CN115291057A - Multi-loop high-voltage cable fault calculation method and device, electronic equipment and medium - Google Patents
Multi-loop high-voltage cable fault calculation method and device, electronic equipment and medium Download PDFInfo
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Abstract
The invention discloses a method and a device for calculating faults of a multi-loop high-voltage cable, electronic equipment and a medium. The method for calculating the fault of the multi-loop high-voltage cable comprises the following steps: when the high-voltage cable metal sheath generates an asymmetric grounding short circuit, converting the asymmetric grounding short circuit into a target symmetric three-phase short circuit by a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit; and calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state. The embodiment researches the insulation state of the high-voltage cable line, predicts the insulation state of the high-voltage cable in advance and takes corresponding measures, thereby being beneficial to the safety and reliability of the high-voltage cable transmission line.
Description
Technical Field
The invention relates to the technical field of cables, in particular to a method and a device for calculating faults of a multi-loop high-voltage cable, electronic equipment and a medium.
Background
With the increase of the speed of urban construction, the available land resources in the construction of power transmission, transformation and distribution projects become more and more tense, and the overhead line is not suitable for urban power transmission and distribution networks with small amount of soil due to the defects of large floor area, difficult access to path corridors and the like. The cables are classified according to different insulating materials and can be classified into oil-impregnated paper insulated cables, rubber insulated cables, plastic insulated cables and gas-filled cables, currently, XLPE (cross-linked polyethylene) cables are commonly used, and due to the limitation of manufacturing processes, defects such as air gaps, impurities, protruding burrs and the like are inevitably generated in insulating layers of the XLPE cables in production although the XLPE cables have excellent electrical properties.
High tension cable generally adopts single core structure, and high tension cable's metal sheath chooses for use the aluminium sheath, can form certain induced voltage on high tension cable metal sheath when the sinle silk flows through alternating current. When the insulation of the high-voltage cable is broken down to generate a ground fault and form a loop with the ground, the induced voltage generates sheath induced circulation in the loop. The circulation can lead to cable loss and generate heat to cause the insulating local temperature of high tension cable to rise for insulating ageing speed can cause very big threat to high tension cable line's safe operation, shortens cable line's normal life greatly. The excessive grounding circulation (the circulation value is more than 50A or more than 20% of the load current or the maximum value/minimum value of the interphase is more than 3) not only affects the current-carrying capacity and the service life of the cable, but also burns the grounding wire or the grounding box due to the serious heating caused by the circulation, and possibly causes a malignant grid accident when the circulation is not in time.
Disclosure of Invention
The invention provides a method and a device for calculating faults of a multi-loop high-voltage cable, electronic equipment and a medium, and aims to solve the problems that the high-voltage cable has potential safety operation hazards and the service life of the high-voltage cable is shortened.
According to an aspect of the present invention, there is provided a method for calculating a fault of a multi-loop high-voltage cable, the method comprising:
when the high-voltage cable metal sheath generates an asymmetric grounding short circuit, converting the asymmetric grounding short circuit into a target symmetric three-phase short circuit by a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit;
and calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state.
Optionally, the principle of the multi-loop high-voltage cable metal sheath circulation calculation is specifically expressed by the following formula:
I s1 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 1 ＝U 1
I s2 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 2 ＝U 2
I s3 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 3 ＝U 3
I s4 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 4 ＝U 4
I s5 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 5 ＝U 5
I s6 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 6 ＝U 6
I s7 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 7 ＝U 7
I s8 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 8 ＝U 8
I s9 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 9 ＝U 9
wherein, I s1 -I s9 Respectively circulating current of a three-phase high-voltage cable metal sheath; r is 1 A first grounding resistor; r 2 A second ground resistor; (R + jX) is the metal sheath self-impedance; r 3 Leakage resistance to earth ground; u shape 1 -U 9 An induced voltage on the sheath for the current of the conductor; u' 1 -U′ 9 Induced voltages respectively generated on the jacket for the jacket circulation and the earth circulation of other phases.
Optionally, the calculating the target symmetric three-phase short circuit based on the multi-loop high-voltage cable metal sheath circulating current calculation principle includes:
acquiring a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance, and respectively generating an induced voltage on the sheath according to the measured current of the conductor and induced voltages on the sheath by other phase sheath circulating currents and ground circulating currents;
and calculating the target symmetrical three-phase short circuit to obtain the three-phase high-voltage cable metal sheath circulating current according to the first ground resistance, the second ground resistance, the earth leakage resistance, the metal sheath self-impedance, the induced voltage generated on the sheath by the current of the conductor and the induced voltages generated on the sheath by other-phase sheath circulating currents and earth circulating currents based on the multi-loop high-voltage cable metal sheath circulating current calculation principle.
Optionally, the calculating the target symmetric three-phase short circuit based on the multi-loop high-voltage cable metal sheath circulating current calculation principle includes:
acquiring induced voltage generated on a sheath by a three-phase high-voltage cable metal sheath circulating current and a conductor current and induced voltage generated on the sheath by other phase sheath circulating currents and earth circulating currents respectively;
and calculating the target symmetrical three-phase short circuit to obtain a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance according to the induced voltage generated on the sheath by the three-phase high-voltage cable metal sheath circulating current, the conductor current and the other phase sheath circulating current and the ground circulating current on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculating principle.
Optionally, the method for calculating a fault of a multi-loop high-voltage cable further includes:
and calculating the equivalent resistance of the metal sheath of the high-voltage cable according to the first grounding resistance, the second grounding resistance, the earth leakage resistance and the self-impedance of the metal sheath.
Optionally, the equivalent resistance of the metal sheath of the high-voltage cable is calculated by the following formula:
R eq ＝R+R 1 +R 2 +R 3
wherein R is eq Is the equivalent resistance of the metal sheath of the high-voltage cable.
Optionally, the method for calculating the fault of the multi-loop high-voltage cable further includes:
the insulation resistance of the outer sheath of the multi-loop high-voltage cable is calculated according to the following formula, and the method specifically comprises the following steps:
wherein R is the insulation resistance of the outer sheath of the multi-loop high-voltage cable; rho i Is the volume resistivity of the outer sheath material; l is the length of the high-voltage cable; d i The outer diameter of the outer sheath of the high-voltage cable; d c Is the inner diameter of the outer sheath of the high-voltage cable.
According to another aspect of the present invention, there is provided a multi-loop high voltage cable fault calculation apparatus including:
the circuit conversion module is used for converting the asymmetrical grounding short circuit into a target symmetrical three-phase short circuit by a symmetrical component method when the asymmetrical grounding short circuit occurs to the high-voltage cable metal sheath, wherein the asymmetrical grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit;
and the fault calculation module is used for calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulating current calculation principle, determining the insulation state of the high-voltage cable and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state.
According to another aspect of the present invention, there is provided an electronic apparatus including:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein,
the memory stores a computer program executable by the at least one processor, the computer program being executable by the at least one processor to enable the at least one processor to perform a method of multi-loop high voltage cable fault calculation according to any of the embodiments of the present invention.
According to another aspect of the present invention, there is provided a computer readable storage medium storing computer instructions for causing a processor to implement the method for calculating a fault of a multi-loop high-voltage cable according to any one of the embodiments of the present invention when the computer instructions are executed.
According to the technical scheme of the embodiment of the invention, when the high-voltage cable metal sheath generates the asymmetric grounding short circuit, the asymmetric grounding short circuit is converted into the target symmetric three-phase short circuit through a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit; and calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state. The problem of high tension cable have safe operation hidden danger to shorten high tension cable life is solved, the insulating state of high tension cable circuit is studied, foresee high tension cable insulating state in advance and take corresponding measure, be favorable to cable transmission line's security and reliability.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present invention, nor do they necessarily limit the scope of the invention. Other features of the present invention will become apparent from the following description.
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In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a flowchart of a method for calculating a fault of a multi-loop high-voltage cable according to an embodiment of the present invention;
fig. 2 is an equivalent circuit diagram of a three-phase cross-connected two-end grounding equivalent circuit of a high-voltage cable outer sheath, which is suitable for being used according to an embodiment of the invention;
fig. 3 is a schematic diagram of a first loop of a metal jacket of a three-loop high-voltage cable adapted according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a second loop of a metal jacket of a three-loop high-voltage cable, to which an embodiment of the invention is applied;
fig. 5 is a schematic diagram of a third loop of a metal jacket of a three-loop high-voltage cable, to which an embodiment of the invention is applied;
FIG. 6 is a schematic diagram of a high voltage cable metal sheath three-phase short circuit ground according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a two-phase short circuit ground for a metal sheath of a high voltage cable to which an embodiment of the present invention is applied;
FIG. 8 is a schematic diagram of a single-phase short-circuit ground of a metal sheath of a high-voltage cable to which an embodiment of the present invention is applied;
FIG. 9 is a schematic diagram of a high voltage cable jacket suitable for use in accordance with an embodiment of the present invention;
fig. 10 is a schematic structural diagram of a multi-loop high-voltage cable fault calculation device according to a third embodiment of the present invention;
fig. 11 is a schematic structural diagram of an electronic device implementing the method for calculating the fault of the multi-loop high-voltage cable according to the embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Example one
Fig. 1 is a flowchart of a method for calculating a fault of a multi-loop high-voltage cable according to an embodiment of the present invention, where the embodiment is applicable to a situation where a fault of a multi-loop high-voltage cable is calculated, the method for calculating a fault of a multi-loop high-voltage cable may be executed by a device for calculating a fault of a multi-loop high-voltage cable, the device for calculating a fault of a multi-loop high-voltage cable may be implemented in a form of hardware and/or software, and the device for calculating a fault of a multi-loop high-voltage cable may be configured in an electronic device of an electrical power system. As shown in fig. 1, the method for calculating the fault of the multi-loop high-voltage cable comprises the following steps:
and S110, when the high-voltage cable metal sheath is subjected to asymmetric grounding short circuit, converting the asymmetric grounding short circuit into a target symmetric three-phase short circuit by a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit.
In brief, the single-phase ground short circuit, the two-phase interphase short circuit, and the like in the short circuit type belong to asymmetric short circuits. A three-phase ground short is a symmetric short, but a short that occurs at a different point for a three-phase ground short is also an asymmetric short. In terms of the actual occurrence probability, 90% of short circuits of the power system are asymmetric ground short circuits, and 90% of the short circuits of the power system are single-phase ground short circuits, so that the short circuit fault of the power system is generally referred to as a single-phase short circuit fault. The asymmetric ground short in the present embodiment mainly relates to a single-phase ground short and a two-phase ground short.
The symmetric component method (method of symmetric components) is a basic method for analyzing the asymmetric operation state of a symmetric system in electricians, and is widely applied to the calculation of electrical quantities with symmetric parameters and asymmetric operation conditions of a three-phase alternating-current system. When an electric power system has asymmetric faults such as single-phase grounding short circuit, two-phase grounding short circuit, single-phase broken line and two-phase broken line, the three-phase impedances are different, the three-phase voltages and the currents are not equal, the phase difference between the phases is also not equal, and the three-phase system cannot analyze only one phase and usually adopts a symmetric component method for analysis. Asymmetric voltage and current quantity generated after an asymmetric fault occurs in a power system can be decomposed into three sequence nets by applying a symmetric component method, the sequence nets are analyzed in a sequence voltage and current symmetric mode, and then the sequence voltage and the current are synthesized into actual ABC quantity, so that the asymmetric fault calculation is greatly simplified.
The high-voltage cable may have a sheath broken during operation, which may cause different grounding resistances and different grounding points. At this time, the conventional and simple calculation formula cannot reflect the actual situation, and the grounding resistance situation, the node voltage distribution situation, the mutual inductance situation between loops and the like need to be comprehensively considered from the whole network of the cable line, so that the distribution characteristics of the sheath circulating current and the induced voltage are obtained. A brief analysis is performed below with a single-loop model, which is mainly divided into symmetric short circuits and asymmetric short circuits, as shown in fig. 6-8.
The cable metal sheath has different grounding resistances under different grounding modes, and also has different grounding resistances at different grounding points, which can be mainly divided into three conditions in the previous figure. When a three-phase grounding short circuit occurs to a cable metal sheath, the circuit can be divided into a plurality of independent networks at a short circuit point for calculation, when an asymmetric grounding short circuit occurs to a high-voltage cable metal sheath, namely, a simple calculation model cannot meet the requirements when a single-phase grounding short circuit and a two-phase grounding short circuit occur, a symmetric component method needs to be introduced, the asymmetry of the fault point is converted into the symmetry when the asymmetric grounding short circuit is calculated, the three-phase circuit with the symmetry broken by the short circuit is converted into a symmetric circuit, the target symmetric three-phase short circuit is obtained, and then the single-phase circuit is used for calculation.
And S120, calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state.
In this embodiment, generally, three phases are laid in parallel, since three phases are asymmetric, even if the segments are uniform, the sum of the induced voltages of the small segments is not zero, a circulating current flows through the high-voltage cable metal sheath, and when a single-phase ground short circuit or a two-phase ground short circuit occurs in the high-voltage cable metal sheath, the single-phase ground short circuit or the two-phase ground short circuit is converted into a target symmetric three-phase short circuit by a symmetric component method. Therefore, an equivalent circuit of sheath circulation in a three-phase cross-connection three-section two-end direct grounding mode is established, and specifically, the equivalent circuit of three-phase cross-connection two-end grounding of the high-voltage cable sheath is shown in figure 2.
In the actual operation of a power system, a multi-loop cable is usually laid in the same channel, and a high-voltage cable is usually laid in parallel by adopting the multi-loop cable, so that the problem of sheath circulation is more complicated. Now, a three-circuit high-voltage cable is taken as a prototype for analysis, and the schematic diagrams of the circulating current of the first circuit, the second circuit and the third circuit of the metal jacket of the three-circuit high-voltage cable are shown in fig. 3-5.
On the basis, the circulation calculation principle of the metal sheath of the multi-loop high-voltage cable is specifically expressed by the following formula:
I s1 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 1 ＝U 1
I s2 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 2 ＝U 2
I s3 (R+jX)+(I 51 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 3 ＝U 3
I s4 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 4 ＝U 4
I s5 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 5 ＝U 5
I s6 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 6 ＝U 6
I s7 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 7 ＝U 7
I s8 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 8 ＝U 8
I s9 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 9 ＝U 9
wherein, I s1 -I s9 Respectively circulating current of a three-phase high-voltage cable metal sheath; r 1 A first ground resistor; r 2 A second grounding resistor; (R + jX) is the metal sheath self-impedance; r 3 Leakage resistance to earth ground; u shape 1 -U 9 An induced voltage on the sheath for the current of the conductor; u' 1 -U′ 9 Induced voltages respectively generated on the sheaths for sheath circulating currents and earth circulating currents of other phases.
Further, acquiring a first grounding resistance, a second grounding resistance, an earth leakage resistance and a metal sheath self-impedance, and respectively generating an induced voltage on the sheath according to the measured current of the conductor and induced voltages on the sheath by other phase sheath circulating currents and earth circulating currents; and calculating the target symmetrical three-phase short circuit to obtain the three-phase high-voltage cable metal sheath circulating current according to the first ground resistance, the second ground resistance, the earth leakage resistance, the metal sheath self-impedance, the induced voltage generated by the current of the conductor on the sheath and the induced voltages generated by other phase sheath circulating currents and earth circulating currents on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculation principle.
Acquiring induced voltage generated on a sheath by a three-phase high-voltage cable metal sheath circulating current and a conductor current and induced voltage generated on the sheath by other phase sheath circulating currents and earth circulating currents respectively; and calculating the target symmetrical three-phase short circuit to obtain a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance according to the induced voltage generated on the sheath by the three-phase high-voltage cable metal sheath circulating current, the conductor current and the other phase sheath circulating current and the ground circulating current on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculating principle.
On the basis, 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. Specifically, the equivalent resistance of the metal sheath of the high-voltage cable can be calculated by the following formula:
R eq ＝R+R 1 +R 2 +R 3
wherein R is eq Is the equivalent resistance of the metal sheath of the high-voltage cable.
On the basis of the above embodiments, the insulation resistance of the metal sheath of the high-voltage cable is also an index for measuring the insulation level of a component or an electric power system, and is related to various factors, including materials (volume resistivity), structural shapes and the like, and has a certain relationship with environmental conditions such as temperature, humidity and the like. The outer sheath material of the high-voltage power cable mainly comprises polyvinyl chloride, polyethylene and flame-retardant polyolefin. For a single-core high-voltage power cable, the insulation resistance of the outer sheath of the multi-loop high-voltage cable is calculated according to the following formula, and the method specifically comprises the following steps:
wherein R is the insulation resistance (omega. M) of the outer sheath of the multi-loop high-voltage cable; ρ is a unit of a gradient i Is the volume resistivity of the outer sheath material; l is the length (m) of the high-voltage cable; d i The outer diameter of the outer sheath of the high-voltage cable; d c Is the inner diameter of the outer sheath of the high-voltage cable.
According to the above formula of calculating the insulation resistance of the outer sheath of the multi-loop high-voltage cable, the insulation resistance of the outer sheath of the multi-loop high-voltage cable is in direct proportion to the volume resistivity of the material and in inverse proportion to the length of the outer sheath of the tested multi-loop high-voltage cable. The higher the volume resistivity of the material, the greater the insulation resistance. For a multi-loop high-voltage cable with the same material and structure, the longer the length is, the smaller the insulation resistance is, and theoretically, when the length is infinite, the insulation resistance approaches zero. For a multi-loop high-voltage cable line with indefinite length, the test result of the insulation resistance of the outer sheath can not be directly used as an examination parameter.
The relationship between the conductor of the high-voltage cable and the sheath can be regarded as an air-core transformer, the conductor of the high-voltage cable is equivalent to a primary winding of the transformer, and the metal sheath of the high-voltage cable is equivalent to a secondary winding. In the case of grounding the two ends of the metal sheath of the high-voltage cable, when the alternating current passes through the conductor of the high-voltage cable, an induced voltage will be generated on the metal sheath of the high-voltage cable, and a loop current will be generated on the high-voltage cable sheath, and the circuit diagram is shown in fig. 9, wherein I s1 -I s3 Respectively circulating current of a three-phase high-voltage cable metal sheath; is a circular flow to the earth; r is 1 A first ground resistor; r is 2 A second grounding resistor; (R + jX) is the metal sheath self-impedance; r is 3 Leakage resistance to earth; u shape 1 -U 3 An induced voltage on the sheath for the current of the conductor; u' 1 -U′ 3 Induced voltages respectively generated on the sheaths for sheath circulating currents and earth circulating currents of other phases.
According to the technical scheme of the embodiment of the invention, when the high-voltage cable metal sheath generates the asymmetric grounding short circuit, the asymmetric grounding short circuit is converted into the target symmetric three-phase short circuit through a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit; and calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state. The problem of high tension cable have safe operation hidden danger to shorten high tension cable life is solved, the insulating state of high tension cable circuit is studied, foresee high tension cable insulating state in advance and take corresponding measure, be favorable to cable transmission line's security and reliability.
Example two
Fig. 10 is a schematic structural diagram of a device for calculating a fault of a multi-loop high-voltage cable according to a third embodiment of the present invention. As shown in fig. 10, the multi-loop high-voltage cable fault calculation apparatus includes:
the circuit conversion module 1010 is used for converting an asymmetric grounding short circuit into a target symmetric three-phase short circuit by a symmetric component method when the high-voltage cable metal sheath generates the asymmetric grounding short circuit, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit;
and a fault calculation module 1020, configured to perform calculation on the target symmetric three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulating current calculation principle, determine an insulation state of the high-voltage cable, and calculate a corresponding multi-loop high-voltage cable fault according to the insulation state.
Optionally, the principle of calculating the circulating current of the metal sheath of the multi-loop high-voltage cable is specifically expressed by the following formula:
I s1 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 1 ＝U 1
I s2 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 2 ＝U 2
I s3 (R+jX)+(I 51 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U′ 3 ＝U 3
I s4 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 4 ＝U 4
I s5 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 5 ＝U 5
I s6 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U′ 6 ＝U 6
I s7 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 7 ＝U 7
I s8 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 8 ＝U 8
I s9 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U′ 9 ＝U 9
wherein, I s1 -I s9 Respectively circulating current of a three-phase high-voltage cable metal sheath; r 1 A first grounding resistor; r 2 A second ground resistor; (R + jX) is the metal sheath self-impedance; r 3 Leakage resistance to earth; u shape 1 -U 9 An induced voltage on the sheath for the current of the conductor; u' 1 -U′ 9 Induced voltages respectively generated on the sheaths for sheath circulating currents and earth circulating currents of other phases.
Optionally, the calculating the target symmetric three-phase short circuit based on the multi-loop high-voltage cable metal sheath circulating current calculation principle includes:
acquiring a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance, and respectively generating an induced voltage on the sheath according to the measured current of the conductor and induced voltages on the sheath by other phase sheath circulating currents and ground circulating currents;
and calculating the target symmetrical three-phase short circuit to obtain the three-phase high-voltage cable metal sheath circulating current according to the first ground resistance, the second ground resistance, the earth leakage resistance, the metal sheath self-impedance, the induced voltage generated by the current of the conductor on the sheath and the induced voltages generated by other phase sheath circulating currents and earth circulating currents on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculation principle.
Optionally, the calculating the target symmetric three-phase short circuit based on the multi-loop high-voltage cable metal sheath circulating current calculation principle includes:
acquiring induced voltage generated on a sheath by a three-phase high-voltage cable metal sheath circulating current and a conductor current and induced voltage generated on the sheath by other phase sheath circulating currents and earth circulating currents respectively;
and calculating the target symmetrical three-phase short circuit to obtain a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance according to the induced voltage generated on the sheath by the three-phase high-voltage cable metal sheath circulating current, the conductor current and the other phase sheath circulating current and the ground circulating current on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculating principle.
Optionally, the device for calculating a fault of a multi-loop high-voltage cable further includes:
and calculating the equivalent resistance of the metal sheath of the high-voltage cable according to the first grounding resistance, the second grounding resistance, the earth leakage resistance and the self-impedance of the metal sheath.
Optionally, the equivalent resistance of the metal sheath of the high-voltage cable is calculated by the following formula:
R eq ＝R+R 1 +R 2 +R 3
wherein R is eq Is the equivalent resistance of the metal sheath of the high-voltage cable.
Optionally, the device for calculating a fault of a multi-loop high-voltage cable further includes:
the insulation resistance of the outer sheath of the multi-loop high-voltage cable is calculated according to the following formula, and the method specifically comprises the following steps:
wherein R is the insulation resistance of the outer sheath of the multi-loop high-voltage cable; rho i The volume resistivity of the outer sheath material; l is the length of the high-voltage cable; d i The outer diameter of the outer sheath of the high-voltage cable; d c Is the inner diameter of the outer sheath of the high-voltage cable.
The multi-loop high-voltage cable fault calculation device provided by the embodiment of the invention can execute the multi-loop high-voltage cable fault calculation method provided by any embodiment of the invention, and has corresponding functional modules and beneficial effects for executing the multi-loop high-voltage cable fault calculation method.
EXAMPLE III
FIG. 11 illustrates a schematic diagram of an electronic device 10 that may be used to implement embodiments of the present invention. Electronic devices are intended to represent various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The electronic device may also represent various forms of mobile devices, such as personal digital assistants, cellular phones, smart phones, 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 meant to be exemplary only, and are not meant to limit implementations of the inventions described and/or claimed herein.
As shown in fig. 11, the electronic device 10 includes at least one processor 11, and a memory communicatively connected to the at least one processor 11, such as a Read Only Memory (ROM) 12, a Random Access Memory (RAM) 13, and the like, wherein the memory stores a computer program executable by the at least one processor, and the processor 11 can perform various suitable actions and processes according to the computer program stored in the Read Only Memory (ROM) 12 or the computer program loaded from a storage unit 18 into the Random Access Memory (RAM) 13. In the RAM 13, various programs and data necessary for the operation of the electronic apparatus 10 may also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other via a bus 14. An input/output (I/O) interface 15 is also connected to the bus 14.
A number of components in the electronic device 10 are connected to the I/O interface 15, including: an input unit 16 such as a keyboard, a mouse, or the like; an output unit 17 such as various types of displays, speakers, and the like; a storage unit 18 such as a magnetic disk, optical disk, or the like; and a communication unit 19 such as a network card, modem, wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information/data with other devices via a computer network such as the internet and/or various telecommunication networks.
In some embodiments, the multi-loop high voltage cable fault calculation method may be implemented as a computer program tangibly embodied on a computer readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program may be loaded and/or installed onto the electronic device 10 via the ROM 12 and/or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the multi-loop high voltage cable fault calculation method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform the multi-loop high voltage cable fault calculation method by any other suitable means (e.g., by means of firmware).
Various implementations of the systems and techniques described here above may be implemented in digital electronic circuitry, integrated circuitry, field Programmable Gate Arrays (FPGAs), application Specific Integrated Circuits (ASICs), application Specific Standard Products (ASSPs), system on a chip (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and/or combinations thereof. These various embodiments may include: implemented in one or more computer programs that are executable and/or interpretable on a programmable system including at least one programmable processor, which may be special or general purpose, receiving data and instructions from, and transmitting data and instructions to, a storage system, at least one input device, and at least one output device.
A computer program for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the computer programs, when executed by the processor, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. A computer program can execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.
In the context of the present invention, a computer-readable storage medium may be a tangible medium that can contain, or store a computer program for use by or in connection with an instruction execution system, apparatus, or device. A computer readable storage medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. Alternatively, the computer readable storage medium may be a machine readable signal medium. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.
To provide for interaction with a user, the systems and techniques described here 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 a user; and a keyboard and a pointing device (e.g., a mouse or a trackball) by which a user can provide input to the electronic device. Other kinds of devices may also be used to provide for interaction with a 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 may be received in any form, including acoustic, speech, or tactile input.
The systems and techniques described here can be implemented in a computing system that includes a back-end component (e.g., as a data server), or that includes a middleware component (e.g., an application server), or that includes a front-end component (e.g., a user computer having a graphical user interface or a web browser through which a user can interact with an implementation of the systems and techniques described here), or any combination of such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: local Area Networks (LANs), wide Area Networks (WANs), blockchain networks, and the internet.
The computing system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. The server can be a cloud server, also called a cloud computing server or a cloud host, and is a host product in a cloud computing service system, so that the defects of high management difficulty and weak service expansibility in the traditional physical host and VPS service are overcome.
It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present invention may be executed in parallel, sequentially, or in different orders, and are not limited herein as long as the desired results of the technical solution of the present invention can be achieved.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A multi-loop high-voltage cable fault calculation method is characterized by comprising the following steps:
when the high-voltage cable metal sheath generates an asymmetric grounding short circuit, converting the asymmetric grounding short circuit into a target symmetric three-phase short circuit by a symmetric component method, wherein the asymmetric grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit;
and calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulation calculation principle, determining the insulation state of the high-voltage cable, and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state.
2. The method for calculating the fault of the multi-loop high-voltage cable according to claim 1, wherein the principle of calculating the metal sheath circulating current of the multi-loop high-voltage cable is specifically expressed by the following formula:
I s1 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U 1 ′＝U 1
I s2 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U 2 ′＝U 2
I s3 (R+jX)+(I s1 +I s2 +I s3 )(R 1 +R 2 +R 3 )+U 3 ′＝U 3
I s4 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U 4 ′＝U 4
I s5 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U 5 ′＝U 5
I 56 (R+jX)+(I s4 +I s5 +I s6 )(R 1 +R 2 +R 3 )+U 6 ′＝U 6
I s7 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U 7 ′＝U 7
I s8 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U 8 ′＝U 8
I s9 (R+jX)+(I s7 +I s8 +I s9 )(R 1 +R 2 +R 3 )+U 9 ′＝U 9
wherein, I s1 -I s9 Respectively circulating current of a three-phase high-voltage cable metal sheath; r 1 A first grounding resistor; r is 2 A second grounding resistor; (R + jX) is the metal sheath self-impedance; r 3 Leakage resistance to earth; u shape 1 -U 9 An induced voltage on the sheath for the current of the conductor; u shape 1 ′-U 9 ' is the induced voltage generated on the sheath by the sheath circular current and the earth circular current of other phases respectively.
3. The method for calculating the fault of the multi-loop high-voltage cable according to claim 2, wherein the calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulating current calculation principle comprises:
acquiring a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance, and respectively generating an induced voltage on the sheath according to the measured current of the conductor and induced voltages on the sheath by other phase sheath circulating currents and ground circulating currents;
and calculating the target symmetrical three-phase short circuit to obtain the three-phase high-voltage cable metal sheath circulating current according to the first ground resistance, the second ground resistance, the earth leakage resistance, the metal sheath self-impedance, the induced voltage generated by the current of the conductor on the sheath and the induced voltages generated by other phase sheath circulating currents and earth circulating currents on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculation principle.
4. The method for calculating the fault of the multi-loop high-voltage cable according to claim 2, wherein the calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulating current calculation principle comprises:
acquiring induced voltage generated on a sheath by a three-phase high-voltage cable metal sheath circulating current and a conductor current and induced voltage generated on the sheath by other phase sheath circulating currents and earth circulating currents respectively;
and calculating the target symmetrical three-phase short circuit to obtain a first grounding resistance, a second grounding resistance, a ground leakage resistance and a metal sheath self-impedance according to the induced voltage generated on the sheath by the three-phase high-voltage cable metal sheath circulating current, the conductor current and the other phase sheath circulating current and the ground circulating current on the sheath based on the multi-loop high-voltage cable metal sheath circulating current calculating principle.
5. The multi-loop high-voltage cable fault calculation method according to claim 4, further comprising:
and calculating the equivalent resistance of the metal sheath of the high-voltage cable according to the first grounding resistance, the second grounding resistance, the earth leakage resistance and the self-impedance of the metal sheath.
6. The method for calculating the fault of the multi-loop high-voltage cable according to claim 5, wherein the equivalent resistance of the metal sheath of the high-voltage cable is calculated by the following formula:
R eq ＝R+R 1 +R 2 +R 3
wherein R is eq Is the equivalent resistance of the metal sheath of the high-voltage cable.
7. The method of claim 1, further comprising:
the insulation resistance of the outer sheath of the multi-loop high-voltage cable is calculated according to the following formula, and the method specifically comprises the following steps:
wherein R is the insulation resistance of the outer sheath of the multi-loop high-voltage cable; rho i Is the volume resistivity of the outer sheath material; l is the length of the high-voltage cable; d i The outer diameter of the outer sheath of the high-voltage cable; d c Is the inner diameter of the outer sheath of the high-voltage cable.
8. A multi-loop high-voltage cable fault calculation device is characterized by comprising:
the circuit conversion module is used for converting the asymmetrical grounding short circuit into a target symmetrical three-phase short circuit by a symmetrical component method when the asymmetrical grounding short circuit occurs to the high-voltage cable metal sheath, wherein the asymmetrical grounding short circuit comprises a single-phase grounding short circuit and a two-phase grounding short circuit;
and the fault calculation module is used for calculating the target symmetrical three-phase short circuit based on a multi-loop high-voltage cable metal sheath circulating current calculation principle, determining the insulation state of the high-voltage cable and calculating the corresponding multi-loop high-voltage cable fault according to the insulation state.
9. An electronic device, characterized in that the electronic device comprises:
at least one processor; and
a memory communicatively coupled to the at least one processor; wherein,
the memory stores a computer program executable by the at least one processor to enable the at least one processor to perform the method of multi-loop high voltage cable fault calculation of any one of claims 1-7.
10. A computer-readable storage medium storing computer instructions for causing a processor to perform the method of calculating a fault in a multi-loop high-voltage cable according to any one of claims 1 to 7 when executed.
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| CN116299050B (en) * | 2023-05-17 | 2023-08-11 | 广东电网有限责任公司汕尾供电局 | Method, system, equipment and storage medium for detecting faults of protective layer |
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