Feeder automation method and system considering dead zone failure of distribution network ring network switch

Abstract

The present invention discloses a feeder automation method and system that takes into account dead zone faults of distribution network ring network switches. The method is applied to distribution network lines. The system specifically includes: a fault protection module for configuring corresponding protection measures for the distribution network, including: a ring network protection unit, a ring network switch protection unit, and a substation protection unit; a fault isolation module for determining the fault location and isolating the fault area according to the action of the protection measures when a short circuit or permanent grounding fault occurs in the line; and a power supply restoration module for restoring power to non-fault areas after fault isolation is completed. The present invention can accurately identify dead zone faults of distribution network ring network switches; can effectively shorten the power outage time caused by dead zone faults of ring network switches; can effectively avoid repeated power outages and other problems caused by dead zone faults of ring network switches, thereby improving power supply reliability; and can reduce the difficulty of fault finding for on-site personnel.

Description

Technical Field

[0001] The present invention relates to a method for automatically isolating a fault area and restoring power supply to loads in non-fault sections when a distribution network fails, and in particular to a feeder automation method that takes into account dead zone faults of distribution network switches. Background Art

[0002] As a crucial link between the main grid or power source and users, the distribution network is undergoing significant development. With the nation's economic growth and user demands for high-quality power supply, power supply companies are accelerating the automation of rural distribution networks. By integrating computer technology, information and communications technology, and modern control technologies, they are implementing a new generation of distribution automation systems to enhance distribution network management. Feeder automation is a crucial component of distribution automation systems and is also their most widely used function. It primarily utilizes three implementation modes: centralized, local, and distributed. Centralized feeder automation is currently the mainstream approach.

[0003] Considering the urban environment, power supply security, and improved reliability, the cable ratio in urban distribution networks is on the rise. Ring main units (RMUs) are increasingly used in distribution networks due to their high cost-effectiveness and reliability. When a dead zone fault occurs in a ring main switch in a distribution network, the position of the current transformer installation can cause the feeder automation to misidentify the fault location and the actual location, significantly reducing the success rate of power operation and causing repeated power outages, fault point shifting, and extended outage coverage.

[0004] Prior art document 1 (CN118100107A) discloses a feeder automation protection system and a fault location method thereof, but does not consider that when a fault occurs between the switch body and the current transformer, the fault location fails, resulting in fault transfer and power outage of the healthy line. Prior art document 2 (CN116014686A) discloses a method for improving the power supply reliability under dead zone faults of distribution network switches, which mainly relies on the master station to achieve fault isolation and load transfer. The protection configuration is complex and the processing time is long. Summary of the Invention

[0005] Purpose of the Invention: This invention aims to develop an innovative method to effectively mitigate the cascading problems caused by the inability to accurately identify dead-zone faults in ring network switches, including but not limited to repeated power outages, the chaotic spread of fault points, and the unnecessary expansion of outage areas. By implementing this invention, we expect to significantly enhance the stability and continuity of power supply, providing users with more reliable power services.

[0006] A first aspect of the present invention provides a feeder automation system that takes into account dead zone faults of distribution network switches, which is applied to distribution network lines and specifically includes:

[0007] The fault protection module is used to configure corresponding protection measures for the distribution network, including: ring network protection unit, ring network switch protection unit and substation protection unit;

[0008] The fault isolation module is used to determine the fault location and isolate the fault area based on the protection measures when a short circuit or permanent ground fault occurs in the line;

[0009] The power supply module for restoring the non-fault area is used to restore the power supply to the non-fault area after the fault isolation is completed.

[0010] Preferably, the fault isolation module is specifically used to:

[0011] If the ring network protection does not operate and the ring network switch protection operates as an alarm, the ring network where the ring network switch is located will send a signal to the connected next-level ring network; if there is no alarm information in the ring network switch of the next-level ring network, the switches on both sides between the ring network where the protection alarm occurs and the connected next-level ring network will be tripped to isolate the fault area; if there is protection alarm information in the next-level ring network switch, the ring network may have a fault, and the switches on both sides between the ring network and the ring network where the protection alarm occurs will not operate, retaining the fault site to prevent further expansion of the fault range.

[0012] If the ring network protection is activated, all switches in the ring network will be tripped and a signal will be sent to the upper-level ring network. If the current in the switch between the ring network where the protection is activated and the upper-level ring network reaches the overcurrent protection condition, it is determined that a dead-zone fault has occurred in the incoming line switch between the ring network where the protection is activated and the upper-level ring network. The ring network switch will trip and isolate the faulty area. If the current in the ring network switch does not meet the overcurrent protection condition, it is determined that the incoming line switch has not suffered a dead-zone fault.

[0013] If the switch protection in the substation is activated and the ring network switch protection is not activated, the switch in the substation will trip, isolating the fault area and determining that the substation outgoing cable is faulty.

[0014] Preferably, the power supply module for restoring the non-fault area is specifically used to:

[0015] After the ring network switch protection is activated, the next-level ring network connected to it retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

[0016] Preferably, the power supply module for restoring the non-fault area is specifically used for:

[0017] After the ring network protection is activated, the next-level ring network connected to the ring network retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

[0018] Preferably, the power supply module in the non-fault area is restored when the outgoing cable of the substation fails, specifically for:

[0019] The substation retrieves the line topology, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

[0020] Preferably, the communication method between the ring networks includes but is not limited to optical cables and 5G.

[0021] Preferably, the tie switch selects a line power supply with a large load margin, a short power supply radius, and good line condition.

[0022] Preferably, all switches have three remote control functions. If they do not have three remote control functions, the fault area will be expanded.

[0023] Preferably, when there is no lower-level ring network, the ring network switch protection action directly trips.

[0024] A second aspect of the present invention provides a feeder automation method that takes into account dead-zone faults of a distribution network ring network switch. The system for improving power supply reliability under dead-zone faults of a ring network switch is based on the above-mentioned method, and includes:

[0025] Step 1: Configure protection measures, including ring network protection, ring network switch protection, and substation protection for the distribution network;

[0026] Step 2: Determine whether a short circuit or permanent ground fault occurs in the line based on the action of the protection measures;

[0027] Step 3: Isolate the fault area;

[0028] Step 4: After the fault is isolated, restore power to the non-faulty area.

[0029] Furthermore, the feeder automation method considering the dead zone faults of distribution network switches is applicable to the distribution network structure with a higher voltage level, and can also be extended to the distribution network self-healing solution when multiple faults occur.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects.

[0031] 1) In the present invention, the dead zone fault of the distribution network ring network switch can be accurately identified.

[0032] 2) The present invention can effectively shorten the power outage time caused by the dead zone fault of the ring network.

[0033] 3) The present invention can effectively avoid problems such as repeated power outages caused by dead zone failures of ring network switches, thereby improving power supply reliability.

[0034] 4) The present invention can reduce the difficulty of fault finding for on-site personnel.

[0035] 5) In the present invention, when a dead zone fault occurs, it will not affect the safe and stable operation of the healthy line, and the fault processing time is shortened. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The flow chart of the feeder automation method considering the dead zone failure of the distribution network ring network switch is shown;

[0037] Figure 2 This is a schematic diagram of a 10KV line;

[0038] Figure 3 This is a schematic diagram of a cable fault between the H1 ring network and the H2 ring network;

[0039] Figure 4 This is a schematic diagram of a dead zone fault occurring on H2 ring network switch K4;

[0040] Figure 5 Schematic diagram of the cable fault between substation switch Q1 and H1 ring network switch K1. DETAILED DESCRIPTION

[0041] The technical solution of the present invention will be further described below in conjunction with specific implementation methods and drawings.

[0042] This embodiment discloses Figure 1 The method for improving the power supply reliability under the dead zone fault of the ring network switch is shown in FIG. 1 , which takes a 10KV full cable line as an example and is appropriately simplified for the convenience of explanation. Figure 2 As shown, the substation outgoing line switches Q1 and Q2, and ring main units H1, H2, H3, and H4 are included. In this embodiment of the present invention, communication between the ring networks at all levels can be achieved using optical cables, 5G, and other methods, and all switches have three-way remote control. If a switch does not have these functions, the fault area will be expanded. The K7 switch in the H4 ring network is the connecting switch between the Q1 and Q2 lines. Solid dots represent the closed position, while hollow dots represent the open position. All connecting switches prioritize line power sources with large load margins, short power supply radius, and good line conditions.

[0043] A first embodiment of the present invention provides a feeder automation system that takes into account dead zone faults in a distribution network ring network switch, including a fault protection module, a fault isolation module, and a power supply restoration module for non-fault areas.

[0044] The fault protection module is used to configure corresponding protection measures for the distribution network to prevent damage to equipment when a fault occurs.

[0045] In a preferred but non-limiting embodiment of the present invention, the fault protection module includes: a ring network protection unit, a ring network switch protection unit and a substation switch protection unit.

[0046] The ring network protection unit specifically sets the current flowing into the busbar between the H1 and H2 ring networks to negative, and the current flowing out of the busbar to positive. When the sum of all the ring network switch currents exceeds a preset current setting, and the busbar zero-sequence voltage exceeds a preset zero-sequence voltage setting for a preset time limit, the ring network protection system trips all the ring network switches. The current setting and time limit setting are adjusted based on the sensitivity of the ring network busbar fault.

[0047] The functions of the ring network switch protection unit are specifically: preferably but not limited to overcurrent or zero-sequence overcurrent protection, the current trigger threshold in the protection function is adjusted to have sufficient sensitivity to line faults, the time limit is guaranteed to have a level difference with the time limit set in the ring network protection, and the protection signal alarm function is activated so that an alarm can be issued in time when an abnormality is detected.

[0048] The functions of the substation switch protection unit are specifically: preferably but not limited to overcurrent or zero-sequence overcurrent protection, the current setting is adjusted to have sufficient sensitivity to line faults, the time limit is guaranteed to have a level difference with the time limit set in the ring network switch protection, the protection signal alarm function is activated, and the protection action tripping function is activated.

[0049] The fault isolation module is used to determine the fault location and isolate the fault area based on the action of the protection measures when a fault occurs.

[0050] In a preferred but non-limiting embodiment of the present invention, the fault isolation module includes: an inter-ring network cable fault area isolation unit, a ring network switch dead zone fault area isolation unit and a substation outgoing cable fault area isolation unit.

[0051] The inter-ring cable fault isolation unit functions as follows: When a fault occurs, the ring network protection does not activate, the ring network switch activates the protection alarm, and the ring network where the ring network switch is located sends a signal to the next-level ring network. If there is no next-level ring network, the ring network switch protection activates and trips the circuit breaker. If the next-level ring network does not have an alarm, the switches on both sides between the ring network where the protection alarm occurred and the next-level ring network are tripped, isolating the fault area. If the next-level ring network switch has a protection alarm, indicating a possible fault in that ring network, the switches on both sides between the ring network where the protection alarm occurred and the next-level ring network are not activated, preserving the fault location and preventing further expansion of the fault range.

[0052] The specific functions of the ring network switch dead-band fault isolation unit are as follows: when a fault occurs, the ring network protection activates, tripping all switches in the ring network. The ring network where the protection activates sends a signal to the ring network above it. If the current in the switch between the ring network where the protection activates and the ring network above it reaches the overcurrent protection condition, the incoming switch between the ring network where the protection activates and the ring network above it is determined to have a dead-band fault, and the ring network switch is tripped, isolating the faulty area. If the current in the ring network switch does not meet the overcurrent protection condition, the incoming switch between the ring network where the protection activates and the ring network above it is determined not to have a dead-band fault. At the same time, the ring network where the protection activates sends a signal to the ring network below it. If the switch in the ring network below it activates, the outgoing switch between the ring network where the protection activates and the ring network below it is determined to have a dead-band fault.

[0053] The specific functions of the substation outgoing cable fault isolation unit are: if the switch protection in the substation trips, the fault area is isolated, and the ring network switch protection does not operate, the ring network protection does not operate, and it is judged that the substation outgoing cable is faulty.

[0054] As a prominent substantive feature of the present invention and one of the significant advances it brings to the prior art, the present invention is configured with three levels of protection: ring network switch protection, ring network protection, and substation switch protection. Relying on peer-to-peer communication between ring network units, reasonable logical coordination is performed on the protection time limit to achieve accurate identification and isolation of dead zone faults. When a dead zone fault occurs, the safe and stable operation of the healthy line can be guaranteed without affecting the safe and stable operation of the healthy line, and the fault handling time is shortened.

[0055] The power supply restoration module for non-fault areas is used to restore power supply to non-fault areas after fault isolation is completed, thereby improving the power supply reliability of the distribution network.

[0056] In a preferred but non-limiting embodiment of the present invention, the module for restoring power supply in non-faulty areas includes: a ring network cable fault recovery unit, a ring network switch dead zone fault recovery unit and a substation outgoing line switch recovery unit.

[0057] The specific functions of the cable fault recovery unit between ring networks are as follows: after the ring network switch protection is activated, the next-level ring network connected to it retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

[0058] The specific function of the ring network switch dead zone fault recovery unit is: after the ring network protection is activated, the next-level ring network connected to the ring network retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

[0059] The specific functions of the substation outgoing cable fault recovery unit are: the substation searches the line topology structure, sends a signal to the ring network where the downstream tie switch is located, remotely closes the tie switch, and restores power supply.

[0060] As a prominent substantive feature of the present invention and one of the significant advances it brings to the prior art, relying on peer-to-peer communication between ring networks and logical coordination between protections, it is possible to accurately identify, isolate and transfer loads to fault areas in seconds, making protection configuration simpler and processing time shorter.

[0061] The feeder automation system of the present invention is described in detail below by taking a cable fault between the H1 ring network and the H2 ring network, a dead zone fault at the H2 ring network switch K4, and a substation outgoing cable fault as examples.

[0062] Example 2

[0063] Reference Figure 3 This is the second embodiment of the present invention, which provides a method for improving power supply reliability in the event of an inter-ring cable fault. Rather than addressing a known fault, this embodiment assumes a possible cable fault between the H1 and H2 ring networks. Through sophisticated protection configuration and fault handling procedures, the fault is quickly located and isolated, thereby maintaining normal power supply in non-faulty areas.

[0064] Step 1. Configure corresponding protections for the ring network, ring network switches, and switches in the substation in accordance with Example 1.

[0065] Step 2: When a fault occurs, the protection measures configured in Step 1 are activated, and the ring network where the fault occurs sends a signal to the next lower ring network. If there is no lower ring network, the ring network switch protection will directly trip.

[0066] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0067] In step 2.1, when the K1 and K2 switches in the H1 ring network detect that the current exceeds the overcurrent protection threshold set in step 1.2, the K1 and K2 switches in the H1 ring network generate a protection action alarm. The current and voltage in the H1 ring network do not reach the protection action conditions set in step 1.1, and the H1 ring network protection does not operate.

[0068] In step 2.2, after the K1 and K2 switches trigger an alarm in step 2.1, the H1 ring network sends a signal to the next-level H2 ring network.

[0069] Step 3: After receiving the signal sent by the H1 ring network in step 2, if the H2 ring network switch has no additional protection alarm information, the H1 ring network K2 switch and the H2 ring network K3 switch are tripped to isolate the fault point.

[0070] Step 4: After isolating the fault point in step 3, the H2 ring network searches the line topology and sends a signal to the ring network H4 where the subsequent tie switch K7 is located to remotely close the tie switch K7 and restore power to the non-fault area.

[0071] Example 3

[0072] Reference Figure 4 This is the second embodiment of the present invention, which provides a method for improving power supply reliability when a dead-band fault occurs at a ring network switch. Rather than addressing a known fault, this embodiment assumes a dead-band fault at the H2 ring network switch K4. Through a detailed fault detection and handling process, accurate fault identification and effective isolation are ensured.

[0073] Step 1: The ring network, ring network switch, and substation outgoing line switch are configured and protected in the same manner as in Example 1.

[0074] Step 2: When a fault occurs, the ring network takes action according to the protection measures configured in step 1 and sends a signal to the next higher level ring network.

[0075] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0076] In step 2.1, when a short circuit or permanent ground fault occurs in the line, the current and voltage in the H2 ring network reach the action threshold set in step 1, and the protection action occurs, tripping the H2 ring network K3, K4, and L2 switches.

[0077] In step 2.2, the H2 ring network sends a signal to its upper-level ring network H1.

[0078] Step 3: Determine whether a dead zone fault occurs in the K3 switch of the H2 ring network.

[0079] In a preferred but non-limiting embodiment of the present invention, step 3 specifically comprises:

[0080] In step 3.1, after the H1 ring network receives the information from the H2 ring network in step 2.2, it further checks the status of the K2 switch between the H1 ring network and the H2 ring network. The current in the K2 switch exceeds the current threshold set in step 1, but the duration does not exceed the protection time limit condition set for the ring network switch in step 1. The K2 switch protection does not operate.

[0081] Step 3.2: Based on the protection action in step 3.1, it is determined that the H2 ring network K3 switch has not experienced a dead zone fault. The H2 ring network sends a signal to its next-level ring network H3. If there is no next-level ring network, the ring network switch protection action will directly trip.

[0082] Step 4: Determine whether a dead zone fault occurs at the K4 switch of the H2 ring network.

[0083] In a preferred but non-limiting embodiment of the present invention, step 4 specifically comprises:

[0084] Step 4.1: The H3 ring network searches for the line topology, sends a signal to the H4 ring network where the downstream tie switch K7 is located, and remotely closes the tie switch K7.

[0085] In step 4.2, after receiving the information sent by the H2 ring network in step 3.2, the H3 ring network further determines the status of the K5 switch between the H1 ring network and the H2 ring network. If the K5 switch meets the overcurrent protection condition set for the ring network switch in step 1, the K5 switch trips due to protection action, and it is determined that a dead zone fault occurs at the K4 switch of the H2 ring network.

[0086] Step 1: The ring network, ring network switch, and substation outgoing line switch are configured and protected in the same manner as described in Example 1.

[0087] In step 2, the current in the switch in the substation exceeds the set value in step 1, and the protection of switch Q1 in the substation is activated, and switch Q1 trips. The current in the ring network switch does not reach the action threshold set in step 1, and the ring network switch protection does not operate. The current and zero-sequence voltage in the ring network do not meet the protection action conditions set in step 1, and the ring network protection does not operate.

[0088] Step 3: After the switch Q1 in the substation is tripped in step 2, the switch Q1 sends a signal to the next level ring network H1.

[0089] Step 4: After receiving the protection information, the H1 ring network trips the incoming line switch K1.

[0090] Step 5: Retrieve the line topology of the H1 ring network.

[0091] Step 6: Send a signal to remotely close the contact switch K7 to restore power supply to the non-fault area.

[0092] The above examples are merely illustrative examples of the present invention. The line topology retains the trunk part, omits the unconnected branches, and sets the dead zone fault points, which are all intuitive and effective to illustrate the present invention and are not intended to limit the present invention. Any modifications, replacements, improvements, etc. made within the scope of the concept of the present invention should be included in the scope of protection of the present invention.

Claims

1. A feeder automation system considering dead zone failure of distribution network ring network switch, characterized in that: Applied to distribution network lines, specifically including: The fault protection module is used to configure corresponding protection measures for the distribution network, including: ring network zero-sequence voltage and zero-sequence current protection units, ring network switch zero-sequence current protection unit and substation zero-sequence current protection unit; the three units are set to cooperate with time-limited level differences; The fault isolation module is used to determine the fault location and isolate the fault area according to the action of the protection units of the ring network, ring network switch and substation when a short circuit or permanent grounding fault occurs in the line; if the ring network protection does not act, and the ring network switch protection acts as an alarm, the ring network where the ring network switch is located sends a signal to the connected next-level ring network; if there is no alarm information in the ring network switch of the next-level ring network, the switches on both sides between the ring network where the protection alarm occurs and the connected next-level ring network are tripped to isolate the fault area; if there is protection alarm information in the next-level ring network switch, the ring network may have a fault, and the switches on both sides between the ring network and the ring network where the protection alarm occurs will not act, and the fault site will be retained to prevent further expansion of the fault range; if the ring network protection acts, all switches in the ring network will be tripped If the current in the switch between the ring network where the protection action occurs and the ring network of the previous level reaches the overcurrent protection condition, it is determined that a dead zone fault has occurred in the incoming switch between the ring network where the protection action occurs and the ring network of the previous level, and the ring network switch trips to isolate the faulty area; if the current in the ring network switch does not meet the overcurrent protection condition, it is determined that no dead zone fault has occurred in the incoming switch; at the same time, the ring network where the protection action occurs sends a signal to the ring network of the next level, and if the protection action of the lower-level ring network switch occurs, it is determined that a dead zone fault has occurred in the outgoing switch between the ring network where the protection action occurs and the ring network of the next level; if the switch protection in the substation occurs and the ring network switch protection does not occur, the switch in the substation trips, isolates the faulty area, and determines that the outgoing cable of the substation is faulty; The power supply module for restoring the non-fault area is used to restore the power supply to the non-fault area after the fault isolation is completed.

2. A feeder automation system considering dead zone failure of a distribution network ring network switch according to claim 1, characterized in that: Restoring the power supply module in the non-faulty area when a ring network fault occurs is specifically used to: After the ring network switch protection is activated, the next-level ring network connected to it retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

3. A feeder automation system taking into account dead zone failures of distribution network ring network switches according to claim 2, characterized in that: Restoring the power supply module in the non-fault area when a dead zone fault occurs in the ring network outgoing line switch is specifically used to: After the ring network protection is activated, the next-level ring network connected to the ring network retrieves the line topology structure, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

4. A feeder automation system taking into account dead zone failures of distribution network ring network switches according to claim 3, characterized in that: Restoring the power supply module in the non-fault area when the substation outgoing cable fails is specifically used for: The substation retrieves the line topology, sends a signal to the ring network where the subsequent interconnection switch is located, remotely closes the interconnection switch, and restores power supply.

5. The feeder automation system considering dead zone failure of distribution network ring network switch according to claim 1, characterized in that: The communication methods between ring networks are optical cables and 5G.

6. A feeder automation system considering dead zone failure of distribution network ring network switches according to claim 2, characterized in that: The tie switch should select a line power supply with large load margin, short power supply radius and good line condition.

7. The feeder automation system considering dead zone failure of distribution network ring network switch according to claim 1, characterized in that: If all switches have the three remote control functions, the fault isolation module will determine the fault location and isolate the fault area based on the action of the protection measures when the fault occurs; if they do not have the three remote control functions, the fault isolation module will process the fault area by expanding it.

8. The feeder automation system considering dead zone failure of distribution network ring network switch according to claim 1, characterized in that: When there is no lower-level ring network, the ring network switch protection action will trip directly.

9. A feeder automation method considering dead zone faults of distribution network ring network switches, based on a feeder automation system considering dead zone faults of distribution network ring network switches according to any one of claims 1 to 8, characterized in that: Step 1: Configure protection measures, including ring network protection, ring network switch protection, and substation protection for the distribution network; Step 2: Determine whether a short circuit or permanent ground fault occurs in the line based on the action of the protection measures; Step 3: Isolate the fault area; Step 4: After the fault is isolated, restore power to the non-faulty areas.

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