Current grounding fault distance measurement method and system

Abstract

The invention belongs to the field of power distribution network fault distance measurement, and discloses a current grounding fault distance measurement method and system, and the method comprises the steps: constructing a zero-sequence network of a grounding fault according to the boundary condition of a single-phase grounding fault, and carrying out the analysis of the zero-sequence network, and obtaining a zero-sequence current relation and a zero-sequence current circulation loop of lines at two sides of a fault point; based on the zero-sequence current circulation loop, ground capacitance current in the zero-sequence current circulation loop is analyzed, and distribution characteristics of the zero-sequence current in the fault line are obtained; obtaining a distance measurement result of the grounding fault by using the distribution characteristic of the zero-sequence current in the fault line and combining the relation of the zero-sequence current on the two sides of the fault point; and verifying the validity of the distance measurement result based on a pre-established power distribution network ground fault simulation model. According to the invention, by analyzing the zero-sequence current relation and distribution characteristics of the lines at the two sides of the fault point, the distance measurement of the fault point is realized, and the maintainer is helped to quickly find the fault point and eliminate the fault.

Description

Technical Field

[0001] The present invention relates to the field of distribution network fault distance measurement, and in particular to a current grounding fault distance measurement method, system, equipment and medium. Background Art

[0002] The distribution network mainly refers to the power grid with a voltage level of 10 to 35 kV. It has a wide distribution range and is responsible for directly supplying power to users. Once a distribution network fails, it will directly affect the reliability of power supply. Statistics show that 90% of user power outages are related to distribution network failures. After a distribution network failure occurs, maintenance personnel are required to quickly find the fault point and eliminate the fault. However, the distribution network has a wide distribution range, complex structure, and diverse operating environment. Therefore, accurate fault distance measurement results are needed to assist maintenance personnel in quickly determining the fault location. Due to the complex structure of the distribution network, diverse operating environment, rich line types, and complex fault characteristics, it is difficult to obtain accurate fault location results. Therefore, the fault location problem of the distribution network has long plagued the power supply operation department, and a better solution is urgently needed from a technical level. Summary of the invention

[0003] The embodiments of the present invention provide a current ground fault distance measurement method, system, device and medium to solve the above technical problems in the prior art.

[0004] In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended to be a general review, nor is it intended to identify key / important components or to delineate the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0005] According to a first aspect of an embodiment of the present invention, a current ground fault location method is provided.

[0006] In one embodiment, a current ground fault location method includes:

[0007] According to the boundary conditions of single-phase grounding fault, the zero-sequence network of grounding fault is constructed and analyzed to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop;

[0008] Based on the zero-sequence current circulation loop, the ground capacitance current in the zero-sequence current circulation loop is analyzed to obtain the distribution characteristics of the zero-sequence current in the fault line;

[0009] The ground fault distance measurement result is obtained by using the distribution characteristics of zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point;

[0010] Based on the pre-built distribution network grounding fault simulation model, the validity of the ranging results is verified.

[0011] In one embodiment, the zero-sequence network of the ground fault is constructed according to the boundary conditions of the single-phase ground fault, and the zero-sequence network is analyzed to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop, including:

[0012] According to the boundary conditions of single-phase grounding fault, the three-phase electrical quantities of the fault line are digitized by using Karenbauer phase model transformation, and the zero-sequence network of grounding fault is constructed based on the digitized processing results.

[0013] By analyzing the zero-sequence network of the ground fault, the two sides of the fault point of the zero-sequence network are divided into the upstream line of the fault point and the downstream line of the fault point;

[0014] Based on the upstream line of the fault point and the downstream line of the fault point, the zero-sequence current relationship on both sides of the fault point is determined, and the zero-sequence current flow loop is obtained.

[0015] In one embodiment, the zero-sequence current relationship calculation formula on both sides of the fault point is:

[0016]

[0017] In the formula, Z 0b Indicates the zero-sequence impedance of the upstream line of the fault point; Z 0a Indicates the zero-sequence impedance of the line downstream of the fault point; I 0b Indicates the zero-sequence current of the upstream line of the fault point; I 0a Indicates the zero-sequence current of the line fault downstream of the fault point.

[0018] In one embodiment, the analyzing the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the distribution characteristics of the zero-sequence current in the fault line includes:

[0019] Based on the zero-sequence current circulation loop, the distribution of the ground capacitance current in the zero-sequence current circulation loop is analyzed to obtain the path result of the zero-sequence current;

[0020] According to the path result of zero-sequence current, the ground capacitance current on both sides of the fault point is analyzed to obtain the change trend of zero-sequence current on both sides of the fault point;

[0021] Based on the changing trend of zero-sequence current, the relationship between zero-sequence current and electrical distance is determined, and the zero-sequence current distribution characteristics of the fault line are obtained.

[0022] In one embodiment, the path result of the zero-sequence current includes: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

[0023] In one embodiment, the variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point;

[0024] The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line;

[0025] The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

[0026] In one embodiment, the relationship between the zero-sequence current and the electrical distance is calculated as follows:

[0027]

[0028] In the formula, I C Indicates the ground capacitance current per unit fault line length; I hcΣ Indicates the total capacitance current of a healthy line to ground; l f Indicates the total length of the fault line; x f Indicates the fault distance; I 0 (x) represents the zero-sequence current at a distance x from the busbar; x represents the distance from the busbar.

[0029] In one embodiment, the method of obtaining the ground fault distance measurement result by utilizing the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point includes:

[0030] According to the previously obtained line unit length impedance parameter and the length of the upstream and downstream lines of the fault point, the zero-sequence impedance results of the upstream and downstream lines of the fault point are obtained;

[0031] Based on the distribution characteristics of zero-sequence current in the fault line, the zero-sequence current results of the upstream and downstream lines of the fault point are obtained;

[0032] Based on the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point, they are substituted into the fault zero-sequence current relationship on both sides of the fault point to obtain the ground fault distance measurement result.

[0033] According to a second aspect of an embodiment of the present invention, a current ground fault distance measurement system is provided.

[0034] In one embodiment, the current ground fault distance measurement system comprises:

[0035] The module for obtaining the zero-sequence current relationship is used to construct the zero-sequence network of the grounding fault according to the boundary conditions of the single-phase grounding fault, and analyze the zero-sequence network to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop;

[0036] A zero-sequence current distribution characteristic determination module is used to analyze the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop, and obtain the distribution characteristics of the zero-sequence current in the fault line;

[0037] The fault distance measurement module is used to obtain the distance measurement result of the ground fault by utilizing the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point;

[0038] The simulation verification module is used to verify the validity of the distance measurement results based on the pre-built distribution network grounding fault simulation model.

[0039] In one embodiment, the module for obtaining zero-sequence current relationship includes: a module for constructing a zero-sequence network, a module for dividing fault point lines, and a module for determining zero-sequence current relationship and zero-sequence current circulation loop, wherein:

[0040] A zero-sequence network module is constructed to perform numerical processing on the three-phase electrical quantities of the fault line according to the boundary conditions of the single-phase grounding fault using the Karenbauer phase model transformation, and to construct a zero-sequence network of the grounding fault based on the numerical processing results;

[0041] A fault point line division module is used to divide the two sides of the fault point of the zero-sequence network into an upstream line of the fault point and a downstream line of the fault point by analyzing the zero-sequence network of the ground fault;

[0042] The zero-sequence current relationship and zero-sequence current circulation loop determination module is used to determine the zero-sequence current relationship on both sides of the fault point based on the upstream line of the fault point and the downstream line of the fault point, and obtain the zero-sequence current circulation loop.

[0043] In one embodiment, the zero-sequence current distribution characteristic determination module includes: a zero-sequence current path result acquisition module, a module for determining the change trend of zero-sequence current on both sides of the fault point, and a zero-sequence current distribution characteristic acquisition module, wherein:

[0044] A zero-sequence current path result acquisition module is used to analyze the ground capacitance current distribution in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the zero-sequence current path result;

[0045] A module for determining the variation trend of zero-sequence current on both sides of the fault point is used to analyze the ground capacitance current on both sides of the fault point according to the path result of the zero-sequence current, and obtain the variation trend of the zero-sequence current on both sides of the fault point;

[0046] The zero-sequence current distribution characteristic acquisition module is used to determine the relationship between the zero-sequence current and the electrical distance based on the change trend of the zero-sequence current, and obtain the zero-sequence current distribution characteristic of the fault line.

[0047] In one embodiment, the path result of the zero-sequence current includes: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

[0048] In one embodiment, the variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point;

[0049] The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line;

[0050] The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

[0051] In one embodiment, the fault distance measurement module includes: a zero-sequence impedance result acquisition module, a zero-sequence current result acquisition module and a distance measurement result determination module, wherein:

[0052] A zero-sequence impedance result acquisition module is used to obtain zero-sequence impedance results of the upstream and downstream lines of the fault point according to the pre-acquired line unit length impedance parameters and the lengths of the upstream and downstream lines of the fault point;

[0053] A zero-sequence current result acquisition module is used to obtain zero-sequence current results of the upstream and downstream lines of the fault point based on the distribution characteristics of the zero-sequence current in the fault line;

[0054] The distance measurement result determination module is used to substitute the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point into the fault zero-sequence current relationship on both sides of the fault point to obtain the distance measurement result of the ground fault.

[0055] According to a third aspect of an embodiment of the present invention, a computer device is provided.

[0056] In some embodiments, the computer device includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0057] According to a fourth aspect of embodiments of the present invention, a computer-readable storage medium is provided.

[0058] In one embodiment, the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0059] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0060] The present invention constructs a zero-sequence network, analyzes the zero-sequence current relationship of the lines on both sides of the fault point, and obtains the distance measurement result of the ground fault in combination with the distribution characteristics of the zero-sequence current; when a fault occurs in the distribution network, the fault point can be measured to help maintenance personnel quickly find the fault point and eliminate the fault. The present invention is suitable for troubleshooting distribution networks with a wide distribution range, complex structure and diverse operating environments, and avoids the situation where, when a fault occurs in the distribution network, auxiliary maintenance personnel find it difficult to quickly determine the fault location, which greatly affects the power supply reliability.

[0061] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0063] Figure 1 is a flow chart of a current ground fault location method according to an exemplary embodiment;

[0064] Figure 2 is a structural schematic diagram of a current ground fault distance measurement system according to an exemplary embodiment;

[0065] Figure 3 is a structural schematic diagram of a computer device according to an exemplary embodiment;

[0066] Figure 4 is a simplified zero-sequence circuit diagram of a power distribution network according to an exemplary embodiment;

[0067] Figure 5 A zero-sequence current circulation loop of a power distribution network is shown according to an exemplary embodiment;

[0068] Figure 6 is a zero-sequence current distribution of a fault line in an ungrounded system according to an exemplary embodiment;

[0069] Figure 7 It is a schematic diagram of a single-phase grounding fault of a 10kV system constructed according to an exemplary embodiment;

[0070] Figure 8 FIG. 1 is a diagram showing zero-sequence current distribution of a 10 kV fault line according to an exemplary embodiment. DETAILED DESCRIPTION

[0071] The following description and accompanying drawings fully illustrate the specific embodiments of this article so that those skilled in the art can practice them. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. The scope of the embodiments of this article includes the entire scope of the claims, as well as all available equivalents of the claims. Herein, the terms "first", "second", etc. are only used to distinguish one element from another, without requiring or implying any actual relationship or order between these elements. In fact, the first element can also be called the second element, and vice versa. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the structure, device or equipment including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also include elements inherent to such structure, device or equipment. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the structure, device or equipment including the elements. Each embodiment is described in a progressive manner herein, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other.

[0072] The terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. in this document indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing this document and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the description of this document, unless otherwise specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, it can also be the internal communication of two elements, it can be a direct connection, or it can be an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0073] As used herein, the term "plurality" means two or more than two, unless otherwise specified.

[0074] In this document, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B means: A or B.

[0075] In this article, the term "and / or" is a description of the association relationship between objects, indicating that three relationships may exist. For example, A and / or B means: A or B, or, A and B.

[0076] It should be understood that, although the various steps in the flow chart are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0077] Each module in the device or system of the present application can be implemented in whole or in part by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above modules.

[0078] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0079] Figure 1 An embodiment of a current ground fault distance measurement method of the present invention is shown.

[0080] In this optional embodiment, the current ground fault distance measurement method includes:

[0081] Step S101, constructing a zero-sequence network of a ground fault according to the boundary conditions of a single-phase ground fault, and analyzing the zero-sequence network to obtain a zero-sequence current relationship of lines on both sides of the fault point and a zero-sequence current flow loop;

[0082] Step S103, based on the zero-sequence current circulation loop, analyzing the ground capacitance current in the zero-sequence current circulation loop to obtain the distribution characteristics of the zero-sequence current in the fault line;

[0083] Step S105, using the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point, obtain the distance measurement result of the ground fault;

[0084] Step S107, verifying the validity of the distance measurement result based on the pre-built distribution network ground fault simulation model.

[0085] In this optional embodiment, the zero-sequence network of the ground fault is constructed according to the boundary conditions of the single-phase ground fault, and the zero-sequence network is analyzed to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop, including:

[0086] According to the boundary conditions of single-phase grounding fault, the three-phase electrical quantities of the fault line are digitized by using Karenbauer phase model transformation, and the zero-sequence network of grounding fault is constructed based on the digitized processing results.

[0087] By analyzing the zero-sequence network of the ground fault, the two sides of the fault point of the zero-sequence network are divided into the upstream line of the fault point and the downstream line of the fault point;

[0088] Based on the upstream line of the fault point and the downstream line of the fault point, the zero-sequence current relationship on both sides of the fault point is determined, and the zero-sequence current flow loop is obtained.

[0089] In this optional embodiment, the zero-sequence current relationship calculation formula on both sides of the fault point is:

[0090]

[0091] In the formula, Z 0b Indicates the zero-sequence impedance of the upstream line of the fault point; Z 0a Indicates the zero-sequence impedance of the line downstream of the fault point; I 0b Indicates the zero-sequence current of the upstream line of the fault point; I 0a Indicates the zero-sequence current of the line fault downstream of the fault point.

[0092] In this optional embodiment, the analyzing the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the distribution characteristics of the zero-sequence current in the fault line includes:

[0093] Based on the zero-sequence current circulation loop, the distribution of the ground capacitance current in the zero-sequence current circulation loop is analyzed to obtain the path result of the zero-sequence current;

[0094] According to the path result of zero-sequence current, the ground capacitance current on both sides of the fault point is analyzed to obtain the change trend of zero-sequence current on both sides of the fault point;

[0095] Based on the changing trend of zero-sequence current, the relationship between zero-sequence current and electrical distance is determined, and the zero-sequence current distribution characteristics of the fault line are obtained.

[0096] In this optional embodiment, the path result of the zero-sequence current includes: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

[0097] In this optional embodiment, the variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point;

[0098] The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line;

[0099] The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

[0100] In this optional embodiment, the relationship between the zero-sequence current and the electrical distance is calculated as follows:

[0101]

[0102] In the formula, I C Indicates the ground capacitance current per unit fault line length; I hcΣ Indicates the total capacitance current of a healthy line to ground; l f Indicates the total length of the fault line; x f Indicates the fault distance; I 0 (x) represents the zero-sequence current at a distance x from the busbar; x represents the distance from the busbar.

[0103] In this optional embodiment, the method of obtaining the ground fault distance measurement result by utilizing the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point includes:

[0104] According to the previously obtained line unit length impedance parameter and the length of the upstream and downstream lines of the fault point, the zero-sequence impedance results of the upstream and downstream lines of the fault point are obtained;

[0105] Based on the distribution characteristics of zero-sequence current in the fault line, the zero-sequence current results of the upstream and downstream lines of the fault point are obtained;

[0106] Based on the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point, they are substituted into the fault zero-sequence current relationship on both sides of the fault point to obtain the ground fault distance measurement result.

[0107] Figure 2 An embodiment of a current ground fault distance measuring system of the present invention is shown.

[0108] In this optional embodiment, the current ground fault distance measurement system includes:

[0109] Module 201 is used to construct a zero-sequence network of a ground fault according to the boundary conditions of a single-phase ground fault, and analyze the zero-sequence network to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop;

[0110] Module 203 is used to analyze the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop, and obtain the distribution characteristics of the zero-sequence current in the fault line;

[0111] Module 205 is used to obtain the distance measurement result of the ground fault by utilizing the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point;

[0112] Module 207 is used to verify the validity of the distance measurement result based on the pre-built distribution network ground fault simulation model.

[0113] In this optional embodiment, the module for obtaining zero-sequence current relationship includes: a module for constructing a zero-sequence network, a module for dividing fault point lines, and a module for determining zero-sequence current relationship and zero-sequence current circulation loop, wherein:

[0114] A zero-sequence network module is constructed to perform numerical processing on the three-phase electrical quantities of the fault line according to the boundary conditions of the single-phase grounding fault using the Karenbauer phase model transformation, and to construct a zero-sequence network of the grounding fault based on the numerical processing results;

[0115] A fault point line division module is used to divide the two sides of the fault point of the zero-sequence network into an upstream line of the fault point and a downstream line of the fault point by analyzing the zero-sequence network of the ground fault;

[0116] The zero-sequence current relationship and zero-sequence current circulation loop determination module is used to determine the zero-sequence current relationship on both sides of the fault point based on the upstream line of the fault point and the downstream line of the fault point, and obtain the zero-sequence current circulation loop.

[0117] In this optional embodiment, the zero-sequence current distribution characteristic determination module includes: a zero-sequence current path result acquisition module, a module for determining the change trend of zero-sequence current on both sides of the fault point, and a zero-sequence current distribution characteristic acquisition module, wherein:

[0118] A zero-sequence current path result acquisition module is used to analyze the ground capacitance current distribution in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the zero-sequence current path result;

[0119] A module for determining the variation trend of zero-sequence current on both sides of the fault point is used to analyze the ground capacitance current on both sides of the fault point according to the path result of the zero-sequence current, and obtain the variation trend of the zero-sequence current on both sides of the fault point;

[0120] The zero-sequence current distribution characteristic acquisition module is used to determine the relationship between the zero-sequence current and the electrical distance based on the change trend of the zero-sequence current, and obtain the zero-sequence current distribution characteristic of the fault line.

[0121] In this optional embodiment, the path result of the zero-sequence current includes: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

[0122] In this optional embodiment, the variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point;

[0123] The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line;

[0124] The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

[0125] In this optional embodiment, the fault distance measurement module includes: a zero-sequence impedance result acquisition module, a zero-sequence current result acquisition module and a distance measurement result determination module, wherein:

[0126] A zero-sequence impedance result acquisition module is used to obtain zero-sequence impedance results of the upstream and downstream lines of the fault point according to the pre-acquired line unit length impedance parameters and the lengths of the upstream and downstream lines of the fault point;

[0127] A zero-sequence current result acquisition module is used to obtain zero-sequence current results of the upstream and downstream lines of the fault point based on the distribution characteristics of the zero-sequence current in the fault line;

[0128] The distance measurement result determination module is used to substitute the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point into the fault zero-sequence current relationship on both sides of the fault point to obtain the distance measurement result of the ground fault.

[0129] It should be noted that the busbar represents the head end of the fault line.

[0130] It should be noted that the relationship between the zero-sequence currents on both sides of the fault point includes: According to the boundary conditions of the single-phase grounding fault, the three-phase electrical quantities of the line can be converted into 0-mode, 1-mode and 2-mode quantities using the Karrenbauer phase mode transformation, thereby establishing a small current grounding fault composite network model including line mode and zero-mode networks, that is, the zero-sequence network (such as Figure 4 As shown in the figure); by analyzing the zero-sequence network, the zero-sequence network can be divided into two parts: upstream of the fault point (bus side) and downstream of the fault point (load side). The two parts are in parallel relationship, that is, the fault zero-sequence current flowing through the upstream and downstream of the fault point is determined by their respective impedance values.

[0131] It should be noted that Z 0b , Z 0a It represents the zero-mode impedance of the upstream line of the fault point (including the section from the fault point to the busbar and all healthy lines) and the downstream line of the fault point. 0b ,I 0a Indicates the zero-mode current of the upstream and downstream lines of the fault point, U f,I f Indicates the voltage and current at the fault point.

[0132] It should be noted that the derivation of the distribution characteristics of the zero-sequence fault current on the fault line includes: when a single-phase grounding fault occurs in the distribution network, the zero-sequence current flows from the fault point to both sides. Due to the shunting effect of the distributed capacitance to the ground along the line, the capacitive zero-sequence current gradually decreases. Since the line is a uniform transmission line, it can be considered that the capacitance current to the ground is uniformly distributed everywhere, and the path of the zero-sequence current is obtained (such as Figure 5 shown).

[0133] In an ungrounded system, since the zero-sequence current is entirely generated by the capacitive current of the distributed capacitance to the ground, due to the shunting effect, for the upstream section of the fault point, the zero-sequence current gradually decreases from the fault point to the bus, and is reduced to the total capacitance current of the sound line to the ground at the bus; for the downstream section of the fault point, the zero-sequence current gradually decreases to 0 from the fault point to the end of the line.

[0134] It should be noted that the relationship between the zero-sequence current at any point in the upstream section and the downstream section of the fault point and the electrical distance x to the busbar is calculated as follows:

[0135]

[0136] In the formula, I C Indicates the ground capacitance current per unit fault line length; I hcΣ Indicates the total capacitance current of a healthy line to ground; l f Indicates the total length of the fault line; x f Indicates the fault distance; I 0 (x) represents the zero-sequence current at a distance x from the busbar (the beginning of the line); x represents the length from the busbar (the beginning of the line).

[0137] It should be noted that based on Figure 5 Analysis,Figure,I C is the ground capacitance current per unit line length, I hcΣ is the total capacitance current of the healthy line to ground; since the zero-sequence current is entirely generated by the capacitive current of the distributed capacitance to ground, due to the shunting effect, for the upstream section of the fault point, the zero-sequence current gradually decreases from the fault point to the busbar, and is reduced to the total capacitance current of the healthy line to ground at the busbar; for the downstream section of the fault point, the zero-sequence current gradually decreases from the fault point to the end of the line to zero, and the zero-sequence current I at the electrical distance x from the busbar is obtained. 0 (x) and the electrical distance x to the busbar (e.g. Figure 6 shown).

[0138] It should be noted that the zero-sequence current distribution of the fault line of the distribution network is obtained by analyzing the currents of the detection points on both sides of the fault section (such as Figure 8Finally, the accurate formula for fault location is obtained.

[0139] It should be noted that the 10kV distribution network ground fault simulation model is built in the software, for example, the 10kV distribution network ground fault simulation model is built in matlab / Simulink, and its topology (such as Figure 7 As shown), line parameters (as shown in Table 1), the lengths of the four feeders are L1 = 10km, L2 = 10km, L3 = 12km, and L4 = 15km respectively; the arc suppression coil is calculated based on 10% overcompensation, and the corresponding inductance value is L = 9.42H; the complete set of distribution control terminals FTU1~FTU5 with measuring devices divides the feeder line into 5 sections; the simulation system is set to have a phase A grounding fault time of t = 0.1s, and the fault section is 5km away from point F3 on the F3-F4 section. The distance measurement result is calculated according to the accurate formula for fault distance measurement obtained above (as shown in Table 2);

[0140] Table 1

[0141]

[0142] Table 2

[0143] Fault location (distance from fault point to F3) / km Distance measurement result (fault point distance F3 distance) / km 5 4.87

[0144] It should be noted that the zero-sequence current distribution of the fault line in the ungrounded system can be obtained from the relationship between the zero-sequence current magnitude at any point in the upstream section and the downstream section of the fault point and the electrical distance x to the busbar (e.g. Figure 6 shown).

[0145] It should be noted that based on the distribution characteristics of zero-sequence fault current, the zero-sequence fault current measured at adjacent detection points is used to achieve fault distance measurement. Based on the distribution characteristics of zero-sequence current in the fault line, the fault distance measurement equation of current grounding fault is obtained to achieve fault distance measurement.

[0146] For example, take a 10kV system single-phase grounding fault as an example (such as Figure 7 Assume that the fault occurs in the section between detection points F3 and F4. Based on the fault section location, the zero-sequence current distribution characteristics of the fault line are analyzed. The zero-sequence current distribution of the fault line L4 (as shown in Figure 8 shown).

[0147] Figure 8 middle, I 03 ,I 04 Indicates the zero-sequence current detected by detection points F3 and F4; x f31 Indicates the distance from the fault point to the detection point F3; l 34 Indicates the line length of section F3-F4; the zero-sequence current I at detection point F303 is the zero-sequence current I upstream of the fault point 0b The value after the capacitance to ground is shunted by the x-length line; similarly, the zero-sequence current I at the detection point F4 04 is the zero-sequence current I downstream of the fault point 0a After (l 34 -x) length line to ground capacitance after shunting; therefore, the zero-sequence current I upstream and downstream of the fault point can be obtained 0b ,I 0a The distance x from the fault point to the detection point F3 f31 Calculation formula.

[0148] Among them, the zero-sequence current I upstream of the fault point 0b The calculation formula for the distance from the fault point to the detection point F3 is:

[0149] I 0b =I 03 +x f31 I C ;

[0150] In the formula, I 0b Indicates the zero-sequence current of the upstream line of the fault point; I 03 Indicates the zero-sequence current detected by detection point F3; x f31 Indicates the distance from the fault point to the detection point F3; I C Indicates the capacitance current to ground per unit fault line length.

[0151] Among them, the zero-sequence current downstream of the fault point I 0a The distance x from the fault point to the detection point F3 f32 Calculation formula:

[0152] I 0a =I 04 +(l 34 -x f32 )I C ;

[0153] In the formula, I 0a Indicates the zero-sequence current of the line fault downstream of the fault point; x f32 Indicates the distance from the fault point to the detection point F3; I C Indicates the ground capacitance current per unit fault line length; l 34 Indicates the line length of section F3-F4; 04 Indicates the zero-sequence current detected by detection point F4.

[0154] Since the distribution line parameters are uniform, the line model can be represented by an RLC series circuit equivalent to lumped parameters. The line parameter calculation formula is:

[0155] Z0 =Z u0 l;

[0156] In the formula, Z u0 It represents the impedance value per unit length of the line, l represents the length of the line; Z 0 Indicates the total impedance of the line.

[0157] For the network upstream of the fault point, its line length includes the length of all healthy lines and the length from the fault point to the bus line. For the network downstream of the fault point, its line length only includes the length from the fault point to the load line. Therefore, the zero-sequence impedance Z of the upstream and downstream lines of the fault point is 0b , Z 0a The distance from the fault point to the detection point F3 can also be expressed as:

[0158] Z 0b =Z u0 (l ∑b +x);

[0159] Z 0a =Z u0 (l ∑a +l 34 -x);

[0160] In the formula, l Σb It represents the sum of the lengths of all healthy lines and the line from the detection point F3 to the busbar; l Σa Indicates the length of the line from the detection point F4 to the load.

[0161] The zero-sequence current I upstream and downstream of the fault point will be derived 0b ,I 0a And the zero-mode impedance Z of the upstream and downstream lines of the fault point 0b , Z 0a Substituting the expression into the flow splitting formula yields the following formula:

[0162]

[0163] Simplified, the distance from the fault point to the detection point F3 is:

[0164]

[0165] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as follows: Figure 3As shown. The computer device includes a processor, a memory and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store static information and dynamic information data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in the above method embodiment are implemented.

[0166] Those skilled in the art will understand that Figure 3 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device to which the solution of the present invention is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0167] In addition, the present invention also provides a computer device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above method embodiment when executing the computer program.

[0168] In addition, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0169] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0170] The present invention is not limited to the structures which have been described above and shown in the drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A current ground fault distance measurement method, characterized in that: The current ground fault distance measurement method comprises: According to the boundary conditions of single-phase grounding fault, the zero-sequence network of grounding fault is constructed and analyzed to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop; Based on the zero-sequence current circulation loop, the ground capacitance current in the zero-sequence current circulation loop is analyzed to obtain the distribution characteristics of the zero-sequence current in the fault line; The ground fault distance measurement result is obtained by using the distribution characteristics of zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point; Based on the pre-built distribution network grounding fault simulation model, the validity of the ranging results is verified.

2. The current ground fault distance measurement method according to claim 1, characterized in that: The method of constructing a zero-sequence network of a ground fault according to the boundary conditions of a single-phase ground fault and analyzing the zero-sequence network to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop includes: According to the boundary conditions of single-phase grounding fault, the three-phase electrical quantities of the fault line are digitized by using Karenbauer phase model transformation, and the zero-sequence network of grounding fault is constructed based on the digitized processing results. By analyzing the zero-sequence network of the ground fault, the two sides of the fault point of the zero-sequence network are divided into the upstream line of the fault point and the downstream line of the fault point; Based on the upstream line of the fault point and the downstream line of the fault point, the zero-sequence current relationship on both sides of the fault point is determined, and the zero-sequence current flow loop is obtained.

3. The current ground fault distance measurement method according to claim 2, characterized in that: The calculation formula for the zero-sequence current relationship on both sides of the fault point is: In the formula, Z 0b Indicates the zero-sequence impedance of the upstream line of the fault point; Z 0a Indicates the zero-sequence impedance of the line downstream of the fault point; I 0b Indicates the zero-sequence current of the upstream line of the fault point; I 0a Indicates the zero-sequence current of the line fault downstream of the fault point.

4. The current ground fault distance measurement method according to claim 2, characterized in that: The method of analyzing the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the distribution characteristics of the zero-sequence current in the fault line includes: Based on the zero-sequence current circulation loop, the distribution of the ground capacitance current in the zero-sequence current circulation loop is analyzed to obtain the path result of the zero-sequence current; According to the path result of zero-sequence current, the ground capacitance current on both sides of the fault point is analyzed to obtain the change trend of zero-sequence current on both sides of the fault point; Based on the changing trend of zero-sequence current, the relationship between zero-sequence current and electrical distance is determined, and the zero-sequence current distribution characteristics of the fault line are obtained.

5. The current ground fault distance measurement method according to claim 4, characterized in that: The path results of the zero-sequence current include: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

6. The current ground fault distance measurement method according to claim 4, characterized in that: The variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point; The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line; The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

7. The current ground fault distance measurement method according to claim 4, characterized in that: The relationship between the zero-sequence current and the electrical distance is calculated as follows: In the formula, I C Indicates the ground capacitance current per unit fault line length; I hcΣ Indicates the total capacitance current of a healthy line to ground; l f Indicates the total length of the fault line; x f represents the fault distance; I0(x) represents the zero-sequence current at a distance x from the bus; x represents the length from the bus.

8. The current ground fault distance measurement method according to claim 4, characterized in that: The method of using the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point to obtain the ground fault distance measurement result includes: According to the previously obtained line unit length impedance parameter and the length of the upstream and downstream lines of the fault point, the zero-sequence impedance results of the upstream and downstream lines of the fault point are obtained; Based on the distribution characteristics of zero-sequence current in the fault line, the zero-sequence current results of the upstream and downstream lines of the fault point are obtained; Based on the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point, they are substituted into the fault zero-sequence current relationship on both sides of the fault point to obtain the ground fault distance measurement result.

9. A current ground fault distance measurement system, characterized in that: The current ground fault distance measuring system comprises: The module for obtaining the zero-sequence current relationship is used to construct the zero-sequence network of the grounding fault according to the boundary conditions of the single-phase grounding fault, and analyze the zero-sequence network to obtain the zero-sequence current relationship of the lines on both sides of the fault point and the zero-sequence current flow loop; A zero-sequence current distribution characteristic determination module is used to analyze the ground capacitance current in the zero-sequence current circulation loop based on the zero-sequence current circulation loop, and obtain the distribution characteristics of the zero-sequence current in the fault line; The fault distance measurement module is used to obtain the distance measurement result of the ground fault by utilizing the distribution characteristics of the zero-sequence current in the fault line and combining the zero-sequence current relationship on both sides of the fault point; The simulation verification module is used to verify the validity of the distance measurement results based on the pre-built distribution network grounding fault simulation model.

10. The current ground fault distance measurement system according to claim 9, characterized in that: The module for obtaining the zero-sequence current relationship includes: a module for constructing a zero-sequence network, a module for dividing the fault point line, and a module for determining the zero-sequence current relationship and the zero-sequence current circulation loop, wherein: A zero-sequence network module is constructed to perform numerical processing on the three-phase electrical quantities of the fault line according to the boundary conditions of the single-phase grounding fault using the Karenbauer phase model transformation, and to construct a zero-sequence network of the grounding fault based on the numerical processing results; A fault point line division module is used to divide the two sides of the fault point of the zero-sequence network into an upstream line of the fault point and a downstream line of the fault point by analyzing the zero-sequence network of the ground fault; The zero-sequence current relationship and zero-sequence current circulation loop determination module is used to determine the zero-sequence current relationship on both sides of the fault point based on the upstream line of the fault point and the downstream line of the fault point, and obtain the zero-sequence current circulation loop.

11. The current ground fault distance measuring system according to claim 10, characterized in that: The zero-sequence current distribution characteristic determination module includes: a zero-sequence current path result acquisition module, a module for determining the change trend of zero-sequence current on both sides of the fault point, and a zero-sequence current distribution characteristic acquisition module, wherein: A zero-sequence current path result acquisition module is used to analyze the ground capacitance current distribution in the zero-sequence current circulation loop based on the zero-sequence current circulation loop to obtain the zero-sequence current path result; A module for determining the variation trend of zero-sequence current on both sides of the fault point is used to analyze the ground capacitance current on both sides of the fault point according to the path result of the zero-sequence current, and obtain the variation trend of the zero-sequence current on both sides of the fault point; The zero-sequence current distribution characteristic acquisition module is used to determine the relationship between the zero-sequence current and the electrical distance based on the change trend of the zero-sequence current, and obtain the zero-sequence current distribution characteristic of the fault line.

12. The current ground fault distance measuring system according to claim 11, characterized in that: The path results of the zero-sequence current include: the capacitive zero-sequence current gradually decreases from the fault point to both sides of the fault point, and the capacitive current to ground is evenly distributed.

13. The current ground fault distance measurement system according to claim 11, characterized in that: The variation trend of the zero-sequence current on both sides of the fault point includes: the variation trend of the upstream line section of the fault point and the variation trend of the downstream line section of the fault point; The change trend of the upstream line section of the fault point is: the zero-sequence current gradually decreases from the fault point to the busbar, and at the busbar it decreases to the total ground capacitance current of the healthy line; The changing trend of the line section downstream of the fault point is: the zero-sequence current gradually decreases to zero from the fault point to the end of the fault line.

14. The current ground fault distance measurement system according to claim 11, characterized in that: The fault distance measurement module includes: a zero-sequence impedance result acquisition module, a zero-sequence current result acquisition module and a distance measurement result determination module, wherein: A zero-sequence impedance result acquisition module is used to obtain zero-sequence impedance results of the upstream and downstream lines of the fault point according to the pre-acquired line unit length impedance parameters and the lengths of the upstream and downstream lines of the fault point; A zero-sequence current result acquisition module is used to obtain zero-sequence current results of the upstream and downstream lines of the fault point based on the distribution characteristics of the zero-sequence current in the fault line; The distance measurement result determination module is used to substitute the zero-sequence impedance results and zero-sequence current results of the upstream and downstream lines of the fault point into the fault zero-sequence current relationship on both sides of the fault point to obtain the distance measurement result of the ground fault.

15. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

16. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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