A method for fast fault isolation of looped line based on medium voltage carrier wave

Abstract

The application belongs to the technical field of primary and secondary fusion in the electric power industry, and particularly relates to a loop closing line fast fault isolation method based on a medium voltage carrier wave. Only one carrier wave master is arranged in a line, an FTU and the carrier wave master share one chip, a carrier wave machine separately uses one chip, the carrier wave machines communicate through 10kv power lines and power lines powered by small hydropower, and the line topology has been sent to each carrier wave machine; the FTU detects a fault, transmits fault information and a fault current direction to the carrier wave machine; loop closing FA information is interacted; the carrier wave machine with a host position interacts with the FTU, interval positioning result notification is performed, isolation operation is started, and the host position is transferred to the next carrier wave machine needing to be cut off; the carrier wave machine reports to the carrier wave master, and the carrier wave master reports to a master station. The application realizes loop closing line fast fault isolation with high efficiency, low cost and high system reliability based on a medium voltage carrier wave communication system.

Description

Technical Field

[0001] This invention belongs to the field of primary and secondary integration technology in the power industry, specifically relating to a fast fault isolation method for loop-connected lines based on medium-voltage carrier wave. Background Technology

[0002] With the advancement of the "dual carbon" target and the construction of new power systems, the State Grid Corporation of China is actively promoting the integration of small hydropower, distributed photovoltaic, and other power sources into the distribution network for closed-loop operation to improve power supply reliability and energy utilization efficiency. Closed-loop operation refers to forming a multi-source closed-loop power supply structure between distributed generation (DER) and the main grid by closing the interconnection switches in the distribution network. Compared with the traditional open-loop radial distribution network, it has significant advantages.

[0003] The State Grid Corporation of China (SGCC) explicitly encourages regions with suitable conditions to carry out loop-loop operation upgrades, supporting the "plug-and-play" and flexible dispatch of distributed power sources. For example, in densely populated small hydropower areas such as Sichuan and Yunnan, SGCC has achieved stable loop-loop operation after small hydropower grid connection by installing bidirectional power flow controllers and intelligent sectionalizing switches (refer to SGCC's "Technical Specifications for Small Hydropower Grid Connection"). Meanwhile, SGCC emphasizes in its "White Paper on Digital Technology Support System for New Power Systems" that loop-loop operation relies on distributed feeder automation (FA) and wide-area measurement systems to address the challenges of multi-source coordinated control.

[0004] Loop operation presents significant challenges to distributed feeder automation (FA). Fault location and isolation become more complex. Under loop operation, distributed power sources provide multi-directional fault currents, rendering the unidirectional fault detection logic relied upon by traditional FAs ineffective. Loop operation also places higher demands on the real-time performance and reliability of FAs. The State Grid Corporation of China (SGCC), in its "White Paper on Digital Technology Support System for New Power Systems," emphasizes the need to build a collaborative "cloud-edge-device" communication network and deploy high-bandwidth, low-latency technologies such as 5G and TSN (Time-Sensitive Networking) to support rapid regulation of distributed power sources by FAs. Simultaneously, the introduction of edge computing nodes enables localized decision-making for functions such as feeder protection and voltage regulation, reducing the pressure on centralized control at the master station.

[0005] However, current 5G public networks have high latency. There is an urgent need for an alternative low-cost, low-latency, and highly reliable communication method to provide communication support for distributed computer-aided systems (FAS). This patent will achieve rapid fault isolation of closed-loop lines through medium-voltage carrier communication. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a FA (Feature Automated Guided Vehicle) fault handling method based on a medium-voltage carrier communication system under closed-loop circuits. This method, based on a medium-voltage carrier communication system, handles FA faults, reduces costs, shortens fault handling time, and provides support for the construction of distribution automation.

[0007] The technical solution adopted by the present invention to solve its technical problem is as follows: a fast fault isolation method for loop-connected lines based on medium-voltage carrier. In the medium-voltage carrier communication system, only one carrier master controller is set in a line. The feeder terminal FTU and the carrier master controller share a chip. The carrier machine uses a separate chip. The carrier machines communicate with each other through 10kV power lines and small hydropower power lines. The line topology has been distributed to each carrier machine.

[0008] The fault isolation steps are as follows:

[0009] S1 and FTU detect the fault and transmit the fault information and fault current direction to the carrier unit through network communication.

[0010] S2, FA information interaction in the loop: the carrier machine seizes the host position by grabbing the token and performs host position interaction. The carrier machine with the host position queries the branch, downstream and upstream carrier machines in sequence for fault information and fault current direction. Except for interaction with its own branch, all other interactions attempt to hand over the host position. If the host position is acquired during the query process, the carrier machine that acquires the host position repeats the host position grabbing operation.

[0011] S3. After the master position preemption information exchange is completed, the carrier unit with the master position interacts with the FTU to notify the interval positioning result, start the isolation operation and transfer the master position to the next carrier unit that needs to be cut off.

[0012] After S4 and FA are completed, the carrier machine will report all information related to FA on the line to the carrier master controller;

[0013] S5, the carrier master controller reports all FA information to the master station.

[0014] Preferably, in step S2, after the carrier machine receives the fault information and the direction of the fault current, if the carrier machine is on the main line of the topology, it participates in the token-grabbing operation; if the carrier machine is on a branch of the topology, it remains silent temporarily. The token-grabbing process is as follows: the carrier machines that receive the fault send token-grabbing frames sequentially from the downstream to the upstream of the topology; the carrier machines that receive the downstream token-grabbing frames record the direction of the downstream fault current and wait for the main line carrier machines to send token-grabbing frames to the upstream; if there is a fault downstream and the carrier machine itself also has a fault, the carrier machine whose downstream fault current direction is opposite to its own fault current direction obtains the master position.

[0015] Preferably, except for the final stage switch, the carrier machine that has not received a downstream fault and whose upstream fault current direction is the same as its own fault current direction automatically acquires the master position.

[0016] Preferably, when multiple carriers compete for the host position, the carrier closer to the fault location in the topology has an interactive command to make the carriers further away from the fault exit the host position.

[0017] Preferably, in step S2, the branch interaction does not initially transfer the master position. After receiving the branch fault information, the upstream mainline master position determines that its own fault direction is the same as the branch fault and needs to transfer the master position before performing the master position transfer interaction. If it determines that its own fault direction is opposite to the branch fault, the mainline master position transfers the master position to the branch after obtaining the upstream and downstream fault information and the fault current direction, and then sends it to the FTU. The master position transfer does not consider whether the FTU meets the tripping conditions. When querying the downstream, the downstream judges based on the fault current direction of its upstream and downstream. If it meets the isolation requirement, it returns the master position and replies with its own fault information and fault current direction, and then notifies other carrier units to isolate. When querying the upstream transfer master position, if the upstream fault direction is the same as the downstream, it replies that it does not need to obtain the master position.

[0018] Preferably, in step S3, the isolation sequence is as follows: downstream equipment of the fault, upstream equipment of the fault, and branch equipment; all power supply equipment around the fault point is isolated.

[0019] Preferably, in step S5, the main station displays the fault and performs fault reversal based on the received information.

[0020] Preferably, during the token grabbing and host position interaction phase, all carrier machines that can hear the fault information and fault current direction sent from the upstream to the upstream and downstream record the information and determine whether to give up the host position.

[0021] Preferably, the carrier unit is connected to the 10kV power line or the power line supplied by small hydropower via a signal line, and the carrier unit is connected to the FTU via a network cable.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The FA fault handling method in this application is based on a medium-voltage carrier communication system. The centralized single-point reporting of FA information reduces the pressure on the master station, improves the efficiency of the master station, and does not require additional communication line costs. It can shorten the fault handling time and provide support for the construction of power distribution automation.

[0024] 2. The processing method of this application first isolates two relatively independent circuits, which can operate normally separately. Each branch carrier machine can also operate normally through power supply self-adaptation, thus reducing the impact of faults.

[0025] 3. The FA fault handling method of this application optimizes the FA fault handling process. The host part interaction process first branches, then downstream and finally upstream, which can reduce the number of interactions, thereby shortening the fault handling time, realizing the rapid isolation of faults and the restoration of power supply to non-faulty areas, that is, realizing the distributed FA function and adapting to various topologies.

[0026] 4. The FA fault handling method of this application has interactive retransmission and host bit error correction mechanism in the FA fault handling process, which can record the interaction union, which is more conducive to the collection of fault information and the system has high reliability.

[0027] 5. The FA fault handling method in this application includes FA information such as upstream transmission and reception, branch transmission and reception, downstream transmission and reception, retransmission, and interaction with FTU. The information is comprehensive, which makes it easy for the master station to realize fault display and fault inversion based on the information.

[0028] In summary, this application, based on a medium-voltage carrier communication system, achieves rapid fault isolation of closed-loop lines with high efficiency, low cost, and high system reliability. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a medium-voltage carrier communication system.

[0030] Figure 2 This is a flowchart for handling faults in the closed-loop FA (Fault-Aided FA) system. Detailed Implementation

[0031] To facilitate understanding of the present invention, it will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0032] Example 1: A fast fault isolation method for loop-connected lines based on medium-voltage carrier wave.

[0033] Combination Figure 1 In a medium-voltage carrier communication system, the FTU and carrier master controller share a single chip (chip 1 in the diagram). There is only one carrier master controller per line, and the carrier master controller function is not enabled in other FTUs. The carrier unit uses a separate chip (chip 2 in the diagram), and the carrier units communicate with each other via 10kV power lines and small hydropower-powered power lines.

[0034] Combination Figure 2 The FA fault handling process is as follows:

[0035] The FTU is capable of detecting short circuits and grounding faults, and the line topology has been distributed to each carrier unit. In this application, the direction closer to the small hydropower source is downstream, the direction closer to the 10kV power source is upstream, and the final stage switch refers to the carrier unit closest to the small hydropower source.

[0036] Step 1: After the FTU detects a fault, it reports the fault information and fault current direction to the carrier unit via network port communication.

[0037] Step 2: In the loop-connected FA information exchange, after receiving the fault information and fault current direction, the carrier unit participates in the token-grabbing operation if it is on the main topology line; otherwise, it remains silent. The token-grabbing process involves the carrier units that receive the fault sending token-grabbing frames sequentially from the downstream to the upstream of the topology. The carrier unit receiving the downstream token-grabbing frame records the downstream fault current direction and waits for the main line carrier units to send their token-grabbing frames upstream. Here, the main line carrier units include those connected to the carrier master controller.

[0038] When a downstream fault occurs, and the carrier machine itself also experiences a fault, the carrier machine whose downstream fault current direction is opposite to its own fault current direction acquires the master position. Specifically, if, except for the final-stage switch, no downstream fault is received, and the upstream fault current direction is the same as its own fault current direction, the master position is automatically acquired. Due to unforeseen circumstances, carrier machines that haven't received downstream fault information may preempt the master position, leading to a multi-master position phenomenon. In the topology, carrier machines closer to the fault location can send an interactive command to carrier machines further away from the fault to relinquish their master position. Furthermore, during the token acquisition and master position interaction phase, all carrier machines that can hear the upstream fault information and fault current direction sent to their upstream counterparts record the information and determine whether to relinquish the master position. For system reliability, the token acquisition operation can be performed multiple times, recording the union of interaction information, which is more conducive to fault information collection.

[0039] The carrier unit with the master bit sequentially queries the branch, downstream, and upstream carrier units for fault information and fault current direction. Except for interactions with its own branch, all other interactions attempt to hand over the master bit. When querying the downstream, the downstream unit determines the fault current direction based on its own upstream and downstream fault current direction. If isolation is required, the downstream unit returns the master bit and replies with its own fault information and fault current direction, and then notifies other carrier units to isolate the fault.

[0040] In branch fault communication, the main line host does not immediately transfer the master position. After receiving the branch fault information, if the upstream main line host determines that its own fault direction is the same as the branch fault, it needs to transfer the master position and then perform the master position transfer communication. If it determines that its own fault direction is opposite to the branch fault, the main line host will transfer the master position to the branch after obtaining the upstream and downstream fault information, the fault current direction, and sending it to the FTU. The master position transfer does not consider whether the FTU meets the tripping conditions.

[0041] To prevent multi-host issues, the upstream server is asked to transfer the host bit. If the upstream failure direction is the same as the downstream failure direction, the server will reply that it will not retrieve the host bit.

[0042] If the host bit is acquired during the query process, the carrier machine that acquired the host bit will repeat the host bit preemption operation.

[0043] Setting the interaction order can reduce the number of interactions, which in turn reduces the overall interaction time and further shortens the fault handling time. For example, if a fault occurs in a branch, the carrier machine with the master position first queries the branch. If the branch replies that there is a fault, then the master position is directly given to the branch carrier machine without querying the downstream, saving this part of the interaction time.

[0044] Step 3: After the master position preemption information exchange is completed, the carrier unit with the master position interacts with the FTU to notify the interval positioning result, start the isolation operation, and transfer the master position to the next carrier unit that needs to be cut off.

[0045] Normally, the isolation sequence is as follows: the downstream device is isolated first. Reason: the local machine obtains downstream fault information during token acquisition. When the upstream host interacts with the downstream node, it obtains upstream fault information. At this point, the local machine has already obtained its own information and the upstream and downstream fault information. The local machine does not need to obtain the host bit, but the isolation conditions are already met. After the upstream node obtains the upstream and downstream node information, it sends the interval location result to the FTU to start the isolation operation. Then, the host bit is transferred to the branch. The branch then obtains the downstream information and then isolates; if there is no branch, the transfer does not occur.

[0046] Step 4: After the FA is completed, the carrier machine will report all information related to the FA on the line to the carrier master controller.

[0047] Step S5: The carrier master controller reports all FA information to the master station, which can then display and invert faults based on the information. This enables rapid isolation of faults and restoration of power to non-faulty areas, thus realizing distributed FA functionality.

[0048] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A fast fault isolation method for loop-connected lines based on medium-voltage carrier wave, characterized in that, In a medium-voltage carrier communication system, only one carrier master controller is set up in a line. The feeder terminal unit (FTU) and the carrier master controller share a chip, while the carrier unit uses a separate chip. The carrier units communicate with each other through 10kV power lines and small hydropower-powered power lines. The line topology has been distributed to each carrier unit. The fault isolation steps are as follows: S1 and FTU detect the fault and transmit the fault information and fault current direction to the carrier unit through network communication. S2, FA information interaction in the loop: the carrier machine seizes the host position by grabbing the token and performs host position interaction. The carrier machine with the host position queries the branch, downstream and upstream carrier machines in sequence for fault information and fault current direction. Except for interaction with its own branch, all other interactions attempt to hand over the host position. If the host position is acquired during the query process, the carrier machine that acquires the host position repeats the host position grabbing operation. S3. After the master position preemption information exchange is completed, the carrier unit with the master position interacts with the FTU to notify the interval positioning result, start the isolation operation and transfer the master position to the next carrier unit that needs to be cut off. After S4 and FA are completed, the carrier machine will report all information related to FA on the line to the carrier master controller; S5, the carrier master controller reports all FA information to the master station.

2. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 1, characterized in that, In step S2, after the carrier machine receives the fault information and the direction of the fault current, if the carrier machine is on the main line of the topology, it participates in the token grabbing operation; if the carrier machine is on the branch of the topology, it remains silent for a while. The token grabbing process is as follows: the carrier machine that receives the fault sends the token grabbing frame from the downstream to the upstream of the topology in sequence. The carrier machine that receives the downstream token grabbing frame records the direction of the downstream fault current and waits for the main line carrier machine to send the token grabbing frame to the upstream. If there is a fault downstream and the machine itself also has a fault, the carrier machine whose fault current direction is opposite to that of its own fault current will acquire the master bit.

3. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 2, characterized in that, Except for the final stage switch, carrier machines that do not receive downstream faults and whose upstream fault current direction is the same as their own fault current direction will automatically acquire the master position.

4. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 3, characterized in that, When multiple carriers compete for the host position, the carrier closer to the fault in the topology has an interactive command to make the carrier further away from the fault vacate the host position.

5. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 4, characterized in that, In step S2, the branch interaction does not initially transfer the master position. After receiving the branch fault information, the upstream mainline master position determines that its own fault direction is the same as the branch fault and needs to transfer the master position before performing the transfer master position interaction. If it determines that its own fault direction is opposite to the branch fault, the mainline master position transfers the master position to the branch after obtaining the upstream and downstream fault information and the fault current direction, and then sends it to the FTU. The transfer master position does not consider whether the FTU meets the tripping conditions. When querying the downstream, the downstream judges based on the fault current direction of its upstream and downstream. If isolation is required, it returns the master position and replies with its own fault information and fault current direction, and then notifies other carrier units to isolate. When querying the upstream transfer master position, if the upstream fault direction is the same as the downstream, it replies that it does not need to obtain the master position.

6. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 5, characterized in that, Step S3, the isolation order is as follows: downstream device of the fault, upstream device of the fault, and branch device; All power supply equipment around the fault point was isolated.

7. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 6, characterized in that, Step S5: The main station displays the fault and performs fault reversal based on the received information.

8. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 1, characterized in that, During the token grabbing and host position interaction phase, all carrier machines that can hear the upstream fault information and fault current direction sent to the upstream and downstream record the information and determine whether to give up the host position.

9. The fast fault isolation method for loop-connected lines based on medium-voltage carrier wave according to claim 1, characterized in that, The carrier unit is connected to the 10kV power line or the power line supplied by small hydropower via a signal line, and the carrier unit is connected to the FTU via a network cable.

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