A 10kV armored cable fault location method based on additional parallel inductance

Abstract

This invention discloses a fault location method for 10kV armored cables based on an additional parallel inductor, relating to the field of power equipment monitoring technology. The specific steps of this location method are as follows: S100, Additional inductor configuration planning: Analyze the resistance, capacitance, inductance distribution of the distribution network line and the parameters of the expected fault current. By introducing an additional parallel inductor, this invention effectively solves the problems of difficult detection of electrical quantities and the impact of asynchronous data on location accuracy in distribution network fault location. After a fault occurs in the distribution network line, by combining control protection actions with algorithms, the additional inductor is engaged to allow the line to run with the fault for a period of time, thereby obtaining steady-state electrical quantities for location calculation. This not only increases the measurement time and the amplitude of the negative sequence component, but also provides steady-state positive and negative sequence electrical quantities for location, enabling more accurate extraction of fault information after a fault occurs.

Description

Technical Field

[0001] This invention relates to the field of power equipment monitoring technology, specifically to a method for fault location of 10kV armored cables based on an additional parallel inductor. Background Technology

[0002] As the topology of power distribution networks becomes increasingly complex, improving the automation level of power distribution networks and ensuring the reliability of power supply and meeting the needs of power users have become increasingly important. Timely and accurate fault location methods are of great significance for quickly repairing line faults and ensuring power supply reliability. Especially in the application of 10kV armored cables, the accuracy of fault location is directly related to the stable operation and maintenance efficiency of the power system.

[0003] Currently, the main methods for fault location in distribution networks are the traveling wave method and the impedance method. The traveling wave method has problems such as difficulty in identifying reflected waves, high requirements for sampling equipment, and the existence of location dead zones, which limit its effectiveness in practical applications. The impedance method is affected by the small current grounding method of the neutral point in the distribution network. When a single-phase ground fault occurs, although it can be operated with the fault for a period of time, the fault current is small, and the fault current generated by other types of faults decays rapidly, resulting in a short effective time window and making it difficult to extract fault information. In addition, although the transient method in the impedance method uses transient signals of the fault process for analysis, the fault components decay quickly and the effective time window is short. The steady-state method has problems such as small amplitude of fault electrical quantities, susceptibility to interference, and the ranging accuracy being affected by asynchronous data.

[0004] Although existing technologies have proposed some improvements, such as simplifying calculations through moment-specific analysis to achieve rapid ranging, or introducing asynchronous phase angle differences at both ends to eliminate the effects of asynchrony, these methods still have certain limitations. For example, moment-specific analysis requires high-performance sampling equipment and is uneconomical, while introducing asynchronous phase angle differences at both ends can eliminate the effects of asynchrony to some extent, but it is difficult to accurately measure positive and negative sequence electrical quantities when the time from the occurrence of a fault to the protection action is short, thus affecting the ranging accuracy. In addition, most existing ranging methods cannot be applied to all types of faults simultaneously, limiting their application scope.

[0005] Therefore, a fault location method for 10kV armored cables based on an additional parallel inductor is developed. By introducing an additional inductor to limit the short-circuit current, increase the measurement time and the amplitude of the negative sequence component, a steady-state positive and negative sequence electrical quantity is provided for fault location, and the influence of asynchronous factors is eliminated in principle, thereby improving the accuracy of fault location. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for fault location of 10kV armored cables based on the additional parallel inductor. This method is based on the technical principle of the additional parallel inductor and effectively solves the problem of fault location in distribution networks. By adding the additional inductor after the line trips, not only is the short-circuit current limited, but the line can also operate with the fault for a period of time, thereby increasing the measurement time and the amplitude of the negative sequence component, and providing stable positive and negative sequence electrical quantities for fault location.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for fault location of 10kV armored cables based on an additional parallel inductor, the specific steps of which are as follows:

[0008] S100, Additional Inductor Configuration Planning: Analyze the resistance, capacitance, inductance distribution and expected fault current parameters of the distribution network lines, use electrical calculation software to simulate the current response under different fault conditions based on the steady-state and transient characteristics theory of the power system, determine the parameters of rated inductance value, current carrying capacity, withstand voltage level and loss, and connect the selected additional inductor to the bus-end circuit breaker through the installation framework and connection components.

[0009] S200, Fault Response Control: Constructs an intelligent power distribution network fault monitoring system, integrating real-time monitoring data from current transformers and voltage transformers with fault diagnosis logic from intelligent protection devices. Once a line fault causes the current and voltage to exceed preset thresholds, the fault monitoring mechanism is immediately triggered to accurately identify the time, type, and phase of the fault. At the moment of the fault, the QF1 circuit breaker trips rapidly according to the set current setting value and simultaneously starts the timing module to record the time of the fault. The timing and mode of inductor connection are determined according to the fault type. During the steady-state phase, the measuring equipment continuously monitors electrical quantities. After the data collection is completed, the switch Q state is intelligently decided based on whether the fault is transient or permanent. When restarting the line for a transient fault, the system electrical parameters and equipment health status are fully verified before the QF1 circuit breaker is accurately closed to restore power supply. For a permanent fault, Q is opened to upload fault information.

[0010] S300, Fault Information Acquisition and Optimization: Based on electromagnetic theory and field measurement data mining technology, finite element analysis is used to determine the location of the first-end electrical quantity measurement point at the optimal negative sequence voltage measurement point. Wide-frequency response voltage transformers and high linearity current transformers are deployed here to construct a multi-sensor collaborative acquisition network, capturing the full-state changes of three-phase voltage and current signals. The signals are transmitted to the field data acquisition terminal via optical fiber, and then pre-processed by a signal conditioning circuit with integrated filtering, amplification, isolation, and anti-interference functions. Based on the accurate power grid model and fault equivalent circuit, the optimal value of the additional inductance is solved. After being put into operation, the dynamic changes of line current and negative sequence voltage are monitored in real time, and the inductance parameters are adaptively fine-tuned.

[0011] S400, fault location calculation:

[0012] The asymmetrical fault location method is described as follows: When an asymmetrical fault occurs on the line, the symmetrical component method is used to analyze the positive and negative sequence networks. Based on Kirchhoff's laws, a complete matrix equation is constructed covering the positive and negative sequence voltages, currents, and impedances on both sides of the line. Data from the electrical quantity measurement point at the beginning of the line, the optimal negative sequence voltage measurement point, and the high-precision voltage acquisition data at the end are substituted into the equation to solve for the theoretical values ​​of the positive and negative sequence voltages at the fault point. Using the S-end measuring device as a precise clock source, the asynchronous phase angle δd caused by the time synchronization error at the N-end is quantified. The asymmetrical fault location function is constructed using the ratio of the positive to negative sequence voltages at the end, as shown in the formula: in and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The ratio of the fault distance to the total line distance is obtained by solving a quadratic complex equation using complex field operations. Among them, l SF Let l be the distance from point S to the fault point F. SN Given the total line length, select effective K values ​​based on preset accuracy requirements and line parameter characteristics, and accurately locate fault points by combining the total line length.

[0013] The symmetrical fault location: Given the absence of negative sequence components, the voltage and current at the S-terminal and the voltage at the N-terminal of phases A and B are selected as variables. Referring to the asymmetrical fault handling process and principles, a symmetrical fault location function is constructed, with the following formula: in These are the voltages at the S terminal of phases A and B, respectively. Let A and B be the N-terminal voltages of phases A and B respectively. The non-synchronous angle error is eliminated by the ratio of the terminal voltages, and the fault distance is obtained by solving the equation.

[0014] Furthermore, in S100, the power distribution network line parameters considered in the additional inductor configuration planning also include the influence factors of conductor material, insulation characteristics, line length, conductor radius, line spacing and ambient temperature on line resistance, capacitance and inductance; the electrical calculation software adopts electromagnetic transient analysis software to set different fault types, fault locations and transition resistance values ​​when simulating fault conditions.

[0015] Furthermore, in S100, the short-circuit current IL is calculated using a formula in the additional inductor configuration plan. The formula is: Where E s The input represents the electromotive force of the power supply, ω0 is the system frequency, j represents the imaginary unit, the j-th element, L represents the additional inductance, and Z represents the... s This indicates the impedance on the power supply side.

[0016] Furthermore, in S100, the additional inductance L is calculated using a formula in the additional inductance configuration planning. The formula is: Among them, I L Represents short-circuit current I L Es The input represents the electromotive force of the power supply, ω0 is the system frequency, j represents the imaginary unit, the j-th element, L represents the additional inductance, and Z represents the... s This indicates the impedance on the power supply side.

[0017] Furthermore, in S200, the determination of current and voltage exceedance thresholds in fault response control is based on the line's rated current, rated voltage, and system operating safety margin factors. For a rated current of I... e The circuit has a current threshold of k1I. e The value of k1 is determined based on the line load characteristics, fault probability, and system stability requirements, and is between 1.2 and 1.5. Regarding voltage, it is based on the rated voltage U. e Based on this, and considering the voltage fluctuation range and the system insulation withstand capability, the voltage threshold is set to U. e (1±k2), where k2 depends on the grid voltage level, line length and surrounding environmental factors, and takes a value in the range of 0.05-0.1.

[0018] Furthermore, in S200, the preset current setting value of the QF1 circuit breaker in the fault response control is determined, a statistical analysis of the line fault current probability is carried out, and based on historical operating data, the frequency and amplitude distribution of fault current occurrence are calculated for different fault scenarios. The mean μ and standard deviation σ of each type of fault current are determined, and the thermal stability limit of the equipment is comprehensively considered, based on the thermal stability current I given in the equipment manual. th and the allowed duration t th Ensure the set value is less than I. th In addition, adhering to the protection selectivity requirement, the action time t1 of the higher-level protection and the action time t2 of the current-level protection must satisfy t1 > t2 + Δt, where Δt is the time difference. Through calculation, analysis, verification, and adjustment, the setting value is determined to be kI. e k takes a value ranging from 1.5 to 3, and can be finely adjusted according to the characteristics of the line.

[0019] Furthermore, in S200, the timing and mode of inductor connection in fault response control are as follows: during the period when a single-phase ground fault occurs and the current does not exceed the set value, it is allowed to operate with the fault. When other faults occur, the auxiliary switch Q is immediately closed to introduce the inductor. In the initial stage of a single-phase ground fault, the current does not exceed the limit, but maintenance and distance measurement are required later. After QF1 trips, the control closes Q. During the transient transition phase, the dynamic changes of electrical quantities are monitored in real time by a high-speed data acquisition system.

[0020] Furthermore, in S300, the determination of the optimal measurement point for negative sequence voltage at the first-end electrical quantity measurement point in fault information acquisition and optimization is achieved by comprehensively utilizing finite element analysis and on-site measured data mining techniques. This considers the physical parameters of the line's conductor material, length, radius, spacing, and insulation medium characteristics, calculating the distribution of line resistance, inductance, and capacitance. Simultaneously, it incorporates power supply characteristics such as electromotive force and internal impedance, as well as load distribution parameters such as power and power factor, constructing a model that highly matches the actual power grid. For different types of faults, parameters for fault location and grounding resistance are set to simulate... The changes in electrical quantities after a fault are analyzed, the distribution pattern of negative sequence voltage along the line is analyzed, the theoretical value and trend of negative sequence voltage at different locations are predicted, and on-site measurement work is carried out. Multiple temporary measuring points are set up at equal intervals along the line, and voltage transformers and data acquisition devices are installed. When an actual fault occurs, three-phase voltage data are collected synchronously, the negative sequence voltage component is extracted, and the mean and standard deviation of the negative sequence voltage at each measuring point are calculated. The theoretical results of finite element analysis are integrated with the on-site measured data. With the core objective of large and stable negative sequence voltage amplitude, the data of each measuring point are classified and the optimal measuring point for negative sequence voltage is selected.

[0021] Furthermore, in S300, the process for finding the optimal value of the additional inductance in fault information acquisition and optimization is based on an accurate model of the power grid system and fault equivalent circuit analysis to find the optimal value of the additional inductance. First, the line impedance, including resistance and reactance, is measured. At the same time, the power supply characteristics, such as the magnitude of electromotive force and internal impedance, as well as the load distribution parameters, are clarified. Corresponding fault equivalent circuits are constructed for different fault types. The changes in electrical quantities after the fault occurs are analyzed. The magnitude of the short-circuit current and its impact on the safe and stable operation of the line are considered. An optimization algorithm is used to find the optimal value of the additional inductance through continuous iterative calculation.

[0022] Furthermore, in S400, the fault location calculation is based on the voltage, current, and line impedance parameters on both sides of the line to calculate the positive and negative sequence voltages at the fault point, assuming... and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The calculation formula is as follows:

[0023]

[0024] in These represent the positive-sequence and negative-sequence voltages and currents at terminal S of the faulty line, respectively. Z1 and Z2 represent the positive and negative sequence voltages and currents at the N terminal of the line, Z1 and Z2 represent the positive and negative sequence impedances of the line, and C1 and C2 represent the positive and negative sequence capacitances of the line. SN Let l be the distance from point S to the fault point F. SN This is the total length of the line.

[0025] Compared with existing technologies, this method for fault location of 10kV armored cables based on additional parallel inductance has the following advantages:

[0026] I. This invention effectively solves the problems of difficult detection of electrical quantities and the impact of asynchronous data on ranging accuracy in fault location in distribution networks by introducing an additional parallel inductor. After a fault occurs in a distribution network line, by combining control protection actions with algorithms, the additional inductor is applied to allow the line to run with the fault for a period of time, thereby obtaining steady-state electrical quantities for ranging calculation. This not only increases the measurement time and the amplitude of the negative sequence component, but also provides steady-state positive and negative sequence electrical quantities for ranging, enabling more accurate extraction of fault information after a fault occurs. At the same time, by using positive and negative sequence electrical quantities to eliminate asynchronous phase angle differences in the ranging equation, the impact of asynchronous data on ranging accuracy is avoided in principle, thus improving the accuracy of fault location.

[0027] Second, this invention constructs an intelligent power distribution network fault monitoring system, integrating real-time monitoring data with intelligent protection device fault diagnosis logic. It can accurately identify the time, type, and phase of fault occurrence, and determine the inductor connection timing and mode based on the fault type. In addition, in terms of fault information acquisition optimization, finite element analysis and on-site measured data mining technology are used to determine the position of the first-end electrical quantity measurement point at the optimal negative sequence voltage measurement point, and a multi-sensor collaborative acquisition network is constructed to capture the full-state changes of three-phase voltage and current signals. After being put into operation, it can also monitor the dynamic changes of line current and negative sequence voltage in real time and adaptively fine-tune the inductor parameters, thereby improving the reliability and accuracy of fault location.

[0028] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0030] Figure 1 A flowchart of a method for fault location of 10kV armored cables based on an additional parallel inductor;

[0031] Figure 2 A schematic diagram of the planning process for configuring additional inductors;

[0032] Figure 3This is a correlation matrix diagram showing the influence of distribution network line parameters on electrical characteristics.

[0033] Figure 4 Mind map for intelligent decision-making in fault response control process;

[0034] Figure 5 A schematic diagram illustrating the principle of multi-source data fusion for selecting fault information collection and measurement points;

[0035] Figure 6 The convergence trajectory of the dynamic optimization iteration for finding the optimal value of the additional inductance;

[0036] Figure 7 A detailed analysis of the calculation principles for symmetrical and asymmetrical fault ranging. Detailed Implementation

[0037] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0038] Example 1

[0039] Application of 10kV armored cable fault location in urban power distribution networks

[0040] In an urban power distribution network environment, a line of length l SN The 10kV armored cable line has a copper core, excellent insulation performance, a conductor radius of r, a wire spacing of d, and the operating environment temperature is usually maintained within a certain range.

[0041] Additional inductor configuration planning utilizes electromagnetic transient analysis software to fully consider conductor material (copper), insulation characteristics, and line length. SN The combined effects of conductor radius r, line spacing d, and ambient temperature on line resistance R, capacitance C, and inductance L are simulated to model three-phase short circuit and single-phase grounding fault types. The fault location is set along the line from the beginning at certain intervals, and the transition resistance value varies within a reasonable range, thereby accurately simulating the current response characteristics under different fault conditions.

[0042] Based on the steady-state and transient characteristics of power systems, and combined with the known electromotive force E of the power source... s System frequency ω0 and power supply impedance Z s The short-circuit current I can be accurately calculated using the formula. L The formula is: Furthermore, the appropriate rated value of the additional inductance L is determined based on the formula: At the same time, its current carrying capacity, withstand voltage level and loss parameters are strictly determined, and high-quality additional inductor components that meet the line operation requirements are selected. With the help of specially designed installation architecture and reliable connection components, the selected additional inductors are accurately connected to the bus end circuit breaker to ensure a stable connection and reliable electrical performance, laying a solid foundation for subsequent fault location work.

[0043] Fault response control process, constructing an intelligent distribution network fault monitoring system, deeply integrating real-time monitoring data from current transformers (CTs) and voltage transformers (PTs) with advanced fault diagnosis logic from intelligent protection devices, based on the line rated current I... e Rated voltage U e And key elements of system operation safety margin, scientifically setting the current threshold as k1I e and voltage threshold is U e (1±k2).

[0044] During line operation, if the current or voltage exceeds a preset threshold, a highly efficient and sensitive fault monitoring mechanism is immediately triggered. This mechanism quickly and accurately identifies the precise time, specific type, and phase information of the fault. At the instant the fault occurs, the QF1 circuit breaker, based on the pre-set current setting value kI... e The circuit breaker trips quickly and decisively, and simultaneously activates a high-precision timing module to record the moment the fault occurs, providing an accurate time reference for subsequent fault location.

[0045] The system intelligently determines the timing and mode of inductor connection based on the fault type. For example, during a single-phase ground fault where the current does not exceed the set value and operation with the fault is permitted, the auxiliary switch Q is quickly closed to introduce an inductor and maintain stable system operation. If other fault types occur immediately, Q is closed to introduce an inductor, enhancing the ability to capture fault electrical characteristics. After a fault occurs, during the steady-state phase, professional measuring equipment is used to continuously and closely monitor changes in electrical quantities. Once the data collection is complete, the system intelligently determines the subsequent state of switch Q based on the transient or permanent nature of the fault. For transient faults, the system's electrical parameters and equipment health status are comprehensively verified when restarting the line. After confirmation, the QF1 circuit breaker is precisely closed to restore power supply. For permanent faults, Q is promptly opened to upload detailed fault information so that maintenance personnel can quickly formulate maintenance strategies.

[0046] Fault information acquisition optimization employs an innovative approach that closely integrates finite element analysis with on-site measured data mining techniques to determine the optimal measurement point location for negative sequence voltage at the beginning of the electrical quantity measurement point. During this process, the conductor material (copper) and length are comprehensively considered. SN The physical parameters of radius r, spacing d, and insulating medium characteristics are used to accurately calculate the distribution of line resistance R, inductance L, and capacitance V, while also incorporating power supply characteristics (electromotive force E). s Internal impedance Z sWe carefully constructed an accurate model that closely matches the actual power grid operating state, using load distribution parameters (power, power factor) as well as load distribution parameters.

[0047] For different types of fault scenarios, the parameters of fault location and grounding resistance are meticulously set to realistically simulate the complex changes in electrical quantities after a fault occurs. The distribution law of negative sequence voltage along the line is deeply analyzed, and the theoretical value and trend of negative sequence voltage at different locations are scientifically predicted. At the same time, on-site measurement work is actively carried out. Multiple temporary measuring points are set up along the line at equal intervals, and high-precision voltage transformers and advanced data acquisition devices are installed. When an actual fault occurs, three-phase voltage data are collected simultaneously. The negative sequence voltage component is extracted using professional algorithms, and the mean and standard deviation of the negative sequence voltage at each measuring point are accurately calculated. The theoretical results obtained from finite element analysis are deeply integrated with the on-site measured data. With the large and stable amplitude of negative sequence voltage as the core guide, the data of each measuring point is systematically classified and strictly screened. Finally, the optimal measuring point for negative sequence voltage is accurately determined, ensuring that the collected fault information is real, reliable, comprehensive and accurate, providing solid data support for fault location.

[0048] The optimal value of the additional inductance is determined based on a precise power grid model and fault equivalent circuit. First, the line impedance is measured using precision measuring instruments, and the power supply characteristics and load distribution parameters are clarified. For different fault types, a fault equivalent circuit is constructed to precisely match them. The dynamic changes of electrical quantities after a fault occur are analyzed in depth. The magnitude of the short-circuit current and its impact on the safe and stable operation of the line are considered. Advanced optimization algorithms are used to continuously optimize the value of the additional inductance through iterative calculations until the optimal solution is found. This ensures that in actual operation, the inductance parameters can be adaptively and finely adjusted in real time according to the dynamic changes of line current and negative sequence voltage, so as to keep the system in the best operating state and effectively improve the fault location accuracy.

[0049] Fault location calculation:

[0050] Asymmetrical fault location: When an asymmetrical fault occurs on a line, the symmetrical component method is used to thoroughly analyze the positive and negative sequence networks. Based on Kirchhoff's laws, a complete matrix equation covering the positive and negative sequence voltage, current, and impedance relationships on both sides of the line is constructed. and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The calculation formula is as follows:

[0051]

[0052] By combining the electrical quantity measurement points at the first end with the optimal measurement point for negative sequence voltage and the high-precision voltage acquisition data at the end, the theoretical values ​​of positive and negative sequence voltages at the fault point are solved using equations. Using the measurement device at the S end as a precise clock source, the asynchronous phase angle δ caused by the time synchronization error at the N end is accurately quantified. dAn asymmetric fault location function is constructed using the ratio of the positive-sequence to the negative-sequence voltage at the terminal, and the formula is: The ratio of fault distance to total distance was obtained by solving a quadratic complex equation using complex field operations. Based on preset accuracy requirements and line parameter characteristics, effective K values ​​are rigorously selected, combined with the total line length l. SN It accurately locates the fault point, providing precise navigation for maintenance personnel to quickly reach the fault site.

[0053] Symmetrical fault location: Given the characteristic that symmetrical faults have no negative sequence components, the voltage and current at the S-terminal and the voltage at the N-terminal of phases A and B are carefully selected as variables. Referring to the handling process and principles of asymmetrical faults, a symmetrical fault location function is constructed, with the following formula: By cleverly eliminating asynchronous angle errors through the end voltage ratio and using professional mathematical methods to solve equations, the fault distance can be accurately obtained, significantly shortening the fault investigation time, improving power supply restoration efficiency, ensuring the reliable operation of the urban power distribution network, and reducing the impact of faults on residents' lives and urban operations.

[0054] In summary, the fault location method for 10kV armored cables based on additional parallel inductors proposed in this invention demonstrates high effectiveness and accuracy in urban power distribution network scenarios. In the additional inductor configuration planning stage, electromagnetic transient analysis software comprehensively considers numerous line parameters and fault conditions, accurately selecting suitable inductor components and ensuring proper connection, laying a solid foundation for subsequent fault handling. The fault response control process, relying on an intelligent monitoring system and reasonable threshold and setting values, achieves rapid fault identification and precise circuit breaker operation. Inductor and switch states are flexibly adjusted according to fault characteristics, effectively ensuring power supply continuity and equipment safety. Fault information collection optimization utilizes advanced technologies to determine high-quality measurement points and solve for optimal inductance values, providing reliable data and parameter support for fault location. Finally, fault location calculation, based on symmetrical and asymmetrical fault models, accurately calculates and locates the fault point, effectively reducing fault investigation time, improving operation and maintenance efficiency, significantly enhancing the reliability of urban power distribution networks, and reducing the adverse impact of faults on residents and urban functions, thus having profound significance for the urban power supply system.

[0055] Example 2:

[0056] Practice of 10kV Armored Cable Fault Location in Industrial Plants

[0057] In complex power supply scenarios within industrial plants, a specific 10kV armored cable line has a length of l SN The conductor is made of aluminum, with stable insulation. The conductor radius is r, and the spacing between the conductors is d. It is subjected to specific industrial environmental temperature conditions all year round.

[0058] Additional inductor configuration planning, leveraging the powerful capabilities of electromagnetic transient analysis software, comprehensively considers aluminum wire core, insulation condition, and line length.SN The combined effects of conductor radius r, line spacing d, and industrial ambient temperature on line resistance R, capacitance C, and inductance L are simulated. The simulation covers a variety of extreme and common fault conditions, including different fault locations and varying transition resistance values. It accurately simulates the fault current response characteristics, providing a reliable basis for subsequent inductance parameter determination.

[0059] Based on the given electromotive force E s System frequency ω0 and power supply impedance Z s Carefully calculate the short-circuit current I using the formula. L The formula is: Furthermore, the rated value of the additional inductance L is precisely determined using the formula: At the same time, its current carrying capacity, withstand voltage level and loss parameters are determined, and additional inductor components suitable for the complex working conditions of industrial plants are selected. They are properly connected to the bus-end circuit breaker through professional installation architecture and connection components to ensure reliable electrical connection and stable signal transmission, laying a solid foundation for the stable operation of the fault monitoring and ranging system.

[0060] The fault response control process meticulously constructs an intelligent distribution network fault monitoring system, achieving deep integration of real-time monitoring data from current transformers (CTs) and voltage transformers (PTs) with the fault diagnosis logic of intelligent protection devices, based on the line rated current I... e Rated voltage U e In accordance with the safety margin requirements for industrial plant system operation, a reasonable current threshold of k1I is set. e and voltage threshold is U e (1±k2)

[0061] During line operation, once the current or voltage exceeds the preset threshold, the fault monitoring mechanism is quickly activated to accurately determine the fault time, type (such as complex types like high-resistance grounding faults or short-circuit faults), and phase. At the moment of the fault, the QF1 circuit breaker activates according to the preset current setting value kI. e The circuit breaker trips quickly and starts the timing module to lock the time coordinates for fault location.

[0062] The system intelligently selects the inductor connection strategy based on the fault type. For example, if the current is not exceeded in the initial stage of a single-phase ground fault, it continuously monitors and introduces an inductor in a timely manner to maintain operation. If the current exceeds the limit or other faults occur, Q is immediately closed to introduce an inductor. In the steady-state stage after the fault, electrical quantities are continuously monitored using precision measuring equipment, and the state of Q is determined according to the instantaneous or permanent characteristics of the fault. After the instantaneous fault is repaired, the system electrical parameters and equipment health status are verified. If there are no errors, QF1 is precisely closed to restore power supply. For permanent faults, the fault information is uploaded in a timely manner to help the maintenance team respond quickly and reduce the loss of industrial production caused by the fault.

[0063] Fault information collection was optimized by comprehensively utilizing finite element analysis and on-site measurement data mining techniques to accurately determine the optimal measurement point for negative sequence voltage at the first-end electrical quantity measurement point, taking into full account the aluminum core material and length of the line. SN The physical parameters of radius r, spacing d, and insulation characteristics are used to accurately calculate the distribution of line resistance R, inductance L, and capacitance C, incorporating power supply characteristics (electromotive force E). s Internal impedance Z s A precise power grid model is constructed using load distribution parameters (power, power factor).

[0064] For typical fault scenarios in industrial plants, the parameters of fault location and grounding resistance are meticulously set to simulate changes in electrical quantities. The distribution law of negative sequence voltage is deeply analyzed to predict theoretical values ​​and trends. On-site measurements are carried out, and temporary measuring points are set up at equal intervals along the line to install high-precision current transformers and data acquisition devices. During actual faults, three-phase voltage data are collected simultaneously to extract the negative sequence voltage component. The mean and standard deviation are calculated, and theoretical and measured data are integrated. The optimal measuring point is selected based on the criterion of large and stable negative sequence voltage amplitude. This ensures that the collected data truly reflects the fault characteristics and provides a highly reliable basis for fault location.

[0065] Based on the accurate power grid model and fault equivalent circuit, the optimal value of the additional inductance is solved, the line impedance is accurately measured, the power supply and load parameters are clarified, and the equivalent circuit is constructed for different faults to analyze the changes in electrical quantities. Combined with the impact of short-circuit current on the line, the optimal value is determined by iterative calculation using optimization algorithms, and the system is dynamically fine-tuned according to the line operating current and negative sequence voltage. This ensures that the fault location of the system is accurate and reliable in complex industrial environments, and improves the power supply reliability and production continuity of the plant area.

[0066] Fault location calculation:

[0067] Asymmetric fault location: When encountering asymmetric faults on a line, skillfully apply the symmetric component method to analyze the positive and negative sequence networks, and construct a complete relation matrix equation based on Kirchhoff's laws. and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The calculation formula is as follows:

[0068]

[0069] By incorporating the positive and negative sequence voltage, current, and impedance parameters from both sides of the line, and combining the optimal measurement point of the negative sequence voltage at the beginning end with high-precision voltage data at the end end, the theoretical values ​​of the positive and negative sequence voltages at the fault point are calculated. The phase angle δ of the time synchronization error at the N end is quantified using the S end as the clock source. d An asymmetric fault location function is constructed using the ratio of the positive-sequence to the negative-sequence voltage at the terminal, and the formula is: The ratio of the fault distance to the total distance is obtained by solving a quadratic complex equation using complex field operations. By selecting effective K values ​​based on accuracy and line characteristics and combining them with the total length, the fault point can be accurately located, accelerating the fault repair process and reducing industrial production interruption time.

[0070] Symmetrical fault location: Considering the non-negative sequence characteristic of symmetrical faults, the voltage and current at the S terminal of phases A and B, and the voltage at the N terminal are carefully selected as variables. Based on the principle of asymmetrical fault handling, the location function formula is constructed as follows: By using the terminal voltage ratio to eliminate timing errors and solving equations to accurately determine the fault distance, the power supply stability of key production equipment in industrial plants is effectively guaranteed, thereby improving overall production efficiency and economic benefits.

[0071] In summary, the fault location method of this invention demonstrates its advantages in the complex power environment of industrial plants. During the configuration planning stage, the characteristics of industrial lines are carefully considered to determine inductance parameters, ensuring system adaptability. The fault response process, based on rigorous threshold and setting values ​​and intelligent inductor control strategies, enables rapid and precise response to diverse and complex faults, minimizing production downtime losses and maintaining production order. Data acquisition and optimization technologies are used to accurately locate measurement points and determine optimal inductance values, providing high-quality data for fault location. The fault location calculation, relying on a rigorous theoretical model and precise algorithms, can accurately pinpoint fault locations in both asymmetrical and symmetrical fault scenarios. This significantly improves the power supply stability of industrial plants, facilitates stable production processes, and provides key technological support for reliable energy supply to industrial production activities, playing a crucial role in ensuring industrial output and improving enterprise operational efficiency.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for fault location of 10kV armored cables based on an additional parallel inductor, characterized in that, The specific steps of this distance measurement method are as follows: S100, Additional Inductor Configuration Planning: Analyze the resistance, capacitance, inductance distribution and expected fault current parameters of the distribution network lines, use electrical calculation software to simulate the current response under different fault conditions based on the steady-state and transient characteristics theory of the power system, determine the parameters of rated inductance value, current carrying capacity, withstand voltage level and loss, and connect the selected additional inductor to the bus-end circuit breaker through the installation framework and connection components. S200, Fault Response Control: Constructs an intelligent power distribution network fault monitoring system, integrating real-time monitoring data from current transformers and voltage transformers with fault diagnosis logic from intelligent protection devices. Once a line fault causes the current and voltage to exceed preset thresholds, the fault monitoring mechanism is immediately triggered to accurately identify the time, type, and phase of the fault. At the moment of the fault, the QF1 circuit breaker trips rapidly according to the set current setting value and simultaneously starts the timing module to record the time of the fault. The timing and mode of inductor connection are determined according to the fault type. During the steady-state phase, the measuring equipment continuously monitors electrical quantities. After the data collection is completed, the switch Q state is intelligently decided based on whether the fault is transient or permanent. When restarting the line for a transient fault, the system electrical parameters and equipment health status are fully verified before the QF1 circuit breaker is accurately closed to restore power supply. For a permanent fault, Q is opened to upload fault information. S300, Fault Information Acquisition and Optimization: Based on electromagnetic theory and field measurement data mining technology, finite element analysis is used to determine the location of the first-end electrical quantity measurement point at the optimal negative sequence voltage measurement point. Wide-frequency response voltage transformers and high linearity current transformers are deployed here to construct a multi-sensor collaborative acquisition network, capturing the full-state changes of three-phase voltage and current signals. The signals are transmitted to the field data acquisition terminal via optical fiber, and then pre-processed by a signal conditioning circuit with integrated filtering, amplification, isolation, and anti-interference functions. Based on the accurate power grid model and fault equivalent circuit, the optimal value of the additional inductance is solved. After being put into operation, the dynamic changes of line current and negative sequence voltage are monitored in real time, and the inductance parameters are adaptively fine-tuned. S400, fault location calculation: Asymmetrical fault location: When an asymmetrical fault occurs on a line, the symmetrical component method is used to analyze the positive and negative sequence networks. Based on Kirchhoff's laws, a complete matrix equation is constructed covering the positive and negative sequence voltages, currents, and impedances on both sides of the line. Data from the electrical quantity measurement point at the beginning of the line, the optimal negative sequence voltage measurement point, and the high-precision voltage acquisition data at the end are substituted into the equation to solve for the theoretical values ​​of the positive and negative sequence voltages at the fault point. Using the measuring device at the S end as a precise clock source, the asynchronous phase angle δd caused by the time synchronization error at the N end is quantified. The asymmetrical fault location function is constructed using the ratio of the positive to negative sequence voltages at the end. The formula is: in and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The ratio of the fault distance to the total line distance is obtained by solving a quadratic complex equation using complex field operations. Among them, l SF Let l be the distance from point S to fault point F. SN Given the total line length, select effective K values ​​based on preset accuracy requirements and line parameter characteristics, and accurately locate fault points by combining the total line length. Symmetrical fault location: Given the absence of negative sequence components, the voltage and current at the S-terminal and the voltage at the N-terminal of phases A and B are selected as variables. Referring to the handling process and principles of asymmetrical faults, a symmetrical fault location function is constructed, with the following formula: in These are the voltages at the S terminal of phases A and B, respectively. Let A and B be the N-terminal voltages of phases A and B respectively. The non-synchronous angle error is eliminated by the ratio of the terminal voltages, and the fault distance is obtained by solving the equation.

2. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, The S100, the distribution network line parameters considered in the additional inductor configuration planning also include the influence factors of wire core material, insulation characteristics, line length, conductor radius, line spacing and ambient temperature on line resistance, capacitance and inductance; the electrical calculation software adopts electromagnetic transient analysis software to set different fault types, fault locations and transition resistance values ​​when simulating fault conditions.

3. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, In S100, the short-circuit current I is calculated using a formula in the additional inductor configuration planning. L The formula is: Where E s The input represents the electromotive force of the power supply, ω0 is the system frequency, j represents the imaginary unit, L represents the additional inductance, and Z represents the input voltage. s This indicates the impedance on the power supply side.

4. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, In S100, the additional inductance L is calculated using a formula in the additional inductance configuration planning. The formula is: Among them, I L E represents the short-circuit current. s The input represents the electromotive force of the power supply, ω0 is the system frequency, j represents the imaginary unit, L represents the additional inductance, and Z represents the input voltage. s This indicates the impedance on the power supply side.

5. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, In S200, the determination of current and voltage exceedance thresholds in fault response control is based on the line's rated current, rated voltage, and system operating safety margin factors. For a rated current of I... e The circuit has a current threshold of k1I. e The value of k1 is determined based on the line load characteristics, fault probability, and system stability requirements, and is between 1.2 and 1.

5. Regarding voltage, it is based on the rated voltage U. e Based on this, and considering the voltage fluctuation range and the system insulation withstand capability, the voltage threshold is set to U. e (1±k2), where k2 depends on the grid voltage level, line length and surrounding environmental factors, and its value is in the range of 0.05-0.

1.

6. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 5, characterized in that, In S200, the preset current setting value of the QF1 circuit breaker in the fault response control is determined. A statistical analysis of the line fault current probability is conducted. Based on historical operating data, the frequency and amplitude distribution of fault currents are calculated for different fault scenarios. The mean μ and standard deviation σ of each type of fault current are determined. Taking into account the equipment's thermal stability limit, the thermal stability current I given in the equipment manual is used. th and the allowed duration t th Ensure the set value is less than I. th In accordance with the protection selectivity requirement, the action time t1 of the higher-level protection and the action time t2 of the current-level protection must satisfy t1>t2+Δt, where Δt is the time difference. Through calculation, analysis, verification, and adjustment, the setting value is determined to be kI. e k takes a value ranging from 1.5 to 3, and can be finely adjusted according to the characteristics of the line.

7. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, S200, in the fault response control, the timing and mode of inductor connection, during the period when a single-phase ground fault is allowed to be operated with the fault and the current does not exceed the set value, and when other faults occur, the auxiliary switch Q is immediately closed to introduce the inductor. In the initial stage of a single-phase ground fault, the current does not exceed the limit, but the distance measurement needs to be checked later. After QF1 trips, the control closes Q. During the transient transition phase, the dynamic changes of electrical quantities are monitored in real time by a high-speed data acquisition system.

8. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, In S300, the determination of the optimal measurement point for negative sequence voltage at the first-end electrical quantity measurement point in fault information acquisition and optimization is achieved by comprehensively utilizing finite element analysis and field measurement data mining techniques. This considers physical parameters such as conductor material, length, radius, spacing, and insulation medium characteristics to calculate the distribution of line resistance, inductance, and capacitance. Simultaneously, it incorporates power supply characteristics such as electromotive force and internal impedance, as well as load distribution parameters such as power and power factor, to construct a model that highly matches the actual power grid. For different types of faults, parameters such as fault location and grounding resistance are set to simulate fault occurrence. The changes in electrical quantities after the fault occurred were analyzed, the distribution pattern of negative sequence voltage along the line was analyzed, the theoretical value and trend of negative sequence voltage at different locations were predicted, and on-site measurement work was carried out. Multiple temporary measuring points were set up at equal intervals along the line, and voltage transformers and data acquisition devices were installed. When an actual fault occurred, three-phase voltage data were collected synchronously, the negative sequence voltage component was extracted, and the mean and standard deviation of the negative sequence voltage at each measuring point were calculated. The theoretical results of finite element analysis were integrated with the on-site measured data. With the core objective of large and stable negative sequence voltage amplitude, the data of each measuring point were classified and the optimal measuring point for negative sequence voltage was selected.

9. The method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, The S300 process for determining the optimal value of additional inductance in fault information acquisition and optimization is based on an accurate model of the power grid system and fault equivalent circuit analysis. First, the line impedance, including resistance and reactance, is measured. At the same time, the power supply characteristics, such as the magnitude of electromotive force and internal impedance, as well as the load distribution parameters, are clarified. Corresponding fault equivalent circuits are constructed for different fault types. The changes in electrical quantities after the fault occurs are analyzed. The magnitude of the short-circuit current and its impact on the safe and stable operation of the line are considered. An optimization algorithm is used to find the optimal value of additional inductance through continuous iterative calculation.

10. A method for fault location of 10kV armored cables based on an additional parallel inductor according to claim 1, characterized in that, In the S400 fault location calculation, based on the voltage, current, and line impedance parameters on both sides of the line, the positive and negative sequence voltages at the fault point are calculated. and These represent the positive and negative sequence fault point voltages inferred from the measurement data at terminals S and N, respectively. The calculation formula is as follows: in These represent the positive-sequence and negative-sequence voltages and currents at terminal S of the faulty line, respectively. Z1 and Z2 represent the positive and negative sequence voltages and currents at the N terminal of the line, Z1 and Z2 represent the positive and negative sequence impedances of the line, and C1 and C2 represent the positive and negative sequence capacitances of the line. SF Let l be the distance from point S to the fault point F. SN This is the total length of the line.

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