System and method for locating three-phase cable faults in medium voltage distribution network

Abstract

The present invention relates to a medium-voltage distribution network three-phase cable fault location system and method based on transient residual current, the system comprising: a terminal subsystem for obtaining transient residual current data of a three-phase cable of a distribution network; a network subsystem for remote communication of the terminal subsystem; a cloud computing subsystem for fault location; a display module for displaying the fault location result; the network subsystem is respectively connected to the terminal subsystem and the cloud computing subsystem, the cloud computing subsystem is connected to the display module, and the terminal subsystem comprises a plurality of terminals, each of which is arranged on a three-phase cable outside a ring network cabinet or a distribution station. Compared with the prior art, the present invention locates the fault of a three-phase cable of a medium-voltage distribution network only by transient residual current, and determines the fault position by multiple location identification algorithms, and has the advantages of high accuracy of the location result, convenience and reliability, etc.

Description

Technical Field

[0001] The present invention relates to the field of distribution network fault detection, and in particular to a medium-voltage distribution network three-phase cable fault location system and method based only on transient residual current. Background Art

[0002] The multi-branch distribution network composed of power supply, ring network cabinet and cable is the basic infrastructure for power supply guarantee. However, due to external environment and internal quality, the short circuit fault between phases of three-phase cables in the distribution network will affect the reliability of power supply. Once the cable fails, it is necessary to quickly know the fault location and eliminate the fault as soon as possible.

[0003] At present, the conventional online cable fault location methods are basically online monitoring methods using cable detection terminals, such as "cable phase / ground current mutation ratio method" and "fault traveling wave point-to-point distance measurement method". Since fault traveling waves propagate on the line at the speed of light, these methods are basically used on long-distance transmission lines to determine the fault location of the cable online.

[0004] However, due to the short length of the cable section of the medium-voltage distribution network, the vertical and horizontal interconnection between the trunk and branches of the distribution network, and the criss-crossing of the three-phase distribution network cables with a mesh-like multi-level distribution, the previous manual offline troubleshooting method to find the fault location is inefficient. Therefore, it is currently necessary to install online monitoring devices for the current and voltage data information of the three-phase line and the grounding line on the three-phase cable of the medium-voltage distribution network under the conditions of power outage and opening the box door to understand the fault message, and quickly and accurately identify and locate the phase-to-phase short-circuit fault of the three-phase cable of the medium-voltage distribution network. The main task of online monitoring. However, in order to improve the power supply reliability of the distribution network, it is necessary to realize the installation and fault location monitoring of the online monitoring device of the three-phase cable fault of the medium-voltage distribution network without opening the box door and without power outage. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a system and method for locating three-phase cable faults in a medium-voltage distribution network based only on transient residual current without opening the box door or shutting down the power supply.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A medium voltage distribution network three-phase cable fault location system based on transient residual current, comprising:

[0008] The terminal subsystem is used to obtain the fault transient residual current waveform data of the three-phase cable of the medium voltage distribution network;

[0009] Network subsystem, used for remote communication of terminal subsystem;

[0010] Cloud computing subsystem, used for fault location;

[0011] Display module, used to display the fault location result;

[0012] The network subsystem is respectively connected to the terminal subsystem and the cloud computing subsystem, the cloud computing subsystem is connected to the display module, and the terminal subsystem includes a plurality of terminals, each of which is arranged on a three-phase cable outside the ring network cabinet or the distribution station.

[0013] Furthermore, the network subsystem includes:

[0014] Low-power wide-area Internet of Things, used for communication between terminals within the terminal subsystem;

[0015] Narrowband wide-area Internet of Things or wireless ad hoc network is used for communication between terminal subsystem and cloud computing subsystem.

[0016] Furthermore, the terminal includes a power supply for supplying power to the terminal, a Rogowski coil sensor, a collector, a memory, an embedded computing module, a fault arc identification module and a communication module, the collector is connected to the Rogowski coil sensor and the embedded computing module, the embedded computing module is also connected to the memory and the fault arc identification module, the fault arc identification module is connected to the communication module, and the Rogowski coil sensor includes an open Rogowski coil.

[0017] Furthermore, the arc fault identification module is an FPGA chip or CPU integrated with arc fault identification software. Based on the fact that cable short circuit and ground fault must have arc fault, the arc must generate a characteristic harmonic spectrum of arc fault on the line, and the arc fault identification module identifies the arc fault characteristics of the fault wave, thereby improving the accuracy of distinguishing three-phase cable faults in the distribution network.

[0018] Furthermore, the communication module includes a LoRa chip or a LoRa module, and a NB-IOT network card or a MESH network card.

[0019] Furthermore, the communication module also includes a near field communication module or a Bluetooth module for communicating with the mobile terminal, thereby realizing on-site information interaction between the mobile terminal of the inspection personnel and the terminal subsystem of the fault location system.

[0020] A method for locating a three-phase cable fault in a medium voltage distribution network using the above system, the method comprising the following steps:

[0021] Terminal installation steps: install each terminal in the terminal subsystem on the outer sheath of the three-phase cable outside the ring main unit or distribution station;

[0022] Network configuration steps: configure the network subsystem for the terminal subsystem;

[0023] Data acquisition step: The cloud computing subsystem acquires the transient residual current waveform data of the three-phase cable fault sensed and identified by each terminal through the network subsystem transmitted by the terminal subsystem; Fault location step: Based on the transient residual current waveform data of the three-phase cable fault sensed and identified by each terminal, the cloud computing subsystem locates the position of the three-phase cable fault section distributed on the distribution network frame through multiple fault location identification algorithms on the pre-established distribution network architecture; Fault display step: The cloud computing subsystem displays the fault location result and the pre-established distribution network architecture on the display module.

[0024] Furthermore, the multiple identification algorithms are located at least two of the amplitude peak sorting identification algorithm, the wave time valley sorting identification algorithm and the terminal correlation calculation identification algorithm. At least two schemes are used to determine the fault location result, and each scheme is independent of each other and does not affect each other, thereby improving the accuracy and reliability of the location result of the fault location method of the present invention.

[0025] Furthermore, the amplitude peak sorting identification algorithm is specifically that the cloud computing subsystem performs amplitude peak sorting on the current waveform of the transient residual current waveform data of each terminal, and the fault location is the fault section location of the three-phase cable between the terminals corresponding to the two current waveforms with the highest amplitude peak values.

[0026] Furthermore, the wave-time valley sequence sorting identification algorithm is specifically that the cloud computing subsystem sorts the moment information data of the transient residual current waveform data of each terminal in wave-time valley sequence, and the fault location is the fault section location of the three-phase cable between the terminals corresponding to the two current waveforms with the lowest wave-time valley sequence.

[0027] Furthermore, the terminal correlation calculation and identification algorithm is specifically that each adjacent terminal performs chain transmission type fault wave communication, and the cloud computing subsystem performs fault location based on the chain transmission fault wave communication information between the terminals;

[0028] The chain transmission fault wave communication of the adjacent terminals is specifically that when a terminal obtains the fault transient residual current wave data, it generates an obtained message and transmits it to the adjacent terminal, and the obtained message includes the location information of the terminal and the time information when the terminal obtains the fault transient residual current wave data;

[0029] The cloud computing subsystem performs fault location based on the fault wave communication information transmitted in a chain between terminals. Specifically, the cloud computing subsystem determines the fault location as the location of the three-phase cable segment between the terminals corresponding to the earliest two time information based on the fault wave communication information transmitted in a chain between terminals. The terminal correlation calculation scheme is a blockchain-based fault location scheme. Through the fault communication chain between each terminal, the fault location is determined based on the time information of the fault communication. This scheme does not need to identify the fault transient residual current wave data, and is independent of the amplitude peak sorting identification algorithm and the wave time valley sorting identification algorithm, further improving the accuracy of the location result.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) The present invention relies only on a single, fleeting source of information, namely, transient residual current on a three-phase cable in a medium-voltage distribution network when a cable fault occurs. The terminal subsystem, the network subsystem, the cloud computing subsystem, and the display module are used to locate the terminal at the fault location in the terminal subsystem. Each terminal of the terminal subsystem is arranged on the outer sheath of the three-phase cable outside the ring main cabinet or the distribution station, so that the three-phase cable segment with the fault can be located without power outage or door opening. Therefore, the fault location system of the present invention has the advantages of being convenient and reliable.

[0032] (2) The present invention adopts multiple positioning and identification algorithm schemes to locate the fault. The multiple positioning schemes are at least two schemes among the amplitude peak sorting scheme, the wave time valley sorting scheme and the terminal correlation calculation scheme, which further improves the accuracy of the fault location result.

[0033] (3) The amplitude peak sorting identification algorithm, the wave time valley sorting identification algorithm and the terminal correlation calculation identification algorithm of the present invention are independent of each other and are not affected by other schemes.

[0034] (4) The terminal of the present invention obtains the transient residual current of the three-phase cable through the Rogowski coil sensor. The Rogowski coil sensor is installed on the outer sheath of the three-phase cable outside the ring network cabinet. During installation, there is no need to power off the ring network cabinet and open the door, which does not affect the power supply reliability of the power grid.

[0035] (5) The terminal of the present invention is provided with a fault arc identification module. The fault arc identification module is based on the fact that cable short circuit and ground fault will inevitably cause fault arc, and the arc will inevitably generate a harmonic spectrum with fault arc characteristics on the line. By re-identifying the extracted fault waveform data, the waveform with fault arc characteristics is extracted, and the waveform belonging to the normal disturbance range is filtered out, thereby improving the accuracy of distinguishing three-phase cable faults in the medium-voltage distribution network.

[0036] (6) Each terminal communication module of the terminal subsystem of the present invention includes a near field communication module or a Bluetooth module, which realizes on-site information interaction between the mobile terminal of the inspection personnel and the terminal subsystem of the present fault location system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the fault location system of the present invention;

[0038] Figure 2 A schematic diagram of the terminal installation position of the terminal subsystem of the present invention;

[0039] Figure 3 It is a schematic diagram of the structure of the terminal of the present invention;

[0040] Figure 4 is a schematic diagram of a network subsystem of the present invention;

[0041] Figure 5 A schematic diagram of a network subsystem including a mobile terminal according to the present invention;

[0042] Figure 6 It is a schematic diagram of the flow of the method for locating a three-phase cable fault in a distribution network of the present invention. DETAILED DESCRIPTION

[0043] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0044] Example 1

[0045] like Figure 1 As shown, this embodiment is a medium voltage distribution network three-phase cable fault location system based on transient residual current, the system comprising:

[0046] The terminal subsystem 10 is used to identify and obtain the fault transient residual current waveform data of the three-phase cable of the medium voltage distribution network;

[0047] The network subsystem 20 is used for remote communication of the terminal subsystem 10;

[0048] A cloud computing subsystem 30, used for fault location;

[0049] Display module 40, used to display the fault location result;

[0050] The network subsystem 20 is connected to the terminal subsystem 10 and the cloud computing subsystem 30 respectively, and the cloud computing subsystem 30 is connected to the display module 40 .

[0051] The terminal subsystem 10, the network subsystem 20 and the display module 40 are described in detail below:

[0052] 1. Terminal subsystem 10

[0053] like Figure 2 As shown, the terminal subsystem 10 includes a plurality of terminals 100, each of which is arranged on an outer sheath of a three-phase cable outside a ring main unit or a distribution station.

[0054] like Figure 3 As shown, the terminal 100 includes a power supply 1 for supplying power to the terminal, a Rogowski coil sensor 2, a collector 3, a memory 4, an embedded computing module 5, a fault arc identification module 6 and a communication module 7. The collector 3 is connected to the Rogowski coil sensor 2 and the embedded computing module 5. The embedded computing module 5 is also connected to the memory 4 and the fault arc identification module 6. The fault arc identification module 6 is connected to the communication module 7.

[0055] The Rogowski coil inductor 2 is composed of an open Rogowski coil 201 and an integrator 202. The Rogowski coil 201 is a non-invasive open Rogowski coil, and the integrator 202 is a high-frequency integrator 202. The non-invasive open Rogowski coil is installed on the outer sheath of the three-phase cable outside the ring main unit without powering off the ring main unit. The open Rogowski coil 201 responds to the electromagnetic field changes caused by the residual current of the three-phase cable in real time. These changes are converted into digital signals through the sensing of the high-frequency integrator 202 and sent to the collector 3.

[0056] The collector 3 is a high-speed clock-synchronized collector 3, which can be a high-speed collector 3 synchronized by GPS / Beidou navigation satellite. The collector 3 collects the digital signal converted by the Rogowski coil sensor 2 online, and generates time-stamped three-phase cable residual current wave data in the control system of the embedded computing module 5, and stores the data in the memory 4.

[0057] The memory 4 stores and updates a plurality of three-phase cable residual current waveform data with time stamps in a stacked manner, and synthesizes them into three-phase cable residual current waveform data with time stamps, and pushes them to the embedded computing module 5 according to their timing.

[0058] The embedded computing module 5 is a CPU. The embedded computing module 5 contains control software stored in the control memory 4 and related computing software for identifying the residual current waveform data of a three-phase cable fault, and identifies suspected fault waveform data with mutation and transient characteristics. The identification measures implemented by the related computing software for identifying the residual current waveform data of a three-phase cable fault include second-level delay avoidance and specific frequency band bandpass filtering.

[0059] The arc fault identification module 6 in this embodiment is an FPGA chip integrated with arc fault identification software.

[0060] The arc fault identification module 6 re-identifies the suspected fault waveform data with mutation and transient characteristics identified by the embedded computing module 5, and identifies the fault waveform data with arc fault characteristics, which is data information composed of transient residual current waveform and time information data caused by a three-phase cable phase-to-phase short circuit fault. This embodiment determines the fault waveform data with arc fault characteristics by identifying the duration, transient, phase, and harmonic characteristics of the waveform.

[0061] The fault arc identification module is based on the fact that cable short circuit and grounding fault will inevitably cause fault arc, and the arc will inevitably generate a harmonic spectrum with fault arc characteristics on the line. By re-identifying the suspected fault waveform data with mutation and transient characteristics, the waveform with fault arc characteristics is extracted, and the waveform belonging to the normal disturbance range is filtered out, thereby improving the accuracy of distinguishing three-phase cable faults in the distribution network.

[0062] 2. Network subsystem 20

[0063] like Figure 4 As shown, the network subsystem 20 includes: a low-power wide-area Internet of Things LoRa, which is used for communication between the terminals 100 in the terminal subsystem 10; a narrowband wide-area Internet of Things NB-IOT or a wireless ad hoc network MESH, which is used for communication between the terminal subsystem 10 and the cloud computing subsystem 30.

[0064] Correspondingly, the communication module 7 of each terminal 100 in the terminal subsystem 10 can adopt a LoRa chip or a LoRa module, and a NB-IOT network card or a MESH network card. This embodiment adopts a LoRa chip and a NB-IOT network card.

[0065] 3. Display module 40

[0066] In this embodiment, a PC is used as the display module 40 .

[0067] Example 2

[0068] like Figure 5 As shown, this embodiment is substantially the same as the fault location system of embodiment 1, except that the display module 40 is provided on the mobile terminal 50. The mobile terminal 50 is provided with a fault location app, and the display module 40 is a screen on the mobile terminal 50.

[0069] Correspondingly, the communication module 7 of each terminal 100 in the terminal subsystem 10 may adopt a near field communication NFC module or a Bluetooth module for communication between the terminal subsystem 10 and the mobile terminal 50. This embodiment adopts a near field communication NFC module.

[0070] Example 3

[0071] like Figure 6 As shown, the present invention implements a method for locating a three-phase cable fault in a medium voltage distribution network using the system of Example 1, and the method includes the following steps:

[0072] Terminal installation step S1: each terminal 100 in the terminal subsystem 10 is installed on the outer sheath of the three-phase cable outside the ring main unit or the distribution station;

[0073] Network configuration step S2: configuring the network subsystem 20 for the terminal subsystem 10;

[0074] Data acquisition step S3: the cloud computing subsystem 30 acquires the three-phase cable fault transient residual current waveform data sensed and identified by each terminal through the terminal subsystem 10 and transmitted by the network subsystem 20;

[0075] Fault location step S4: The cloud computing subsystem 30 locates the position of the three-phase cable fault section distributed on the distribution network frame through multiple fault location identification algorithm schemes on the pre-established distribution network frame based on the transient residual current waveform data of the three-phase cable fault sensed and identified by each terminal 100;

[0076] Fault display step S5: the cloud computing subsystem 30 displays the fault location result and the pre-established distribution network architecture on the display module 40.

[0077] The multiple positioning schemes are the amplitude peak sorting identification algorithm S41, the wave time valley sorting identification algorithm S42 and the terminal correlation calculation identification algorithm S43.

[0078] The amplitude peak sorting identification algorithm S41 is specifically that the cloud computing subsystem 30 performs amplitude peak sorting on the current waveform of the three-phase cable fault transient residual current data sensed and identified by each terminal 100, and the fault location is the location of the three-phase cable segment between the terminals corresponding to the two current waveforms with the highest amplitude peaks.

[0079] The wave-time valley sequence sorting identification algorithm S42 is specifically that the cloud computing subsystem 30 sorts the moment information data of the transient residual current data of the three-phase cable fault sensed and identified by each terminal 100 in wave-time valley sequence, and the fault position is the position of the three-phase cable segment between the terminals corresponding to the two current waveforms with the lowest wave-time valley sequence.

[0080] The terminal correlation calculation identification algorithm S43 is specifically that each adjacent terminal 100 performs chain transmission fault wave communication, and the cloud computing subsystem 30 performs fault location based on the fault communication information between the terminals;

[0081] The chain transmission fault wave communication of each adjacent terminal is specifically as follows: when a terminal 100 obtains the fault transient residual current wave data, it generates an obtained message and transmits it to the adjacent terminal 100, wherein the obtained message includes the location information of the terminal 100 and the time information when the terminal 100 obtains the fault transient residual current data;

[0082] The cloud computing subsystem 30 performs fault location based on the fault wave communication information transmitted in a chain between terminals. Specifically, the cloud computing subsystem 30 determines the fault location as the location of the three-phase cable between the terminals 100 corresponding to the earliest two time information, based on the fault wave communication information transmitted in a chain between the terminals 100. The common fault location of at least two of the amplitude peak sorting scheme S41, the wave time valley sorting scheme S42, and the terminal correlation calculation scheme S43 is used as the fault location result. The display module 40 displays the pre-established medium-voltage distribution network primary line architecture and / or geographic information map. Based on the fault location result, the location of the three-phase cable segment where the fault occurs is displayed on the pre-established medium-voltage distribution network architecture and / or geographic information map.

[0083] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A three-phase cable fault location system for medium voltage distribution network based on transient residual current, characterized in that: include: A terminal subsystem (10) is used to obtain a single source of information data, namely transient residual current data of a three-phase cable in a medium voltage distribution network; A network subsystem (20), used for remote communication of the terminal subsystem; The cloud computing subsystem (30) is used to locate the position of the three-phase cable fault section distributed on the distribution network frame through multiple fault location identification algorithms on the pre-established distribution network frame based on the transient residual current waveform data of the three-phase cable fault sensed and identified by each terminal subsystem (10); A display module (40), used to display the fault location result; The network subsystem (20) is respectively connected to the terminal subsystem (10) and the cloud computing subsystem (30); the cloud computing subsystem (30) is connected to the display module (40); the terminal subsystem (10) comprises a plurality of terminals (100); each terminal (100) is arranged on an outer sheath of a three-phase cable outside a ring main unit or a power distribution station; The network subsystem (20) comprises: A low power wide area Internet of Things, used for communication between terminals (100) in the terminal subsystem; A narrowband wide area Internet of Things or a wireless ad hoc network, used for communication between the terminal subsystem (10) and the cloud computing subsystem (30); The terminal (100) comprises a power supply (1) for supplying power to the terminal, a Rogowski coil inductor (2), a collector (3), a memory (4), an embedded computing module (5), a fault arc identification module (6) and a communication module (7); the collector (3) is connected to the Rogowski coil inductor (2) and the embedded computing module (5); the embedded computing module (5) is further connected to the memory (4) and the fault arc identification module (6); the fault arc identification module (6) is connected to the communication module (7); the Rogowski coil inductor (2) comprises an open Rogowski coil (201); The multiple fault location identification algorithms are at least two of the following: an amplitude peak sorting identification algorithm, a wave time valley sorting identification algorithm, and a terminal correlation calculation identification algorithm; The peak amplitude sorting and identification algorithm is specifically that the cloud computing subsystem (30) sorts the current waveforms of transient residual current data of each terminal by peak amplitude, and the fault location is the location of the three-phase cable segment between the terminals corresponding to the two current waveforms with the highest peak amplitudes; The wave-time valley sequence sorting identification algorithm is specifically that the cloud computing subsystem (30) sorts the moment information data of the transient residual current data of each terminal in wave-time valley sequence, and the fault position is the position of the three-phase cable segment between the terminals corresponding to the two current waveforms with the lowest wave-time valley sequence; The terminal correlation calculation and identification algorithm is specifically that chain-transmission type fault wave communication is performed between adjacent terminals, and the cloud computing subsystem (30) performs fault location based on the fault wave chain-transmission type communication information between the terminals; The fault communication between the adjacent terminals is specifically that when a terminal obtains transient residual current data, an obtained message is generated and transmitted to the adjacent terminal via the low-power wide-area Internet of Things, and the obtained message includes the location information of the terminal and the time information when the terminal obtains the transient residual current data; The cloud computing subsystem (30) performs fault location based on the chain-transmission type fault wave communication information between terminals. Specifically, the cloud computing subsystem (30) determines the fault location as the location of the three-phase cable segment between the terminals corresponding to the earliest two time information based on the chain-transmission type fault wave communication information between the terminals.

2. A medium voltage distribution network three-phase cable fault location system based on transient residual current according to claim 1, characterized in that: The communication module (7) comprises a LoRa chip or a LoRa module, and a NB-IOT network card or a MESH network card.

3. A medium voltage distribution network three-phase cable fault location system based on transient residual current according to claim 1, characterized in that: The communication module (7) also includes a near field communication module or a Bluetooth module for communicating with a mobile terminal.

4. A method for locating three-phase cable faults in a medium voltage distribution network using the system of claim 1, characterized in that: The method comprises the following steps: Terminal installation step: each terminal in the terminal subsystem (10) is arranged on the outer sheath of the three-phase cable outside the ring main unit or the distribution station; Network configuration step: configuring the network subsystem (20) for the terminal subsystem (10); Data acquisition step: the cloud computing subsystem (30) acquires the three-phase cable fault transient residual current waveform data sensed and identified by each terminal (100) and transmitted by the terminal subsystem (10) via the network subsystem (20); Fault location step: the cloud computing subsystem (30) locates the position of the three-phase cable fault section distributed on the distribution network frame through multiple fault location identification algorithms on the pre-established distribution network frame based on the transient residual current waveform data of the three-phase cable fault sensed and identified by each terminal (100); Fault display step: the cloud computing subsystem (30) displays the fault location result and the pre-established distribution network architecture on the display module (40).

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