Distributed feeder automation protection fault positioning and power supply recovery method and system

Abstract

The embodiment of the invention discloses a distributed feeder automation protection fault positioning and power supply recovery method and system. The method comprises the following steps: collecting short-circuit current of a distributed power supply, judging that a short-circuit fault occurs in a first power distribution network according to the short-circuit current, controlling a branch switch to open, and cutting off the distributed power supply; a fault point is positioned through differential protection, disconnecting switches on the two sides of the fault point are controlled to be switched off, and a first GOOSE signal is sent; and the first isolation switch of the second power distribution network controls the interconnection switch to be switched on according to the residual capacity of the second power distribution network and the first GOOSE signal, and the second power distribution network supplies power to a non-fault area of the first power distribution network. According to the technical scheme provided by the invention, the safety and reliability of fault positioning and power supply recovery of distributed feeder automation protection are improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of distribution network automation, and in particular to a distributed feeder automation protection fault location and power supply restoration method and system. Background Art

[0002] At present, with the development of new energy sources such as photovoltaics, more and more distributed power sources are connected to the power grid, forming a complex multi-power distribution network structure. Although the capacity of distributed power sources is relatively small compared to the main line, distributed power sources will provide a certain short-circuit current, making it difficult for traditional intelligent distributed feeder automation (FA) logic to locate the actual fault point through node overcurrent, and it cannot be applied to the hybrid grid of multiple power sources.

[0003] At present, there are two common ways to implement the interconnection switch power transfer after the fault isolation is successful: local voltage loss judgment and centralized topology analysis. In the local voltage loss judgment method, the interconnection switch judges that one side has voltage loss and closes the switch to transfer power, which may face problems such as insufficient capacity and overload operation, and the power supply quality cannot be guaranteed and may cause equipment damage. The centralized topology analysis method mainly makes a comprehensive judgment based on the information sent from each area of ​​the master station, and the real-time and reliability cannot be guaranteed.

[0004] The existing distributed feeder automation protection fault location and power supply restoration methods have problems with poor safety and reliability, which has become a technical problem that needs to be solved urgently in the industry. Summary of the invention

[0005] The embodiment of the present invention provides a distributed feeder automation protection fault location and power supply restoration method and system to solve the problem of poor safety and reliability of the existing distributed feeder automation protection fault location and power supply restoration method.

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

[0007] An embodiment of the present invention provides a distributed feeder automation protection fault location and power supply restoration method, the method is applied to a distributed feeder automation protection fault location and power supply restoration system, the system comprising:

[0008] A distributed power source, a first distribution network, and a second distribution network, wherein a tie switch is connected between the first distribution network and the second distribution network; a branch switch is connected between the distributed power source and the first distribution network; and the method comprises:

[0009] Collecting the short-circuit current of the distributed power source, determining that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and controlling the branch switch to open to cut off the distributed power source;

[0010] Locate the fault point through differential protection, control the disconnectors on both sides of the fault point to disconnect and send a first GOOSE signal;

[0011] The first isolating switch of the second distribution network controls the connecting switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0012] Optionally, the collecting the short-circuit current of the distributed power source, determining that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and controlling the branch switch to open to cut off the distributed power source includes:

[0013] The branch switch collects the short-circuit current of the distributed power source;

[0014] When the distributed power source provides a short-circuit current, determining that a short-circuit fault occurs in the first distribution network connected to the distributed power source;

[0015] The branch switch of the first distribution network is opened by overcurrent speed-breaking protection to cut off the distributed power source.

[0016] Optionally, locating the fault point by differential protection, controlling disconnectors on both sides of the fault point to disconnect and sending a first GOOSE signal includes:

[0017] The first distribution network locates the fault point through differential protection, and the first isolating switch upstream of the fault point and the second isolating switch downstream of the fault point are both opened;

[0018] The first isolating switch sends a "fault isolation successful" GOOSE signal and a "node fault" GOOSE signal through the first data transmission terminal within a first preset time;

[0019] The second isolating switch is used to calculate the maximum load of the fault area of ​​the first distribution network where the fault point is located based on the cached data before the fault, and send "fault isolation successful" and "fault load" GOOSE signals to the adjacent isolating switches through the second data transmission terminal; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal, a "node fault" GOOSE signal and a "fault load" GOOSE signal.

[0020] Optionally, the first isolating switch of the second distribution network controls the tie switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network, including:

[0021] The first isolating switch of the second distribution network receives the “fault isolation successful” GOOSE signal through the fourth data transmission terminal;

[0022] The first disconnector of the second distribution network determines the remaining capacity of the second distribution network according to the current power supply load of the second distribution network and the power supply capacity of the second distribution network;

[0023] The first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; and sends a "transfer allowed" GOOSE signal to an adjacent disconnector through the fourth data transmission terminal according to the comparison result;

[0024] The tie switch receives the "transfer allowed" GOOSE signal through the third data transmission terminal, closes according to the "transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0025] Optionally, the first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; and sends a "transfer allowed" GOOSE signal to an adjacent disconnector through a fourth data transmission terminal according to the comparison result, including:

[0026] Obtaining a margin coefficient of the second distribution network;

[0027] Subtract the product of the fault load of the first distribution network and the margin coefficient from the remaining capacity of the second distribution network to obtain a comparison result;

[0028] When the remaining capacity of the second distribution network is greater than or equal to the product of the fault load of the first distribution network and the margin coefficient, a "transfer allowed" GOOSE signal is sent to the adjacent disconnector through the fourth data transmission terminal;

[0029] The adjacent isolating switch receives the "power transfer allowed" GOOSE signal through the third data transmission terminal, and the adjacent isolating switch in the closed state transmits the "power transfer allowed" GOOSE signal to the contact switch.

[0030] Optionally, the tie switch receives the “transfer allowed” GOOSE signal through a third data transmission terminal, closes the switch according to the “transfer allowed” GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network, including:

[0031] The tie switch receives the "power transfer allowed" GOOSE signal through the third data transmission terminal, starts power transfer judgment, and judges that the tie switch meets the conditions that there is no voltage on the fault side, there is voltage on the non-fault side of the tie switch, and there is no discharge condition for the tie switch;

[0032] The tie switch delays for a second preset time, performs power transfer and closing, and restores power supply to the non-fault area of ​​the first distribution network.

[0033] According to another aspect of the present invention, this embodiment provides a distributed feeder automation protection fault location and power supply restoration system, including:

[0034] A distributed power source, a first distribution network and a second distribution network, wherein a tie switch is connected between the first distribution network and the second distribution network; a branch switch is connected between the distributed power source and the first distribution network;

[0035] The branch switch is used to collect the short-circuit current of the distributed power source, determine that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and open the switch to cut off the distributed power source;

[0036] The isolating switch of the first distribution network is used to locate the fault point through differential protection, control the isolating switches on both sides of the fault point to disconnect and send a first GOOSE signal;

[0037] The isolating switch of the second distribution network is used to control the closing of the tie switch according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0038] Optionally, the branch switch is specifically used to: collect the short-circuit current of the distributed power source; when the distributed power source provides a short-circuit current, determine that a short-circuit fault occurs in the first distribution network connected to the distributed power source; and the branch switch of the first distribution network is used to disconnect the distributed power source by opening the switch through overcurrent fast-breaking protection.

[0039] Optionally, the first distribution network is specifically used to: locate the fault point through differential protection, and the first isolating switch upstream of the fault point and the second isolating switch downstream of the fault point are evenly disconnected; the first isolating switch is used to send a "fault isolation success" GOOSE signal through a first data transmission terminal within a first preset time, and send a "node failure" GOOSE signal;

[0040] The second isolating switch is used to calculate the maximum load of the fault area of ​​the first distribution network where the fault point is located based on the cached data before the fault, and send "fault isolation successful" and "fault load" GOOSE signals to the adjacent isolating switches through the second data transmission terminal; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal, a "node fault" GOOSE signal and a "fault load" GOOSE signal.

[0041] Optionally, the first isolating switch of the second distribution network is used to receive the "fault isolation successful" GOOSE signal through a fourth data transmission terminal; determine the remaining capacity of the second distribution network according to the current power supply load of the second distribution network and the power supply capacity of the second distribution network; and compare the remaining capacity of the second distribution network with the fault load; according to the comparison result, send a "transfer allowed" GOOSE signal to the adjacent isolating switch through the fourth data transmission terminal;

[0042] The contact switch is used to receive the "transfer allowed" GOOSE signal through the third data transmission terminal, close the switch according to the "transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0043] The distributed feeder automatic protection fault location and power supply restoration method provided in the embodiment of the present invention first collects the short-circuit current of the distributed power source through the branch switch, determines that the first distribution network has a short-circuit fault based on the short-circuit current, and cuts off the distributed power source. Then, the fault point is located through the differential protection of the isolating switch of the first distribution network, and the isolating switches on both sides of the fault point are controlled to disconnect and send a first GOOSE signal. Finally, the first isolating switch of the second distribution network controls the closing of the connecting switch according to the remaining capacity of the second distribution network and the first GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network. The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment can not only isolate the fault in time, but also restore the power supply to the non-fault area of ​​the first distribution network, thereby improving the real-time fault removal of the first distribution network connected to the distributed power source and the reliability of load power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] 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 of the present invention. 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 the contents of the embodiments of the present invention and these drawings without paying any creative work.

[0045] Figure 1 It is a flow chart of a distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention;

[0046] Figure 2 It is a structural schematic diagram of a distributed feeder automation protection fault location and power supply restoration system provided by an embodiment of the present invention;

[0047] Figure 3 It is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention;

[0048] Figure 4 It is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention;

[0049] Figure 5 It is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention;

[0050] Figure 6 It is a schematic diagram of a node model of an isolating switch provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0052] Based on the above technical problems, this embodiment proposes the following solutions:

[0053] Figure 1 The present invention provides a flow chart of a distributed feeder automation protection fault location and power supply restoration method. Figure 2 1 is a schematic diagram of the structure of a distributed feeder automation protection fault location and power supply restoration system provided by an embodiment of the present invention. Figure 1 and Figure 2 The distributed feeder automation protection fault location and power supply restoration method provided in the embodiment of the present invention is performed by a distributed feeder automation protection fault location and power supply restoration system. The distributed feeder automation protection fault location and power supply restoration system includes: a distributed power source, a first distribution network and a second distribution network, wherein a tie switch is connected between the first distribution network and the second distribution network; and a branch switch is connected between the distributed power source and the first distribution network.

[0054] See also Figure 2 , the first distribution network and the second distribution network may be the same or different. The first distribution network and the second distribution network are both power networks composed of multiple components, which may mainly include overhead lines, cables, poles, distribution transformers, circuit breakers, disconnectors, reactive power compensators and some ancillary facilities. These components work together to distribute electrical energy to various users locally or step by step according to voltage through distribution facilities. The distribution network plays an important role in distributing electrical energy in the power system, and its structure is usually a closed-loop design that can meet the needs of different voltage levels. According to the voltage level, the distribution network can be divided into high-voltage distribution network, medium-voltage distribution network and low-voltage distribution network.

[0055] In a place with dual power supply, when the main power supply fails, the tie switch can transfer important loads to the backup power supply to ensure uninterrupted power supply. In the power grid, the tie switch can also be used for load allocation and backup supply during line maintenance to ensure the stable operation of the power grid. For example, when the first distribution network fails, the tie switch can transfer the load of the first distribution network to the second distribution network, thereby improving the reliability and flexibility of power supply. When the second distribution network fails, the tie switch can transfer the load of the second distribution network to the first distribution network, thereby improving the reliability and flexibility of power supply.

[0056] With the development of new energy sources such as photovoltaics, more and more distributed power sources are integrated into the power grid, forming a complex multi-power distribution network structure. A branch switch is connected between the distributed power source and the first distribution network. When the branch switch is closed, the distributed power source is connected to the first distribution network. When the branch switch is opened, the distributed power source is cut off from the first distribution network.

[0057] See also Figure 1 The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment includes:

[0058] S101. Collect the short-circuit current of the distributed power source, determine that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and control the branch switch to open to cut off the distributed power source.

[0059] Specifically, when a short-circuit fault occurs in the first distribution network, the distributed power source will generate a short-circuit current. When the branch switch collects the short-circuit current of the distributed power source, it can be determined that a short-circuit fault has occurred in the first distribution network based on the short-circuit current. The branch switch can be opened to cut off the distributed power source, so that the first distribution network where the fault occurs does not have the distributed power source, which is convenient for fault location and removal.

[0060] S102: locate the fault point through differential protection, control the disconnectors on both sides of the fault point to disconnect and send a first GOOSE signal.

[0061] Specifically, the first distribution network may be provided with a plurality of disconnectors. The differential protection of the disconnector refers to current differential protection, which is a protection method in relay protection. The differential protection uses Kirchhoff's current theorem to determine whether a fault exists by detecting the imbalance of the current and quickly perform protection.

[0062] By connecting complementary current transformers at both ends of the disconnector, the secondary currents of the current transformers are compared and action decisions are made. When the current flowing into the protected device is equal to the current flowing out, and the differential current is zero, it is determined that there is no short-circuit fault; when the current flowing in and out is not equal, and the differential current is greater than zero, it is determined that the device has a fault. When the differential current is greater than the setting value of the differential protection device, the differential protection is activated, and the disconnectors on both sides of the fault point are opened to remove the fault.

[0063] GOOSE signal is the abbreviation of Generic Object Oriented Substation Events, which is mainly used for the needs of fast messages in substation automation systems. It is a mechanism defined in the IEC 61850 standard, which realizes the information exchange between protections and the interlocking function of monitoring intervals through the characteristics of fast Ethernet. GOOSE signals have real-time and low latency. GOOSE messages carry priority / VLAN tags, and Ethernet switches that support VLAN tag protocols will process them in real time according to the priority to ensure the real-time nature of data transmission. GOOSE transmission services are directly mapped to the data link layer and physical layer, without passing through the network layer and transport layer, with short transmission delay, improved reliability and reduced transmission delay, and are particularly suitable for relay protection applications with high real-time requirements. GOOSE signals are used to transmit control instructions and signals, such as switch / knife switch position, control switch position, abnormal / alarm signals, locking signals, etc.

[0064] Exemplarily, the first GOOSE signal may include a signal indicating successful fault isolation of disconnectors on both sides of the fault point and a signal indicating a node fault has occurred, and may also include a power supply capacity required for the fault load of the first distribution network.

[0065] S103: The first isolating switch of the second distribution network controls the connecting switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0066] Specifically, the first isolating switch of the second distribution network refers to the first isolating switch at the power outlet of the second distribution network. The first isolating switch of the second distribution network can send a GOOSE signal based on the remaining capacity of the second distribution network and the received first GOOSE signal, when the first GOOSE signal is received and the remaining capacity of the second distribution network can cover the power supply capacity required for the fault load of the first distribution network. When the connecting switch receives the GOOSE signal sent by the first isolating switch of the second distribution network and the connecting switch meets its own closing conditions, the connecting switch closes. The second distribution network supplies power to the non-fault area of ​​the first distribution network through the turned-on connecting switch, so that the first distribution network can quickly remove the fault and restore power supply to the non-fault area of ​​the first distribution network in time.

[0067] The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment first collects the short-circuit current of the distributed power source through the branch switch, determines that the first distribution network has a short-circuit fault based on the short-circuit current, and cuts off the distributed power source. Then, the fault point is located through the differential protection of the isolating switch of the first distribution network, and the isolating switches on both sides of the fault point are controlled to disconnect and send the first GOOSE signal. Finally, the first isolating switch of the second distribution network controls the closing of the connecting switch according to the remaining capacity of the second distribution network and the first GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network. The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment can not only isolate the fault in time, but also restore the power supply to the non-fault area of ​​the first distribution network, thereby improving the real-time fault removal of the first distribution network connected to the distributed power source and the reliability of load power supply.

[0068] Optionally, based on the above embodiment, Figure 3 FIG. 1 is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention. Figure 3 The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment includes:

[0069] S201. The branch switch collects the short-circuit current of the distributed power source.

[0070] Specifically, the first distribution network is connected to a distributed power source. The distributed power source may include a branch line of a distributed small power source, such as a new energy power source such as photovoltaic power. Although the capacity of the distributed power source is smaller than that of the main line, the distributed power source will also provide a certain short-circuit current. The existence of the short-circuit current will affect the accuracy of the fault point location.

[0071] S202: When the distributed power source provides a short-circuit current, determine that a short-circuit fault occurs in the first distribution network connected to the distributed power source.

[0072] Specifically, the branch switch connected between the distributed power source and the first distribution network determines that a short circuit fault occurs in the first distribution network according to the short circuit current provided by the distributed power source.

[0073] S203. The branch switch of the first distribution network is opened through over-current rapid-break protection to cut off the distributed power source.

[0074] Specifically, the branch switch can cut off the distributed power supply when a fault occurs in the first distribution network through overcurrent protection and island protection. This arrangement makes it easy to eliminate the short-circuit current interference of the distributed power supply, thereby improving the positioning accuracy of the fault point of the first distribution network.

[0075] S102: locate the fault point through differential protection, control the disconnectors on both sides of the fault point to disconnect and send a first GOOSE signal.

[0076] S103: The first isolating switch of the second distribution network controls the connecting switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0077] Optionally, based on the above embodiments, Figure 4 FIG. 1 is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention. Figure 4 The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment includes:

[0078] S101. Collect the short-circuit current of the distributed power source, determine that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and control the branch switch to open to cut off the distributed power source.

[0079] S301. The first distribution network locates a fault point through differential protection, and a first isolating switch upstream of the fault point and a second isolating switch downstream of the fault point are both opened.

[0080] Specifically, when a line of the first distribution network fails, the fault point is located and isolated through line differential protection, bus differential protection, and the like. It can be determined whether the isolating switch is upstream or downstream of the fault point based on the positive and negative values ​​of the differential currents on both sides of the isolating switch. The isolating switch located upstream of the fault point can be determined as the first isolating switch. The isolating switch located downstream of the fault point can be determined as the second isolating switch.

[0081] S302. The first isolating switch sends a "fault isolation successful" GOOSE signal and a "node fault" GOOSE signal through the first data transmission terminal within a first preset time; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal and a "node fault" GOOSE signal.

[0082] Specifically, the first isolating switch located upstream of the fault point blocks and forwards the "fault isolation successful" GOOSE signal within a first preset time from the start of the differential protection to the differential protection action. The first preset time is, for example, 10 seconds, 8 seconds, or 9 seconds. After the first isolating switch performs the differential protection action, the first isolating switch sends the "node fault" GOOSE signal.

[0083] S303, the second isolating switch is used to calculate the maximum load of the fault area of ​​the first distribution network where the fault point is located according to the cached data before the fault, and send "fault isolation successful" and "fault load" GOOSE signals to the adjacent isolating switches through the second data transmission terminal; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal and a "fault load" GOOSE signal.

[0084] Specifically, after the second isolating switch downstream of the fault point is successfully isolated, the maximum load of the fault area of ​​the first distribution network is calculated based on the cached data before the fault. The cached data may include the maximum three-phase load of the first distribution network in a period of time before the fault. The second isolating switch sends a "fault isolation successful" GOOSE signal and a "fault load" GOOSE signal to the adjacent isolating switch. The isolating switches adjacent to the second isolating switch combine and forward the "fault isolation successful" signal and the "fault load" GOOSE signal. The "fault load" GOOSE signal includes an analog value of the "fault load".

[0085] S103: The first isolating switch of the second distribution network controls the connecting switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0086] Optionally, based on the above embodiments, Figure 5 This is a flow chart of another distributed feeder automation protection fault location and power supply restoration method provided by an embodiment of the present invention. Figure 2 and Figure 5 The distributed feeder automatic protection fault location and power supply restoration method provided in this embodiment includes:

[0087] S101. Collect the short-circuit current of the distributed power source, determine that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and control the branch switch to open to cut off the distributed power source.

[0088] S102. The isolating switch of the first distribution network locates the fault point through differential protection, controls the isolating switches on both sides of the fault point to disconnect and sends a first GOOSE signal.

[0089] S501. The first isolating switch of the second distribution network receives the "fault isolation successful" GOOSE signal through the fourth data transmission terminal.

[0090] Specifically, the first isolating switch of the second distribution network is the isolating switch closest to the power supply of the second distribution network. The fourth data transmission terminal in the second distribution network mainly realizes data collection and transmission. The first isolating switch is located closest to the second power supply S2, and the current power supply load of the second distribution network can be calculated more accurately through the first isolating switch.

[0091] S502: The first isolating switch of the second distribution network determines the remaining capacity of the second distribution network according to the current power supply load of the second distribution network and the power supply capacity of the second distribution network.

[0092] Specifically, the first isolating switch can obtain the power supply capacity of the second distribution network. The power supply capacity of the second distribution network refers to the maximum power supply load capacity of the second distribution network. The power supply capacity of the second distribution network is subtracted from the current power supply load of the second distribution network to determine the remaining capacity of the second distribution network.

[0093] S503. The first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; and according to the comparison result, sends a "transfer allowed" GOOSE signal to the adjacent disconnector through the fourth data transmission terminal.

[0094] Specifically, the remaining capacity of the second distribution network and the total load capacity that needs to be restored after the failure of the first distribution network can be subtracted or divided. When the remaining capacity of the second distribution network is greater than or equal to the total load capacity that needs to be restored after the failure of the first distribution network, the second distribution network can supply power to the first distribution network. Based on the comparison result, the first disconnector of the second distribution network sends a "transfer allowed" GOOSE signal to the adjacent disconnector through the fourth data transmission terminal.

[0095] In an optional implementation manner, the first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; based on the comparison result, sends a "transfer allowed" GOOSE signal to an adjacent disconnector through a fourth data transmission terminal, including: obtaining the margin coefficient of the second distribution network; subtracting the product of the fault load of the first distribution network and the margin coefficient from the remaining capacity of the second distribution network to obtain a comparison result; when the remaining capacity of the second distribution network is greater than or equal to the product of the fault load of the first distribution network and the margin coefficient, sending a "transfer allowed" GOOSE signal to an adjacent disconnector through the fourth data transmission terminal; the adjacent disconnector receives the "transfer allowed" GOOSE signal through the third data transmission terminal, and the adjacent disconnector in a closed state transmits the "transfer allowed" GOOSE signal to the contact switch.

[0096] Specifically, after receiving the "fault isolation successful" GOOSE signal, the second distribution network, that is, the first isolating switch of the opposite distribution network without fault, calculates the current remaining capacity C of the second distribution network according to the average power supply load within the second preset time of the current cache, such as 30 seconds or 20 seconds or 25 seconds, and the power supply capacity of the second distribution network. The product of the margin coefficient K of the second distribution network and the load I of the fault area of ​​the first distribution network, if the current remaining capacity C of the second distribution network ≥ KI, it means that the current remaining capacity of the second distribution network can support the load of the fault area of ​​the first distribution network. Then the first isolating switch sends a "transfer allowed" GOOSE signal to the adjacent isolating switch. If the adjacent isolating switches are in the closed state, the adjacent isolating switches merge and forward the "transfer allowed" GOOSE signal. Among them, K is the margin coefficient of the second distribution network, and the value of K is greater than or equal to 1.

[0097] In the case of unsuccessful locking, the "fault isolation success" GOOSE signal is sent to the first disconnector on the fault side, that is, the first disconnector of the first distribution network. The disconnector at the closing node retransmits the "fault isolation success" GOOSE signal, while the disconnector does not retransmit it, which ensures that the "transfer permission" GOOSE signal sent by the first disconnector on the fault side cannot be transmitted to the contact switch.

[0098] S504: The tie switch receives the “supply transfer allowed” GOOSE signal through the third data transmission terminal, closes the switch according to the “supply transfer allowed” GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

[0099] Specifically, the tie switch receives the "transfer allowed" GOOSE signal from the first isolating switch of the second distribution network through the third data transmission terminal, the tie switch is closed, and the second power supply S2 of the second distribution network supplies power to the load of the first distribution network. The location where the fault occurs needs to be repaired, and the power supply will be restored after the fault is eliminated.

[0100] An optional implementation manner, the connecting switch receives the "supply transfer allowed" GOOSE signal through a third data transmission terminal, closes according to the "supply transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network, including: the connecting switch receives the "supply transfer allowed" GOOSE signal through the third data transmission terminal, starts the supply transfer judgment, and judges that the connecting switch satisfies the conditions that there is no voltage on the fault side, there is voltage on the non-fault side of the connecting switch, and there is no discharge condition for the connecting switch; the connecting switch delays for a second preset time, performs supply transfer and closes, and restores power supply to the non-fault area of ​​the first distribution network.

[0101] Specifically, the "transfer allowed" GOOSE signal is transmitted to the contact switch via the disconnector in the closed state. According to the "transfer allowed" GOOSE signal and the voltage on one side of itself, and when there is no discharge condition, the contact switch starts the delayed transfer closing to restore power supply to the non-fault area of ​​the first distribution network.

[0102] Through the combination of intelligent distributed FA logic and differential protection, the fault area can be quickly determined for a hybrid grid structure with multiple power sources. Distributed FA logic in the distribution network refers to the use of automated devices or systems to monitor the operation of the distribution network, promptly detect distribution line faults, and perform fault isolation and power restoration operations in non-fault sections. The technical solution provided in this embodiment avoids the problem of insufficient capacity after the transfer by making a transfer capacity judgment at the first disconnector of the second distribution network on the opposite side. This arrangement realizes automatic isolation, fault removal, and restoration of power supply to non-fault areas, thereby improving the power supply reliability and safety of the distribution network with distributed power sources.

[0103] An optional implementation method, Figure 6 Schematic diagram of a node model of an isolating switch provided in an embodiment of the present invention. Figure 2 and Figure 6 In the distributed FA logic, each isolating switch will obtain the node information on both sides through peer-to-peer communication or locally. The node model is shown in Figure 6 . Combined Figure 2 and Figure 6 , the specific method is as follows:

[0104] Step 1: When a fault occurs at position d, the distributed power source AC will provide a short-circuit current, and the branch switch SW9 will immediately cut off the distributed power source AC through overcurrent protection. Alternatively, the distributed power source can be cut off through island protection after the main line has cut off the fault.

[0105] Step 2: When the first distribution network fails at position d, the disconnector will quickly locate the fault point through differential protection, and will trip disconnector SW2 and disconnector SW3. Disconnector SW2 determines that it is located upstream of the fault point. Disconnector SW2 is locked from the start of differential protection to the first preset time after differential protection action, for example, 10 seconds, and forwards the "fault isolation successful" GOOSE signal. This setting can prevent the "fault isolation successful" GOOSE signal from being transmitted to the first disconnector SW1 on the fault side. After the differential protection is activated, disconnector SW2 and disconnector SW3 send a "node fault" GOOSE signal. Disconnector SW3 determines that it is downstream of the fault point. After the disconnector SW3 is successfully isolated, the maximum load of the fault area of ​​the first distribution network is calculated based on the cached data before the fault, and the "fault isolation successful" GOOSE signal and the "fault load" GOOSE signal are sent to the adjacent disconnector.

[0106] Step 3: After the first disconnector SW8 of the non-faulty second distribution network on the opposite side receives the "fault isolation successful" GOOSE signal, it calculates the current remaining capacity C of the second distribution network based on the average power supply load of the second distribution network currently cached and the power supply capacity of the second distribution network. If C≥KI, where K is the margin coefficient of the second distribution network and I is the load in the fault area, the current capacity of the second distribution network can support the load in the fault area of ​​the first distribution network, and the disconnector SW8 sends a "transfer allowed" GOOSE signal to the adjacent node. The margin coefficient K can be set according to the actual situation.

[0107] Step 4: If the "transfer allowed" GOOSE signal sent in step 3 is transmitted to the contact switch SW5 via the disconnector SW6 and the disconnector SW7 in the closed state, the contact switch SW5 starts the transfer judgment after receiving the "transfer allowed" GOOSE signal. When it determines that it meets the conditions of no pressure on the fault side, pressure on the other side and no discharge, the contact switch SW5 closes after delayed transfer to restore the power supply to the load LD in the non-fault area.

[0108] It should be noted that Figure 2The first distribution network 10 and the second distribution network 20 are shown as examples. A first circuit breaker CB1 is provided between the first power source S1 of the first distribution network 10 and the isolating switch SW1. A second circuit breaker CB2 is provided between the second power source S2 of the second distribution network 20 and the first isolating switch SW8. DTU1 is a first data transmission terminal, DTU2 is a second data transmission terminal, DTU3 is a third data transmission terminal, and DTU4 is a fourth data transmission terminal. SW1 and SW4, SW6 to SW7 and SW10 are isolating switches. SW2 is a first isolating switch, and SW3 is a second isolating switch. SW5 is a contact switch. SW8 is a first isolating switch. SW9 is a branch switch, which is not limited here.

[0109] It should be noted that Figure 6 It is exemplarily shown in FIG. 1 that the two sides of the isolating switch SW are respectively an M side and an N side, the M side may include M1 , M2 and M3 branches, and the N side may include N1 , N2 and N3 sides.

[0110] The embodiment of the present invention provides a distributed feeder automatic protection fault location and power supply restoration system. Figure 2 The distributed feeder automation protection fault location and power supply restoration system provided in this embodiment includes: a distributed power source AC, a first distribution network 10 and a second distribution network 20, wherein a tie switch SW5 is connected between the first distribution network 10 and the second distribution network 20; and a branch switch SW9 is connected between the distributed power source AC and the first distribution network 10. The branch switch SW9 is used to collect the short-circuit current of the distributed power source AC, determine that a short-circuit fault occurs in the first distribution network 10 according to the short-circuit current, and open the gate and cut off the distributed power source AC. The isolating switch of the first distribution network 10 is used to locate the fault point through differential protection, control the isolating switches on both sides of the fault point to disconnect and send a first GOOSE signal. The isolating switch of the second distribution network 20 is used to control the tie switch SW5 to close according to the remaining capacity of the second distribution network 20 and the first GOOSE signal, and the second distribution network 20 supplies power to the non-fault area of ​​the first distribution network 10.

[0111] Optionally, based on the above embodiments, continue to refer to Figure 2 The branch switch SW9 is specifically used for: collecting the short-circuit current of the distributed power source AC; when the distributed power source AC provides a short-circuit current, determining that a short-circuit fault occurs in the first distribution network 10 connected to the distributed power source AC; the branch switch SW9 of the first distribution network 10 is used to disconnect the distributed power source AC through an overcurrent fast-breaking protection.

[0112] Optionally, based on the above embodiments, continue to refer to Figure 2, the first distribution network 10 is specifically used for: locating the fault point through differential protection, and the first isolating switch SW2 upstream of the fault point and the second isolating switch SW3 downstream of the fault point are evenly divided; the first isolating switch SW2 is used to send a "fault isolation success" GOOSE signal and a "node fault" GOOSE signal through the first data transmission terminal within a first preset time; the second isolating switch SW3 is used to calculate the maximum load of the fault area of ​​the first distribution network 10 where the fault point is located according to the cached data before the fault, and send "fault isolation success" and "fault load" GOOSE signals to adjacent isolating switches through the second data transmission terminal; wherein, the first GOOSE signal includes a "fault isolation success" GOOSE signal, a "node fault" GOOSE signal and a "fault load" GOOSE signal.

[0113] Optionally, based on the above embodiments, continue to refer to Figure 2 , the first isolating switch SW8 of the second distribution network 20 is used to receive the "fault isolation successful" GOOSE signal through the fourth data transmission terminal; according to the current power supply load of the second distribution network 20 and the power supply capacity of the second distribution network 20, the remaining capacity of the second distribution network 20 is determined; and the remaining capacity of the second distribution network 20 is compared with the fault load; according to the comparison result, a "transfer allowed" GOOSE signal is sent to the adjacent isolating switch through the fourth data transmission terminal; the connecting switch SW5 is used to receive the "transfer allowed" GOOSE signal through the third data transmission terminal, and closes according to the "transfer allowed" GOOSE signal, and the second distribution network 20 supplies power to the non-fault area of ​​the first distribution network 10.

[0114] In the distributed feeder automatic protection fault location and power supply restoration system provided in this embodiment, the branch switch SW9 of the first distribution network 10 collects the short-circuit current of the distributed power source AC, determines that the first distribution network 10 has a short-circuit fault according to the short-circuit current, and cuts off the distributed power source AC. Then, the isolating switch of the first distribution network 10 locates the fault point based on the differential protection, controls the isolating switches on both sides of the fault point to disconnect and send the first GOOSE signal. Furthermore, the first isolating switch SW8 of the second distribution network 20 controls the contact switch SW5 to close according to the remaining capacity of the second distribution network 20 and the first GOOSE signal, and the second distribution network 20 supplies power to the non-fault area of ​​the first distribution network 10. The distributed feeder automatic protection fault location and power supply restoration system provided in this embodiment can not only isolate the fault in time, but also restore the power supply to the non-fault area of ​​the first distribution network 10, thereby improving the real-time fault removal of the first distribution network 10 connected to the distributed power source AC and the reliability of load power supply.

[0115] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A distributed feeder automatic protection fault location and power supply restoration method, characterized in that: The method is used for a distributed feeder automation protection fault location and power supply restoration system, and the system comprises: A distributed power source, a first distribution network, and a second distribution network, wherein a tie switch is connected between the first distribution network and the second distribution network; a branch switch is connected between the distributed power source and the first distribution network; and the method comprises: Collecting the short-circuit current of the distributed power source, determining that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and controlling the branch switch to open to cut off the distributed power source; Locate the fault point through differential protection, control the disconnectors on both sides of the fault point to disconnect and send a first GOOSE signal; The first isolating switch of the second distribution network controls the connecting switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

2. The method according to claim 1, characterized in that The collecting of the short-circuit current of the distributed power source, determining that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and controlling the branch switch to open to cut off the distributed power source include: The branch switch collects the short-circuit current of the distributed power source; When the distributed power source provides a short-circuit current, determining that a short-circuit fault occurs in the first distribution network connected to the distributed power source; The branch switch of the first distribution network is opened by overcurrent speed-breaking protection to cut off the distributed power source.

3. The method according to claim 1, characterized in that Locating a fault point through differential protection, controlling disconnectors on both sides of the fault point to disconnect and sending a first GOOSE signal, including: The first distribution network locates the fault point through differential protection, and the first isolating switch upstream of the fault point and the second isolating switch downstream of the fault point are both opened; The first isolating switch sends a "fault isolation success" GOOSE signal through the first data transmission terminal within a first preset time, and sends a "node failure" GOOSE signal; The second isolating switch is used to calculate the maximum load of the fault area of ​​the first distribution network where the fault point is located based on the cached data before the fault, and send "fault isolation successful" and "fault load" GOOSE signals to the adjacent isolating switches through the second data transmission terminal; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal, a "node fault" GOOSE signal and a "fault load" GOOSE signal.

4. The method according to claim 3, characterized in that The first isolating switch of the second distribution network controls the tie switch to close according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network, including: The first isolating switch of the second distribution network receives the "fault isolation successful" GOOSE signal through the fourth data transmission terminal; The first disconnector of the second distribution network determines the remaining capacity of the second distribution network according to the current power supply load of the second distribution network and the power supply capacity of the second distribution network; The first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; and sends a "transfer allowed" GOOSE signal to an adjacent disconnector through the fourth data transmission terminal according to the comparison result; The tie switch receives the "transfer allowed" GOOSE signal through the third data transmission terminal, closes according to the "transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

5. The method according to claim 4, characterized in that The first disconnector of the second distribution network compares the remaining capacity of the second distribution network with the fault load; According to the comparison result, a "transfer permission" GOOSE signal is sent to the adjacent disconnector through the fourth data transmission terminal, including: Obtaining a margin coefficient of the second distribution network; Subtract the product of the fault load of the first distribution network and the margin coefficient from the remaining capacity of the second distribution network to obtain a comparison result; When the remaining capacity of the second distribution network is greater than or equal to the product of the fault load of the first distribution network and the margin coefficient, a "transfer allowed" GOOSE signal is sent to the adjacent disconnector through the fourth data transmission terminal; The adjacent isolating switch receives the "power transfer allowed" GOOSE signal through the third data transmission terminal, and the adjacent isolating switch in the closed state transmits the "power transfer allowed" GOOSE signal to the contact switch.

6. The method according to claim 5, characterized in that The tie switch receives the "transfer allowed" GOOSE signal through the third data transmission terminal, closes the switch according to the "transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network, including: The tie switch receives the "power transfer allowed" GOOSE signal through the third data transmission terminal, starts power transfer judgment, and judges that the tie switch meets the conditions that there is no voltage on the fault side, there is voltage on the non-fault side of the tie switch, and there is no discharge condition for the tie switch; The tie switch delays for a second preset time, performs power transfer and closing, and restores power supply to the non-fault area of ​​the first distribution network.

7. A distributed feeder automation protection fault location and power supply restoration system, characterized in that: include: A distributed power source, a first distribution network and a second distribution network, wherein a tie switch is connected between the first distribution network and the second distribution network; A branch switch is connected between the distributed power source and the first distribution network; The branch switch is used to collect the short-circuit current of the distributed power source, determine that a short-circuit fault occurs in the first distribution network according to the short-circuit current, and open the switch to cut off the distributed power source; The isolating switch of the first distribution network is used to locate the fault point through differential protection, control the isolating switches on both sides of the fault point to disconnect and send a first GOOSE signal; The isolating switch of the second distribution network is used to control the closing of the tie switch according to the remaining capacity of the second distribution network and the first GOOSE signal, so that the second distribution network supplies power to the non-fault area of ​​the first distribution network.

8. The system according to claim 7, characterized in that The branch switch is specifically used for: collecting the short-circuit current of the distributed power source; when the distributed power source provides the short-circuit current, determining that a short-circuit fault occurs in the first distribution network connected to the distributed power source; and the branch switch of the first distribution network is used to disconnect the distributed power source through overcurrent fast-breaking protection.

9. The system according to claim 7, characterized in that The first distribution network is specifically used for: The fault point is located by differential protection, and the first isolating switch upstream of the fault point and the second isolating switch downstream of the fault point are both opened; the first isolating switch is used to send a "fault isolation success" GOOSE signal through the first data transmission terminal within a first preset time, and send a "node failure" GOOSE signal; The second isolating switch is used to calculate the maximum load of the fault area of ​​the first distribution network where the fault point is located based on the cached data before the fault, and send "fault isolation successful" and "fault load" GOOSE signals to the adjacent isolating switches through the second data transmission terminal; wherein the first GOOSE signal includes a "fault isolation successful" GOOSE signal, a "node fault" GOOSE signal and a "fault load" GOOSE signal.

10. The system according to claim 9, characterized in that The first isolating switch of the second distribution network is used to receive the "fault isolation successful" GOOSE signal through the fourth data transmission terminal; determine the remaining capacity of the second distribution network according to the current power supply load of the second distribution network and the power supply capacity of the second distribution network; and compare the remaining capacity of the second distribution network with the fault load; according to the comparison result, send a "transfer allowed" GOOSE signal to the adjacent isolating switch through the fourth data transmission terminal; The tie switch is used to receive the "transfer allowed" GOOSE signal through the third data transmission terminal, close the switch according to the "transfer allowed" GOOSE signal, and the second distribution network supplies power to the non-fault area of ​​the first distribution network.

Images