Low-current grounding line selection method and system based on transient integral energy method
By employing an adaptive dual-start mode and feature consistency processing based on the transient integral energy method, the problem of accurate line selection in low-current grounding systems under high-resistance and strong interference environments is solved. This enables accurate identification of high-resistance faults and improves anti-interference capabilities, thereby enhancing the sensitivity and reliability of fault detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-03
AI Technical Summary
Existing methods for selecting grounding systems with low current are not accurate or reliable enough in high-resistance faults and strong interference environments. Fixed threshold start criteria have poor adaptability, weak anti-interference ability, imperfect transient characteristic processing, and lack of grounding probability quantification indicators, resulting in a high misjudgment rate.
An adaptive dual-start mode based on transient integral energy method is adopted. By acquiring the sudden change energy and fundamental effective value of zero-sequence voltage and current, and combining the data in the transient analysis window, the transient energy sum and consistency measure are calculated to perform distributed and centralized line selection. The adaptive exponential moving average method and confidence probability fusion decision are used to improve the accuracy and robustness of fault location.
It enables accurate detection of faults with high resistance and small initial phase angle, dynamically tracks load fluctuations, suppresses high-frequency noise, improves fault detection sensitivity and identification accuracy, eliminates misjudgments caused by differences in system parameters, and enhances the reliability and anti-interference capability of line selection.
Smart Images
Figure CN121784458A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power system protection technology, specifically, it relates to a method and system for selecting low-current grounding faults based on the transient integral energy method. Background Technology
[0002] The neutral point grounding methods in power systems are mainly divided into two categories: directly grounded neutral point (high-current grounding system) and not directly grounded neutral point (low-current grounding system). Low-current grounding systems are widely used in 6-66kV distribution networks because the fault current flowing through the fault point during a single-phase ground fault is very small, and the line voltage can still remain symmetrical, not affecting the power supply to the load. Due to the weak fault characteristics of low-current systems, traditional steady-state fault location methods have low success rates. To improve the accuracy of ground fault location, some technologies utilize a steady-state zero-sequence voltage over-limit start criterion. This criterion accurately determines the fault location by comparing the change in transient zero-sequence voltage and the direction of transient zero-sequence current at the fault point during a single-phase ground fault. This method has high reliability and accuracy, is unaffected by the grounding method, and does not require an additional signal source. However, this method requires setting a start-up threshold. When facing high-resistance faults, the size of this threshold directly affects whether the algorithm can abruptly start. Furthermore, this method only captures the sign of the point with the maximum absolute value within a window, which is prone to misjudgment. Some technologies calculate the instantaneous value of transient zero-sequence active power and use low-pass filtering to form an array of active power integral values. These integrated active power values are then used to identify whether a low-current grounding fault is inside or outside the fault zone. While this invention improves the accuracy of identifying low-current grounding faults inside and outside the fault zone, it struggles to extract effective information when high-frequency signals of transient power instantaneous values are prominent during short circuits. Furthermore, it uses a fixed threshold for startup, making it more prone to failure when facing high-impedance faults, and its computational complexity and real-time performance are insufficient.
[0003] The fault location function of low-current grounding systems still faces many challenges: Poor adaptability of fixed threshold initiation criteria: Existing fault location methods mostly use fixed threshold initiation criteria. When faced with weak fault wavefront signals, fixed thresholds often fail to initiate, leading to missed faults. Furthermore, in low signal-to-noise ratio and strong interference environments, abrupt change criteria based on fixed thresholds are prone to misclassifying normal fluctuations as faults, failing to track real-time changes in the power grid and increasing the misjudgment rate. Insufficient anti-interference: Existing identification methods based on analog signals, when facing high-impedance faults and faults with an initial phase angle of 0, suffer from weak transient effective signals generated by the fault, which are easily masked by high-frequency noise, making accurate fault line identification impossible. Inadequate transient feature processing: Most current fault location methods do not effectively process transient features; comparing only maximum values easily leads to misjudgments. Moreover, different lines exhibit different transient features due to parameter differences (such as line length and load conditions), making it difficult to unify judgment standards. Simultaneously, the lack of quantitative indicators for grounding probability makes it impossible to accurately measure the likelihood of grounding faults on each line, resulting in low reliability of fault location. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a method and system for selecting low-current ground faults based on the transient integral energy method. This method overcomes the inherent defects of traditional low-current ground fault selection methods in terms of startup reliability, anti-interference capability, and transient feature processing. Through adaptive dual startup, transient integral signal amplification, feature normalization consistency processing, and confidence probability fusion decision-making, it improves the accuracy, sensitivity, and robustness of single-phase ground fault location, especially in high-resistance, weak signal, and strong interference environments.
[0005] The present invention adopts the following technical solution.
[0006] This invention proposes a method for selecting low-current grounding lines based on the transient integral energy method, characterized by comprising: Obtain the zero-sequence voltage mutation energy and zero-sequence current mutation energy, the fundamental RMS value of the zero-sequence voltage, and the root mean square value of the zero-sequence current; when the zero-sequence voltage mutation energy and zero-sequence current mutation energy satisfy the mutation energy criterion and the fundamental RMS value of the zero-sequence voltage and the half-cycle root mean square value of the zero-sequence current satisfy the steady-state start-up criterion, start the grounding line selection; Set a transient analysis window; after the grounding selection is started, based on the data in the transient analysis window, calculate the amplitude characteristics of the zero-sequence current at the transient moment and the zero-sequence power at each transient moment, and calculate the total transient energy and the consistency measure of transient energy. Distributed line selection is performed based on the sum of transient energy in each bay of the power distribution equipment and the consistency measure of transient energy; centralized line selection is performed based on the sum of transient energy in each bay of the power distribution equipment, the consistency measure of transient energy, and the amplitude characteristic of the zero-sequence current at the transient moment.
[0007] Preferably, the number of sampling points in one power frequency cycle is Sampling time With sampling time - The abrupt change energy of the zero-sequence voltage and the abrupt change energy of the zero-sequence current are shown in the following equations:
[0008]
[0009] In the formula, , Sampling time The energy of the sudden change in zero-sequence voltage and the energy of the sudden change in zero-sequence current. , Sampling time The zero-sequence voltage sample value and the zero-sequence current sample value; The historical average values of the abrupt change energy of the zero-sequence voltage and the abrupt change energy of the zero-sequence current are determined using the adaptive exponential moving average method, as shown in the following equations:
[0010]
[0011] In the formula, , Sampling time The historical average energy of the abrupt change in zero-sequence voltage and the historical average energy of the abrupt change in zero-sequence current. The parameters are for the adaptive exponential moving average. like continuous Second greater than and continuous Second greater than If the mutation energy criterion is met, then the mutation energy criterion is satisfied; otherwise, the mutation energy criterion is not satisfied. It is an integer not less than 3.
[0012] Preferably, a zero-sequence voltage setpoint and a zero-sequence current setpoint are set; if the fundamental effective value of the zero-sequence voltage is greater than the zero-sequence voltage setpoint and the half-cycle root mean square value of the zero-sequence current is greater than the zero-sequence current setpoint, then the steady-state start-up criterion is satisfied; otherwise, the steady-state start-up criterion is not satisfied.
[0013] Preferably, based on the grounding line selection start time Set the transient analysis window to [ - , + The transient analysis window contains a total of A transient moment; The RMS value of the transient zero-sequence current over the entire cycle within the transient analysis window is calculated as the amplitude characteristic of the zero-sequence current at the transient moment, as shown in the following formula:
[0014] In the formula, For transient analysis window The transient zero-sequence current full-cycle RMS value calculated from each sampling point. For the first Zero-sequence current at each sampling point; Transient moment zero-sequence voltage transient component As shown in the following formula:
[0015] Transient moment zero-sequence current transient component As shown in the following formula:
[0016] Transient moment zero-sequence power As shown in the following formula: = ×
[0017] In the formula, , Transient time points The zero-sequence voltage sample value and the zero-sequence current sample value.
[0018] Preferably, the total transient energy is as shown in the following formula:
[0019] The consistency measure of transient energy is shown in the following formula:
[0020] In the formula, The sum of transient energies. It is a measure of the consistency of transient energy.
[0021] Preferably, in the distributed line selection mode, the values of each bay of the power distribution unit are calculated separately. and If a certain interval satisfies > and If the value is less than the set value X, then the outgoing line corresponding to that interval is determined to be a faulty line. Among these measures, zero-sequence voltage and zero-sequence current are collected in real time, and the maximum value of zero-sequence power in each power frequency cycle under non-fault conditions is calculated as the fault energy threshold. .
[0022] Preferably, in the centralized line selection mode, the selection is based on the individual bays of the power distribution equipment. and The product of these values represents the polarity composite index for each interval. = × , , The number of intervals; Using the polarity composite index of all intervals The transient energy probability index for line grounding faults is calculated as follows: ,
[0023] In the formula, This represents the maximum absolute value of the polarity composite index for each interval; This is a transient energy probability index for line grounding faults. ; The normalized amplitude of the transient zero-sequence current of the line is calculated using the amplitude characteristics of the zero-sequence current at all intervals, as shown in the following formula: ,
[0024] In the formula, This represents the maximum value of the amplitude characteristic of the zero-sequence current at each transient moment; This is the normalized amplitude of the transient zero-sequence current of the line.
[0025] Preferably, the interval The ground fault confidence level of the corresponding outgoing line is shown in the following formula:
[0026] In the formula, For interval The grounding fault confidence level of the corresponding outgoing line. These are the transient energy weighting coefficients. The weighting coefficients for transient zero-sequence current. These are the dual-feature collaborative weighting coefficients. To obtain Functions with the symbol .
[0027] The ground fault confidence probability of the line is calculated using the ground fault confidence levels of all intervals, as shown in the following formula: ,
[0028] In the formula, This represents the maximum confidence level of ground faults in each interval. The confidence probability of a ground fault in the line; When the interval The confidence probability of grounding fault in the corresponding outgoing line If the value is greater than or equal to the preset value Y, then the outgoing line corresponding to that interval is determined to be a faulty line.
[0029] This invention also proposes a low-current grounding fault location system based on the transient integral energy method, comprising: The startup module is used to acquire the zero-sequence voltage mutation energy and zero-sequence current mutation energy, the fundamental RMS value of the zero-sequence voltage, and the root mean square value of the zero-sequence current. When the zero-sequence voltage mutation energy and zero-sequence current mutation energy satisfy the mutation energy criterion and the fundamental RMS value of the zero-sequence voltage and the half-cycle root mean square value of the zero-sequence current satisfy the steady-state startup criterion, the grounding line selection is started. The line selection criterion calculation module is used to set the transient analysis window. After the grounding line selection is started, based on the data in the transient analysis window, the amplitude characteristics of the zero-sequence current at the transient moment and the zero-sequence power at each transient moment are calculated, and the total transient energy and the consistency measure of transient energy are calculated. The distributed fault selection module is used to perform distributed fault selection based on the sum of transient energy of each bay of the power distribution equipment and the consistency measure of transient energy. The centralized line selection module is used to perform centralized line selection based on the sum of transient energy of each bay of the power distribution device, the consistency measure of transient energy, and the amplitude characteristics of the zero-sequence current at the transient moment.
[0030] The present invention is also a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to perform operations according to the instructions to execute the steps of the method.
[0031] The present invention is also a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method.
[0032] The beneficial effects of this invention are as follows: Compared with the prior art, the method proposed in this invention adopts a dual-start mode of energy mutation start-up + steady-state start-up. The energy mutation start-up introduces an adaptive mechanism to dynamically track load fluctuations without the need for a fixed threshold, thus achieving accurate start-up discrimination for high-resistance and small initial phase angle faults and improving fault detection sensitivity. After half-cycle integration of the zero-sequence voltage and zero-sequence current sampling values within the transient window before and after start-up, the transient energy is judged, which can amplify the effective signal and suppress high-frequency harmonics, ensuring the accuracy and reliability of fault identification. By integrating the transient energy and combining it with the transient characteristic consistency measure, the fault branch is judged. The normalization factor can effectively suppress misjudgments caused by waveform distortion (grid load fluctuations, harmonic interference). The confidence probability formula integrates the dual transient information of "transient energy + transient zero-sequence current" to highlight the fault direction characteristics of the branch.
[0033] This invention addresses the problem of poor adaptability of fixed thresholds by using dynamic dual-start logic and EMA to dynamically track historical fluctuations; it employs transient feature enhancement technology, which amplifies transient features through half-cycle integral accumulation and suppresses high-frequency noise; based on a fault probability quantification model, transient feature consistency measurement eliminates system parameter differences and avoids single-point misjudgment; and confidence probability is fused with dual transient features to make fault features more apparent. Attached Figure Description
[0034] Figure 1 This is a flowchart of a low-current grounding line selection method based on transient integral energy method proposed in this invention. Detailed Implementation
[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.
[0036] This invention provides a method for selecting low-current grounding lines based on the transient integral energy method, such as... Figure 1 As shown, the method includes: Step 1: Obtain the zero-sequence voltage mutation energy and zero-sequence current mutation energy, the fundamental effective value of the zero-sequence voltage, and the root mean square value of the zero-sequence current; when the zero-sequence voltage mutation energy and zero-sequence current mutation energy satisfy the mutation energy criterion and the fundamental effective value of the zero-sequence voltage and the root mean square value of the zero-sequence current satisfy the steady-state start-up criterion, start the grounding line selection.
[0037] Initialization parameters, including: power frequency period Sampling frequency Number of sampling points per power frequency cycle ; Zero-sequence voltage and zero-sequence current are collected, and the electrical quantity characteristics are calculated after anti-aliasing filtering of the analog signals. Specifically, the effective value of the fundamental frequency of the zero-sequence voltage is calculated using FFT. , as a characteristic quantity of zero-sequence voltage; Specifically, a rectangular window function is used to perform a half-cycle on the filtered zero-sequence current. Using a sliding window with 2 sampling points, the root mean square (RMS) value of the zero-sequence current half-cycle is calculated to ensure that the half-cycle RMS value can track the transient changes of the current in real time. The calculation formula is as follows:
[0038] In the formula, This represents the RMS value of the zero-sequence current during the half-cycle. For the first Zero-sequence current at each sampling point; The half-cycle RMS value of the zero-sequence current is used as a characteristic quantity of the zero-sequence current.
[0039] Specifically, the multidimensional criteria include the sudden change energy criterion and the steady-state start-up criterion; when both the sudden change energy criterion and the steady-state start-up criterion are met, the grounding selection start-up condition is determined to be met; otherwise, the grounding selection start-up condition is determined not to be met.
[0040] Number of sampling points in one power frequency cycle Therefore, sampling time With sampling time - This represents the corresponding time within two adjacent power frequency cycles, and the sampling time is calculated. With sampling time - The abrupt change energy of the zero-sequence voltage and the abrupt change energy of the zero-sequence current are shown in the following equations: ,
[0041] In the formula, , Sampling time The energy of the sudden change in zero-sequence voltage and the energy of the sudden change in zero-sequence current. , Sampling time The zero-sequence voltage sample value and the zero-sequence current sample value.
[0042] The historical average values of the sudden change energy of zero-sequence voltage and the sudden change energy of zero-sequence current are determined using the adaptive exponential moving average (EMA) method, as shown in the following equations:
[0043]
[0044] In the formula, , Sampling time The historical average energy of the abrupt change in zero-sequence voltage and the historical average energy of the abrupt change in zero-sequence current. The parameters are for the adaptive exponential moving average. like continuous Second greater than and continuous Second greater than If the mutation energy criterion is met, then the mutation energy criterion is satisfied; otherwise, the mutation energy criterion is not satisfied. In the embodiments, , Adaptive moving average parameters Number of consecutive fault start determinations The program is preset to a certain value; in the example, It is an integer not less than 3; Zero-sequence voltage setting for ground fault selection and zero-sequence current setting The set value is set for the device; if the effective value of the fundamental wave of the zero-sequence voltage is greater than the set value of the zero-sequence voltage and the half-cycle RMS value of the zero-sequence current is greater than the set value of the zero-sequence current, then the steady-state start-up criterion is satisfied; otherwise, the steady-state start-up criterion is not satisfied. The grounding selection start condition is determined to be met when both the sudden change energy criterion and the steady-state start-up criterion are met; otherwise, the grounding selection start condition is determined not to be met.
[0045] Step 2: Real-time acquisition of zero-sequence voltage and zero-sequence current; calculation of the maximum value of zero-sequence power in each power frequency cycle under non-fault conditions as the fault energy threshold value.
[0046] Specifically, the zero-sequence power for each power frequency cycle is calculated using the filtered zero-sequence voltage and zero-sequence current, as shown in the following formula:
[0047] In the formula, For the first Zero-sequence voltage at each sampling point; The maximum zero-sequence power value in each power frequency cycle under non-fault conditions obtained through iterative updates. , which serves as the fault energy threshold value.
[0048] The method proposed in this invention adopts a dual-start mode of energy-fluctuation start-up and steady-state start-up. The energy-fluctuation start-up introduces an adaptive mechanism to dynamically track load fluctuations without the need for a fixed threshold, thereby achieving accurate start-up discrimination for faults with high resistance and small initial phase angle and improving fault detection sensitivity.
[0049] Step 3: Set the transient analysis window; after the grounding selection is started, based on the data in the transient analysis window, calculate the amplitude characteristics of the zero-sequence current at each transient moment and the zero-sequence power at each transient moment, and calculate the total transient energy and the consistency measure of transient energy.
[0050] Specifically, based on the grounding line selection start time Set the transient analysis window to [ - , + The transient analysis window contains a total of Each transient moment; for any transient moment within the transient analysis window Calculate the zero-sequence voltage at the transient time. The half-cycle integral as the transient moment Calculate the zero-sequence voltage transient component and the zero-sequence current at the transient moment. The half-cycle integral as the transient moment The zero-sequence current transient component; half-cycle integration can amplify transient characteristics and effectively suppress high-frequency noise; The full-cycle RMS value of the transient zero-sequence current within the transient analysis window is calculated as shown in the following formula:
[0051] In the formula, For transient analysis window The transient zero-sequence current full-cycle RMS value calculated from each sampling point. For the first Zero-sequence current at each sampling point; The full-cycle RMS value of the transient zero-sequence current is used as the amplitude characteristic quantity of the zero-sequence current at the transient moment.
[0052] Transient moment zero-sequence voltage transient component As shown in the following formula:
[0053] Transient moment zero-sequence current transient component As shown in the following formula:
[0054] In the formula, , Transient time points The zero-sequence voltage sample value and the zero-sequence current sample value.
[0055] Transient moment zero-sequence power As shown in the following formula: = ×
[0056] The sign of zero-sequence power reflects the direction of transient power. There is a significant difference in the sign of zero-sequence power between faulty and non-faulty lines. The zero-sequence power of faulty branches is negative, while that of non-faulty branches is positive. Therefore, faulty branches can be screened based on the sign of zero-sequence power at transient moments.
[0057] The present invention integrates the zero-sequence voltage and zero-sequence current sampling values within the transient window before and after the grounding line selection is started, and then judges the transient energy. This can amplify the effective signal and suppress high-frequency harmonics, thus ensuring the accuracy and reliability of fault identification.
[0058] The zero-sequence power at each transient moment within the transient analysis window is summed to obtain the total transient energy. As shown in the following formula:
[0059] The larger the absolute value, the more significant the transient characteristics, and the higher the probability of line failure. Consistency measure for calculating transient energy As shown in the following formula:
[0060] Calculate a consistency metric for transient energy to eliminate the effects of differences in system parameters (such as line length and load).
[0061] This invention uses transient integral energy, combined with transient characteristic consistency measurement, to determine faulty branches.
[0062] Step 4: Perform distributed line selection based on the total transient energy of each bay of the power distribution device and the consistency measure of transient energy; perform centralized line selection based on the total transient energy of each bay of the power distribution device, the consistency measure of transient energy, and the amplitude characteristic of the zero-sequence current at the transient moment.
[0063] Distributed fault location is suitable for fault location functions deployed in single bays. Distributed fault location adopts a single bay judgment mode, where each line bay (such as the protection device of each branch line) acts independently as a detection unit, and makes fault judgment only based on the zero-sequence voltage and zero-sequence current data collected by itself in a single bay, without relying on data from other bays. Centralized fault location is suitable for centralized fault location systems or devices. Centralized fault location adopts a multi-bay data judgment mode, where the centralized protection device aggregates the zero-sequence voltage and zero-sequence current data of all line bays (at least 2 bays) and realizes fault location through multi-bay data comparison and analysis.
[0064] Specifically, step 4 includes: Step 4.1, in distributed line selection mode, calculate the values of each bay of the power distribution unit. and If a certain interval satisfies > and If the value is less than the set value X, the outgoing line corresponding to that interval is determined to be a faulty line, thus realizing distributed low-current grounding line selection.
[0065] In the embodiment, each distributed single-bay sub-machine device calculates the power distribution equipment for each bay. and According to simulation analysis, the false positive rate is lowest when the set value X is -0.7±0.1.
[0066] Step 4.2, in the centralized line selection mode, based on the various bays of the power distribution equipment... and The product of these values represents the polarity composite index for each interval. = × , , The number of intervals; In this embodiment, a centralized device uniformly completes the power distribution of each bay. and The data is collected and the polarity comprehensive index of each interval is calculated, or the data of each interval is collected through each distributed single-interval sub-device. and The polarity comprehensive index of each interval is calculated and then summarized on the host computer.
[0067] Step 4.3, utilize the polarity composite index of all intervals. The transient energy probability index for line grounding faults is calculated as follows: ,
[0068] In the formula, This represents the maximum absolute value of the polarity composite index for each interval; This is a transient energy probability index for line grounding faults. ; The normalized amplitude of the transient zero-sequence current of the line is calculated using the amplitude characteristics of the zero-sequence current at all intervals, as shown in the following formula: ,
[0069] In the formula, This represents the maximum value of the amplitude characteristic of the zero-sequence current at each transient moment; This is the normalized amplitude of the transient zero-sequence current of the line.
[0070] In the embodiment, the polarity comprehensive index and transient zero-sequence current amplitude characteristics of all intervals are normalized, which can effectively suppress misjudgments caused by waveform distortion, including power grid load fluctuations and harmonic interference.
[0071] Step 4.4: Calculate the ground fault confidence probability of the outgoing lines corresponding to each bay; Transient energy probability index to avoid multiple intervals of line grounding faults Misjudgment occurs when they are close; calculate the interval. The ground fault confidence level of the corresponding outgoing line is shown in the following formula:
[0072] In the formula, For interval The grounding fault confidence level of the corresponding outgoing line. For interval The corresponding transient energy probability of the outgoing line. This represents the normalized amplitude of the transient zero-sequence current of the outgoing line corresponding to interval j. This is the transient energy weighting coefficient, which is set to 60% in this example. This is the weighting factor for the transient zero-sequence current; in this example, it is set to 20%. This is the dual-feature collaborative weighting coefficient, which is set to 20% in this example. To obtain Functions with the symbol .
[0073] When calculating the confidence level of a ground fault, 60% is based on the transient energy probability intensity, 20% on the relative contribution of the transient zero current amplitude, and 20% on the transient dual-feature coordinated intensity. This strengthens the energy characteristics of the line fault itself, weakens the single-feature interference of the zero current amplitude, increases the dual-feature coordinated compensation index, and improves the identification capability of high-resistance faults.
[0074] Similarly, the ground fault confidence probability of the line is calculated using the ground fault confidence scores of all intervals, as shown in the following formula: ,
[0075] In the formula, This represents the maximum confidence level of ground faults in each interval. This represents the confidence probability of a ground fault in the line.
[0076] When the interval The confidence probability of grounding fault in the corresponding outgoing line If the value is greater than or equal to the preset value Y, then the outgoing line corresponding to that interval is determined to be a faulty line.
[0077] In the embodiment, the preset value Y was determined to be 0.75±0.15 through simulation.
[0078] This invention combines grounding probability confidence probability to highlight the polarity characteristics of faulty branches.
[0079] This invention also proposes a low-current grounding fault location system based on the transient integral energy method, comprising: The startup module is used to acquire the zero-sequence voltage mutation energy and zero-sequence current mutation energy, the fundamental RMS value of the zero-sequence voltage, and the root mean square value of the zero-sequence current. When the zero-sequence voltage mutation energy and zero-sequence current mutation energy satisfy the mutation energy criterion and the fundamental RMS value of the zero-sequence voltage and the half-cycle root mean square value of the zero-sequence current satisfy the steady-state startup criterion, the grounding line selection is started. The line selection criterion calculation module is used to set the transient analysis window. After the grounding line selection is started, based on the data in the transient analysis window, the amplitude characteristics of the zero-sequence current at the transient moment and the zero-sequence power at each transient moment are calculated, and the total transient energy and the consistency measure of transient energy are calculated. The distributed fault selection module is used to perform distributed fault selection based on the sum of transient energy of each bay of the power distribution equipment and the consistency measure of transient energy. The centralized line selection module is used to perform centralized line selection based on the sum of transient energy of each bay of the power distribution device, the consistency measure of transient energy, and the amplitude characteristics of the zero-sequence current at the transient moment.
[0080] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.
[0081] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.
[0082] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.
[0083] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages such as Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.
[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.
Claims
1. A method for selecting grounding faults with low current based on transient integral energy method, characterized in that, include: Obtain the zero-sequence voltage change energy and zero-sequence current change energy, the fundamental RMS value of the zero-sequence voltage, and the root mean square value of the zero-sequence current; When the zero-sequence voltage mutation energy and the zero-sequence current mutation energy satisfy the mutation energy criterion, and the effective value of the fundamental wave of the zero-sequence voltage and the root mean square value of the half-cycle of the zero-sequence current satisfy the steady-state start-up criterion, the grounding selection is initiated. Set up the transient analysis window; After the grounding selection is initiated, based on the data in the transient analysis window, the amplitude characteristics of the zero-sequence current at the transient moment and the zero-sequence power at each transient moment are calculated, and the total transient energy and the consistency measure of transient energy are also calculated. Distributed line selection is performed based on the sum of transient energy in each bay of the power distribution equipment and the consistency measure of transient energy; centralized line selection is performed based on the sum of transient energy in each bay of the power distribution equipment, the consistency measure of transient energy, and the amplitude characteristic of the zero-sequence current at the transient moment.
2. The low-current grounding fault location method based on transient integral energy method according to claim 1, characterized in that, The number of sampling points in one power frequency cycle is Sampling time With sampling time - The abrupt change energy of the zero-sequence voltage and the abrupt change energy of the zero-sequence current are shown in the following equations: In the formula, , Sampling time The energy of the sudden change in zero-sequence voltage and the energy of the sudden change in zero-sequence current. , Sampling time The zero-sequence voltage sample value and the zero-sequence current sample value; The historical average values of the abrupt change energy of the zero-sequence voltage and the abrupt change energy of the zero-sequence current are determined using the adaptive exponential moving average method, as shown in the following equations: In the formula, , Sampling time The historical average energy of the abrupt change in zero-sequence voltage and the historical average energy of the abrupt change in zero-sequence current. The parameters are for the adaptive exponential moving average. like continuous Second greater than and continuous Second greater than If the mutation energy criterion is met, then the mutation energy criterion is satisfied; otherwise, the mutation energy criterion is not satisfied. It is an integer not less than 3.
3. The low-current grounding fault location method based on transient integral energy method according to claim 1, characterized in that, Set the zero-sequence voltage setpoint and the zero-sequence current setpoint; if the effective value of the fundamental wave of the zero-sequence voltage is greater than the zero-sequence voltage setpoint and the root mean square value of the half-cycle of the zero-sequence current is greater than the zero-sequence current setpoint, then the steady-state start-up criterion is satisfied. Otherwise, the steady-state start-up criterion is not met.
4. The low-current grounding fault location method based on transient integral energy method according to claim 1, characterized in that, Based on the grounding line selection start time Set the transient analysis window to [ - , + The transient analysis window contains a total of A transient moment; The RMS value of the transient zero-sequence current over the entire cycle within the transient analysis window is calculated as the amplitude characteristic of the zero-sequence current at the transient moment, as shown in the following formula: In the formula, For transient analysis window The transient zero-sequence current full-cycle RMS value calculated from each sampling point. For the first Zero-sequence current at each sampling point; Transient moment zero-sequence voltage transient component As shown in the following formula: Transient moment zero-sequence current transient component As shown in the following formula: Transient moment zero-sequence power As shown in the following formula: = × In the formula, , Transient time The zero-sequence voltage sample value and the zero-sequence current sample value.
5. The low-current grounding fault location method based on transient integral energy method according to claim 4, characterized in that, The total transient energy is shown in the following formula: The consistency measure of transient energy is shown in the following formula: In the formula, The sum of transient energies. It is a measure of the consistency of transient energy.
6. The low-current grounding fault location method based on transient integral energy method according to claim 5, characterized in that, In distributed line selection mode, the calculation of each bay of the power distribution unit is performed separately. and If a certain interval satisfies > and If the value is less than the set value X, then the outgoing line corresponding to that interval is determined to be a faulty line. Among these methods, zero-sequence voltage and zero-sequence current are collected in real time, and the maximum value of zero-sequence power in each power frequency cycle under non-fault conditions is calculated as the fault energy threshold. .
7. The low-current grounding fault location method based on transient integral energy method according to claim 5, characterized in that, In centralized line selection mode, based on the individual bays of the power distribution equipment and The product of these values represents the polarity composite index for each interval. = × , , The number of intervals; Using the polarity composite index of all intervals The transient energy probability index for line grounding faults is calculated as follows: ， In the formula, This represents the maximum absolute value of the polarity composite index for each interval; This is a transient energy probability index for line grounding faults. ; The normalized amplitude of the transient zero-sequence current of the line is calculated using the amplitude characteristics of the zero-sequence current at all intervals, as shown in the following formula: ， In the formula, This represents the maximum value of the amplitude characteristic of the zero-sequence current at each transient moment; This is the normalized amplitude of the transient zero-sequence current of the line.
8. The low-current grounding fault location method based on transient integral energy method according to claim 7, characterized in that, interval The ground fault confidence level of the corresponding outgoing line is shown in the following formula: In the formula, For interval The grounding fault confidence level of the corresponding outgoing line. These are the transient energy weighting coefficients. The weighting coefficients for transient zero-sequence current. These are the dual-feature collaborative weighting coefficients. To obtain Functions with the symbol . The ground fault confidence probability of the line is calculated using the ground fault confidence levels of all intervals, as shown in the following formula: ， In the formula, This represents the maximum confidence level of ground faults in each interval. The confidence probability of a ground fault in the line; When the interval The confidence probability of grounding fault in the corresponding outgoing line If the value is greater than or equal to the preset value Y, then the outgoing line corresponding to that interval is determined to be a faulty line.
9. A low-current grounding fault location system based on the transient integral energy method, used to implement the low-current grounding fault location method based on the transient integral energy method as described in any one of claims 1 to 8, characterized in that, include: The startup module is used to acquire the zero-sequence voltage mutation energy and the zero-sequence current mutation energy, as well as the fundamental RMS value of the zero-sequence voltage and the root mean square value of the zero-sequence current. When the zero-sequence voltage mutation energy and the zero-sequence current mutation energy satisfy the mutation energy criterion, and the effective value of the fundamental wave of the zero-sequence voltage and the root mean square value of the half-cycle of the zero-sequence current satisfy the steady-state start-up criterion, the grounding selection is initiated. The line selection criterion calculation module is used to set the transient analysis window. After the grounding line selection is started, based on the data in the transient analysis window, the amplitude characteristics of the zero-sequence current at the transient moment and the zero-sequence power at each transient moment are calculated, and the total transient energy and the consistency measure of transient energy are calculated. The distributed fault selection module is used to perform distributed fault selection based on the sum of transient energy of each bay of the power distribution equipment and the consistency measure of transient energy. The centralized line selection module is used to perform centralized line selection based on the sum of transient energy of each bay of the power distribution device, the consistency measure of transient energy, and the amplitude characteristics of the zero-sequence current at the transient moment.
10. A terminal, comprising a processor and a storage medium; characterized in that: The storage medium is used to store instructions; The processor is configured to operate according to the instructions to perform the steps of the method according to any one of claims 1-8.
11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the method according to any one of claims 1-8.