Medium-voltage line fault positioning method, device and system

Abstract

The embodiment of the invention discloses a medium-voltage line fault positioning method, device and system. The medium-voltage line fault positioning method comprises the following steps: acquiring a 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, and the node monitoring device is used for acquiring voltage and current of a line monitoring node, and determining impedance magnitude and impedance angle of the line monitoring node according to the voltage and current of the line monitoring node; determining the node state of the line monitoring node according to the impedance size and the impedance angle of the line monitoring node; and marking the node state of each line monitoring node in the wiring topological graph, and determining a line fault section according to a marking result. The method has the advantages of being accurate in fault positioning, small in calculation amount and capable of adapting to various forms of complex power grids.

Description

Technical Field

[0001] The present invention relates to the technical field of line fault locating, and in particular to a medium voltage line fault locating method, device and system. Background Art

[0002] Distribution network fault location refers to the ability to quickly and accurately find the fault location when a fault occurs in the distribution system, so as to eliminate the fault in time and ensure power supply reliability.

[0003] In the existing technology, the distribution network fault location technology mainly has the following problems: 1. It is only applicable to traditional distribution networks. After the access of distributed new energy, the distribution network is equivalent to a multi-source power grid. When a fault occurs, the fault current may flow through both the upstream and downstream of the fault point, and the fault section cannot be judged only by the fault current, time, etc. 2. By sending electrical vectors such as voltage and current to the main station, and the main station calculates and analyzes, each measurement point has at least three-phase voltage amplitude and phase, three-phase current amplitude and phase, a total of 12 measurement points, there are problems such as a large amount of data sent, squeezing the main station computing resources, etc. Summary of the invention

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

[0005] According to a first aspect of the present invention, there is provided a method for locating a medium voltage line fault, comprising:

[0006] Obtaining the node status 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 obtain 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 status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node;

[0007] The node status of each line monitoring node is marked in the wiring topology diagram, and the line fault section is determined based on the marking result.

[0008] Optionally, 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;

[0009] When the impedance of the line monitoring node is less than the set value and the impedance angle is within the preset angle range, the node state of the line monitoring node is the first state;

[0010] When the impedance of the line monitoring node is less than or equal to 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.

[0011] Optionally, different line monitoring nodes have different setting values.

[0012] Optionally, marking the node status of each line monitoring node in the wiring topology diagram, and determining the line fault section according to the marking result, including:

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

[0014] Optionally, marking the node status of each line monitoring node in the wiring topology diagram, and determining the line fault section 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 wiring topology diagram.

[0016] According to a second aspect of the present invention, there is provided a medium voltage line fault locating device, comprising:

[0017] A node status acquisition module, used to acquire the node status 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, 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 status 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 used to mark the node status of each line monitoring node in the wiring topology diagram and determine the line fault section according to the marking result.

[0019] Optionally, when the impedance 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 of the line monitoring node is less than or equal to the set value and the impedance angle is within the preset angle range, the node state of the line monitoring node is the first state;

[0021] When the impedance of the line monitoring node is less than or equal to 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.

[0022] Optionally, different line monitoring nodes have different setting values.

[0023] Optionally, the fault section determination module is specifically used for:

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

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

[0026] A node monitoring device and a medium voltage line fault locating device according to any one of claims 6 to 9.

[0027] The method for locating a medium voltage line fault provided by an embodiment of the present invention includes: 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, the node monitoring device is used to obtain 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, determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node, and the analysis of the impedance size and impedance angle helps to identify potential problems or faults in the power grid, thereby improving the accuracy of fault location. 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. Through visual analysis, the fault section can be quickly located, thereby reducing the time for troubleshooting. The technical solution of this embodiment only transmits the node state of each monitoring line, and does not need to transmit the three-phase voltage amplitude, phase and three-phase current amplitude, phase, a total of 12 measurement points, which has the advantages of simple and fast calculation, and solves the problem that a large amount of data in the new power system squeezes the computing resources of the master station. This solution only sends the positive and negative directions of the fault current of the master station to determine the fault section of the line. By real-time monitoring and analysis of node status, anomalies can be discovered in time before a fault occurs, and corresponding preventive measures can be taken, which helps reduce power outage time and losses caused by faults, achieves rapid location and accurate judgment of faults, and improves the power supply reliability and stability of the power grid.

[0028] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 is a flow chart of a medium voltage line fault locating method provided by an embodiment of the present invention;

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

[0032] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

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

[0034] The embodiment of the present invention provides a method for locating a medium voltage line fault. Figure 1 is a flow chart of a medium voltage line fault location method provided by an embodiment of the present invention, with reference to Figure 1 , the medium voltage line fault location method includes:

[0035] S110. Obtain the node status 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 obtain 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 status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node.

[0036] Among them, the node state refers to the current status or condition of the line monitoring node in the power grid. In the power system, the node state usually 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. By measuring the voltage and current of the line monitoring node and using Ohm's law, the impedance size of the node can be calculated. In the medium-voltage line, the impedance size reflects the resistance of the line to the alternating current. When the line is in a normal state, its impedance value remains in a relatively stable range. When the line fails, the impedance value of the fault point will change. The impedance angle is determined based on the voltage and current of the line monitoring node. The impedance angle is the phase angle of the impedance on the complex plane. In the medium-voltage line, the impedance angle reflects the phase difference between the voltage and the 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 status 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 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 various lines, switches, transformers, node monitoring devices and other equipment in the power distribution network.

[0039] Specifically, a 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 based on the collected voltage and current data, and compare the calculated impedance size and impedance angle with the preset impedance to determine the positive and negative directions of each line monitoring node. According to the wiring topology diagram of the known distribution network line, the monitoring device is matched to the corresponding position of the wiring topology diagram, and the positive and negative directions of the monitoring device are matched one by one, and the positive and negative directions of each node are marked on the wiring topology diagram. According to the marking results of each node on the wiring topology diagram, the line fault section is determined.

[0040] The method for locating a medium voltage line fault provided by an embodiment of the present invention includes: 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, the node monitoring device is used to obtain 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, determine the node state of the line monitoring node according to the impedance size and impedance angle of the line monitoring node, and the analysis of the impedance size and impedance angle helps to identify potential problems or faults in the power grid, thereby improving the accuracy of fault location. 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. Through visual analysis, the fault section can be quickly located, thereby reducing the time for troubleshooting. The technical solution of this embodiment only transmits the node state of each monitoring line, and does not need to transmit the three-phase voltage amplitude, phase and three-phase current amplitude, phase, a total of 12 measurement points, which has the advantages of simple and fast calculation, and solves the problem that a large amount of data in the new power system squeezes the computing resources of the master station. This solution only sends the positive and negative directions of the fault current of the master station to determine the fault section of the line. By real-time monitoring and analysis of node status, anomalies can be discovered in time before a fault occurs, and corresponding preventive measures can be taken, which helps reduce power outage time and losses caused by faults, achieves rapid location and accurate judgment of faults, and improves the power supply reliability and stability of the power grid.

[0041] Optionally, 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;

[0042] When the impedance of the line monitoring node is less than the set value and the impedance angle is within the preset angle range, the node state of the line monitoring node is the first state;

[0043] When the impedance of the line monitoring node is less than or equal to 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.

[0044] The first state is used to characterize 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 in the positive direction. The second state is also used to characterize 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 in the reverse direction.

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

[0046] Optionally, different line monitoring nodes have different setting values.

[0047] Specifically, different line monitoring nodes are set with different set values ​​in order to better adapt to the complexity of the grid structure, the diversity of load characteristics, the diversity of fault types, the needs of operation and maintenance management, and the possibility of technical implementation. It can better reflect the operating status and fault characteristics of the line monitoring nodes, and help improve the accuracy and reliability of fault location.

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

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

[0050] The line section refers to a section of the line defined by two or more adjacent line monitoring nodes. The line fault section refers to a line section where both currents flow to the section and at least two positive polarities are formed at both ends of the section, which is 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 corresponded one by one, and the positive and negative directions of each node are marked on the wiring topology diagram. According to the marking results of each node on the wiring topology diagram, the line fault section is judged. When the node status of all line monitoring nodes in the line section is in the positive direction, the line section is determined as a line fault section.

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

[0053] 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 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 corresponded one by one. 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 reverse 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] Exemplarily, set the fault discrimination impedance of a certain node in the power grid as Zd (a variable parameter). When any device installed on the medium-voltage line of the distribution network detects the flow of fault current, it calculates the measured impedance Zc and the angle φc based on 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 the positive direction; in other cases where Zc < Zd, the direction of the fault current is considered the reverse direction; when Zc ≥ Zd, no calculation result is generated. The master station system establishes or obtains the known wiring diagram of the distribution network line, maps the monitoring device to the corresponding position in the wiring topology diagram, and corresponds the positive and negative directions of the installed equipment one by one. After a fault occurs, the monitoring device sends the "positive direction" or "reverse direction" action signal to the master station through telemetry. Based on the positive and negative direction signals sent by the monitoring device during the fault, the master station marks them on the wiring diagram. When the measuring node receives the positive direction signal, the positive direction defined in the wiring diagram is the positive pole, and the reverse direction defined in the wiring diagram is the negative pole; when the measuring node receives the reverse direction signal, the reverse direction defined in the wiring diagram is the positive pole, and the positive direction defined in the wiring diagram is the negative pole. When there are two or more positive polarity marks in a certain section and no negative polarity marks, it is the fault section.

[0056] The technical solution of this embodiment solves the problems that after the access of distributed power sources in the distribution network, affected by factors such as the多变 operation mode of the distribution network and the dynamic change of the real-time power generation power of distributed power sources, compared with the traditional power grid, it is difficult to predict the fault current and match the setting values during grid faults, and it is difficult to accurately locate the fault section after the fault through the operation of relay protection. The present invention calculates the impedance direction within the protection range of the measuring point through the method of calculating the fault transient impedance and sends it to the master station, and then accurately locates the fault point through the topology analysis of the master station. It has the advantages of accurate fault location, small calculation amount, and can adapt to various complex power grids. Judging faults according to the states of each node in the entire wiring topology diagram and comprehensively judging the fault section by each node can solve the problem that during a fault, there may be fault current flowing upstream or downstream of the fault point, and the fault section cannot be judged only by the fault current, time, etc.

[0057] Figure 2 It is a module schematic diagram of a medium-voltage line fault location device provided by an embodiment of the present invention. The medium-voltage line fault location method is executed by this device, and the device is integrated in the master station. The master station only needs to obtain the node status sent by the monitoring device, without obtaining the voltage amplitude, phase, current amplitude, and phase of each phase.

[0058] Optionally, referring to Figure 2 , the medium-voltage line fault location device includes:

[0059] The node status acquisition module 10 is used to acquire the node status 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, 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 status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node;

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

[0061] Specifically, a 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 based on the collected voltage and current data, and compare the calculated impedance size and impedance angle with the preset impedance to determine the positive and negative directions of each line monitoring node. According to the wiring topology diagram of the known distribution network line, the monitoring device is matched to the corresponding position of the wiring topology diagram, and the positive and negative directions of the monitoring device are matched one by one, and the positive and negative directions of each node are marked on the wiring topology diagram. According to the marking results of each node on the wiring topology diagram, the line fault section is determined.

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

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

[0064] When the impedance of the line monitoring node is less than or equal to 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.

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

[0066] Optionally, different line monitoring nodes have different setting values.

[0067] Optionally, the fault section determination module is specifically used for:

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

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

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

[0071] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0072] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for locating a medium voltage line fault. It is characterized in that include: Obtaining the node status 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 obtain 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 status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node; The node status of each line monitoring node is marked in the wiring topology diagram, and the line fault section is determined according to the marking result.

2. The fault location method according to claim 1, Features: 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 a 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 or equal to a set value and the impedance angle is not within a preset angle range, the node state of the line monitoring node is a second state.

3. The fault location method according to claim 2, Features: Different line monitoring nodes have different setting values.

4. The fault location method according to claim 2, It is characterized in that Marking the node status of each line monitoring node in the wiring topology diagram, and determining the line fault section according to the marking result, including: When the node states of all the line monitoring nodes in the line section are in the first state, the line section is determined as a line fault section.

5. The fault location method according to claim 2, It is characterized in that Marking the node status of each line monitoring node in the wiring topology diagram, and determining the line fault section according to the marking result, including: 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 wiring topology diagram.

6. A medium voltage line fault location device, It is characterized in that include: A node status acquisition module, used to acquire the node status 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, 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 status of the line monitoring node according to the impedance size and impedance angle of the line monitoring node; The fault section determination module is used to mark the node status of each line monitoring node in the wiring topology diagram and determine the line fault section according to the marking result.

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

8. The fault locating device according to claim 7, Features: Different line monitoring nodes have different setting values.

9. The fault locating device according to claim 7, It is characterized in that The fault section determination module is specifically used for: When the node states of all the line monitoring nodes in the line section are in the first state, the line section is determined as a line fault section.

10. A medium voltage line fault location system, It is characterized in that include: A node monitoring device and a medium voltage line fault locating device as described in any one of claims 6 to 9.

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