Zero-sequence voltage projection quantity distance measurement method and system, electronic equipment and storage medium

Abstract

The invention discloses a zero-sequence voltage projection quantity distance measurement method and system, electronic equipment and a storage medium, and the method comprises the steps: collecting the zero-sequence voltage data of each feeder line, positioning a fault section of a fault feeder line, and dividing each detection point on the feeder line into an upstream detection point and a downstream detection point by taking the fault section as a boundary; detecting whether the fault upstream detection point has a branch line or not, and if so, taking an access point of the branch line as a supplementary detection point at the upstream of the fault section; respectively calculating the zero-sequence voltage projection quantity of each detection point according to the zero-sequence electrical quantity of each detection point based on the supplementary detection point; and determining a distribution function of distances from upstream and downstream of the fault point to the bus according to the zero-sequence voltage projection quantity, and solving the distribution function of distances from upstream and downstream of the fault point to the bus to obtain the distance from the fault point to the bus. The invention provides a calculation method of the equivalent length for the hybrid line, and the distance measurement of the hybrid line has higher precision under the condition of accurate parameters.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network fault distance measurement, and in particular to a zero-sequence voltage projection distance measurement method, system, electronic equipment and storage medium. Background Art

[0002] Fault location technology is mainly divided into fault line selection, fault section location and fault distance measurement. At present, fault line selection and fault section location technology have been developed to a relatively mature stage, and relatively reliable location results can be obtained. Fault distance measurement methods in transmission networks have also been relatively complete. However, at present, the main methods for fault distance measurement in distribution networks are traveling wave method, impedance method and intelligent algorithm distance measurement. Due to the complex topological structure of the distribution network and the large number of branch lines, the identification of the wave head of the traveling wave method and the determination of the fault time are relatively difficult, and further exploration is still needed. The impedance method has poor tolerance to the transition resistance of the fault point and the system operation formula will also affect the distance measurement accuracy. Pseudo roots may appear in the solution process and some algorithms are relatively complex. Intelligent algorithm distance measurement mainly uses neural network training models, which requires a large number of training sets to help modeling, but the faults in the distribution network are small samples, and it is actually difficult to provide a large amount of data for training. In addition, the rapid change of the distribution network topology is also a challenge for it. Therefore, intelligent algorithm distance measurement needs to overcome these difficulties, and it is necessary to continue to study transfer learning and how to use simulation to complete the training set. Therefore, in general, the characteristics of distribution network with many branches, variable operating formulas and many mixed lines have led to the slow development of fault location technology, and there is still no better method for single-phase grounding fault location in distribution network. Summary of the invention

[0003] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a zero-sequence voltage projection distance measurement method, system, electronic device and storage medium to solve the problem of low accuracy in distance measurement of single-phase grounding faults in distribution networks.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a zero-sequence voltage projection distance measurement method, comprising:

[0008] Collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section;

[0009] Detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section;

[0010] Based on the supplementary detection points, the zero-sequence voltage projection quantity of each detection point is calculated according to the zero-sequence electrical quantity of each detection point;

[0011] The distribution function of the distance between the upstream and downstream of the fault point and the busbar is determined according to the zero-sequence voltage projection, and the distribution function of the distance between the upstream and downstream of the fault point and the busbar is solved in parallel to obtain the distance from the fault point to the busbar.

[0012] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0013] The fault feeder comprises the following steps:

[0014] Several detection points are set on each feeder of the distribution network, among which the detection point at the busbar outlet of each feeder is set as 1# detection point;

[0015] The zero-sequence voltage at the 1# detection point of each feeder is collected to determine whether the zero-sequence voltage amplitude is greater than a preset threshold. If so, the feeder is determined to be a faulty feeder.

[0016] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0017] Before respectively calculating the zero-sequence voltage projection quantity of each detection point according to the zero-sequence electrical quantity of each detection point, the following steps are also included:

[0018] Determine the type of faulty feeder;

[0019] If the faulty feeder is a single type of line, the zero-sequence voltage projection quantity of each detection point is calculated according to the zero-sequence electrical quantity of each detection point;

[0020] If the faulty feeder is a hybrid line, the actual length of the hybrid line is converted into an equivalent length and then the zero-sequence voltage projection of each detection point is calculated based on the zero-sequence electrical quantity of each detection point.

[0021] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0022] The actual length of the hybrid line is converted into an equivalent length as follows:

[0023]

[0024] l′=x1+x2′;

[0025] Among them, Z is the impedance parameter of the baseline in the hybrid line; Z′ is the impedance parameter of the hybrid line in the hybrid line; β is the difference between the impedance angles of the two impedance parameters Z and Z′; l′ is the total length of the fault feeder after the line is equivalent; x1 is the length of the baseline in the hybrid line; x2 is the actual length of the hybrid line in the hybrid line; x2′ is the equivalent length of the hybrid line in the hybrid line.

[0026] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0027] The calculation of the zero-sequence voltage projection of each detection point is expressed as:

[0028]

[0029] in, is the zero-sequence voltage at each detection point; δ is the zero-sequence voltage at each detection point With zero sequence current The angle of is the impedance angle of the line impedance; x is the distance to the busbar or the equivalent distance corresponding to each detection point; U0(x) is the zero-sequence voltage projection of the detection point at x.

[0030] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0031] The distribution function of the distance from the upstream and downstream of the fault point to the busbar is determined according to the zero-sequence voltage projection, and the distribution function of the distance from the upstream and downstream of the fault point to the busbar is solved in parallel to obtain the distance from the fault point to the busbar expressed as:

[0032]

[0033] Among them, x ui is the horizontal coordinate of the distance from each upstream detection point to the busbar; U0(x ui ) is x ui The zero-sequence voltage projection at the detection point; k u b is the slope of the distribution function of the distance from the upstream of the fault point to the busbar; u is the constant term of the distribution function of the distance from the fault point upstream to the busbar; n is the number of detection points upstream of the fault point; U(x f ) is the distribution function; x f is the distance from the fault point to the bus; c is the zero-sequence voltage projection at the end detection point.

[0034] As a preferred solution of the zero-sequence voltage projection distance measurement method described in the present invention, wherein:

[0035] The obtaining of the distance from the fault point to the bus includes: if the fault feeder is a hybrid line, the distance from the fault point to the bus is an equivalent distance, and converting the equivalent distance into an actual distance;

[0036] The process of converting the equivalent distance into the actual distance comprises the following steps:

[0037] Determine the line where the fault point is located based on the equivalent distance of the fault point;

[0038] If the fault point is on the reference line segment in the hybrid line, the equivalent fault distance at this time is the actual fault distance;

[0039] If the fault point is in the mixed line segment of the mixed line, the actual fault distance calculation formula is expressed as:

[0040]

[0041]

[0042] Among them, x f is the equivalent distance from the fault point to the busbar; x f实 is the actual distance from the fault point to the busbar.

[0043] In a second aspect, the present invention provides a zero-sequence voltage projection distance measurement system, comprising:

[0044] A positioning module is used to collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section;

[0045] A detection module is used to detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section;

[0046] A calculation module, for calculating the zero-sequence voltage projection quantity of each detection point based on the supplementary detection points and the zero-sequence electrical quantity of each detection point;

[0047] The solution module is used to determine the distribution function of the distance between the upstream and downstream of the fault point and the busbar according to the zero-sequence voltage projection, and solve the distribution function of the distance between the upstream and downstream of the fault point and the busbar in parallel to obtain the distance from the fault point to the busbar.

[0048] In a third aspect, the present invention provides a computing device, comprising:

[0049] Memory, used to store programs;

[0050] A processor is used to execute the computer executable instructions, and the computer executable instructions, when executed by the processor, implement the steps of the zero-sequence voltage projection distance measurement method.

[0051] In a fourth aspect, the present invention provides a computer-readable storage medium, comprising: when the program is executed by a processor, the steps of implementing the zero-sequence voltage projection distance measurement method are implemented.

[0052] Beneficial effects of the present invention: The present invention fully considers the characteristics of many branch lines and many hybrid lines in the distribution network, utilizes the zero-sequence information detected at the end of the branch line as the zero-sequence information at the access point, supplements the number of detection points, and can reduce the ranging cost of the present application to a certain extent. In addition, a method for calculating the equivalent length of the hybrid line is proposed, and the hybrid line ranging has a higher accuracy when the parameters are accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0054] Figure 1 A basic flow chart of a zero-sequence voltage projection distance measurement method provided by an embodiment of the present invention;

[0055] Figure 2 A schematic diagram of a hybrid circuit structure of a zero-sequence voltage projection distance measurement method provided by an embodiment of the present invention;

[0056] Figure 3 A schematic diagram of a simulation circuit of a fault line with a branch line in a zero-sequence voltage projection distance measurement method provided by an embodiment of the present invention;

[0057] Figure 4 A simulation circuit diagram of a hybrid line is provided for a zero-sequence voltage projection distance measurement method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation formula of the present invention is described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0060] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented using other methods different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0061] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0062] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0063] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0064] In the present invention, unless otherwise specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0065] Example 1

[0066] Reference Figure 1-4 Tables 1-4 are an embodiment of the present invention, which provides a zero-sequence voltage projection distance measurement method, such as Figure 1 As shown, the following steps are included:

[0067] S1: Collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section;

[0068] In the embodiment of the present application, a number of detection points are set on each feeder of the distribution network, wherein the detection point at the bus outlet of each feeder is set as the 1# detection point. Figure 3 , Figure 4 As shown in the simulation circuit diagram, Figure 3 Feeder 4, Figure 4 Several detection points A, B, C, D, and E are respectively set on the feeder 5.

[0069] In the embodiment of the present application, the zero-sequence voltage at the 1# detection point of each feeder is collected to determine whether the zero-sequence voltage amplitude is greater than a preset threshold. If so, the feeder is determined to be a faulty feeder.

[0070] In the embodiments of the present application, Figure 3 As shown, a phase A ground fault is set at a distance of 2 km from the busbar on feeder 4, and the transition resistance is 10. The zero-sequence voltage at the busbar is monitored online. At this time, the amplitude of the zero-sequence voltage is greater than the preset threshold, and it is determined that a single-phase ground fault has occurred.

[0071] In the embodiment of the present application, the zero-sequence voltage at the 1# detection point (at the bus outlet) of each feeder is When the bus zero-sequence voltage amplitude is monitored Greater than the preset bus zero-sequence voltage amplitude threshold U 0set When , it indicates that a single-phase grounding fault has occurred in the system, and then the process goes to step S1.

[0072] In the embodiment of the present application, the fault section of the faulty feeder is located, and the detection points on the feeder are divided into upstream detection points and downstream detection points based on the fault section.

[0073] In the embodiment of the present application, after determining that a single-phase grounding fault has occurred in the system, the distribution automation system is used to realize the section positioning according to the existing fault section positioning method, and each detection point is divided into upstream detection points 1#, 2#, ..., (i-1)#, i# of the fault point i (because the fault point is in the fault section) and downstream detection points (i+1)#, (i+2)#, ... of the fault point i. Further, if the number of upstream and downstream detection points of the fault point i is not less than one, then step S2 is entered, otherwise this method cannot measure the distance.

[0074] In the embodiments of the present application, Figure 3 As shown, according to the section positioning of the distribution automation system, the detection point A is divided into the upstream of the fault point, and the detection points B, C, and D are the downstream of the fault point. At this time, only A and D are valid detection points.

[0075] S2: Detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section;

[0076] In the embodiment of the present application, it is detected whether there is a branch line upstream of the fault point. If there is a branch line, the branch line end detection point information (that is, the subsequent zero-sequence electrical quantity) is regarded as the branch line access point information, that is, the branch line access point is used as a supplementary detection point upstream of the fault point. For example, if there are three detection points upstream of the fault point normally, if there is one branch line, then one supplementary detection point is added, and four detection points are calculated in subsequent calculations.

[0077] In the embodiments of the present application, Figure 3 As shown, at this time, there is a branch line upstream of the fault point, so the detection point E at the end of the branch line is used as a supplementary detection point of the access point. The upstream of the fault point is equivalent to having two detection points A and a supplementary detection point.

[0078] In the embodiment of the present application, the zero-sequence electrical quantity of each detection point of the faulty feeder is collected and recorded.

[0079] In the embodiment of the present application, after the fault occurs for one power frequency cycle and the electrical quantities enter a steady state, the zero-sequence electrical quantities of each detection point 1# (busbar outlet), 2#, ..., (i-1)#, i#, (i+1)#, (i+2)#... and the branch line access point (i.e., the supplementary detection point) are collected and recorded, including the zero-sequence voltage And zero sequence current The data at each detection point (except the end detection point) needs to be transmitted to determine the type of fault feeder to calculate the zero-sequence voltage projection (this application only has synchronization requirements for the detection devices at the beginning and end of the line).

[0080] In the embodiments of the present application, Figure 3 As shown, after 20ms after the fault, when all electrical quantities enter a steady state, the zero-sequence voltage of each detection point is collected and recorded. And zero sequence current

[0081] In the embodiment of the present application, when collecting and recording the zero-sequence electrical quantities of each detection point of the faulty feeder, if there is a supplementary detection point, the zero-sequence electrical quantity of the detection point at the end of the branch line is used as the zero-sequence electrical quantity of the supplementary detection point, such as Figure 3 As shown, the zero-sequence electrical quantity of the detection point E is used as the zero-sequence electrical quantity of the supplementary detection point.

[0082] In the embodiment of the present application, the type of the faulty feeder is determined; if the faulty feeder is a single type line, the process directly proceeds to step S3, such as Figure 3 If the fault feeder is a hybrid line, the actual length of the hybrid line is converted to an equivalent length and then the process proceeds to step S3. Figure 4For the fault shown, the equivalent length is calculated and then the process goes to step S3.

[0083] In the embodiment of the present application, when determining the type of the faulty feeder, when converting the actual length of the hybrid line into an equivalent length, the difference in impedance is used to convert the actual length of the hybrid line into an equivalent length.

[0084] In the embodiment of the present application, in step S6, the calculation formula for converting the actual length of the hybrid line into the equivalent length is as follows:

[0085]

[0086] l′=x1+x2′ (2)

[0087] In the above formula, Z is the impedance parameter of the baseline in the hybrid line; Z' is the impedance parameter of the hybrid line in the hybrid line; β is the difference between the impedance angles of the two impedance parameters Z and Z'; l' is the total length of the fault feeder after the line is equivalent, and the equivalent distance is used instead of the actual distance in subsequent calculations; x1 is the length of the baseline in the hybrid line; x2 is the actual length of the hybrid line in the hybrid line; x'2 is the equivalent length of the hybrid line in the hybrid line. For example, this application uses overhead lines and cable lines as hybrid lines, overhead lines as baselines, and cable lines as hybrid lines, and converts the actual length of the cable into an equivalent length (for multiple line types with different parameters, any one type can be selected as the baseline type).

[0088] In the embodiment of the present application, since there are many hybrid lines in the distribution network, the distance measurement of the hybrid lines is particularly important. In order to verify the feasibility of the method proposed in this article for hybrid line distance measurement, as shown in FIG. Figure 4 As shown, a phase A ground fault is set at a distance of 8 km from the busbar on feeder 5, and the transition resistance is 10. The simulation circuit diagram is as follows Figure 4 As shown. According to the distribution automation system, the section positioning is performed, and the detection points A, B, and C are divided into the upstream of the fault point, and the detection point D is the downstream of the fault point. At this time, the detection points A, B, and C are effective detection points. The fault line of feeder 5 is a mixed line. First, the length of the fault line is converted to an equivalent length. The equivalent length of the fault line is 10.24 km. The equivalent lengths of each detection point from the busbar are 0, 3, 6, and 10.24 respectively.

[0089] S3: Based on the supplementary detection points, the zero-sequence voltage projection quantity of each detection point is calculated according to the zero-sequence electrical quantity of each detection point;

[0090] In the embodiment of the present application, in step S3, the formula for calculating the zero-sequence voltage projection amount of each detection point is as follows:

[0091]

[0092] In the above formula, is the zero-sequence voltage at each detection point; δ is the zero-sequence voltage at each detection point With zero sequence current The angle of is the impedance angle of the line impedance; x is the distance to the bus or the equivalent distance corresponding to each detection point, that is, if the faulty line is a hybrid line, x is the equivalent distance to the bus; U0(x) is the zero-sequence voltage projection of the detection point at x; it should be noted that this method requires the line head and end to have a synchronization function, and the zero-sequence voltage projection at the end is based on the zero-sequence current at the head end to calculate the angle between the zero-sequence voltage and the zero-sequence current.

[0093] In the embodiments of the present application, Figure 3 As shown, the zero-sequence voltage projection amount U0(x) of each detection point is calculated respectively, and the zero-sequence voltage projection amount corresponding to the distance of the A, E, and D detection points is obtained as shown in the following Table 1:

[0094] Table 1 Zero-sequence voltage projection scale corresponding to the distance between detection points A, E, and D

[0095] Detection point Distance from busbar x / km Zero sequence voltage projection / v A 0 1251.803 E 1 1474.429 D 12 1697.152

[0096] In the embodiments of the present application, Figure 4 As shown in the circuit diagram, the zero-sequence voltage projection amount U(x) of each detection point is calculated respectively. The zero-sequence voltage projection amounts corresponding to the detection points A, B, C, and D are shown in Table 2 below:

[0097] Table 2 Zero-sequence voltage projection scale corresponding to detection points A, B, C, and D

[0098] Detection point Distance from busbar / km Zero sequence voltage projection / v A 0 1091.636 B 3 1657.983 C 6 2224.323 D 10.24 2383.247

[0099] S4: Determine the distribution function of the distances from the upstream and downstream of the fault point to the busbar according to the zero-sequence voltage projection, and solve the distribution functions of the distances from the upstream and downstream of the fault point to the busbar in parallel to obtain the distance from the fault point to the busbar.

[0100] S41: If there is only one detection point upstream of the fault point (i.e., at the busbar), the slope of the distribution function can be determined based on the zero-sequence current at the busbar and the line parameters, as shown in formula (4), and then the distribution function can be obtained based on formula (5):

[0101]

[0102] U(x)=k u x+U0(0) (5)

[0103] In the above formula, k u is the slope of the distribution function of the distance from the upstream of the fault point to the busbar, is the zero-sequence current at the busbar; Z0 is the zero-sequence impedance of the line; U(x) is the distribution function; U0(0) is the zero-sequence voltage projection at the 1# detection point.

[0104] S42: If there are two detection points x upstream of the fault point u1 、x u2 , then k can be obtained according to formulas (6) and (7): u , b u , the distribution function of the zero-sequence voltage projection upstream of the fault point with respect to the distance x to the busbar is formula (8);

[0105]

[0106] b u =U0(x u2 )-k u x u2 (7)

[0107] U(x)=k u x+b u (8)

[0108] In the above formula, b u is the constant term of the distribution function of the distance from the upstream of the fault point to the busbar; x u1 、x u2 is the distance from two detection points to the busbar or equivalent distance. u2 ) and U0(x u1 ) are the zero-sequence voltage projections of the corresponding detection points.

[0109] S43: In step S4, the distribution function of the distance from the upstream and downstream of the fault point to the bus is determined according to the zero-sequence voltage projection, and the distribution function of the distance from the upstream and downstream of the fault point to the bus is solved in parallel to obtain the distance from the fault point to the bus as follows: In step S4, if there are more than two detection points upstream of the fault point, the distance x from each upstream detection point to the bus is ui The horizontal axis is the zero-sequence voltage projection value U(x ui ) is the ordinate, and the least squares method is used to fit the linear function expression formula U(x)=k u x+b u , where k u and b u The solution process is shown in formula (9) and formula (10):

[0110]

[0111] The end detection point downstream of the fault point is fitted as a constant c;

[0112] In the embodiment of the present application, the fitting function of the upstream and downstream of the fault point is formula (11), and the position of the fault point can be obtained immediately, such as formula (12);

[0113]

[0114] In the above formula, x ui is the horizontal coordinate of the distance from each upstream detection point to the busbar; U0(x ui ) is x ui The zero-sequence voltage projection at the detection point; k u b is the slope of the distribution function of the distance from the upstream of the fault point to the busbar; u is the constant term of the distribution function of the distance from the fault point upstream to the busbar; n is the number of detection points upstream of the fault point; U(x f ) is the distribution function; x f is the distance from the fault point to the busbar (i.e., the actual distance or equivalent distance); c is the zero-sequence voltage projection at the end detection point.

[0115] In the embodiments of the present application, Figure 3 As shown in the figure, the distribution function upstream of the fault point selects the fitting method with 2 detection points to obtain k u =222.626, b u =1697.152, combining the upstream and downstream distribution functions, we get:

[0116]

[0117] Solving for x f =2000.4, the absolute error is 0.4m. By changing the transition resistance, the distance measurement results are shown in Table 3:

[0118] Table 3 Branch line distance measurement results

[0119]

[0120]

[0121] like Figure 4 As shown, the distribution function upstream of the fault point selects the fitting method with more than 2 detection points to obtain k u =188.781, b u =1091.637, combining the upstream and downstream distribution functions, we get:

[0122]

[0123] Solving for x f =6.8418, because Figure 4 The circuit is a hybrid circuit, and x f is the equivalent distance.

[0124] In the embodiment of the present application, if the faulty feeder is a hybrid line, the distance from the fault point to the bus is the equivalent distance, and the equivalent distance is converted into the actual distance.

[0125] In the embodiment of the present application, if the faulty line is a single-type line, the x calculated in step S4 is directly f output as the ranging result of the position of the fault point. If the faulty line is a hybrid line, the calculated x above f is the equivalent distance, and it is necessary to further restore the equivalent distance to the actual fault distance. To illustrate the calculation process, take Figure 2 the faulty line in as an example. If the distance x obtained in step S4 f is the equivalent distance, then according to x f judge which section of the line has a fault. In this example, it is to judge whether the fault point is on the overhead line (section AB) or the cable (section BC). When x f < x1 (x1 is the distance of section AB), the fault point is located in section AB, and the equivalent fault distance at this time is the actual fault distance; when x f > x1, the fault point is located in section BC, and the actual fault distance can be obtained by formula (13) and the ranging result is output.

[0126] In the embodiment of the present application, if the faulty feeder is a hybrid line, the distance from the fault point to the bus is the equivalent distance, and in converting the equivalent distance into the actual distance, the specific steps of converting the equivalent distance into the actual distance are as follows:

[0127] In the embodiment of the present application, judge the line where the fault point is located according to the equivalent distance of the fault point; if the fault point is on the reference line segment in the hybrid line, the equivalent fault distance at this time is the actual fault distance; if the fault point is on the hybrid line segment in the hybrid line, the formula for the actual fault distance is as follows:

[0128]

[0129] In the above formula, x f is the equivalent distance from the fault point to the bus; x f实 is the actual distance from the fault point to the bus.

[0130] In the embodiment of the present application, as Figure 4 the circuit diagram of, restore the equivalent fault distance to the actual fault distance according to formula (13), x f实 = 8.0372m, and the absolute error is 0.0372m;

[0131] In the embodiment of the present application, change the magnitude of the transition resistance, and the ranging results are as shown in Table 4 below. It can be seen that for the hybrid line, accurate ranging results can be obtained:

[0132] Table 4 Mixed line distance measurement results

[0133] Transition resistance / Ω Distance measurement result / m Absolute error / m 10 8.0372 0.0372 50 8.0373 0.0373 100 8.0371 0.0371 500 8.0371 0.0371

[0134] It should be noted that the characteristics of many branch lines and hybrid lines in the distribution network are fully taken into consideration. The zero-sequence information detected at the end of the branch line is used as the zero-sequence information at the access point, which supplements the number of detection points. The ranging cost of this application can be reduced to a certain extent. In addition, a method for calculating the equivalent length of the hybrid line is proposed. When the parameters are accurate, the hybrid line ranging has a higher accuracy.

[0135] This embodiment also provides a zero-sequence voltage projection distance measurement system, including:

[0136] A positioning module is used to collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section;

[0137] A detection module is used to detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section;

[0138] A calculation module, for calculating the zero-sequence voltage projection quantity of each detection point based on the supplementary detection points and the zero-sequence electrical quantity of each detection point;

[0139] The solution module is used to determine the distribution function of the distance between the upstream and downstream of the fault point and the busbar according to the zero-sequence voltage projection, and solve the distribution function of the distance between the upstream and downstream of the fault point and the busbar in parallel to obtain the distance from the fault point to the busbar.

[0140] Furthermore, it also includes:

[0141] Memory, used to store programs;

[0142] A processor is used to load the program to execute the zero-sequence voltage projection distance measurement method.

[0143] This embodiment also provides a computer-readable storage medium storing a program, and when the program is executed by a processor, the zero-sequence voltage projection distance measurement method is implemented.

[0144] The storage medium proposed in this embodiment and the zero-sequence voltage projection distance measurement method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be referred to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0145] Through the above description of the implementation formula, the technicians in the relevant field can clearly understand that the present invention can be implemented by means of software and necessary general hardware, and of course it can also be implemented by hardware, but in many cases the former is a better implementation formula. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as a computer's floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of various embodiments of the present invention.

[0146] Example 2

[0147] This is an embodiment of the present invention, which provides a zero-sequence voltage projection distance measurement system, including a positioning module, a detection module, a calculation module and a solution module;

[0148] In an embodiment of the present application, the positioning module includes collecting zero-sequence voltage data of each feeder, locating the faulty section of the faulty feeder, and dividing the detection points on the feeder into upstream detection points and downstream detection points based on the faulty section; the module is responsible for determining the specific faulty section of the faulty feeder, and dividing all detection points on the feeder into upstream detection points and downstream detection points according to this section.

[0149] In the embodiment of the present application, the faulty feeder includes setting a plurality of detection points on each feeder of the distribution network, wherein the detection point of each feeder at the bus outlet is set as the 1# detection point; collecting the zero-sequence voltage at the 1# detection point of each feeder, judging whether the zero-sequence voltage amplitude is greater than a preset threshold, and if so, judging that the feeder is a faulty feeder;

[0150] In an embodiment of the present application, the detection module includes detecting whether there is a branch line at the upstream detection point of the fault, and if there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section; the task of this module is to check whether there is a branch line in the upstream detection point that has been divided, and when a branch line is found, its access point is added as a supplementary detection point to the upstream detection point, so as to perform subsequent analysis more accurately.

[0151] In the embodiment of the present application, the calculation module includes collecting and recording the zero-sequence electrical quantity of each detection point of the fault feeder; determining the type of the fault feeder; if the fault feeder is a single type line, directly calculating the zero-sequence voltage projection of each detection point according to the zero-sequence electrical quantity of each detection point; if the fault feeder is a hybrid line, converting the actual length of the hybrid line into an equivalent length and then calculating the zero-sequence voltage projection of each detection point according to the zero-sequence electrical quantity of each detection point;

[0152] In an embodiment of the present application, the calculation module includes calculating the zero-sequence voltage projection of each detection point based on the supplementary detection point and the zero-sequence electrical quantity of each detection point; this module calculates the zero-sequence voltage projection of each detection point based on the zero-sequence electrical quantity data of all relevant detection points including the supplementary detection point, and provides basic data for the subsequent distance calculation.

[0153] In the embodiment of the present application, the solution module includes determining the distribution function of the distance from the upstream and downstream of the fault point to the bus according to the zero-sequence voltage projection, and solving the distribution function of the distance from the upstream and downstream of the fault point to the bus in parallel to obtain the distance from the fault point to the bus. This module uses the zero-sequence voltage projection calculated above to determine the distribution function of the distance from the upstream and downstream of the fault point to the bus, and solves these distribution functions in parallel to finally obtain the actual distance from the fault point to the bus.

[0154] In an embodiment of the present application, obtaining the distance from the fault point to the bus includes: if the fault feeder is a hybrid line, the distance from the fault point to the bus is an equivalent distance, and converting the equivalent distance into an actual distance.

[0155] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A zero-sequence voltage projection distance measurement method, characterized in that: include: Collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section; Detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section; Based on the supplementary detection points, the zero-sequence voltage projection quantity of each detection point is calculated according to the zero-sequence electrical quantity of each detection point; The distribution function of the distance between the upstream and downstream of the fault point and the busbar is determined according to the zero-sequence voltage projection, and the distribution function of the distance between the upstream and downstream of the fault point and the busbar is solved in parallel to obtain the distance from the fault point to the busbar.

2. The zero-sequence voltage projection distance measurement method according to claim 1, characterized in that: The fault feeder comprises the following steps: Several detection points are set on each feeder of the distribution network, among which the detection point at the busbar outlet of each feeder is set as 1# detection point; The zero-sequence voltage at the 1# detection point of each feeder is collected to determine whether the zero-sequence voltage amplitude is greater than a preset threshold. If so, the feeder is determined to be a faulty feeder.

3. The zero-sequence voltage projection distance measurement method according to claim 1 or 2, characterized in that: Before respectively calculating the zero-sequence voltage projection quantity of each detection point according to the zero-sequence electrical quantity of each detection point, the following steps are also included: Determine the type of faulty feeder; If the faulty feeder is a single type of line, the zero-sequence voltage projection quantity of each detection point is calculated according to the zero-sequence electrical quantity of each detection point; If the faulty feeder is a hybrid line, the actual length of the hybrid line is converted into an equivalent length and then the zero-sequence voltage projection of each detection point is calculated based on the zero-sequence electrical quantity of each detection point.

4. The zero-sequence voltage projection distance measurement method according to claim 3, characterized in that: The actual length of the hybrid line is converted into an equivalent length as follows: l′=x1+x2′; Among them, Z is the impedance parameter of the baseline in the hybrid line; Z′ is the impedance parameter of the hybrid line in the hybrid line; β is the difference between the impedance angles of the two impedance parameters Z and Z′; l′ is the total length of the fault feeder after the line is equivalent; x1 is the length of the baseline in the hybrid line; x2 is the actual length of the hybrid line in the hybrid line; x2′ is the equivalent length of the hybrid line in the hybrid line.

5. The zero-sequence voltage projection distance measurement method according to claim 4, characterized in that: The calculation of the zero-sequence voltage projection of each detection point is expressed as: in, is the zero-sequence voltage at each detection point; δ is the zero-sequence voltage at each detection point With zero sequence current The angle of is the impedance angle of the line impedance; x is the distance to the busbar or the equivalent distance corresponding to each detection point; U0(x) is the zero-sequence voltage projection of the detection point at x.

6. The zero-sequence voltage projection distance measurement method according to claim 5, characterized in that: The distribution function of the distance from the upstream and downstream of the fault point to the busbar is determined according to the zero-sequence voltage projection, and the distribution function of the distance from the upstream and downstream of the fault point to the busbar is solved in parallel to obtain the distance from the fault point to the busbar expressed as: Among them, x ui is the horizontal coordinate of the distance from each upstream detection point to the busbar; U0(x ui ) is x ui The zero-sequence voltage projection at the detection point; k u b is the slope of the distribution function of the distance from the upstream of the fault point to the busbar; u is the constant term of the distribution function of the distance from the fault point upstream to the busbar; n is the number of detection points upstream of the fault point; U(x f ) is the distribution function; x f is the distance from the fault point to the bus; c is the zero-sequence voltage projection at the end detection point.

7. The zero-sequence voltage projection distance measurement method according to claim 6, characterized in that: The obtaining of the distance from the fault point to the bus includes: if the fault feeder is a hybrid line, the distance from the fault point to the bus is an equivalent distance, and converting the equivalent distance into an actual distance; The process of converting the equivalent distance into the actual distance comprises the following steps: Determine the line where the fault point is located based on the equivalent distance of the fault point; If the fault point is on the reference line segment in the hybrid line, the equivalent fault distance at this time is the actual fault distance; If the fault point is in the mixed line segment of the mixed line, the actual fault distance calculation formula is expressed as: Among them, x f is the equivalent distance from the fault point to the busbar; x f实 is the actual distance from the fault point to the busbar.

8. A system based on the zero-sequence voltage projection distance measurement method according to claim 1, characterized in that: A positioning module is used to collect zero-sequence voltage data of each feeder, locate the fault section of the faulty feeder, and divide each detection point on the feeder into upstream detection points and downstream detection points based on the fault section; A detection module is used to detect whether there is a branch line at the upstream detection point of the fault. If there is a branch line, the branch line access point is used as a supplementary detection point upstream of the fault section; A calculation module, for calculating the zero-sequence voltage projection quantity of each detection point based on the supplementary detection points and the zero-sequence electrical quantity of each detection point; The solution module is used to determine the distribution function of the distance between the upstream and downstream of the fault point and the busbar according to the zero-sequence voltage projection, and solve the distribution function of the distance between the upstream and downstream of the fault point and the busbar in parallel to obtain the distance from the fault point to the busbar.

9. A computing device, characterized in that include: Memory, used to store programs; A processor, used to load the program to execute the steps of the zero-sequence voltage projection distance measurement method as described in any one of claims 1-7.

10. A computer-readable storage medium storing a program, characterized in that: When the program is executed by a processor, the steps of the zero-sequence voltage projection distance measurement method as described in any one of claims 1 to 7 are implemented.

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