A power transmission line ground hazard early warning system and method

Abstract

This invention discloses a grounding hazard early warning system and method for power transmission lines, relating to the field of power system transmission line operation and maintenance technology. It includes a dual-ended CVT voltage acquisition module for connecting to the secondary circuits of CVTs on both sides of the line; a grounding switch and operating condition acquisition module; a data preprocessing module electrically connected to both the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module; a segmented coupled dynamic reference library module; a grounding hazard identification module; a grounding section location module; a permanent fault judgment module; a closing interlocking module; and a monitoring system access module. This invention can replace traditional single-sided judgment with dual-sided voltage linkage verification, and combined with dynamic references to adapt to all operating conditions, improve the accuracy of identifying hidden grounding hazards, and ensure the safety of power outage maintenance and power restoration operations of transmission lines.

Description

Technical Field

[0001] This invention belongs to the field of power system transmission line operation and maintenance technology, specifically relating to a transmission line grounding hazard early warning system and method. Background Technology

[0002] 220kV and above high-voltage transmission lines form the backbone of the power system. The safety of their outage maintenance operations and restoration operations after fault tripping directly determines the stable operation of the power grid and the safety of equipment. After a line is de-energized, problems such as unreliable tripping of the line-side grounding switch, left-behind grounding wires, and unresolved single-phase grounding hazards can easily lead to serious accidents such as closing the circuit with the ground fault still in place. If it is not possible to accurately distinguish between transient faults and permanent grounding faults after a fault tripping reclosing fails, blindly forcing power back on will exacerbate line damage, expand the scope of power grid faults, and even cause grid instability. Current technologies for detecting grounding hazards during power outages and judging power supply conditions in transmission lines generally adopt a single-sided voltage monitoring and fixed threshold judgment mode. However, relying solely on single-sided electrical quantities cannot distinguish between hazards in different locations such as grounding within the station and grounding of the line itself. The accuracy rate for identifying hidden hazards such as false tripping of single-phase grounding switches and residual grounding in the middle section of the line is extremely low, affecting the reliability of power grid operation. Summary of the Invention

[0003] The purpose of this invention is to provide a power transmission line grounding hazard early warning system and method to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A grounding hazard early warning system for transmission lines includes: a dual-ended CVT voltage acquisition module, used to connect to the secondary circuits of CVTs on both sides of the line and synchronously acquire the analog quantities of three-phase induced voltages at both ends of the line; The grounding switch and operating condition acquisition module is used to connect to the station's monitoring and control device to collect the positions of the grounding switches on both sides, the operating status of adjacent lines, and environmental parameters. The data preprocessing module is electrically connected to the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module, respectively, and is used to preprocess the acquired data. The segmented coupling dynamic reference library module receives pre-processed data and constructs a dynamic voltage reference library according to line parameters, parallel connection, phase commutation, and grounding switch status. The grounding hazard identification module, based on a dynamic voltage reference library and pre-processed data, uses dual-side voltage linkage logic to identify potential hazards such as unconnected grounding switches and leftover grounding wires. The grounding section positioning module distinguishes between in-station, parallel section and independent section grounding according to the hazard judgment results and completes the quantitative calculation of grounding points; The permanent fault diagnosis module receives the hazard identification and location data, calls the dynamic voltage reference to distinguish between instantaneous or permanent grounding faults, and verifies whether the conditions for power supply are met. The closing interlocking module receives the fault judgment result and generates a dual interlocking signal consisting of hard contacts and soft messages to prevent unauthorized closing. The monitoring system access module is electrically connected to the closing interlocking module to realize early warning transmission, status display and interlocking execution.

[0005] Preferably, the dual-ended CVT voltage acquisition module includes: a CVT capacitive voltage transformer connected to the high-voltage side of the line, used to convert the high-voltage induced voltage into a standard secondary low-voltage signal; The synchronous sampling unit is connected to the output terminal of the CVT capacitive voltage transformer and realizes synchronous acquisition of voltage data on both sides through the unified time synchronization signal in the station. The A / D conversion unit is connected to the output of the synchronous sampling unit to convert analog voltage signals into digital electrical signals; The data caching unit is connected to the output of the A / D conversion unit, temporarily storing the raw sampled data and uploading it to the data preprocessing module.

[0006] Preferably, the grounding switch and operating condition acquisition module includes: a grounding switch position auxiliary contact, for acquiring remote signaling data of the grounding switch's open and closed status; The telemetry and control device input unit collects and uploads remote signaling signals; Adjacent line operation status acquisition unit, used to acquire the operating conditions of parallel energized lines; An environmental sensor interface is used to input environmental parameters such as temperature and humidity. The output terminals of the grounding switch position auxiliary contact, the measurement and control device input unit, the adjacent line operation status acquisition unit, and the environmental sensor interface are all connected to the input terminal of the data preprocessing module.

[0007] Preferably, the closing interlocking module includes an interlocking logic unit, a hard contact output unit, and a soft message generation unit arranged in parallel. It receives the verification conclusion output by the permanent fault judgment module. When a grounding hazard or permanent fault is determined, the interlocking logic unit triggers an interlocking command, and the hard contact output unit and the soft message generation unit output interlocking signals through dual paths to achieve forced interlocking of the closing circuit. After the hazard is eliminated, the interlocking is automatically released, allowing normal power supply.

[0008] Preferably, the segmented coupled dynamic reference library module performs the following dynamic voltage reference library construction process: A1. Enter the fixed parameters of line voltage level, length, parallel section, and commutation method; A2. Group by dimension according to the status of the grounding switch, the operating condition of the parallel line, the paralleling method, and the commutation status; A3. Based on the electrostatic-electromagnetic dual-component coupling model, calculate the coupling voltage of the parallel section and the distributed capacitance voltage of the independent section respectively, and combine the commutation compensation to obtain the theoretical induced voltage at both ends of the line. A4. Store theoretical references under different operating conditions, and automatically match and call dynamic voltage references according to real-time operating conditions during operation to realize adaptive generation and updating of induced voltage references.

[0009] Preferably, the process for identifying potential problems using the dual-side voltage linkage logic is as follows: B1. Collect the status of the grounding switch on both sides of the line and the three-phase induced voltage on both sides; B2. Perform linkage verification according to three working conditions: both sides are equally connected, one side is connected, and both sides are equally divided. B3. When the voltage of a certain phase is evenly distributed on both sides, if the voltage of a certain phase is lower than the voltage reference value of that phase in the dynamic voltage reference library, and the voltage difference between the two phases exceeds the voltage difference reference value of the same phase in the dynamic voltage reference library, it is determined that the phase of the grounding switch on the low voltage side is not actually separated or a grounding wire is left. B4. After identifying the phase and location of the potential hazard, output an early warning and lock the circuit breaker.

[0010] Preferably, the grounding section positioning module includes: a three-segment section discrimination unit, which distinguishes between station grounding, parallel section grounding and independent section grounding based on the voltage amplitude and asymmetry on both sides; The amplitude ratio calculation unit is connected to the output of the three-segment segment discrimination unit and is used to calculate the amplitude ratio of the induced voltage on both sides of the line. The grounding point quantitative calculation unit is connected to the output of the amplitude ratio calculation unit and is used to complete the location calculation based on the dual-side voltage amplitude ratio model.

[0011] Preferably, after the line tripping and reclosing fails, the permanent fault judgment module collects the real-time induced voltage and compares it with the dynamic reference library. It then uses a fault judgment algorithm to judge the fault. If the real-time induced voltage is low and there is an asymmetrical gradient between the voltages on both sides, it is judged as a permanent grounding fault. If the voltage recovers to the voltage reference, it is judged as an instantaneous fault. Based on this, a power supply condition verification conclusion is formed and output to the closing interlocking module.

[0012] Preferably, the monitoring system access module includes: a communication protocol stack unit, compatible with standard power protocols; The data encapsulation unit, connected to the output of the communication protocol stack unit, is used to encapsulate early warning information, positioning results, and lockout status into standard monitoring data. The human-machine interface unit is connected to the output of the data encapsulation unit to enable visualization and remote monitoring. The communication protocol stack unit receives the warning and interlocking information output by the closing interlocking module, performs protocol encapsulation by the data encapsulation unit, and then uploads the encapsulated data to the D5000 system, the central control station automation system, and the station monitoring system by the human-machine interface unit.

[0013] Based on the above-described early warning system for grounding hazards in transmission lines, this invention also provides an early warning method for grounding hazards in transmission lines, comprising the following steps: S1. Synchronously collect the three-phase induced voltage on both sides of the line, the position signal of the grounding switch on both sides of the line, and the operating condition data of the parallel line, and perform filtering and preprocessing on the voltage data. S2. Construct a dynamic voltage reference library by grouping the total line length, the length of the parallel section on the same tower, the length of the independent section, the commutation method, and the status of the ground switch. S3. Based on the timing of the grounding switch opening and closing and the linkage law of the double-sided induced voltage, it is preliminarily determined that the grounding switch is not disconnected and there is a potential grounding hazard due to the grounding wire being left behind. S4. Based on the amplitude and asymmetry of the dual-sided induced voltage, perform three-stage connection area discrimination for in-station, parallel section, and independent section; S5. For lines with uniform coupling throughout the entire length, the location of the grounding point is quantitatively calculated by the voltage amplitude ratio on both sides. S6. After the line reclosing fails, compare the induced voltage with the dynamic reference to determine the permanent grounding fault and check the power supply conditions, triggering the hidden danger warning and closing lockout.

[0014] The present invention provides a transmission line grounding hazard early warning system and method, which has the following advantages compared with the prior art: 1. This invention utilizes the coordinated operation of a dual-end CVT voltage acquisition module, a grounding switch and operating condition acquisition module, a data preprocessing module, a segmented coupled dynamic reference library module, a grounding hazard identification module, a grounding section location module, a permanent fault judgment module, a closing interlocking module, and a monitoring system access module. By replacing traditional single-sided judgment with dual-sided voltage linkage verification and combining dynamic references to adapt to all operating conditions, it significantly improves the accuracy of identifying hidden grounding hazards, ensures the safety of power outage maintenance and power restoration operations of transmission lines, can automatically distinguish between permanent and transient faults, and intelligently interlocks the closing circuit to effectively ensure the stable operation of the power grid and the safety of power equipment. At the same time, it realizes remote visual monitoring of early warning information, location results, and interlocking status, improving the level of intelligent operation and maintenance of transmission lines. 2. This invention adopts a three-segment grounding section identification and grounding point quantitative calculation function. It can distinguish between grounding in the station, parallel section and independent section by only the voltage amplitude of both sides, and accurately invert the grounding point location. No special fault location device is required, which can effectively shorten the time for troubleshooting and maintenance and improve the efficiency of line power restoration. 3. This invention has extremely strong adaptability to various operating conditions, covering 220kV-1000kV AC transmission lines. It is suitable for various complex scenarios such as full parallel tower construction, partial parallel construction, and line phase switching, meeting the application requirements of different voltage levels and line structures. At the same time, the system fully reuses existing primary and secondary power equipment, requiring no hardware modification or additional wiring, resulting in low engineering implementation costs. It also has strong compatibility with existing measurement and control systems, facilitating large-scale promotion and application. 4. The method of this invention forms a closed-loop process from data acquisition, benchmark construction, initial assessment of potential hazards, section identification, quantitative location to fault verification. The steps are clear and the standards are unified. It can be directly applied to various high-voltage transmission lines of 220kV and above. It can be implemented without complicated debugging. It can automatically complete the determination of permanent faults and the verification of power supply conditions, actively trigger early warning and closing interlock, replace manual operation judgment, reduce the risk of human operation error, prevent serious accidents such as closing with grounding and blind forced power supply from the source, ensure the safety of power grid operation and the integrity of equipment, and improve the safety and intelligence level of high-voltage transmission line operation and maintenance. Attached Figure Description

[0015] Figure 1 A system architecture diagram according to an embodiment of the present invention is shown; Figure 2 A flowchart illustrating the construction process of a dynamic voltage reference library according to an embodiment of the present invention is shown; Figure 3 A flowchart illustrating the identification of potential problems using dual-side voltage linkage logic according to an embodiment of the present invention is shown; Figure 4 A flowchart illustrating fault determination by a permanent fault determination module according to an embodiment of the present invention is shown; Figure 5 A schematic diagram of the transmission principle of the monitoring system access module according to an embodiment of the present invention is shown. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention provides, for example Figures 1-5The transmission line grounding hazard early warning system shown includes a dual-end CVT voltage acquisition module, a grounding switch and operating condition acquisition module, a data preprocessing module, a segmented coupling dynamic reference library module, a grounding hazard identification module, a grounding section location module, a permanent fault identification module, a closing interlocking module, and a monitoring system access module. The dual-end CVT voltage acquisition module is used to connect to the secondary circuit of the CVT on both sides of the line and synchronously acquire the analog three-phase induced voltage at both ends of the line. The dual-ended CVT voltage acquisition module includes a CVT capacitive voltage transformer connected to the high-voltage side of the line, a synchronous sampling unit, an A / D conversion unit, and a data buffer unit. The CVT capacitive voltage transformer is used to convert the high-voltage induced voltage into a standard secondary low-voltage signal. The synchronous sampling unit is connected to the output of the CVT capacitive voltage transformer and realizes synchronous acquisition of voltage data on both sides through a unified time synchronization signal within the station. The A / D conversion unit is connected to the output of the synchronous sampling unit and converts the analog voltage signal into a digital electrical signal. The data buffer unit is connected to the output of the A / D conversion unit, temporarily stores the raw sampled data, and uploads it to the data preprocessing module. During voltage acquisition, such as Figure 2 As shown, the CVT capacitive voltage transformer is directly connected to the high-voltage side of the line, converting the high-voltage induced voltage into a low-voltage analog signal that conforms to the standards of power secondary equipment, thus completing high-voltage isolation and amplitude conversion. The output of the CVT capacitive voltage transformer is connected to a synchronous sampling unit, which is connected to a unified time synchronization signal within the station, such as GPS / BeiDou time synchronization or station SNTP time synchronization, to ensure that the voltage data on both sides of the line are synchronously triggered for sampling under the same time scale, ensuring that the phase of the data on both sides is aligned and the amplitude is comparable. The synchronous sampling unit outputs an analog signal to the A / D conversion unit, which discretizes the continuous analog voltage signal into a digital electrical signal to adapt to the subsequent digital processing flow. The back end of the A / D conversion unit is connected to a data buffer unit, which temporarily stores the original sampled digital data for one cycle or more, eliminates instantaneous fluctuation interference, and stably uploads it to the data preprocessing module, providing reliable original data for dual-side linkage judgment.

[0018] The grounding switch and operating condition acquisition module is used to connect to the station's monitoring and control devices to collect the positions of the grounding switches on both sides, the operating status of adjacent lines, and environmental parameters. The grounding switch and operating condition acquisition module includes a grounding switch position auxiliary contact, a measurement and control device input unit, an adjacent line operating status acquisition unit, and an environmental sensor interface. The grounding switch position auxiliary contact is used to acquire remote signaling quantities of the grounding switch's open and closed states; the measurement and control device input unit is used to acquire and upload remote signaling signals; the adjacent line operating status acquisition unit is used to acquire the operating conditions of parallel energized lines; and the environmental sensor interface is used to input environmental parameters such as temperature and humidity. The output terminals of the grounding switch position auxiliary contact, the measurement and control device input unit, the adjacent line operating status acquisition unit, and the environmental sensor interface are all connected to the input terminal of the data preprocessing module. The grounding switch position, parallel line operating conditions, and environmental data are acquired in real time through the grounding switch position auxiliary contact, the measurement and control device input unit, the adjacent line operating status acquisition unit, and the environmental sensor interface. After being summarized, the data is uploaded to the data preprocessing module to provide boundary conditions for dynamic benchmark construction and hazard identification. like Figure 3 As shown, the auxiliary contact of the grounding switch position directly collects the physical position of the grounding switch when it is open or closed, and converts it into a remote signaling quantity; the measurement and control device input unit receives the auxiliary contact signal and completes the remote signaling upload; the adjacent line operation status acquisition unit is connected to the parallel live line measurement and control device to obtain the operating conditions such as the energized state and load current; the environmental sensor interface is connected to environmental monitoring equipment such as temperature, humidity, and air pressure to collect environmental parameters; the data from the four units are summarized and transmitted to the data preprocessing module to provide boundary conditions for the construction of dynamic benchmarks; the closing interlocking module includes interlocking logic units set in parallel and hard contact outputs. The circuit breaker consists of a control unit and a soft message generation unit. The interlocking logic unit receives the power-on verification conclusion from the permanent fault judgment module and triggers an interlocking command when a hidden danger or permanent fault is detected. The command is simultaneously transmitted to the hard contact output unit and the soft message generation unit. The hard contact output unit outputs a passive interlocking contact that is connected to the circuit breaker closing circuit to achieve physical forced interlocking. The soft message generation unit generates interlocking messages according to IEC61850, 104 and other standard protocols to achieve software interlocking. After the hidden danger is eliminated, the interlocking logic unit automatically outputs a release command, and the interlocking is simultaneously canceled on both paths, allowing normal closing.

[0019] The data preprocessing module is electrically connected to the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module, respectively, and is used to preprocess the acquired data. The data preprocessing module includes a second-order low-pass filter unit, a noise removal unit, a data synchronization calibration unit, and an RMS value calculation unit connected in sequence. The second-order low-pass filter unit is used to filter out high-frequency electromagnetic interference. The noise removal unit removes random noise and outliers. The data synchronization calibration unit performs phase and amplitude correction on the comparison side voltage data. The RMS value calculation unit is used to calculate the true RMS value of the three-phase voltage. The formula for calculating the true RMS value of voltage is: , In the formula, U is the true effective value of the voltage. Let N be the instantaneous value of the kth sampling, and N be the number of sampling points in one period; During data preprocessing, the raw data output from the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module are received and sequentially filtered, denoised, and synchronized. Stable and reliable effective voltage values ​​and operating condition data are then calculated and output to the segmented coupling dynamic reference library module and the grounding hazard identification module, respectively.

[0020] The segmented coupling dynamic reference library module receives pre-processed data and constructs a dynamic voltage reference library based on line parameters, parallel connection, phase commutation, and grounding switch status. like Figure 4 As shown, the segmented coupled dynamic reference library module executes the following dynamic voltage reference library construction process: A1. Enter the fixed parameters of line voltage level, length, parallel section, and commutation method; A2. Group by dimension according to the status of the grounding switch, the operating condition of the parallel line, the paralleling method, and the commutation status; A3. Based on the electrostatic-electromagnetic dual-component coupling model, the coupling voltage of the parallel section and the distributed capacitance voltage of the independent section are calculated respectively, and the theoretical induced voltage at both ends of the line is obtained by combining commutation compensation; the formula expression of the electrostatic-electromagnetic dual-component coupling model is: , In the formula, For dynamic reference voltage, The electrostatic coupling coefficient is... This is the static coupling voltage component. The electromagnetic coupling coefficient is... This refers to the electromagnetic coupling voltage component. A4. The theoretical references under different operating conditions are stored. During operation, the dynamic voltage reference is automatically matched and called based on real-time operating conditions, realizing the adaptive generation and updating of the induced voltage reference. The automatic matching formula for the dynamic voltage reference is: In the formula, This is the reference voltage after complete commutation at the midpoint. This is the dynamic reference voltage.

[0021] The grounding hazard identification module uses a dynamic voltage reference library and pre-processed data to identify potential hazards such as unconnected grounding switches and left-behind grounding wires by employing dual-side voltage linkage logic. like Figure 4 As shown, the process for identifying potential problems using the dual-side voltage linkage logic is as follows: B1. Collect the status of the grounding switch on both sides of the line and the three-phase induced voltage on both sides; B2. Perform linkage verification according to three working conditions: both sides equally connected, one side connected, and both sides equally divided; the linkage verification formula is: In the formula, This represents the voltage difference between the two in-phase sides. This refers to the voltage amplitude at station A. The voltage amplitude on the B-side is determined by the condition that it is evenly distributed on both sides. Normal; in any phase Identify potential grounding hazards; B3. When the voltage of a certain phase is evenly distributed on both sides, if the voltage of a certain phase is lower than the voltage reference value of that phase in the dynamic voltage reference library, close to 0V, and the voltage difference between the two phases exceeds the voltage difference reference value of the same phase in the dynamic voltage reference library, it is determined that the phase of the grounding switch on the low voltage side is not actually separated or has a residual grounding. B4. After identifying the phase and location of the potential hazard, output an early warning and lock the circuit breaker.

[0022] The grounding section positioning module distinguishes between in-station, parallel section and independent section grounding according to the hazard judgment results and completes the quantitative calculation of grounding points; The grounding section location module includes a three-segment section discrimination unit, an amplitude ratio calculation unit, and a grounding point quantitative calculation unit. The three-segment section discrimination unit distinguishes between in-station grounding, parallel section grounding, and independent section grounding based on the amplitude and asymmetry of the voltage on both sides. The amplitude ratio calculation unit is connected to the output of the three-segment section discrimination unit and is used to calculate the amplitude ratio of the induced voltage on both sides of the line. The grounding point quantitative calculation unit is connected to the output of the amplitude ratio calculation unit and is used to complete the location calculation based on the dual-side voltage amplitude ratio model. The formula expression for the dual-side voltage amplitude ratio model is: In the formula, x is the distance from the grounding point to end A, and L is the total length of the line. This refers to the voltage amplitude at station A. This refers to the voltage amplitude on the B-station side. Section determination thresholds: When one side is ≤0.2kV and the other side is ≥1.5kV, it is grounding within the station; when both sides are ≥1.0kV and the amplitude ratio is between 1.2 and 3.0, it is grounding of the parallel section; when one side is ≤0.5kV and the other side is between 1.0 and 1.5kV, it is grounding of the independent section.

[0023] For example, grounding identification of parallel line sections: both grounding switches are in the open position. The induced voltage of a certain phase measured at station A is approximately 1.2kV, and the induced voltage of the same phase measured at station B is approximately 1.8kV. The voltages at both ends are higher than 1.0kV and neither side approaches 0V. The amplitude ratio is 1.5, which meets the characteristics of grounding in parallel sections. Through quantitative calculation, the grounding point is approximately 46.8km away from station A, allowing maintenance personnel to accurately locate and investigate.

[0024] Single-phase grounding hazard identification within the station: After the line was de-energized, both grounding switches on both sides were in the open position. The induced voltage of a certain phase measured on the A side was ≤0.2kV, while the induced voltage of the same phase on the B side was ≈2.0kV. The voltage levels on both sides were asymmetrical. Based on the three-stage discrimination logic, it was determined that the grounding hazard was located within the A side. The corresponding phase grounding switch was not reliably tripped, and the system immediately sent an early warning and blocked the closing.

[0025] Independent section grounding detection: After the line is de-energized, both grounding switches are in the open position. The induced voltage of a certain phase measured on the A station side is approximately 0.4kV (≤0.5kV), and the induced voltage of the same phase on the B station side is approximately 1.3kV (between 1.0kV and 1.5kV). One side is at a low level and the other side is at a medium level. It is determined that the grounding is located on the independent section on the A side, and the system pushes the section warning information.

[0026] It adopts a three-segment grounding section identification and grounding point quantitative calculation function, which can distinguish between grounding in the station, parallel section and independent section by only the voltage amplitude of both sides, and accurately invert the grounding point location. No special fault location device is required, which can effectively shorten the time for troubleshooting and maintenance and improve the efficiency of line restoration.

[0027] The permanent fault diagnosis module receives the hidden danger identification and location data, calls the dynamic voltage reference to distinguish between instantaneous or permanent grounding faults, and verifies whether the conditions for power supply are met. After a line tripping and reclosing failure, the permanent fault detection module collects the real-time induced voltage T over a certain period and compares it with a dynamic reference library. It then uses a fault detection algorithm to determine the fault. The formula for the fault detection algorithm is as follows: In the formula, This is the voltage deviation coefficient. This is the measured voltage value. The dynamic reference voltage is determined as follows: when When, it is determined to be a permanent grounding fault; when At that time, it was determined to be a transient fault; If the real-time induced voltage is low and there is an asymmetrical gradient between the voltages on both sides, it is determined to be a permanent grounding fault. If the voltage recovers to the voltage reference, it is determined to be a transient fault. Based on this, a power supply condition verification conclusion is formed and output to the closing interlocking module. For example, if the automatic reclosing fails after a 500kV line trips due to a fault, and the induced voltage of a certain phase on both sides is significantly lower than the dynamic reference and shows an obvious asymmetrical gradient, the system will determine that it is a permanent grounding fault and immediately output a closing lockout signal to prohibit maintenance personnel from forcibly energizing the line. The lockout will be lifted after the fault is completely eliminated.

[0028] The closing interlocking module receives the fault judgment result and generates a dual interlocking signal consisting of hard contacts and soft messages to prohibit unauthorized closing. The closing interlocking module includes an interlocking logic unit, a hard contact output unit, and a soft message generation unit arranged in parallel. It receives the verification conclusion output by the permanent fault judgment module. When a grounding hazard or permanent fault is determined, the interlocking logic unit triggers an interlocking command, and the hard contact output unit and the soft message generation unit output interlocking signals through dual paths to achieve forced interlocking of the closing circuit. After the hazard is eliminated, the interlocking is automatically released, allowing normal power supply.

[0029] The monitoring system access module is electrically connected to the closing interlocking module to realize early warning transmission, status display and interlocking execution.

[0030] The monitoring system access module includes a communication protocol stack unit, a data encapsulation unit, and a human-machine interface unit. The communication protocol stack unit is compatible with standard power protocols, such as IEC61850 and IEC104. The data encapsulation unit is connected to the output of the communication protocol stack unit and is used to encapsulate early warning information, positioning results, and lockout status into standard monitoring data. The human-machine interface unit is connected to the output of the data encapsulation unit and is used to realize visualization and remote monitoring. like Figure 5 As shown, the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module are located in the perception layer, responsible for acquiring all the field status quantities required to determine grounding hazards. The monitoring system access module is located in the transmission layer, which realizes data transmission and interaction between the perception layer and the processing layer based on the IEC61850 protocol. The data processing module, the segmented coupling dynamic reference library module, the permanent fault judgment module, and the grounding hazard discrimination module are located in the processing layer, responsible for completing data preprocessing, dynamic reference construction, and core judgment of hazards and power supply conditions. The grounding section location module and the closing interlocking module are located in the application layer. The application layer also has an early warning push module, which realizes fault location, closing interlocking, and early warning push functions based on the discrimination results of the processing layer. The D5000 system, the centralized control station automation system, and the station monitoring system are located in the platform layer, responsible for connecting the information output by the application layer to the existing operation and maintenance system to realize visual monitoring and operation and maintenance decision support.

[0031] The system receives warning and interlocking information from the closing interlocking module via the communication protocol stack unit. This information is then encapsulated by the data encapsulation unit and uploaded to the D5000 system, the central control station automation system, and the station monitoring system via the human-machine interface unit. It boasts strong adaptability to various operating conditions, covering 220kV-1000kV AC transmission lines. It is suitable for complex scenarios such as full-line parallel operation, partial parallel operation, and line phase switching, meeting the application requirements of different voltage levels and line structures. Furthermore, the system fully reuses existing primary and secondary power equipment, requiring no hardware modifications or additional wiring, resulting in low project implementation costs. It also exhibits strong compatibility with existing measurement, control, and monitoring systems, facilitating large-scale deployment and application.

[0032] like Figure 1As shown, after the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module synchronously acquire the on-site electrical quantities and operating conditions, the raw data are transmitted in parallel to the data preprocessing module. After the data preprocessing module completes filtering, noise reduction, synchronous calibration and effective value calculation, it outputs stable data to the segmented coupling dynamic reference library module and the grounding hazard identification module. The segmented coupling dynamic reference library module generates a dynamic voltage reference based on the fixed parameters of the line and the real-time operating conditions, providing a standard basis for hazard identification. The grounding hazard identification module completes the initial hazard judgment based on the dual-sided voltage linkage logic and transmits the result to the grounding section location module and the permanent fault judgment module. The grounding section location module realizes the grounding point location through three-segment discrimination and amplitude ratio calculation. The permanent fault judgment module distinguishes between instantaneous and permanent faults and verifies the power supply conditions. The output results of the two modules are summarized to the closing interlocking module to generate a hard contact and soft message dual interlocking signal. Finally, the monitoring system access module uploads the early warning, location and interlocking information to the dispatching and station monitoring system to realize remote visual control and achieve zero false alarms and zero missed alarms in grounding hazard identification. By replacing the traditional single-sided judgment with dual-sided voltage linkage verification, and combining dynamic benchmarks to adapt to all operating conditions, the accuracy of identifying hidden grounding hazards is greatly improved, ensuring the safety of power outage maintenance and power restoration operations of transmission lines. It can automatically distinguish between permanent and transient faults, and intelligently lock the closing circuit, eliminating serious power grid accidents such as closing with grounding or forcibly energizing permanent faults from the source, effectively ensuring the stable operation of the power grid and the safety of power equipment. At the same time, it realizes remote visual monitoring of early warning information, positioning results, and lockout status, improving the level of intelligent operation and maintenance of transmission lines.

[0033] Based on the above-described early warning system for grounding hazards in transmission lines, this invention also provides an early warning method for grounding hazards in transmission lines, comprising the following steps: S1. Synchronously collect the three-phase induced voltage on both sides of the line, the position signal of the grounding switch on both sides of the line, and the operating condition data of the parallel line, and perform filtering and preprocessing on the voltage data. S2. Construct a dynamic voltage reference library by grouping the total line length, the length of the parallel section on the same tower, the length of the independent section, the commutation method, and the status of the ground switch. S3. Based on the timing of the grounding switch opening and closing and the linkage law of the double-sided induced voltage, it is preliminarily determined that the grounding switch is not disconnected and there is a potential grounding hazard due to the grounding wire being left behind. S4. Based on the amplitude and asymmetry of the dual-sided induced voltage, perform three-stage connection area discrimination for in-station, parallel section, and independent section; S5. For lines with uniform coupling throughout the entire length, the location of the grounding point is quantitatively calculated by the voltage amplitude ratio on both sides. S6. After the line reclosing fails, compare the induced voltage with the dynamic reference to determine the permanent grounding fault and check the power supply conditions, triggering the hidden danger warning and closing lockout. This method forms a closed-loop process from data acquisition, benchmark construction, initial hazard assessment, section identification, quantitative location to fault verification. The steps are clear and the standards are unified. It can be directly applied to various high-voltage transmission lines of 220kV and above. It can be implemented without complicated debugging. It can automatically complete the determination of permanent faults and the verification of power supply conditions, actively trigger early warning and closing interlock, replace manual operation judgment, reduce the risk of human operation error, prevent serious accidents such as closing with grounding and blind forced power supply from the source, ensure the safety of power grid operation and the integrity of equipment, and improve the safety and intelligence level of high-voltage transmission line operation and maintenance.

[0034] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A grounding hazard early warning system for power transmission lines, characterized in that: include: The dual-ended CVT voltage acquisition module is used to connect to the secondary circuits of CVTs on both sides of the line and synchronously acquire the analog three-phase induced voltage at both ends of the line. The grounding switch and operating condition acquisition module is used to connect to the station's monitoring and control device to collect the positions of the grounding switches on both sides, the operating status of adjacent lines, and environmental parameters. The data preprocessing module is electrically connected to the dual-ended CVT voltage acquisition module and the grounding switch and operating condition acquisition module, respectively, and is used to preprocess the acquired data. The segmented coupling dynamic reference library module receives pre-processed data and constructs a dynamic voltage reference library according to line parameters, parallel connection, phase commutation, and grounding switch status. The grounding hazard identification module, based on a dynamic voltage reference library and pre-processed data, uses dual-side voltage linkage logic to identify potential hazards such as unconnected grounding switches and leftover grounding wires. The grounding section positioning module distinguishes between in-station, parallel section and independent section grounding according to the hazard judgment results and completes the quantitative calculation of grounding points; The permanent fault diagnosis module receives the hazard identification and location data, calls the dynamic voltage reference to distinguish between instantaneous or permanent grounding faults, and verifies whether the conditions for power supply are met. The closing interlocking module receives the fault judgment result and generates a dual interlocking signal consisting of hard contacts and soft messages to prevent unauthorized closing. The monitoring system access module is electrically connected to the closing interlocking module to realize early warning transmission, status display and interlocking execution.

2. The early warning system for grounding hazards in transmission lines according to claim 1, characterized in that: The dual-ended CVT voltage acquisition module includes: a CVT capacitive voltage transformer connected to the high-voltage side of the line, used to convert the high-voltage induced voltage into a standard secondary low-voltage signal; The synchronous sampling unit is connected to the output terminal of the CVT capacitive voltage transformer and realizes synchronous acquisition of voltage data on both sides through the unified time synchronization signal in the station. The A / D conversion unit is connected to the output of the synchronous sampling unit to convert analog voltage signals into digital electrical signals; The data caching unit is connected to the output of the A / D conversion unit, temporarily storing the raw sampled data and uploading it to the data preprocessing module.

3. The early warning system for grounding hazards in transmission lines according to claim 1, characterized in that: The grounding switch and working condition acquisition module includes: an auxiliary contact for the grounding switch position, which acquires remote signaling data of the grounding switch's open and closed status; The telemetry and control device input unit collects and uploads remote signaling signals; Adjacent line operation status acquisition unit, used to acquire the operating conditions of parallel energized lines; An environmental sensor interface is used to input environmental parameters such as temperature and humidity. The output terminals of the grounding switch position auxiliary contact, the measurement and control device input unit, the adjacent line operation status acquisition unit, and the environmental sensor interface are all connected to the input terminal of the data preprocessing module.

4. The early warning system for grounding hazards in transmission lines according to claim 1, characterized in that: The closing interlocking module includes an interlocking logic unit, a hard contact output unit, and a soft message generation unit arranged in parallel. It receives the verification conclusion output by the permanent fault judgment module. When a grounding hazard or permanent fault is determined, the interlocking logic unit triggers an interlocking command, and the hard contact output unit and the soft message generation unit output interlocking signals through dual paths to achieve forced interlocking of the closing circuit. After the hazard is eliminated, the interlocking is automatically released, allowing normal power supply.

5. The early warning system for grounding hazards in transmission lines according to claim 1, characterized in that: The segmented coupled dynamic reference library module executes the following dynamic voltage reference library construction process: A1. Enter the fixed parameters of line voltage level, length, parallel section, and commutation method; A2. Group by dimension according to the status of the grounding switch, the operating condition of the parallel line, the paralleling method, and the commutation status; A3. Based on the electrostatic-electromagnetic dual-component coupling model, calculate the coupling voltage of the parallel section and the distributed capacitance voltage of the independent section respectively, and combine the commutation compensation to obtain the theoretical induced voltage at both ends of the line. A4. Store theoretical references under different operating conditions, and automatically match and call dynamic voltage references according to real-time operating conditions during operation to realize adaptive generation and updating of induced voltage references.

6. A transmission line grounding hazard early warning system according to claim 5, characterized in that: The process for identifying potential problems using the dual-side voltage linkage logic is as follows: B1. Collect the status of the grounding switch on both sides of the line and the three-phase induced voltage on both sides; B2. Perform linkage verification according to three working conditions: both sides are equally connected, one side is connected, and both sides are equally divided. B3. When the voltage of a certain phase is lower than the voltage reference value of that phase in the dynamic voltage reference library, and the voltage difference between the two phases exceeds the voltage difference reference value of the same phase in the dynamic voltage reference library, it is determined that the phase of the grounding switch on the low voltage side is not actually separated or has a residual grounding. B4. After identifying the phase and location of the potential hazard, output an early warning and lock the circuit breaker.

7. A transmission line grounding hazard early warning system according to claim 1, characterized in that: The grounding section positioning module includes: a three-segment section discrimination unit, which distinguishes between station grounding, parallel section grounding and independent section grounding based on the voltage amplitude and asymmetry of both sides; The amplitude ratio calculation unit is connected to the output of the three-segment segment discrimination unit and is used to calculate the amplitude ratio of the induced voltage on both sides of the line. The grounding point quantitative calculation unit is connected to the output of the amplitude ratio calculation unit and is used to complete the location calculation based on the dual-side voltage amplitude ratio model.

8. The early warning system for grounding hazards in transmission lines according to claim 1, characterized in that: After a line trip and reclosing fails, the permanent fault judgment module collects the real-time induced voltage and compares it with the dynamic reference library. It then uses a fault discrimination algorithm to judge the fault. If the real-time induced voltage is low and there is an asymmetrical gradient between the voltages on both sides, it is judged as a permanent grounding fault. If the voltage recovers to the voltage reference, it is judged as an instantaneous fault. Based on this, a power supply condition verification conclusion is formed and output to the closing interlocking module.

9. A transmission line grounding hazard early warning system according to claim 1, characterized in that: The monitoring system access module includes: a communication protocol stack unit, compatible with standard power protocols; The data encapsulation unit, connected to the output of the communication protocol stack unit, is used to encapsulate early warning information, positioning results, and lockout status into standard monitoring data. The human-machine interface unit is connected to the output of the data encapsulation unit to enable visualization and remote monitoring. The communication protocol stack unit receives the warning and interlocking information output by the closing interlocking module, performs protocol encapsulation by the data encapsulation unit, and then uploads the encapsulated data to the D5000 system, the central control station automation system, and the station monitoring system by the human-machine interface unit.

10. A method for early warning of grounding hazards in transmission lines, using the early warning system for grounding hazards in transmission lines as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Synchronously collect the three-phase induced voltage on both sides of the line, the position signal of the grounding switch on both sides of the line, and the operating condition data of the parallel line, and perform filtering and preprocessing on the voltage data. S2. Construct a dynamic voltage reference library by grouping the total line length, the length of the parallel section on the same tower, the length of the independent section, the commutation method, and the status of the ground switch. S3. Based on the timing of the grounding switch opening and closing and the linkage law of the double-sided induced voltage, it is preliminarily determined that the grounding switch is not disconnected and there is a potential grounding hazard due to the grounding wire being left behind. S4. Based on the amplitude and asymmetry of the dual-sided induced voltage, perform three-stage connection area discrimination for in-station, parallel section, and independent section; S5. For lines with uniform coupling throughout the entire length, the location of the grounding point is quantitatively calculated by the voltage amplitude ratio on both sides. S6. After the line reclosing fails, compare the induced voltage with the dynamic reference to determine the permanent grounding fault and check the power supply conditions, triggering the hidden danger warning and closing lockout.

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