Method and system for locating voltage sag source on network side based on limited monitoring point data
By using a voltage sag source localization method based on limited monitoring point data, the fault distance and calculation error are filtered out, solving the problems of large calculation volume and inaccurate positioning of traditional methods. This method achieves efficient and accurate voltage sag source localization, meeting the rapid positioning needs of modern industrial equipment.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JINING POWER SUPPLY CO OF STATE GRID SHANDONG ELECTRIC POWER CO
- Filing Date
- 2023-06-08
- Publication Date
- 2026-08-04
AI Technical Summary
Traditional methods for locating voltage sag sources require traversing all lines, resulting in a large computational load and low accuracy, which cannot meet the needs of modern industrial equipment for rapid location of power quality problems.
A location method based on limited monitoring point data is adopted. By acquiring multiple sets of possible sag source locations, the fault distance that meets the conditions is screened. By using the error between the calculated and actual values of the monitoring point voltage, a discriminant function is established, and the fault point with the smallest error is selected as the fault line.
It achieves efficient and accurate voltage sag source location, reduces computational load, shortens computation time, and meets the needs of modern industrial equipment for rapid location of power quality problems.
Smart Images
Figure CN116660684B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power quality technology, and in particular relates to a method and system for locating grid-side voltage sag sources based on data from limited monitoring points. Background Technology
[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.
[0003] With the development of the power industry and high technology, and the application of various highly automated and intelligent modern industrial equipment, power quality issues have increasingly attracted attention. Among these, voltage sags are considered the most significant power quality problem affecting the normal and safe operation of electrical equipment. One important factor is that, among the many causes of power quality problems, user complaints due to voltage sags account for more than 80% of all power quality complaints, while complaints caused by harmonics, switching operation overvoltages, etc., account for less than 20%.
[0004] Electrical faults (short circuit faults) are the most common cause of voltage sags. Accurately locating the source of a sag helps in quickly troubleshooting and implementing repairs, which is crucial for improving power supply reliability. Furthermore, with the increasing construction of urban power distribution networks and the growing prevalence of underground cabling, precise location of sag sources is also important for facilitating inspection work during fault diagnosis, shortening the duration of faults, and reducing their impact.
[0005] Traditional methods for locating voltage sag sources establish an objective function and solve it through least squares iteration, traversing all lines to improve the accuracy of location. However, because they require traversing all lines and substituting the obtained fault distance into the voltage value of the monitoring point, the computational workload is large. Summary of the Invention
[0006] To address at least one of the technical problems mentioned in the background section, this invention provides a method and system for locating grid-side voltage sag sources based on data from limited monitoring points. This method eliminates the need to traverse every line in the system; it only requires voltage data from any two monitoring points to locate faulty lines. Furthermore, this method involves less computation and achieves higher accuracy. From an economic perspective, it meets the practical needs of systems with varying voltage sag monitoring accuracy requirements.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] The first aspect of the present invention provides a method for locating grid-side voltage sag sources based on data from limited monitoring points, comprising the following steps:
[0009] Obtain a set of multiple possible temporary landing source locations;
[0010] Determine whether the elements in the temporary drop source location set are within the set range. If so, do not store them in the set; otherwise, store them in the set.
[0011] The fault type is determined based on the set of filtered sag source locations, and the voltage at the monitoring point is obtained by the fault distance that meets the conditions.
[0012] Establish a discriminant function, compare the error between the calculated and actual voltage values at the monitoring points, and select the line corresponding to the fault point with the minimum error between the calculated and actual voltage values as the fault line.
[0013] A second aspect of the present invention provides a grid-side voltage sag source location system based on data from limited monitoring points, comprising:
[0014] A limited monitoring point data acquisition module is used to acquire a set of multiple possible transient descent source locations;
[0015] The set filtering module is used to determine whether the elements in the temporary drop source location set are within the set range. If they are, they are not stored in the set; otherwise, they are stored in the set.
[0016] The monitoring point voltage calculation module is used to determine the fault type based on the set of filtered sag source locations and to obtain the monitoring point voltage by the fault distance that meets the conditions.
[0017] The voltage sag source location module is used to establish a discrimination function, compare the error between the calculated and actual voltage values at the monitoring points, and select the line corresponding to the fault point with the smallest error between the calculated and actual voltage values as the fault line.
[0018] A third aspect of the present invention provides a computer-readable storage medium.
[0019] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described above.
[0020] A fourth aspect of the present invention provides a computer device.
[0021] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described above.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] This invention determines the fault type and calculates the voltage at monitoring points by calculating the set of possible locations of voltage sag sources. Using the actual voltage at each monitoring point and the calculated voltage, the minimum error is calculated, thus identifying the possible faulty line. This method eliminates the need to traverse every line in the system; it only requires voltage data from any two monitoring points to locate the faulty line. Furthermore, the method involves relatively little computation and offers high accuracy. From an economic perspective, it meets the practical needs of systems with varying voltage sag monitoring accuracy requirements.
[0024] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.
[0026] Figure 1 A flowchart of the grid-side voltage sag source localization method based on limited monitoring point data provided in this embodiment of the invention;
[0027] Figure 2 The optimal embodiment provided in this invention uses an IEEE 9 node system diagram. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0029] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.
[0031] Example 1
[0032] like Figure 1 As shown, this embodiment provides a method for locating grid-side voltage sag sources based on data from limited monitoring points, including the following steps:
[0033] Step 1: Identify the type of voltage sag source
[0034] The operation records, i.e. the operation plan, directly locate the starting of the induction motor and the switching of the transformer. The others are voltage dips caused by transient short circuit faults.
[0035] Step 2: Obtain the set of possible fault locations using the voltage sag source localization method based on data from two monitoring points;
[0036] After detecting a voltage dip due to a transient short-circuit fault, the source of the dip is located using a voltage dip source localization method based on data from two monitoring points. Based on the optimized layout of the monitoring points, the voltages of the monitoring points before and after the dip are obtained. Two monitoring points are randomly selected from the installed monitoring points, and the location of the dip source is calculated. A set can be obtained for each pair of monitoring points under each fault type. This set represents the calculated value of each group of monitoring points on each line. Finally, multiple sets of possible dip source locations can be obtained.
[0037] The set of multiple possible temporary landing source locations is further filtered. Therefore, the values that meet the requirements are selected from the set and stored in the following set:
[0038]
[0039] Where m i M1 represents the possible fault distance and is the set of values that meet the requirements.
[0040] Step 3: Determine the fault type and obtain the monitoring point voltage based on the fault distance that meets the conditions;
[0041] Before calculating the voltage at the monitoring point using the fault distance, the type of fault must first be determined. The obtained data is transformed by a symmetrical component transformation to obtain positive-sequence, negative-sequence, and zero-sequence voltage components, which are then calculated. The presence of negative-sequence and zero-sequence components determines whether it is a symmetrical or asymmetrical fault, a ground fault or a two-phase fault. The absolute value of the sum of the positive-sequence and negative-sequence voltages is less than the absolute value of the difference between the positive-sequence and negative-sequence voltages, indicating a single-phase ground fault. If the absolute value of the sum of the positive-sequence and negative-sequence voltages is greater than the absolute value of the difference between the positive-sequence and negative-sequence voltages, it indicates a two-phase ground fault.
[0042] Then, the voltage values at the monitoring points corresponding to each fault distance are calculated.
[0043] Equation (2) is the voltage vector of each monitoring point obtained by calculation. After a voltage dip occurs, the fault type is judged. If it is a symmetrical fault, it is obtained by equation (3). If it is an asymmetrical fault, it is judged to be a two-phase short circuit fault, a two-phase short circuit to ground fault, or a single-phase ground fault. Then it is calculated by equations (4) to (6).
[0044] F(m) = [f1(m), f2(m), L, f i (m)] T (2)
[0045] Three-phase fault:
[0046]
[0047] In case of a single-phase fault:
[0048]
[0049] When two phases are short-circuited:
[0050]
[0051] During a two-phase ground fault:
[0052] in:
[0053]
[0054]
[0055]
[0056]
[0057]
[0058] In the formula, These are the elements of the system node impedance matrix, which can be obtained through system structure and network parameters. k is a monitoring point in the system, r is the voltage sag source point, pq is a line in the system, m is the distance of the voltage sag source from endpoint p, and a, b, and c are the three phases. i = 1, 2, 0 represent positive sequence, negative sequence, and zero sequence, respectively. α = e j120 .
[0059] Step 4: Establish a discriminant function and select the fault distance corresponding to the smallest error between the calculated and actual voltage values at the monitoring points;
[0060] Establish a discriminant function
[0061] J(m)=(ZF(m)) T (ZF(m)) (12)
[0062] Where F(m) is Equation (8), which is the measured voltage vector of each node obtained by the monitoring point, and Z is Equation (2), which is the voltage vector of each monitoring point calculated.
[0063] Z = [V]m1 V m2 ,L,V mq ] T (13)
[0064] When an asymmetrical fault occurs in the system, the three-phase voltage amplitudes at the monitoring point are different, and the voltage amplitude of any one phase is less than V. m A voltage dip will occur at any time, so the phase with the lowest voltage amplitude is used to determine whether a voltage dip has occurred at that point.
[0065] In this embodiment, Vm is preferably 0.9 pu.
[0066] At this point, the analytical expression is equivalent to:
[0067] f i eq (m)=min(f ia (m),f ib (m),f ic (m)) (14)
[0068] Then F(p) can be equivalent to:
[0069]
[0070] The smallest discriminant function J(m) means the smallest error between the calculated value F(m) and the measured value Z, indicating that the calculated voltage value is closest to the actual voltage value, which is a possible fault point. The line where this fault point is located is the faulty line.
[0071] like Figure 2 As shown, the optimal embodiment is demonstrated using the IEEE 9-node system. It is known that a transient fault F1 single-phase short-circuit to ground (LG) occurs on line 7.
[0072] 1. Identification of voltage sag source types
[0073] The absence of corresponding operation records led to the conclusion that the voltage dip was caused by a transient short-circuit fault.
[0074] 2. The set of possible fault locations is obtained by using the voltage sag source localization method based on data from two monitoring points.
[0075] Four monitoring points were selected: 5, 6, 7, and 9. The voltage sag source was located by using data from every two monitoring points. There were a total of 6 different combinations of monitoring points. Each combination of monitoring points could calculate the assumed fault distance value for 6 lines. Each fault type corresponds to a 6×9 matrix.
[0076] Based on the two-monitoring-point calculation method, the fault distance under this condition is selected as shown in Table 1.
[0077] Table 1. Calculation results of voltage sag source location method (fault distance) from two monitoring points.
[0078]
[0079]
[0080] After obtaining the fault distance set for each fault type at each fault point, the fault distance values in [0,1] are filtered using equation (1) to form a new set, as shown in Table 1 (the matching fault distance values are bolded). For ease of explanation, we take line 5 as an example and select it as a set. The set consists of the four values (0.5472, 0.0489, 0.3957, 0.5133). That is, the fault distance values in [0,1] of line 5 are filtered to form a new set.
[0081] 3. Determine the fault type and obtain the monitoring point voltage based on the fault distance that meets the conditions.
[0082] First, the obtained data is transformed by symmetrical component transformation to obtain positive sequence, negative sequence, and zero sequence voltage components. The results are then calculated, and the presence of a negative sequence component indicates an asymmetrical fault. Then, based on the fact that the absolute value of the sum of the positive sequence voltage and the negative sequence voltage is less than the absolute value of the difference between the positive sequence voltage and the negative sequence voltage, it is determined to be a single-phase ground fault.
[0083] After obtaining all the sets, the voltage values of each monitoring point are calculated by substituting the obtained fault distance values into equations (3) to (6). The set contains four fault distances, and the voltages of four monitoring points can be calculated for each fault distance: 5, 6, 7, and 9. Since it is a single-phase ground fault, the voltage of the monitoring point is calculated using equation (4). For example, the voltages of the four monitoring points corresponding to m = 0.5472 are: monitoring point 5 (0.8887), monitoring point 6 (0.5259), monitoring point 7 (0.6455), and monitoring point 9 (0.7754). The voltages of the four monitoring points are calculated in the same way for the other three m values. Then, the actual voltage values after the fault occurs at the monitoring point are read: monitoring point 5 (0.861), monitoring point 6 (0.696), monitoring point 7 (0.917), and monitoring point 9 (0.839).
[0084] 4. Establish a discriminant function and select the fault distance corresponding to the smallest error between the calculated and actual voltage values at the monitoring points.
[0085] Finally, F(m) and Z were obtained, namely the measured voltage vector of each node obtained from the monitoring point and the calculated voltage vector of each monitoring point. Then, the error can be calculated using the discriminant function (7). The errors of lines 4-9 are: line 4 (0.3382), line 5 (0.3382), line 6 (0.3382), line 7 (0.3252), line 8 (0.3519), and line 9 (0.4328).
[0086] The smallest discriminant function J(m) means the smallest difference between the calculated value F(m) and the measured value Z, indicating that the calculated voltage value is closest to the actual voltage value, making it the most likely fault point. The line containing this fault point is the faulty line. The line 7 has the smallest error, so it can be determined that line 7 is the line where the voltage sag source is located, approximately between 0.11 and 0.26.
[0087] In summary, the grid-side voltage sag source location method based on limited monitoring point data significantly reduces the number of calculations, shortens the calculation time, and enables the location of voltage sag source lines.
[0088] Example 2
[0089] This embodiment provides a grid-side voltage sag source location system based on limited monitoring point data, including:
[0090] A limited monitoring point data acquisition module is used to acquire a set of multiple possible transient descent source locations;
[0091] The set filtering module is used to determine whether the elements in the temporary drop source location set are within the set range. If they are, they are not stored in the set; otherwise, they are stored in the set.
[0092] The monitoring point voltage calculation module is used to determine the fault type based on the set of filtered sag source locations and to obtain the monitoring point voltage by the fault distance that meets the conditions.
[0093] The voltage sag source location module is used to establish a discrimination function, compare the error between the calculated and actual voltage values at the monitoring points, and select the line corresponding to the fault point with the smallest error between the calculated and actual voltage values as the fault line.
[0094] Example 3
[0095] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described above.
[0096] Example 4
[0097] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described above.
[0098] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.
[0099] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0100] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.
[0101] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0102] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.
[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for locating grid-side voltage sag sources based on limited monitoring point data, characterized in that, Includes the following steps: Obtain a set of multiple possible temporary landing source locations; Determine whether the elements in the temporary drop source location set are within the set range. If so, do not store them in the set; otherwise, store them in the set. The process of obtaining the set of sag source locations is as follows: Based on the optimized layout of monitoring points, the voltages of the monitoring points before and after sag are obtained. Two monitoring points are randomly selected from the installed monitoring points, and the sag source locations are calculated. A set can be obtained for each pair of monitoring points under each fault type. This set represents the calculated value of each group of monitoring points on each line. Finally, multiple sets of possible sag source locations can be obtained. The fault type is determined based on the set of filtered sag source locations, and the voltage at the monitoring point is obtained by the fault distance that meets the conditions. Establish a discriminant function, compare the error between the calculated and actual voltage values at the monitoring points, and select the line corresponding to the fault point with the minimum error between the calculated and actual voltage values at the monitoring points as the fault line. The discriminant function is: in, F(m) It uses the measured voltage vectors of each node obtained from the monitoring points. Z These are the voltage vectors at each monitoring point. This is the distance from the voltage sag source to the beginning of the line.
2. The grid-side voltage sag source localization method based on limited monitoring point data as described in claim 1, characterized in that, The method of determining the fault type based on the filtered set of temporary descent source locations includes: The positive-sequence, negative-sequence, and zero-sequence voltage components are obtained by performing a symmetrical component transformation on the data of the sag source location set. These components are then processed. The presence of negative-sequence and zero-sequence components determines whether the fault is symmetrical or asymmetrical, ground fault or two-phase fault. Further judgment is made based on the difference between the positive-sequence and negative-sequence voltages. If the absolute value of the sum of the positive-sequence and negative-sequence voltages is less than the absolute value of the difference between the positive-sequence and negative-sequence voltages, it is a single-phase ground fault. If the absolute value of the sum of the positive-sequence and negative-sequence voltages is greater than the absolute value of the difference between the positive-sequence and negative-sequence voltages, it is a two-phase ground fault.
3. The grid-side voltage sag source localization method based on limited monitoring point data as described in claim 2, characterized in that, The symmetrical faults include three-phase faults, and the asymmetrical faults include two-phase short-circuit faults, two-phase short-circuit to ground faults, or single-phase to ground faults.
4. The grid-side voltage sag source localization method based on limited monitoring point data as described in claim 1, characterized in that, When an asymmetrical fault occurs in the system, the three-phase voltage amplitudes at the monitoring point are different, and the voltage amplitude of any one phase is less than [a certain value]. A voltage dip will occur at any time, so the phase with the lowest voltage amplitude is used to determine whether a voltage dip has occurred at that point.
5. The grid-side voltage sag source localization method based on limited monitoring point data as described in claim 1, characterized in that, Before obtaining a set of multiple possible sources of voltage dips, the methods include direct location via operation records, i.e., by using the operation plan to locate the starting of the induction motor and the switching of the transformer, and others are voltage dips caused by transient short-circuit faults.
6. A grid-side voltage sag source location system based on limited monitoring point data, characterized in that, include: A limited monitoring point data acquisition module is used to acquire a set of multiple possible transient descent source locations; The set filtering module is used to determine whether the elements in the temporary drop source location set are within the set range. If they are, they are not stored in the set; otherwise, they are stored in the set. The process of obtaining the set of sag source locations is as follows: Based on the optimized layout of monitoring points, the voltages of the monitoring points before and after sag are obtained. Two monitoring points are randomly selected from the installed monitoring points, and the sag source locations are calculated. A set can be obtained for each pair of monitoring points under each fault type. This set represents the calculated value of each group of monitoring points on each line. Finally, multiple sets of possible sag source locations can be obtained. The monitoring point voltage calculation module is used to determine the fault type based on the set of filtered sag source locations and to obtain the monitoring point voltage by the fault distance that meets the conditions. The voltage sag source location module is used to establish a discrimination function, compare the error between the calculated and actual values of the voltage at the monitoring point, and select the line corresponding to the fault point with the minimum error between the calculated and actual values of the voltage at the monitoring point as the fault line. The discriminant function is: Where F(m) is the measured voltage vector of each node obtained from the monitoring points, and Z is the voltage vector of each monitoring point. This is the distance from the voltage sag source to the beginning of the line.
7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described in any one of claims 1-5.
8. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the grid-side voltage sag source location method based on limited monitoring point data as described in any one of claims 1-5.