A method, device and system for locating a fault on a medium voltage line

Abstract

The embodiment of the application discloses a kind of medium voltage line fault location method, device and system, comprising: the node state of line monitoring node is sent by each node monitoring device;Wherein, node monitoring device is arranged in distribution network line, node monitoring device is used to obtain the voltage and current of line monitoring node, the impedance size and impedance angle of line monitoring node are determined according to the voltage and current of line monitoring node, the node state of line monitoring node is determined according to the impedance size and impedance angle of line monitoring node;Mark the node state of each line monitoring node in connection topology diagram, determine line fault section according to the marking result.The application has the advantages of accurate fault location, small amount of calculation, can adapt to various forms of complex power grid.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of line fault location, in particular to a medium-voltage line fault location method, device and system. BACKGROUND

[0002] The distribution network fault location refers to that in the distribution system, when a fault occurs, the fault location can be quickly and accurately found so as to timely eliminate the fault and ensure the power supply reliability.

[0003] In the prior art, the distribution network fault location technology mainly has the following problems: 1. It is only applicable to the traditional distribution network, and after the distributed new energy is connected, the distribution network is equivalent to a multi-source power grid, and when a fault occurs, the fault current may flow upstream or downstream of the fault point, and the fault section cannot be determined only by the fault current, time and the like. 2. The way of sending the voltage, current and the like to the main station for calculation and analysis by the main station, each measurement point has at least 12 measurement points of three-phase voltage amplitude, phase, three-phase current amplitude and phase, and there are problems of large amount of data sent, occupation of main station calculation resources and the like. SUMMARY

[0004] The present application provides a medium-voltage line fault location method, device and system, which has the advantages of fast and accurate fault location, small calculation amount and adaptability to various forms of complex power grids, and improves the power grid operation and maintenance efficiency.

[0005] According to a first aspect of the present application, a medium-voltage line fault location method is provided, comprising:

[0006] Obtaining the node state of the line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in the distribution network line, and the node monitoring device is used for obtaining the voltage and current of the line monitoring node, determining the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and determining the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node;

[0007] Marking the node state of each line monitoring node in the connection topology diagram, and determining the line fault section according to the marking result.

[0008] Optionally, when the impedance size of the line monitoring node is greater than or equal to a set value, the node state of the line monitoring node is normal.

[0009] When the impedance size of the line monitoring node is less than the set value and the impedance angle is in a preset angle range, the node state of the line monitoring node is the first state.

[0010] When the impedance size of the line monitoring node is less than or equal to the set value and the impedance angle is not in the preset angle range, the node state of the line monitoring node is the second state.

[0011] Optionally, the set values of different line monitoring nodes are different.

[0012] Optionally, the node state of each line monitoring node is marked in the connection topology diagram, and the line fault section is determined according to the marking result, including:

[0013] When the node states of all line monitoring nodes in the line section are the first state, the line section is determined as the line fault section.

[0014] Optionally, the node state of each line monitoring node is marked in the connection topology diagram, and the line fault section is determined according to the marking result, including:

[0015] When the node state of the line monitoring node is the first state or the second state, the node state of the line monitoring node is marked in the connection topology diagram.

[0016] According to a second aspect of the present application, a medium-voltage line fault positioning device is provided, including:

[0017] The node state acquisition module is configured to acquire the node state of the line monitoring node sent by each node monitoring device, wherein the node monitoring device is arranged in the distribution network line, and the node monitoring device is configured to acquire the voltage and current of the line monitoring node, determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node.

[0018] The fault section determination module is configured to mark the node state of each line monitoring node in the connection topology diagram, and determine the line fault section according to the marking result.

[0019] Optionally, when the impedance size of the line monitoring node is greater than a set value, the node state of the line monitoring node is normal.

[0020] When the impedance size of the line monitoring node is less than or equal to a set value, and the impedance angle is in a preset angle range, the node state of the line monitoring node is the first state.

[0021] When the impedance size of the line monitoring node is less than or equal to a set value, and the impedance angle is not in a preset angle range, the node state of the line monitoring node is the second state.

[0022] Optionally, the set values of different line monitoring nodes are different.

[0023] Optionally, the fault section determination module is specifically configured to:

[0024] When the node status of all line monitoring nodes in the line section is the first status, the line section is determined as a line fault section.

[0025] According to a third aspect of the present application, there is provided a medium voltage line fault location system comprising:

[0026] The node monitoring device and the medium voltage line fault location device of any one of claims 6-9.

[0027] The medium voltage line fault location method provided by the embodiment of the present application comprises: acquiring the node status of the line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in a distribution network line, the node monitoring device is used to acquire the voltage and current of the line monitoring node, to determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and to determine the node status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node; the analysis of the impedance size and impedance angle helps to identify potential problems or faults in the power grid, and improves the accuracy of fault location. The node status of each line monitoring node is marked in a connection topology diagram, and the line fault section is determined according to the marking result; through visual analysis, the fault section can be quickly located, and the troubleshooting time is reduced. The technical solution of the embodiment only transmits the node status of each monitoring line, without transmitting 12 measurement points including three-phase voltage amplitude, phase and three-phase current amplitude, phase, which has the advantages of simple and fast calculation, and solves the problem of a large amount of data of the new power system occupying the computing resources of the master station. The present scheme only sends the positive and negative directions of the fault current to the master station, so as to determine the fault section of the line. Through real-time monitoring and analysis of the node status, abnormalities can be found in time before the fault occurs, and corresponding preventive measures can be taken, which helps to reduce the power-off time and loss caused by the fault, realizes the rapid positioning and accurate judgment of the fault, and improves the power supply reliability and stability of the power grid.

[0028] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0030] Figure 1 is a flowchart of a medium voltage line fault location method provided by the embodiment of the present application;

[0031] Figure 2 is a module schematic diagram of a medium voltage line fault location device provided by the embodiment of the present application. DETAILED DESCRIPTION

[0032] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0033] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0034] The embodiment of the present application provides a medium voltage line fault location method, Figure 1 is a flow chart of a medium voltage line fault location method provided by the embodiment of the present application, referring to Figure 1 The medium voltage line fault location method comprises the following steps.

[0035] S110, acquiring the node state of the line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in the distribution network line, and the node monitoring device is used to acquire the voltage and current of the line monitoring node, to determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and to determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node.

[0036] The node state refers to the current condition or status of the line monitoring node in the power grid. In the power system, the node state generally reflects the combination of electrical parameters such as voltage, current, power factor, etc. at the node. The node state is determined by the voltage and current data obtained by the monitoring device, and the impedance size and impedance angle are calculated by the voltage and current data. The impedance size is the ratio of voltage to current in the circuit, and the impedance size of the node can be calculated by measuring the voltage and current of the line monitoring node and using Ohm's law. In the medium-voltage line, the impedance size reflects the impedance of the line to alternating current, and when the line is in a normal state, the impedance value remains in a relatively stable range, and when the line fails, the impedance value at the fault point will change. The impedance angle is determined according to the voltage and current of the line monitoring node, and the impedance angle is the phase angle of the impedance in the complex plane. In the medium-voltage line, the impedance angle reflects the phase difference between voltage and current. For example, for a pure resistance circuit, the voltage and current are in phase, and the impedance angle is 0°; for a pure inductance or pure capacitance circuit, there is a 90° phase difference between the voltage and the current.

[0037] S120, marking the node state of each line monitoring node in the wiring topology diagram, and determining the line fault section according to the marking result.

[0038] The wiring topology diagram is a kind of graph used to show the connection relationship and layout between components in a power system, a communication network, a power distribution network or any other electrical or electronic system. In this embodiment, the wiring topology diagram is used to show the connection mode and physical layout between lines, switches, transformers, node monitoring devices and other devices in the power distribution network.

[0039] Specifically, the monitoring device is installed at the node of the distribution network line, which can collect the voltage and current at the location in real time, calculate the impedance size and impedance angle of each line monitoring node according to the collected voltage and current data, compare the calculated impedance size and impedance angle with the preset impedance, and determine the forward and reverse directions of each line monitoring node. According to the wiring topology diagram of the known distribution network line, the monitoring device is corresponded to the corresponding position of the wiring topology diagram, and the forward and reverse directions of the monitoring device are one-to-one corresponded, the forward and reverse directions of each node are marked on the wiring topology diagram, and the line fault section is determined according to the marking result of each node on the wiring topology diagram.

[0040] The medium-voltage line fault positioning method provided by the embodiment of the application comprises: acquiring the node state of a line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in a distribution network line, the node monitoring device is used to acquire the voltage and current of the line monitoring node, to determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and to determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node, the analysis of the impedance size and impedance angle helps to identify potential problems or faults in the power grid, and the accuracy of fault positioning is improved. The node state of each line monitoring node is marked in a connection topology diagram, and the line fault section is determined according to the marking result, through visual analysis, the fault section can be quickly positioned, and the fault troubleshooting time is reduced. The technical scheme of the embodiment only transmits the node state of each monitoring line, without transmitting 12 measurement points including three-phase voltage amplitude, phase and three-phase current amplitude, phase, has the advantages of simple and fast calculation, and solves the problem of a large amount of data of the new power system occupying the computing resources of the master station. The positive and negative directions of the fault current are sent to the master station, and the fault section of the line can be determined. By monitoring and analyzing the node state in real time, abnormalities can be found in time before the fault occurs, and corresponding preventive measures can be taken, which helps to reduce the power-off time and loss caused by the fault, realizes the rapid positioning and accurate judgment of the fault, and improves the power supply reliability and stability of the power grid.

[0041] Optionally, when the impedance size of the line monitoring node is greater than or equal to a set value, the node state of the line monitoring node is normal;

[0042] When the impedance size of the line monitoring node is less than the set value and the impedance angle is in a preset angle range, the node state of the line monitoring node is the first state.

[0043] When the impedance size of the line monitoring node is less than or equal to the set value and the impedance angle is not in the preset angle range, the node state of the line monitoring node is the second state.

[0044] The first state is used to represent the direction of the fault current of the line monitoring node, for example, the first state determines that the direction of the fault current is positive. The second state is also used to represent the direction of the fault current of the line monitoring node, for example, the second state determines that the direction of the fault current is negative.

[0045] Specifically, when the impedance size of a certain node is greater than or equal to a set value, the node state of the node is normal, that is, a non-line fault section; when the impedance size of a certain node is less than the set value and the impedance angle is in a preset angle range, the node state of the node is determined to be positive; when the impedance size of a certain node is less than the set value and the impedance angle is not in the preset angle range, the node state of the node is determined to be negative.

[0046] Optionally, the setting values of different line monitoring nodes are different.

[0047] Specifically, the different line monitoring nodes set different setting values to better adapt to the complexity of power grid structure, the diversity of load characteristics, the diversity of fault types, the demand of operation and maintenance management, and the possibility of technical implementation. The operation state and fault characteristics of the line monitoring nodes can be better reflected, which helps to improve the accuracy and reliability of fault location.

[0048] Optionally, the node state of each line monitoring node is marked in the wiring topology diagram, and the line fault section is determined according to the marking result, including:

[0049] When the node state of all line monitoring nodes in the line section is the first state, the line section is determined as the line fault section.

[0050] Wherein, the line section refers to a section of line defined by two or more adjacent line monitoring nodes. The line fault section refers to a section in which the current flows to both ends of the section, forming at least two positive polarities at both ends of the section, i.e. the fault section.

[0051] Specifically, according to the wiring topology diagram of the known distribution network line, the monitoring device is corresponded to the corresponding position of the wiring topology diagram, and the positive and negative directions of the monitoring device are one-to-one corresponded. The positive and negative directions of each node are marked on the wiring topology diagram. According to the marking result of each node on the wiring topology diagram, the line fault section is determined. When the node state of all line monitoring nodes in the line section is the positive direction, the line section is determined as the line fault section.

[0052] Optionally, the node state of each line monitoring node is marked in the wiring topology diagram, and the line fault section is determined according to the marking result, including:

[0053] When the node state of each line monitoring node is the first state or the second state, the node state of the line monitoring node is marked in the wiring topology diagram.

[0054] Specifically, according to the wiring topology diagram of the known distribution network line, the monitoring device is corresponded to the corresponding position of the wiring topology diagram, and the positive and negative directions of the monitoring device are one-to-one corresponded. The node state of the line monitoring node is the first state or the second state. The positive direction of the fault current is represented by the first state, and the negative direction of the fault current is represented by the second state. The node state of each line monitoring node is marked on the wiring topology diagram.

[0055] For example, the fault discrimination impedance of a node of the power grid is set as Zd (a variable parameter). When any device installed on the medium voltage line of the distribution network detects the flow of the fault current, the measured impedance Zc and the angle φc are calculated according to the fault voltage and current. If Zc < Zd and the measured angle φc is within a certain range, the direction of the fault current is considered as the positive direction; if Zc < Zd in other cases, the direction of the fault current is considered as the reverse direction; if Zc ≥ Zd, no calculation result is generated. The master station system establishes or acquires the known line connection mode graph of the distribution network, and corresponds the monitoring device to the corresponding position of the line topology graph, and corresponds the positive and reverse directions of the installed device one by one. After the fault occurs, the monitoring device sends the positive direction or reverse direction action signal to the master station through the remote signaling. The master station marks on the line graph according to the positive and reverse direction signals sent by the monitoring device during the fault. When the positive direction signal is received by the measuring node, the positive direction defined by the line graph is positive, and the reverse direction defined by the line graph is negative. When the reverse direction signal is received by the measuring node, the reverse direction defined by the line graph is positive, and the positive direction defined by the line graph is negative. When there are two or more positive polarity marks in a certain section, and there is no negative polarity mark, the section is the fault section.

[0056] The technical scheme of the embodiment solves the problem that, after the distributed power supply is connected to the distribution network, the fault current is difficult to predict, the fixed value is difficult to match, and the fault section after the fault is difficult to accurately locate through the action of the relay protection due to the influence of factors such as the changeable operation mode of the distribution network and the dynamic change of the real-time power generation of the distributed power supply compared with the traditional power grid. The master station is accurately located through the fault transient impedance calculation mode, and the master station topology analysis is used to accurately locate the fault point. The method has the advantages of accurate fault location, small calculation amount and adaptability to various complex power grids. The fault is judged according to the state of each node in the entire line topology graph, and the fault section is judged comprehensively according to each node. The method can solve the problem that the fault current may flow upstream or downstream of the fault point during the fault, and the fault section cannot be determined only by the fault current and time.

[0057] Figure 2 The module schematic diagram of the medium voltage line fault positioning device provided by the embodiment of the application, and the medium voltage line fault positioning method is executed by the device. The device is integrated in the master station, and the master station only needs to acquire the node state sent by the monitoring device, without acquiring the voltage amplitude, phase and current amplitude, phase of each phase.

[0058] Optionally, with reference to Figure 2 The medium voltage line fault positioning device comprises:

[0059] The node state acquisition module 10 is configured to acquire the node state of the line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in the distribution network line, and the node monitoring device is configured to acquire the voltage and the current of the line monitoring node, determine the impedance size and the impedance angle of the line monitoring node according to the voltage and the current of the line monitoring node, and determine the node state of the line monitoring node according to the impedance size and the impedance angle of the line monitoring node.

[0060] The fault section determination module 20 is configured to mark the node state of each line monitoring node in the wiring topology graph, and determine the line fault section according to the marking result.

[0061] Specifically, the monitoring device is installed at the node of the distribution network line, and can collect the voltage and the current at the location in real time, calculate the impedance size and the impedance angle of each line monitoring node according to the collected voltage and current data, compare the calculated impedance size and impedance angle with the preset impedance, and determine the positive direction and the reverse direction of each line monitoring node. According to the wiring topology graph of the known distribution network line, the monitoring device is corresponded to the corresponding position of the wiring topology graph, and the positive direction and the reverse direction of the monitoring device are corresponded one by one, the positive direction and the reverse direction of each node are marked on the wiring topology graph, and the line fault section is determined according to the marking result of each node on the wiring topology graph.

[0062] Optionally, when the impedance size of the line monitoring node is greater than the set value, the node state of the line monitoring node is normal.

[0063] When the impedance size of the line monitoring node is less than or equal to the set value, and the impedance angle is in the preset angle range, the node state of the line monitoring node is the first state.

[0064] When the impedance size of the line monitoring node is less than or equal to the set value, and the impedance angle is not in the preset angle range, the node state of the line monitoring node is the second state.

[0065] Specifically, when the impedance size of a certain node is greater than or equal to the set value, the node state of the node is normal, that is, the node is not in the line fault section; when the impedance size of a certain node is less than the set value, and the impedance angle is in the preset angle range, the node state of the node is determined as the positive direction; when the impedance size of a certain node is less than the set value, and the impedance angle is not in the preset angle range, the node state of the node is determined as the reverse direction.

[0066] Optionally, the set values of different line monitoring nodes are different.

[0067] Optionally, the fault section determination module is specifically configured to:

[0068] When the node states of all line monitoring nodes in the line section are the first state, the line section is determined as the line fault section.

[0069] Specifically, when the node status of all line monitoring nodes in the line section is positive direction, the line section is determined as a line fault section.

[0070] Optionally, the application further provides a medium-voltage line fault locating system, comprising the node monitoring device and the medium-voltage line fault locating device in the embodiment of the application.

[0071] It should be understood that the various forms of flow shown above can be reordered, steps added or deleted. For example, the steps described in the application can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions of the application can be achieved, which is not limited herein.

[0072] The above detailed description does not constitute a limitation on the protection scope of the application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method for fault location on a medium voltage line, characterized in that, The method comprises the following steps: acquiring the node state of a line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in a distribution network line, the node monitoring device is used to acquire the voltage and current of the line monitoring node, to determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and to determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node; the node state of the line monitoring node is a first state or a second state; wherein when the direction of the fault current of the line monitoring node is a positive direction, the node state of the line monitoring node is the first state; when the direction of the fault current of the line monitoring node is a reverse direction, the node state of the line monitoring node is the second state; marking the node state of each line monitoring node in a connection topology diagram, and determining the line fault section according to the marking result.

2. The fault locating method according to claim 1, wherein: when the impedance size of the line monitoring node is greater than or equal to a set value, the node state of the line monitoring node is normal; when the impedance size of the line monitoring node is less than the set value and the impedance angle is within a preset angle range, the node state of the line monitoring node is the first state; when the impedance size of the line monitoring node is less than the set value and the impedance angle is not within the preset angle range, the node state of the line monitoring node is the second state.

3. The fault locating method according to claim 2, wherein: the set values of different line monitoring nodes are different.

4. The fault locating method of claim 2, wherein, The method of marking the node state of each line monitoring node in a connection topology diagram and determining the line fault section according to the marking result comprises: when the node states of all line monitoring nodes in a line section are the first state, the line section is determined as the line fault section.

5. The fault locating method of claim 2, wherein, The method of marking the node state of each line monitoring node in a connection topology diagram and determining the line fault section according to the marking result comprises: when the node state of the line monitoring node is the first state or the second state, the node state of the line monitoring node is marked in the connection topology diagram.

6. A medium voltage line fault location device, characterized in that, The method comprises the following steps: a node state acquisition module, used to acquire the node state of a line monitoring node sent by each node monitoring device; wherein the node monitoring device is arranged in a distribution network line, the node monitoring device is used to acquire the voltage and current of the line monitoring node, to determine the impedance size and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node, and to determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node; the node state of the line monitoring node is a first state or a second state; wherein when the direction of the fault current of the line monitoring node is a positive direction, the node state of the line monitoring node is the first state; when the direction of the fault current of the line monitoring node is a reverse direction, the node state of the line monitoring node is the second state; A fault section determination module is configured to mark a node state of each line monitoring node in the wiring topology map, and determine a line fault section according to a marking result.

7. The fault location device according to claim 6, characterized in that: when the impedance of the line monitoring node is greater than or equal to a set value, the node state of the line monitoring node is normal; when the impedance of the line monitoring node is less than the set value and the impedance angle is within a preset angle range, the node state of the line monitoring node is a first state; when the impedance of the line monitoring node is less than the set value and the impedance angle is not within the preset angle range, the node state of the line monitoring node is a second state.

8. The fault location device according to claim 7, characterized in that: the set values of different line monitoring nodes are different.

9. The fault location device of claim 7, wherein, The fault section determination module is specifically configured to: when the node states of all line monitoring nodes in a line section are the first state, determine the line section as a line fault section.

10. A medium voltage line fault location system characterized by, The application further provides: a node monitoring device and the medium voltage line fault location device according to any one of claims 6-9.

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