High-voltage cable induced voltage monitoring method and system
By selecting the cable model according to the grounding method of the high-voltage cable and calculating the circulation to obtain the electromagnetic induction voltage, the problem of cable connections in the prior art is solved, and efficient and applicable induced voltage monitoring is achieved.
Patent Information
- Application Number
- CN202411865709.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-03-18
AI Technical Summary
The existing high-voltage cable induction voltage monitoring methods require disconnection of the cable, affecting the normal operation of the system, or are costly and unsuitable for monitoring in long-distance and complex environments.
Through the grounding method of high-voltage cable, the corresponding cable model is selected, the circulation under different grounding methods is calculated, and the electromagnetic induction voltage is indirectly obtained based on the circulation.
It enables monitoring of high-voltage cable induction voltage without disconnecting the cable, reduces the impact of system operation, and is suitable for monitoring in long-distance and complex environments.
Smart Images
Figure CN119643945A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of high-voltage power transmission, and in particular to a method and system for monitoring induced voltage of a high-voltage cable. Background Art
[0002] When an alternating current flows through the core of a high-voltage cable, an alternating magnetic field is generated in the surrounding space. This alternating magnetic field intersects with the metal sheath or shield of the cable, thereby generating an induced electromotive force on the metal sheath or shield. The relationship between the core and the metal sheath or shield of a single-core cable can be regarded as the relationship between the primary winding and the iron core of a transformer. When current passes through the core, magnetic lines of force intersect the metal sheath or shield, causing an induced voltage to appear at both ends. The longer the cable and the greater the load current in the core, the higher the induced voltage generated. This is because longer cables and larger currents will generate stronger alternating magnetic fields in the surrounding space, thereby generating higher induced electromotive forces on the metal sheath or shield.
[0003] Monitoring the induced voltage of high-voltage cables is a key link in ensuring the safe and stable operation of power systems. Use current transformers (CT) or voltage transformers (VT) to directly measure the current and voltage in the cable. This method is simple and intuitive, but it requires disconnecting the cable for measurement, which may affect the normal operation of the system. Using optical fiber as a sensor, the current and voltage in the cable are measured by detecting the changes in the optical signal during transmission in the optical fiber. This method has the advantages of high precision, high reliability and anti-electromagnetic interference, and is suitable for monitoring over long distances and in complex environments, but it is relatively expensive. Summary of the invention
[0004] The present invention selects a corresponding cable model according to the grounding mode of the high-voltage cable, calculates the circulating current under different grounding modes, and indirectly obtains the electromagnetic induction voltage based on the circulating current.
[0005] The technical solution proposed by the present invention is: a method for monitoring the induced voltage of a high-voltage cable, the method comprising: Step 1: query the database for the line information of the high-voltage cable to be monitored in the high-voltage line, and receive the query feedback result; determine whether the feedback result is empty, if so, proceed to step 7; otherwise, output the line information and proceed to step 2; Step 2: Identify the grounding line characteristics based on the acquired line information of the high-voltage cable to be monitored; Step 3: Select a matching cable model from a plurality of preset cable models according to the identified ground line characteristics; Step 4: Obtain high-voltage cable parameters and power transmission parameters, wherein the high-voltage cable parameters include one or more of the length, diameter, resistance, capacitance and inductance of the cable; and the power transmission parameters include the voltage value and current frequency in the high-voltage cable; Step 5: After preprocessing, the obtained high-voltage cable parameters and power supply parameters are input into the corresponding cable model, and the induced voltage of the high-voltage cable voltage is obtained through the cable model calculation; Step 6: Determine whether the induced voltage at the monitoring point is within the safety threshold range. If yes, return to step 1; otherwise, issue a warning message and then return to step 1; Step 7: Obtain the electromagnetic field distribution characteristics and the loop current characteristics of the high-voltage cable, determine the grounding method of the high-voltage cable according to the electromagnetic field distribution characteristics and the loop current characteristics, and then return to step 2.
[0006] Preferably, the step of identifying the grounding line characteristics according to the acquired line information of the high-voltage cable to be monitored comprises the following steps: Acquiring line information, wherein the line information includes design drawings and design documents of the power system, cable laying construction drawings and construction documents; Extract ground line features from line information; specifically including: Screening out the grounding line drawings of the high-voltage cables to be monitored from the design drawings of the power system, and screening out the design documents of the high-voltage cables to be monitored from the design documents of the power system; Extracting grounding line features from the screened grounding line drawings through image processing algorithms; Extracting grounding line features from power system design documents using word processing algorithms; The grounding line characteristics include the number of direct grounding points, the number of sheath voltage limiters, the number of sheath voltage limiter grounding points, the number of insulating joints and the number of insulating joint grounding points.
[0007] Preferably, the cable model is one or more of a one-end single-point grounding model, a central portion single-point grounding model, a two-end grounding model and a cross-connected grounding model.
[0008] Preferably, the selecting a matching cable model from a plurality of preset cable models according to the identified ground line characteristics comprises the following steps: After preprocessing, the identified grounding line features of the high-voltage cable are composed into a grounding line feature vector that uniquely corresponds to the high-voltage cable. ; in, Respectively represent the number of direct grounding points, the number of sheath voltage limiter grounding points, the number of insulating joint grounding points, the number of sheath voltage limiters and the number of insulating joints; Assigning an identifying feature vector to each line model; Specifically, the identification feature vector of the one-end single-point grounding model is: , the identification feature vector of the central single-point grounding model is , identification of the two-terminal grounding model , the identification feature vector of the cross-connection grounding model is ;in Indicates the number of units the cable is divided into; Calculate the similarity between the ground line feature vector and the identification feature vector of the line model; If the similarity is greater than a preset similarity threshold, it is determined that the ground line feature vector matches the identification feature vector; The cable model corresponding to the identified feature vector is used as the cable model matching the high-voltage cable.
[0009] Preferably, the obtained high-voltage cable parameters and power supply parameters are pre-processed and input into a corresponding cable model, and the induced voltage of the high-voltage cable voltage is obtained by calculating the cable model, including the following steps: If the cable model that matches the cable to be monitored is a single-point grounding model at one end or a single-point grounding model in the middle, the induced voltage is obtained by the following steps: Assume the characteristic impedance of the cable is: ; The propagation coefficient is: ;use and Indicates the distance from the cable start point The voltage and current at is the resistance per unit length of the cable, The inductance per unit length of the cable, is the capacitance per unit length of the cable; Apply Kirchhoff's voltage law to simplify the calculation: ; Since the voltage at the grounding point is zero, the current at the grounding point ; The grounding point is at the beginning of the cable, that is ; Current at the grounding point ; In case of central grounding, the grounding point is selected in the middle of the cable, i.e. ; Current at the grounding point , is the length of the cable; In this simplified calculation, the influence of the reflection coefficient of the grounding point is ignored and the ring current is considered to be and equal; The ring pressure is ,in, is the total impedance of the cable; Calculate the magnetic flux generated by circulating current in the cable ;in, is the average cross-sectional area of the cable, is the average radius of the cable, represents magnetic permeability; According to Faraday's law of electromagnetic induction, the electromagnetic induced voltage of the circulating current is ; The electromagnetic induced voltage of the cable is ; in, is the electromagnetic induction voltage of the cable core current to be monitored at the grounding point, express The sum of the induced voltages on the cable to be monitored generated by the electromagnetic fields of the surrounding cables; Indicates the total number of surrounding cables; Indicates cable The influence coefficient of the magnetic field on the electromagnetic induction voltage at the voltage monitoring point of the monitored cable.
[0010] Preferably, the method of preprocessing the obtained high-voltage cable parameters and power supply parameters and inputting them into a corresponding cable model, and obtaining the induced voltage of the high-voltage cable voltage by calculating the cable model, further includes the following steps: If the cable model that matches the cable to be monitored is a cross-connected grounding model, the induced voltage is obtained by the following steps: Assuming that the core current of the three-phase cable is balanced, the induced voltage generated by the core of any phase on the metal sheath is: ; Assume the cross-connection matrix is: ; in, express Any one of the three phases; Take the value from the second column of the cross-connection matrix, Take the value from the third column of the cross-connection matrix, Take the value from the fourth column of the cross-connection matrix; The equation for solving the metal sheath grounding loop current is: ; in, They represent grounding point resistance 1, grounding point resistance 2 and earth equivalent resistance respectively; Indicates the self-impedance of the cable metal sheath. represents the coefficient matrix; By solving the equations through the MATLAB program, the metal sheath grounding loop current can be obtained; Through the metal sheath grounding loop current and combined with the principle of electromagnetic induction, the electromagnetic induction voltage of each phase cable can be obtained.
[0011] Preferably, the step of determining whether the induced voltage at the monitoring point is within a safety threshold range comprises the following steps: Setting safety thresholds ; If the electromagnetic induction voltage satisfies: , it is judged that the induced voltage meets the safety threshold requirement; otherwise, it is judged that the induced voltage does not meet the safety threshold requirement.
[0012] Preferably, the obtaining of the electromagnetic field distribution characteristics and the loop current characteristics of the high-voltage cable, and determining the grounding mode of the high-voltage cable according to the electromagnetic field distribution characteristics and the loop current characteristics, comprises the following steps: Measuring the electromagnetic field data of the high-voltage cable along the time-delay direction of the high-voltage cable; Extracting magnetic field distribution characteristics from the electromagnetic field data, wherein the magnetic field distribution characteristics include a maximum magnetic flux value, a minimum magnetic flux value, a maximum magnetic flux position, and a minimum magnetic flux position; According to the distribution position of the maximum magnetic flux on the high-voltage cable, the grounding method of the high-voltage cable is determined; specifically: If the maximum magnetic flux position is only distributed at one end of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a single-point grounding method at one end; If the maximum magnetic flux position is distributed at both ends of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a two-end grounding method or a cross-connection grounding method.
[0013] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method for monitoring the induced voltage of a high-voltage cable.
[0014] Beneficial effects of the present invention: 1. The present invention selects a cable model corresponding to the grounding method according to the grounding method of the cable, calculates the circulating current of the metal sheath under different grounding methods through the cable model, and indirectly obtains the ring pressure according to the circulating current value. In combination with the law of electromagnetic induction, the influence of the surrounding cables on the induced voltage of the high-voltage cable to be monitored can be obtained, and the electromagnetic induction voltage generated by the core current itself (which can be the voltage value measured by historical data or a circuit-breaking experiment) can be combined to obtain the electromagnetic induction voltage of the grounding point.
[0015] 2. The cable model in the present invention includes a single-point grounding model at one end, a single-point grounding model in the central part, a grounding model at both ends and a cross-interconnected grounding model, which includes the grounding methods of the existing high-voltage transmission system, and constructs an identification feature vector by extracting the characteristics of each grounding method (the number of direct grounding points, the number of sheath voltage limiters, etc.); the extracted grounding line feature vector of the line to be monitored is matched with the identification feature vector to determine which model to use for circulating current calculation. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 A flow chart of a high-voltage cable induced voltage monitoring method according to the present invention; Figure 2 This is a schematic diagram of a single-point grounding method at one end of the present invention; Figure 3 It is a schematic diagram of the single-point grounding method of the central part of the present invention; Figure 4 It is a schematic diagram of the grounding method at both ends of the present invention; Figure 5 It is a schematic diagram of the cross-interconnection grounding method of the present invention. DETAILED DESCRIPTION
[0017] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.
[0018] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.
[0019] refer to Figure 1 The technical solution provided by the present invention is: a method for monitoring the induced voltage of a high-voltage cable, comprising the following steps: Step 1: query the database for the line information of the high-voltage cable to be monitored in the high-voltage line, and receive the query feedback result; determine whether the feedback result is empty, if so, proceed to step 7; otherwise, output the line information and proceed to step 2; Step 2: Identify the grounding line characteristics based on the acquired line information of the high-voltage cable to be monitored; specifically: Obtain line information from the power system database, including power system design drawings and design documents, cable laying construction drawings and documents; Through the keyword recognition algorithm, the grounding line drawings containing the high-voltage cables to be monitored are screened out from the design drawings of the power system; Similarly, the keyword recognition algorithm is used to select design documents related to the high-voltage cables to be monitored from the design documents of the power system; The grounding line features are extracted from the selected grounding line drawings through image processing algorithms (OpenCV); the grounding line features are extracted from the design documents of the power system through text processing algorithms; The grounding line characteristics here include the number of direct grounding points, the number of sheath voltage limiters, the number of sheath voltage limiter grounding points, the number of insulating joints and the number of insulating joint grounding points.
[0020] Step 3: Select a matching cable model from a plurality of preset cable models according to the identified grounding line characteristics; in this embodiment, the cable model is one or more of a single-point grounding model at one end, a single-point grounding model at the center, a grounding model at both ends, and a cross-connected grounding model.
[0021] Step 4: Obtain high-voltage cable parameters and power transmission parameters, wherein the high-voltage cable parameters include one or more of the length, diameter, resistance, capacitance and inductance of the cable; and the power transmission parameters include the voltage value and current frequency in the high-voltage cable; Step 5: After preprocessing, the obtained high-voltage cable parameters and power supply parameters are input into the corresponding cable model, and the induced voltage of the high-voltage cable voltage is obtained through the cable model calculation; Step 5.1: The process of matching the line model is as follows: After preprocessing, the identified grounding line features of the high-voltage cable are composed into a grounding line feature vector that uniquely corresponds to the high-voltage cable. ; in, Respectively represent the number of direct grounding points, the number of sheath voltage limiter grounding points, the number of insulating joint grounding points, the number of sheath voltage limiters and the number of insulating joints; Assigning an identifying feature vector to each line model; refer to Figure 2-5 , the identification feature vector of the one-end single-point grounding model is , the identification feature vector of the central single-point grounding model is , identification of the two-terminal grounding model , the identification feature vector of the cross-connection grounding model is ;in Indicates the number of units the cable is divided into; For example Figure 2 As shown, one end of the cable is directly grounded, and the other end is grounded through a sheath voltage limiter. A sheath voltage limiter is required for cables above 35kv; no sheath voltage limiter is required for cables below 35kv.
[0022] Therefore, this model can be divided into sub-model 1 including the sheath voltage limiter and sub-model 2 not including the sheath voltage limiter. The identification feature vector of the one-end single-point grounding model is or ; Choose to use according to transmission parameters still ; Calculate the similarity between the ground line feature vector and the identification feature vector of the line model. Specifically, the cosine similarity of the two vectors may be calculated to determine whether the two vectors are related. If the similarity is greater than a preset similarity threshold, it is determined that the ground line feature vector matches the identification feature vector; The cable model corresponding to the identified feature vector is used as the cable model matching the high-voltage cable.
[0023] For example Figure 5 As shown, the cross-connected grounding method is sampled, the cable is divided into multiple units, each unit is divided into three sections, multiple insulating joints are set in each section, each insulating joint is grounded through a sheath voltage limiter, each unit is connected through a joint, the joint is directly grounded, and the two ends of the cable are sampled directly grounded; this grounding method is suitable for cables with longer distances. The transmission voltage in this case is usually higher than 35kv. Therefore, this line model requires the identification of the number of insulating joints and the number of sheath voltage limiters.
[0024] Step 5.2: If the cable model matching the cable to be monitored is a single-point grounding model at one end or a single-point grounding model at the center, the induced voltage is obtained by the following steps: Assume the characteristic impedance of the cable is: ; The propagation coefficient is: ;use and Indicates the distance from the cable start point The voltage and current at is the resistance per unit length of the cable, The inductance per unit length of the cable, is the capacitance per unit length of the cable; Apply Kirchhoff's voltage law to simplify the calculation: ; Since the voltage at the grounding point is zero, the current at the grounding point ; The grounding point is at the beginning of the cable, that is ; Current at the grounding point ; In case of central grounding, the grounding point is selected in the middle of the cable, i.e. ; Current at the grounding point , is the length of the cable; In this simplified calculation, the influence of the reflection coefficient of the grounding point is ignored and the ring current is considered to be and equal; The ring pressure is ,in, is the total impedance of the cable; Calculate the magnetic flux generated by circulating current in the cable ;in, is the average cross-sectional area of the cable, is the average radius of the cable, represents magnetic permeability; According to Faraday's law of electromagnetic induction, the electromagnetic induced voltage of the circulating current is ; The electromagnetic induced voltage of the cable is ; in, is the electromagnetic induction voltage of the cable core current to be monitored at the grounding point, express The sum of the induced voltages on the cable to be monitored generated by the electromagnetic fields of the surrounding cables; Indicates the total number of surrounding cables; Indicates cable The influence coefficient of the magnetic field on the electromagnetic induction voltage at the voltage monitoring point of the monitored cable.
[0025] Step 5.3: If the cable model matching the cable to be monitored is a cross-connected grounding model, the induced voltage is obtained by the following steps: Assuming that the core current of the three-phase cable is balanced, the induced voltage generated by the core of any phase on the metal sheath is: ; Assume the cross-connection matrix is: ; in, express Any one of the three phases; Take the value from the second column of the cross-connection matrix, Take the value from the third column of the cross-connection matrix, Take the value from the fourth column of the cross-connection matrix; The equation for solving the metal sheath grounding loop current is: (1); in, They represent grounding point resistance 1, grounding point resistance 2 and earth equivalent resistance respectively; Indicates the self-impedance of the cable metal sheath. represents the coefficient matrix; For example, if the cable to be monitored is Phase, then (1) can be expressed as: (2); in, .
[0026] By solving the equation through the MATLAB program, the metal sheath grounding loop current can be obtained; through the metal sheath grounding loop current, combined with the principle of electromagnetic induction, the electromagnetic induction voltage of each phase cable can be obtained.
[0027] Step 6: Determine whether the induced voltage at the monitoring point is within the safety threshold range. If yes, return to step 1; otherwise, issue a warning message and then return to step 1; Specifically: Setting safety thresholds , if the electromagnetic induced voltage satisfies: , the induced voltage is judged to meet the safety threshold requirements; otherwise, the induced voltage is judged not to meet the safety threshold requirements. Output induced voltage alarm information to notify technicians to take corresponding measures. For example, check whether the grounding point is in good contact and whether the grounding method matches the cable transmission characteristics.
[0028] Step 7: Obtain the electromagnetic field distribution characteristics and the loop current characteristics of the high-voltage cable, determine the grounding method of the high-voltage cable according to the electromagnetic field distribution characteristics and the loop current characteristics, and then return to step 2.
[0029] The electromagnetic field data of the high-voltage cable is measured along the delay direction of the high-voltage cable; and the magnetic field distribution characteristics are extracted from the electromagnetic field data, wherein the magnetic field distribution characteristics include a maximum magnetic flux value, a minimum magnetic flux value, a maximum magnetic flux position, and a minimum magnetic flux position.
[0030] The grounding method of the high-voltage cable is determined based on the distribution position of the maximum magnetic flux on the high-voltage cable. Specifically, if the maximum magnetic flux position is only distributed at one end of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a single-point grounding method at one end; if the maximum magnetic flux position is distributed at both ends of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a two-end grounding method or a cross-interconnected grounding method.
[0031] Because, in reality, there are many cases where it is impossible to obtain the design drawings of the cable in time. In the case of not knowing the grounding method, the grounding method and the location of the grounding point can be determined by measuring the distribution of the cable's electromagnetic field. Because the grounding point is the convergence point of the current, the electromagnetic field at this location changes greatly and can be clearly identified; if the electromagnetic field at only one end of a line cable is strong, and other parts are relatively low, it means that this location may be the grounding point, and this grounding method is a single-point grounding method at one end; If the electromagnetic field at both ends of a line cable is strong and the other parts are low, and the line length is more than 1000 meters, and the magnetic field distribution characteristics of multiple sections of the entire cable are similar, then this grounding method may be a cross-interconnection grounding method.
[0032] By measuring the electromagnetic field and combining it with visual observation, the grounding method of the cable can be determined more accurately, providing support for the subsequent calculation of circulating current and induced voltage.
[0033] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method for monitoring the induced voltage of a high-voltage cable.
[0034] In the embodiments disclosed in the present invention, the process described above with reference to the flowchart can be implemented as a computer software program. The embodiments disclosed in the present invention include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program contains a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part, and / or installed from a removable medium. When the computer program is executed by the central processing unit (CPU), the above functions defined in the method of the present application are executed. It should be noted that the computer-readable medium mentioned above in the present application can be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to, an electrical connection with one or more wire segments, a portable computer disk, 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 portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present application, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the present application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries a computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device. The program code embodied on the computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, electrical wire, optical cable, RF, etc., or any suitable combination of the foregoing.
[0035] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the boxes can also occur in a different order than the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.
[0036] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments. Without departing from the principles, the implementation methods of the present invention may be subject to any changes or modifications.
Claims
1. A method for monitoring induced voltage of a high-voltage cable, characterized in that: The method comprises: Step 1: query the database for the line information of the high-voltage cable to be monitored in the high-voltage line, and receive the query feedback result; determine whether the feedback result is empty, if so, proceed to step 7; otherwise, output the line information and proceed to step 2; Step 2: Identify the grounding line characteristics based on the acquired line information of the high-voltage cable to be monitored; Step 3: Select a matching cable model from a plurality of preset cable models according to the identified ground line characteristics; Step 4: Obtain high-voltage cable parameters and power transmission parameters, wherein the high-voltage cable parameters include one or more of the length, diameter, resistance, capacitance and inductance of the cable; and the power transmission parameters include the voltage value and current frequency in the high-voltage cable; Step 5: After preprocessing, the obtained high-voltage cable parameters and power supply parameters are input into the corresponding cable model, and the induced voltage of the high-voltage cable voltage is obtained through the cable model calculation; Step 6: Determine whether the induced voltage at the monitoring point is within the safety threshold range. If yes, return to step 1; otherwise, issue a warning message and then return to step 1; Step 7: Obtain the electromagnetic field distribution characteristics and the loop current characteristics of the high-voltage cable, determine the grounding method of the high-voltage cable according to the electromagnetic field distribution characteristics and the loop current characteristics, and then return to step 2.
2. A high-voltage cable induced voltage monitoring method according to claim 1, characterized in that: The method of identifying the grounding line characteristics according to the acquired line information of the high-voltage cable to be monitored comprises the following steps: Acquiring line information, wherein the line information includes design drawings and design documents of the power system, cable laying construction drawings and construction documents; Extract ground line features from line information; specifically including: Screening out the grounding line drawings of the high-voltage cables to be monitored from the design drawings of the power system, and screening out the design documents of the high-voltage cables to be monitored from the design documents of the power system; Extracting grounding line features from the screened grounding line drawings through image processing algorithms; Extracting grounding line features from power system design documents using word processing algorithms; The grounding line characteristics include the number of direct grounding points, the number of sheath voltage limiters, the number of sheath voltage limiter grounding points, the number of insulating joints and the number of insulating joint grounding points.
3. A high-voltage cable induced voltage monitoring method according to claim 2, characterized in that: The cable model is one or more of a one-end single-point grounding model, a central portion single-point grounding model, a two-end grounding model, and a cross-connected grounding model.
4. A high-voltage cable induced voltage monitoring method according to claim 3, characterized in that: The step of selecting a matching cable model from a plurality of preset cable models according to the identified ground line characteristics comprises the following steps: After preprocessing, the identified grounding line features of the high-voltage cable are formed into a grounding line feature vector that uniquely corresponds to the high-voltage cable. ; in, Respectively represent the number of direct grounding points, the number of sheath voltage limiter grounding points, the number of insulating joint grounding points, the number of sheath voltage limiters and the number of insulating joints; Assigning an identifying feature vector to each line model; Specifically, the identification feature vector of the one-end single-point grounding model is: , the identification feature vector of the central single-point grounding model is , identification of the two-terminal grounding model , the identification feature vector of the cross-connection grounding model is ;in Indicates the number of units the cable is divided into; Calculate the similarity between the ground line feature vector and the identification feature vector of the line model; If the similarity is greater than a preset similarity threshold, it is determined that the ground line feature vector matches the identification feature vector; The cable model corresponding to the identified feature vector is used as the cable model matching the high-voltage cable.
5. A high-voltage cable induced voltage monitoring method according to claim 4, characterized in that: The obtained high-voltage cable parameters and power supply parameters are pre-processed and input into the corresponding cable model, and the induced voltage of the high-voltage cable voltage is obtained by calculating the cable model, including the following steps: If the cable model that matches the cable to be monitored is a single-point grounding model at one end or a single-point grounding model in the middle, the induced voltage is obtained by the following steps: Assume the characteristic impedance of the cable is: ; The propagation coefficient is: ;use and Indicates the distance from the cable start point The voltage and current at is the resistance per unit length of the cable, The inductance per unit length of the cable, is the capacitance per unit length of the cable; Apply Kirchhoff's voltage law to simplify the calculation: ； Since the voltage at the grounding point is zero, the current at the grounding point ; The grounding point is at the beginning of the cable, that is ; Current at the grounding point ; In case of central grounding, the grounding point is selected in the middle of the cable, i.e. ; Current at the grounding point , is the length of the cable; In this simplified calculation, the influence of the reflection coefficient of the grounding point is ignored and the ring current is considered to be and equal; The ring pressure is ,in, is the total impedance of the cable; Calculate the magnetic flux generated by circulating current in the cable ;in, is the average cross-sectional area of the cable, is the average radius of the cable, represents magnetic permeability; According to Faraday's law of electromagnetic induction, the electromagnetic induced voltage of the circulating current is ; The electromagnetic induced voltage of the cable is ; in, is the electromagnetic induction voltage of the cable core current to be monitored at the grounding point, express The sum of the induced voltages on the cable to be monitored generated by the electromagnetic fields of the surrounding cables; Indicates the total number of surrounding cables; Indicates cable The influence coefficient of the magnetic field on the electromagnetic induction voltage at the voltage monitoring point of the monitored cable.
6. A high-voltage cable induced voltage monitoring method according to claim 5, characterized in that: The method of preprocessing the obtained high-voltage cable parameters and power supply parameters and inputting them into the corresponding cable model, and calculating and obtaining the induced voltage of the high-voltage cable voltage through the cable model, further includes the following steps: If the cable model that matches the cable to be monitored is a cross-connected grounding model, the induced voltage is obtained by the following steps: Assuming that the core current of the three-phase cable is balanced, the induced voltage generated by the core of any phase on the metal sheath is: ; Assume the cross-connection matrix is: ; in, express Any one of the three phases; Take the value from the second column of the cross-connection matrix, Take the value from the third column of the cross-connection matrix, Take the value from the fourth column of the cross-connection matrix; The equation for solving the metal sheath grounding loop current is: ； in, They represent grounding point resistance 1, grounding point resistance 2 and earth equivalent resistance respectively; Indicates the self-impedance of the cable metal sheath. represents the coefficient matrix; By solving the equations through the MATLAB program, the metal sheath grounding loop current can be obtained; Through the metal sheath grounding loop current and combined with the principle of electromagnetic induction, the electromagnetic induction voltage of each phase cable can be obtained.
7. A high-voltage cable induced voltage monitoring method according to claim 6, characterized in that: The step of judging whether the induced voltage at the monitoring point is within a safety threshold range comprises the following steps: Setting safety thresholds ; If the electromagnetic induction voltage satisfies: , it is judged that the induced voltage meets the safety threshold requirement; otherwise, it is judged that the induced voltage does not meet the safety threshold requirement.
8. A high-voltage cable induced voltage monitoring method according to claim 7, characterized in that: The method of obtaining the electromagnetic field distribution characteristics and the loop current characteristics of the high-voltage cable and determining the grounding mode of the high-voltage cable according to the electromagnetic field distribution characteristics and the loop current characteristics comprises the following steps: Measuring the electromagnetic field data of the high-voltage cable along the time-delay direction of the high-voltage cable; Extracting magnetic field distribution characteristics from the electromagnetic field data, wherein the magnetic field distribution characteristics include a maximum magnetic flux value, a minimum magnetic flux value, a maximum magnetic flux position, and a minimum magnetic flux position; According to the distribution position of the maximum magnetic flux on the high-voltage cable, the grounding method of the high-voltage cable is determined; specifically: If the maximum magnetic flux position is only distributed at one end of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a single-point grounding method at one end; If the maximum magnetic flux position is distributed at both ends of the high-voltage cable, it can be determined that the grounding method of the high-voltage cable is a two-end grounding method or a cross-connection grounding method.
9. A high voltage cable induction voltage monitoring system, characterized in that: The system is used to execute a high-voltage cable induced voltage monitoring method as described in any one of claims 1 to 8.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement a high-voltage cable induced voltage monitoring method as described in any one of claims 1 to 8.