between the core sheaths is componentized, and the componentized leakage current is superimposed on the induced current value on the metal sheath to obtain the actual value of the three-phase sheath circulating current in each segment of the current cross-connected cable. This invention solves the problems of not considering the influence of leakage current when calculating the induced voltage generated by the core current, and not considering the distribution of the sheath circulating current in the sheath circuit when calculating the sheath circulating current. This invention considers the influence of leakage current in the core, and obtains the distribution of the sheath circulating current in each cross-connection segment more accurately, which facilitates the laying, monitoring and protection of cables.

[0067] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 This is a schematic diagram of the structure of an existing single-core cable;

[0070] Figure 2 This is a flowchart of a method for calculating the circulating current of a cross-connected cable sheath according to Embodiment 1 of the present invention;

[0071] Figure 3 This is a schematic diagram of the circuit structure of the π-type equivalent circuit of the complete cross-interconnection segment provided in Embodiment 1 of the present invention;

[0072] Figure 4 This is a schematic diagram of the circuit structure of the π-type equivalent circuit between the miniaturized core sheaths provided in Embodiment 1 of the present invention;

[0073] Figure 5 This is an equivalent circuit diagram of the cross-connected cable sheath circulating current calculation method provided in Embodiment 1 of the present invention;

[0074] Figure 6 This is a schematic diagram of the leakage current component calculation in the cross-connected cable sheath circulating current calculation method provided in Embodiment 1 of the present invention;

[0075] Figure 7 This is a schematic diagram of the structure of a cross-connected cable sheath circulating current calculation device according to Embodiment 2 of the present invention;

[0076] Figure 8 This is a schematic diagram of the structure of an electronic device that implements the cross-connection cable sheath circulating current calculation method of the present invention. Detailed Implementation

[0077] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0078] 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.

[0079] Example 1

[0080] Figure 2This invention provides a flowchart of a method for calculating the circulating current of a cross-connected cable sheath, according to Embodiment 1. This embodiment is applicable to situations where the circulating current of a cross-connected cable sheath is calculated considering the leakage current of the conductor core. This method can be executed by a cross-connected cable sheath circulating current calculation device, which can be implemented in hardware and / or software and can be configured in an electronic device. Figure 2 As shown, the method for calculating the circulating current in the sheath of the cross-connected cable includes:

[0081] S210. Obtain the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Calculate the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature.

[0082] Among them, cable cross-interconnection refers to the cable line being divided into several large sections, each of which is in principle divided into three smaller sections of equal length. Each smaller section is connected by an insulating joint. At the insulating head, the three phases of the metal sheath are connected by a coaxial cable through a junction box (also known as a transposition box). A set of sheath protectors is installed in the transposition box at the insulating joint. The sheaths at both ends of each large section are interconnected and grounded.

[0083] The units for the three-phase load current of cross-connected cables are: A; the units for the inner and outer radii of the sheath are: mm; the units for the phase spacing are: mm; the units for the total cable length and the length of each segment of the cross-connected cable are: m; and the units for the sheath resistivity are: Ω·m.

[0084] Specifically, the metal sheath resistance, metal sheath self-inductance, and ground equivalent resistance of the current cross-connection cable are calculated according to the following formulas (I), (II), and (III):

[0085]

[0086]

[0087] R e =π 2 f×10 -7 Formula L (III)

[0088] Where R is the resistance of the metal sheath; X is the self-inductance of the metal sheath; R eρ is the equivalent resistance of the earth; α is the sheath resistivity; T is the sheath resistance temperature coefficient; r1 is the inner radius of the sheath; r2 is the outer radius of the sheath; L is the total length of the cable; ω is the angular frequency; D e R represents the geodetic depth. av denoted as the geometric mean radius of the sheath; f is the frequency.

[0089] S220. The leakage current between the core sheaths is calculated based on the length of each segment of the cross-connected cable using a π-type equivalent circuit. The leakage current is then superimposed with the three-phase load current to obtain the three-phase core current of the cross-connected cable.

[0090] In this embodiment, the equivalent circuit between the conductor sheaths adopts a π-type equivalent circuit. To obtain the sheath current on each segment of the cross-connect cable, a complete cross-connect cable is divided into 9 π-type equivalent circuits, such as... Figure 3 As shown, to obtain a continuous distribution of the sheath current along the sheath circuit, a miniaturized π-type equivalent circuit is used, such as... Figure 4 As shown.

[0091] Specifically, the leakage current between the conductor sheaths is calculated according to the following formulas (iv) and (v):

[0092] I Lji ≈jωC / 2×U j ×L i Formula (IV)

[0093]

[0094] Among them, I Lij L is the i-th leakage current in the π-type equivalent circuit of the j-phase conductor sheath; C is the capacitance between the metal sheath and the conductor per unit length of the cable; L i U is the length of the i-th crossover cable segment; j ε is the system voltage on phase j conductor under normal operating conditions; r ε is the relative permittivity; ε0 is the vacuum permittivity; D c δ represents the diameter of the cable core; δ represents the thickness of the cable insulation.

[0095] The voltage drop along the cable core is relatively low, so the system voltage on the core can be considered constant. Under normal operating conditions, the leakage current is a constant value, so it can be replaced by an equivalent current source. Since the leakage current also induces a voltage on the metal sheath, the effect of the leakage current needs to be considered when calculating the core current and the induced voltage on the metal sheath. That is, the core current consists of two parts: the load current and the leakage current.

[0096] Specifically, the three-phase core currents of the cross-connecting cable are obtained according to the following formula:

[0097]

[0098]

[0099]

[0100] Among them, I Ai (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase A cable; I Bi (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase B cable; I Ci (i = 1, 2, 3) represents the core current on the i-th cross-connecting cable of phase C cable.

[0101] S230. Calculate the induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable based on the phase spacing, which is generated by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current.

[0102] See also Figure 4 The induced electromotive force generated by the three-phase cable core current and the three-phase sheath circulating current in each phase and section of the current cross-connection cable is calculated according to the following formula:

[0103]

[0104]

[0105]

[0106] Among them, E ji Let S be the induced voltage generated by the conductor current on the i-th segment of the j-phase sheath; GMR is the geometric mean radius of the metal sheath; S jj This refers to the phase spacing;

[0107] Understandably, S AB The distance between the cores of phase A and phase B cables (unit: mm) depends on the cable arrangement. The spacing between other phases is similar, and will not be described in detail in this embodiment.

[0108]

[0109]

[0110]

[0111] Among them, E′ jiI represents the induced voltage generated by the sheath current of other phases on the i-th cross-interconnection segment in the j-phase sheath circuit; SA I SB I SC These are the induced currents in the three-phase sheathing circuit;

[0112] The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current is calculated according to the following formula:

[0113]

[0114]

[0115] Among them, U SA U SB U SC U′ is the total induced voltage generated by the conductor current in each sheath circuit; SA 、U′ SB 、U′ SC L1, L2, and L3 represent the total induced voltage generated by the sheath current of other phases in each sheath circuit; L1, L2, and L3 are the lengths of each segment of the cross-connecting cable.

[0116] S240. The induced current value on the metal sheath is calculated based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit.

[0117] Specifically, the induced current value on the metal sheath is calculated using the following formula:

[0118]

[0119] Among them, I SA I SB I SC R1 and R2 are the induced current values ​​on the metal sheath; R1 and R2 are the grounding resistances at both ends of the metal sheath.

[0120] S250. The leakage current between the core sheaths is divided into components, and the leakage current after componentization is superimposed with the induced current value on the metal sheath to obtain the actual circulating current value of each three-phase sheath of the current cross-connected cable.

[0121] In this embodiment, the final calculated sheath circulating current also needs to include the leakage current between the cable core and the sheath. See also... Figure 5 As shown, the leakage current is considered as an equivalent current source. After flowing into the sheath circuit, the leakage current will cause a shunt, therefore the sheath circulating current value is different on each cross-connection segment. Specifically, as... Figure 6 As shown, Z LZ represents the impedance value of the left circulating loop with the endpoint of the cross-connection section as the reference point. R Given the impedance value of the right-side circulating loop with the cross-interconnection point as the reference point, the leakage current between the core sheaths is divided into components according to the following formula:

[0122]

[0123] Among them, I LjiL I LjiR This represents the left and right components of the i-th leakage current in the j-phase conductor sheath in a π-type equivalent circuit.

[0124] Furthermore, the actual circulating current value of each three-phase sheath of the current cross-connecting cable is obtained by superimposing the leakage current after component analysis with the induced current value on the metal sheath.

[0125] The actual values ​​of the three-phase sheath circulating current in each section of the current cross-connected cable are obtained according to the following formula:

[0126]

[0127]

[0128]

[0129] Among them, I SA1 I SA2 I SA3 This indicates the circulating current in the sheath of phase A, specifically in sections 1, 2, and 3 of the sheath circuit; I SB1 I SB2 I SB3 This indicates the circulating current in the sheath on sections 1, 2, and 3 of the B-phase sheath circuit; I SC1 I SC2 I SC3 This indicates the circulating current in the sheath on the first, second, and third sections of the C-phase sheath circuit.

[0130] This invention considers the influence of leakage current in the conductor core when calculating the circulating current in the metal sheath of cross-connected cables, thus obtaining a more accurate sheath circulating current on each cross-connection section. This more closely reflects actual operating conditions and facilitates cable monitoring and protection. To obtain the continuous distribution of sheath current along the sheath loop, the π-type equivalent circuit between the conductor cores and sheaths is minimized to obtain a distributed equivalent circuit. Similar calculations can then be performed to obtain a more accurate distribution of sheath circulating current on each cross-connection section, facilitating cable laying, monitoring, and protection.

[0131] Example 2

[0132] Figure 7This is a schematic diagram of a cross-connected cable sheath circulating current calculation device provided in Embodiment 3 of the present invention. Figure 7 As shown, the cross-connection cable sheath circulating current calculation device includes:

[0133] The information acquisition module 710 is used to acquire the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature, the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable are calculated.

[0134] The three-phase conductor current determination module 720 is used to calculate the leakage current between conductor sheaths based on the length of each segment of the cross-interconnected cable using a π-type equivalent circuit, and then superimpose the leakage current with the three-phase load current to obtain the three-phase conductor current of the cross-interconnected cable.

[0135] The induced electromotive force generation module 730 is used to perform calculation based on the phase spacing to obtain the induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-interconnected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current.

[0136] The induced current value determination module 740 is used to calculate the induced current value on the metal sheath based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit.

[0137] The three-phase sheath circulating current actual value determination module 750 is used to perform the following: the leakage current between the core sheaths is divided into components, and the actual value of the three-phase sheath circulating current of each segment of the current cross-connected cable is obtained by superimposing the componentized leakage current with the induced current value on the metal sheath.

[0138] Optionally, the step of calculating the metal sheath resistance, metal sheath self-inductance, and ground equivalent resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total length of the cable, the resistivity of the sheath, and the operating temperature of the sheath includes:

[0139] The resistance of the metal sheath, the self-inductance of the metal sheath, and the equivalent resistance of the ground of the current cross-connection cable are calculated according to the following formulas (I), (II), and (III):

[0140]

[0141]

[0142] R e =π 2 f×10 -7 Formula L (III)

[0143] Where R is the resistance of the metal sheath; X is the self-inductance of the metal sheath; R e ρ is the equivalent resistance of the earth; α is the sheath resistivity; T is the sheath resistance temperature coefficient; r1 is the inner radius of the sheath; r2 is the outer radius of the sheath; L is the total length of the cable; ω is the angular frequency; D e R represents the geodetic depth. av denoted as the geometric mean radius of the sheath; f is the frequency.

[0144] Optional, the three-phase conductor current determination module 720 includes:

[0145] The leakage current between the conductor sheaths is calculated using the following formulas (iv) and (v):

[0146] I Lji ≈jωC / 2×U j ×L i Formula (IV)

[0147]

[0148] Among them, I Lij L is the i-th leakage current in the π-type equivalent circuit of the j-phase conductor sheath; C is the capacitance between the metal sheath and the conductor per unit length of the cable; L i U is the length of the i-th crossover cable segment; j ε is the system voltage on phase j conductor under normal operating conditions; r ε is the relative permittivity; ε0 is the vacuum permittivity; D c δ represents the diameter of the cable core; δ represents the thickness of the cable insulation.

[0149] The three-phase core currents of the cross-connecting cable are obtained according to the following formula:

[0150]

[0151]

[0152]

[0153] Among them, I Ai (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase A cable; I Bi (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase B cable; I Ci(i = 1, 2, 3) represents the core current on the i-th cross-connecting cable of phase C cable.

[0154] Optionally, the induced potential generation module 730 includes:

[0155] The induced electromotive force generated by the three-phase cable core current and the three-phase sheath circulating current in each phase and segment of the current cross-connection cable is calculated according to the following formula:

[0156]

[0157]

[0158]

[0159] Among them, E ji Let S be the induced voltage generated by the conductor current on the i-th segment of the j-phase sheath; GMR is the geometric mean radius of the metal sheath; S jj This refers to the phase spacing;

[0160]

[0161]

[0162]

[0163] Among them, E′ ji I represents the induced voltage generated by the sheath current of other phases on the i-th cross-interconnection segment in the j-phase sheath circuit; SA I SB I SC These are the induced currents in the three-phase sheathing circuit;

[0164] The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current is calculated according to the following formula:

[0165]

[0166]

[0167] Among them, U SA U SB U SC U′ is the total induced voltage generated by the conductor current in each sheath circuit; SA 、U′ SB 、U′ SC L1, L2, and L3 represent the total induced voltage generated by the sheath current of other phases in each sheath circuit; L1, L2, and L3 are the lengths of each segment of the cross-connecting cable.

[0168] Optionally, the induced current value determination module 740 includes:

[0169] The induced current value on the metal sheath is calculated using the following formula:

[0170]

[0171] Among them, I SA I SB I SC R1 and R2 are the induced current values ​​on the metal sheath; R1 and R2 are the grounding resistances at both ends of the metal sheath.

[0172] Optionally, the step of dividing the leakage current between the core sheaths includes:

[0173] The leakage current between the core sheaths can be divided into components according to the following formula:

[0174]

[0175] Among them, I LjiL I LjiR This represents the left and right components of the i-th leakage current in the j-phase conductor sheath in a π-type equivalent circuit.

[0176] Optionally, the actual circulating current value of each three-phase sheath of the current cross-connecting cable is obtained by superimposing the leakage current after componentization with the induced current value on the metal sheath.

[0177] The actual values ​​of the three-phase sheath circulating current in each section of the current cross-connected cable are obtained according to the following formula:

[0178]

[0179]

[0180]

[0181] Among them, I SA1 I SA2 I SA3 This indicates the circulating current in the sheath of phase A, specifically in sections 1, 2, and 3 of the sheath circuit; I SB1 I SB2 I SB3 This indicates the circulating current in the sheath on sections 1, 2, and 3 of the B-phase sheath circuit; I SC1 I SC2 I SC3 This indicates the circulating current in the sheath on the first, second, and third sections of the C-phase sheath circuit.

[0182] The cross-connected cable sheath circulating current calculation device provided in this embodiment of the invention can execute the cross-connected cable sheath circulating current calculation method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the cross-connected cable sheath circulating current calculation method.

[0183] Example 3

[0184] Figure 8 A schematic diagram of an electronic device 810 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.

[0185] like Figure 8 As shown, the electronic device 810 includes at least one processor 811 and a memory, such as a read-only memory (ROM) 812 or a random access memory (RAM) 813, communicatively connected to the at least one processor 811. The memory stores computer programs executable by the at least one processor. The processor 811 can perform various appropriate actions and processes based on the computer program stored in the ROM 812 or loaded from storage unit 818 into the RAM 813. The RAM 813 can also store various programs and data required for the operation of the electronic device 810. The processor 811, ROM 812, and RAM 813 are interconnected via a bus 814. An input / output (I / O) interface 815 is also connected to the bus 814.

[0186] Multiple components in electronic device 810 are connected to I / O interface 815, including: input unit 816, such as keyboard, mouse, etc.; output unit 817, such as various types of displays, speakers, etc.; storage unit 818, such as disk, optical disk, etc.; and communication unit 819, such as network card, modem, wireless transceiver, etc. Communication unit 819 allows electronic device 810 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0187] Processor 811 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 811 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, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 811 performs the various methods and processes described above, such as the cross-connection cable sheath circulating current calculation method.

[0188] In some embodiments, the cross-connect cable sheath circulating current calculation method can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 818. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 810 via ROM 812 and / or communication unit 819. When the computer program is loaded into RAM 813 and executed by processor 811, one or more steps of the cross-connect cable sheath circulating current calculation method described above can be performed. Alternatively, in other embodiments, processor 811 can be configured to perform the cross-connect cable sheath circulating current calculation method by any other suitable means (e.g., by means of firmware).

[0189] 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.

[0190] 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.

[0191] 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.

[0192] 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).

[0193] 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.

[0194] 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.

[0195] 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.

[0196] 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 circulating current in the sheath of cross-connected cables, characterized in that, include: Obtain the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Calculate the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature. The leakage current between the conductor sheaths is calculated based on the length of each segment of the cross-connected cable using a π-type equivalent circuit. The leakage current is then superimposed with the three-phase load current to obtain the three-phase conductor current of the cross-connected cable. The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase core current and the three-phase sheath circulating current is calculated based on the phase spacing. The induced current value on the metal sheath is calculated based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit. The leakage current between the core sheaths is divided into components, and the actual circulating current value of each three-phase sheath of the current cross-connected cable is obtained by superimposing the componentized leakage current with the induced current value on the metal sheath.

2. The method for calculating the circulating current of the cross-connected cable sheath according to claim 1, characterized in that, The calculation of the metal sheath resistance, metal sheath self-inductance, and ground equivalent resistance of the current cross-connection cable based on the inner radius of the sheath, the outer radius of the sheath, the total length of the cable, the sheath resistivity, and the sheath operating temperature includes: The resistance of the metal sheath, the self-inductance of the metal sheath, and the equivalent resistance to ground of the current cross-connection cable are calculated according to the following formulas (I), (II), and (III): R e =π 2 f×10 -7 Formula L (III) Where R is the resistance of the metal sheath; X is the self-inductance of the metal sheath; R e ρ is the equivalent resistance of the earth; α is the sheath resistivity; T is the sheath resistance temperature coefficient; r1 is the inner radius of the sheath; r2 is the outer radius of the sheath; L is the total length of the cable; ω is the angular frequency; D e R represents the geodetic depth. av denoted as the geometric mean radius of the sheath; f is the frequency.

3. The method for calculating the circulating current of the cross-connected cable sheath according to claim 2, characterized in that, The leakage current between the conductor sheaths is calculated using a π-type equivalent circuit based on the length of each segment of the cross-connecting cable. This leakage current is then superimposed with the three-phase load current to obtain the three-phase conductor current of the cross-connecting cable, including: The leakage current between the conductor sheaths is calculated using the following formulas (iv) and (v): I Lji ≈jωC / 2×U j ×L i Formula (IV) Among them, I Lij L is the i-th leakage current in the π-type equivalent circuit of the j-phase conductor sheath; C is the capacitance between the metal sheath and the conductor per unit length of the cable; L i U is the length of the i-th crossover cable segment; j ε is the system voltage on phase j conductor under normal operating conditions; r ε is the relative permittivity; ε0 is the vacuum permittivity; D c δ represents the diameter of the cable core; δ represents the thickness of the cable insulation. The three-phase core currents of the cross-connecting cable are obtained according to the following formula: Among them, I Ai (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase A cable; I Bi (i = 1, 2, 3) represents the conductor current on the i-th cross-connecting cable segment of phase B cable; I Ci (i = 1, 2, 3) represents the core current on the i-th cross-connecting cable of phase C cable.

4. The method for calculating the circulating current of the cross-connected cable sheath according to claim 3, characterized in that, The calculation based on the phase spacing to obtain the induced electromotive force generated in each phase and segment of the sheath circuit of the currently cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current includes: The induced electromotive force generated by the three-phase cable core current and the three-phase sheath circulating current in each phase and segment of the current cross-connection cable is calculated according to the following formula: Among them, e ji Let S be the induced voltage generated by the conductor current on the i-th segment of the j-phase sheath; GMR is the geometric mean radius of the metal sheath; S jj This refers to the phase spacing; Among them, E′ ji I represents the induced voltage generated by the circulating current of other phase sheaths on the i-th cross-interconnection segment in the j-phase sheath circuit; SA I SB I SC These are the induced currents in the three-phase sheathing circuit; The induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase cable core current and the three-phase sheath circulating current is calculated according to the following formula: Among them, U SA U SB U SC U′ is the total induced voltage generated by the conductor current in each sheath circuit; SA 、U′ SB 、U′ SC L1, L2, and L3 represent the total induced voltage generated by the circulating current of other phase sheaths in each sheath circuit; L1, L2, and L3 are the lengths of each section of the cross-connected cable.

5. The method for calculating circulating current in the sheath of cross-connected cables according to claim 4, characterized in that, The calculation of the induced current value on the metal sheath based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit includes: The induced current value on the metal sheath is calculated using the following formula: Among them, I SA I SB I SC R1 and R2 are the induced current values ​​on the metal sheath; R1 and R2 are the grounding resistances at both ends of the metal sheath.

6. The method for calculating circulating current in the sheath of cross-connected cables according to claim 5, characterized in that, The step of dividing the leakage current between the core sheaths includes: The leakage current between the core sheaths can be divided into components according to the following formula: Among them, I LjiL I LjiR This represents the left and right components of the i-th leakage current in the j-phase conductor sheath in a π-type equivalent circuit.

7. The method for calculating circulating current in the sheath of cross-connected cables according to claim 6, characterized in that, The actual circulating current value of each three-phase sheath of the current cross-connected cable is obtained by superimposing the leakage current value after componentization with the induced current value on the metal sheath. The actual values ​​of the three-phase sheath circulating current in each section of the current cross-connected cable are obtained according to the following formula: Among them, I SA1 I SA2 I SA3 This indicates the circulating current in the sheath of phase A, specifically in sections 1, 2, and 3 of the sheath circuit; I SB1 I SB2 I SB3 This indicates the circulating current in the sheath on sections 1, 2, and 3 of the B-phase sheath circuit; I SC1 I SC2 I SC3 This indicates the circulating current in the sheath on the first, second, and third sections of the C-phase sheath circuit.

8. A device for calculating the circulating current of a cross-connected cable sheath, characterized in that, include: The information acquisition module is used to acquire the three-phase load current, inner radius of the sheath, outer radius of the sheath, phase spacing, total cable length, length of each segment of the cross-connection cable, sheath resistivity, sheath operating temperature, and grounding resistance at both ends of the metal sheath of the current cross-connection cable. Based on the inner radius of the sheath, the outer radius of the sheath, the total cable length, the sheath resistivity, and the sheath operating temperature, the metal sheath resistance, metal sheath self-inductance, and equivalent ground resistance of the current cross-connection cable are calculated. The three-phase conductor current determination module is used to calculate the leakage current between conductor sheaths based on the length of each segment of the cross-interconnected cable using a π-type equivalent circuit, and then superimpose the leakage current with the three-phase load current to obtain the three-phase conductor current of the cross-interconnected cable. An induced electromotive force generation module is used to perform calculations based on the phase spacing to obtain the induced electromotive force generated in each phase and segment of the sheath circuit of the current cross-connected cable by the current values ​​of the three-phase core current and the three-phase sheath circulating current. The induced current value determination module is used to calculate the induced current value on the metal sheath based on the grounding resistance at both ends of the metal sheath and the induced electromotive force generated on each phase and segment of the sheath circuit. The three-phase sheath circulating current actual value determination module is used to perform the following: the leakage current between the core sheaths is divided into components, and the actual value of the three-phase sheath circulating current of each segment of the current cross-connected cable is obtained by superimposing the componentized leakage current with the induced current value on the metal sheath.

9. 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 cross-connected cable sheath circulating current calculation method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the cross-connected cable sheath circulating current calculation method according to any one of claims 1-7.

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