A method and system for improving power supply reliability under dead zone fault of ring network switch

Abstract

The present invention discloses a method and system for improving power supply reliability during dead-zone faults in a ring network switch. The method comprises: configuring overcurrent and ground fault protection in the ring network; overcurrent and ground fault protection in the ring network switch; configuring overcurrent and ground fault protection in the substation; and determining whether a dead-zone fault has occurred based on whether the substation switch protection has operated, whether the ring network protection has operated, and whether the upper-level ring network switch has operated, and restoring power supply to the non-faulty section. This method effectively solves the problem of traditional feeder automation technology being unable to identify dead-zone faults in the ring network, avoids repeated power outages and expanded power outage ranges caused by dead-zone faults, improves the power supply reliability of the distribution network, and has promising application prospects.

Description

Technical Field

[0001] The present invention relates to a method for automatically isolating a fault area and restoring power supply to loads in a non-fault section under a distribution network fault condition, and in particular to a method for improving power supply reliability under a ring network switch dead zone fault condition. Background Art

[0002] With the rapid development of my country's economy, dependence on electric energy has increased, placing higher demands on power supply reliability and power quality. To improve urban land utilization and enhance the cityscape, some power supply companies are converting their urban distribution networks to fully cabled lines. Ring main units are being widely used in these areas. Simultaneously, computer, communications, and measurement and control technologies are being fully utilized in modern distribution networks. Some developed cities in China have already established fully self-healing distribution network systems, offering capabilities such as data collection and monitoring, fault handling, and load management.

[0003] Literature indicates that in a certain region of southern China, failures in the busbar compartment or switchroom of a cable ring main unit (RMU) account for 9.28% of all insulation failures in the distribution network, while failures in the cable compartment or at the cable terminal connectors account for 13.11%. Due to the installation location of current transformers (CTs), when a dead-zone fault occurs in a RMU, there is a 58.6% probability that the cable terminal connector will not be properly isolated if traditional self-healing strategies are used for fault isolation and power restoration. This can lead to repeated power outages, fault point shifts, and widespread outages, severely impacting normal electricity use for businesses, businesses, and residents, and damaging the image of power supply companies.

[0004] Feeder automation is an important component of the distribution automation system and is also the most widely used function. It mainly adopts three implementation modes: centralized, on-site, and distributed. Among them, centralized is the mainstream solution for feeder automation construction.

[0005] Prior Art Document 1 (CN117691742A) discloses a self-healing distribution automation terminal based on the IEC61850 protocol, and Prior Art Document 2 (CN116505493A) discloses a distributed fault location and isolation method for a multi-power distribution network. Both documents require peer-to-peer communication between ring networks, and the success rate of these methods depends on communication quality. They also fail to consider the impact of dead-zone faults on protection alarms and switch operations. Furthermore, they are unable to identify faults between ring network switches and current transformers, and without isolating dead-zone faults, switching power can lead to a wider range of power outages. Summary of the Invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a method that can avoid the adverse effects such as repeated power outages, fault point transfer, and expansion of power outage scope caused by the failure to identify the dead zone fault of the ring network switch, thereby improving the power supply reliability.

[0007] Technical solution: To achieve this purpose, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a method for improving power supply reliability under a ring network switch dead zone fault, comprising the following steps:

[0009] The ring network is equipped with overcurrent and ground fault protection;

[0010] Overcurrent and ground fault protection for ring network switches and user demarcation point switches;

[0011] The substation is equipped with overcurrent and ground fault protection;

[0012] Distribution network failure, switch protection tripping;

[0013] Based on whether the substation switch protection is activated, whether the ring network protection is activated, and whether the upper-level ring network switch is activated, it is determined whether the fault occurs in a dead zone and power supply to the non-fault section is restored.

[0014] Preferably, the current and time limit values ​​of the ring network protection are set to have sufficient sensitivity to the ring network bus fault;

[0015] The current setting of the ring network switch and the user demarcation point switch protection is set to have sufficient sensitivity to line faults, and the time limit is guaranteed to be one level different from the time limit set in the ring network protection;

[0016] The current setting of the substation switch protection is set to have sufficient sensitivity to line faults, and the time limit is guaranteed to be one level different from the time limit set in the ring network switch;

[0017] Preferably, judging whether a dead zone fault occurs and restoring power supply to the non-fault section is performed based on whether the substation switch protection is activated, whether the ring network protection is activated, and whether the upper-level ring network switch is activated, specifically including:

[0018] If the switch protection in the substation trips, and the ring network protection also trips, the upper switch on the ring network will send out an alarm signal, and it will be determined that the incoming switch of the tripped ring network has a dead zone fault, and the fault point will be isolated, and the power supply to the non-fault area will be restored;

[0019] If the switch protection in the substation trips and the ring network protection does not trip, search for the switch protection signal on the line to determine whether the cable between the ring networks is faulty, isolate the faulty area, and restore power supply to the non-faulty area.

[0020] If the switch protection in the substation does not trip, the ring network protection will trip, determine and isolate the fault area, and restore power supply to the non-fault area.

[0021] Preferably, when a dead zone fault occurs in the incoming switch of the tripping ring network, the specific measures to isolate the fault point include: retrieving the line topology structure, forming a power supply path topology from the switches on each side of the fault area to the substation outgoing switch and the substation outgoing switch on the opposite side of the interconnecting switch, remotely separating the upper-level switch of the tripping ring network, and constructing a link structure from the substation outgoing switch and the substation outgoing switch on the opposite side of the interconnecting switch to the switch on the fault area.

[0022] Preferably, when a cable between ring networks fails, the operation of isolating the faulty area specifically includes: remotely separating switches on each side of the faulty area, and constructing a link structure from the outgoing line switch of the substation on the opposite side of the tie switch to the switch on the local side of the faulty area.

[0023] Preferably, when the switch protection in the substation does not trip and the ring network protection trips, the operation of isolating the fault area is as follows: retrieving the line topology structure, forming a power supply path topology from the switches on each side of the fault area to the outgoing line switches of the substation on the opposite side of the tie switch, constructing a link structure from the outgoing line switches of the substation on the opposite side of the tie switch to the switches on the fault area, identifying the upper-level switches of the switches on each side of the fault area and activating the protection tripping function.

[0024] Preferably, if the upper level switches of the switches on each side of the fault area do not trip, it is determined that a ring network bus fault occurs in the tripped ring network switch; otherwise, it is determined that a dead zone fault occurs on the opposite side of the tripped ring network switch.

[0025] Preferably, specific measures to restore power supply to non-fault areas include:

[0026] Remotely close the tripped substation switch, tie switch, any feeder outgoing line switch with tie switch in the rear section of the tripped ring network, and any feeder outgoing line switch without tie switch in the rear section of the tripped ring network.

[0027] Retrieve the line topology structure, form the power supply path topology from the switches on each side of the fault area to the substation outgoing line switches on the opposite side of the tie switch, and remotely close the tie switch and the tripped substation switch.

[0028] The interconnecting switch, the incoming line switch on the tripped power supply side of the tripped ring network and the outgoing line switch on the feeder without interconnecting switch in the rear section of the tripped ring network are closed remotely, and the upper level switch protection action tripping function of the switches on each side of the fault area is exited.

[0029] Preferably, the switch has three remote control functions. If it does not have three remote control functions, the fault area will be expanded.

[0030] A second aspect of the present invention provides a system for improving power supply reliability under a ring network switch dead zone fault, and executing the above-mentioned method for improving power supply reliability under a ring network switch dead zone fault includes:

[0031] The fault protection module is used to configure corresponding protection measures for the distribution network to prevent damage to equipment when a fault occurs;

[0032] 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 the fault occurs;

[0033] 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.

[0034] Beneficial effects: Compared with the prior art, the present invention has the following beneficial effects.

[0035] 1) In the present invention, switch dead zone faults can be accurately identified.

[0036] 2) In the present invention, the power supply to the non-fault section can be quickly restored.

[0037] 3) The present invention can effectively avoid problems such as repeated power outages caused by switch dead zone failures, thereby improving power supply reliability.

[0038] 4) The present invention can accelerate the progress of accident handling. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a method for improving power supply reliability under dead zone faults of ring network switches;

[0040] Figure 2 This is a schematic diagram of a 10KV line;

[0041] Figure 3 This is a schematic diagram of a cable fault between the H1 ring network and the H2 ring network;

[0042] Figure 4 This is a schematic diagram of a dead zone fault occurring on H2 ring network switch K3;

[0043] Figure 5 This is a schematic diagram of a dead zone fault occurring in H2 ring network switch K4. DETAILED DESCRIPTION

[0044] The technical solution of the present invention will be further described below in conjunction with specific implementation methods and drawings.

[0045] 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. , taking the full cable line as an example, and appropriately simplifying it for the convenience of explanation, as shown in FIG. Figure 2 As shown, the substation outgoing line switches Q1 and Q2, and the distributed terminal ring network cabinets H1, H2, H3, and H4 all have three-way remote control functionality. If these switches do not, the fault area will be expanded. Switch K7 in the H4 ring network serves as the tie switch between the Q1 and Q2 lines. Solid areas represent the closed position, while hollow areas represent the open position. These examples include a cable fault between the H1 and H2 ring networks, and a dead zone fault in switch K4 in the H2 ring network. All tie switches prioritize line power sources with high load margins, short power supply radii, and good line conditions. For power transmission to the front section of the fault area, the power source from the fault-tripping line is preferred. For trial power transmission to the fault area, the power source from the fault-tripping line is preferred.

[0046] Example 1

[0047] Reference Figure 3 This is the first embodiment of the present invention, which provides a method for improving power supply reliability when a cable fault occurs between ring networks. In this embodiment, it is assumed that a cable fault occurs between the H1 ring network and the H2 ring network. Based on the operation of the protection measures, the fault area is determined and isolated, and power supply to the non-fault area is restored.

[0048] Step 1: Configure protection measures for the ring network, ring network switches, and substation outgoing line switches.

[0049] In a preferred but non-limiting embodiment of the present invention, step 1 specifically comprises:

[0050] Step 1.1, set the direction of the current flowing into the busbar of the ring network switch to negative, and the direction of the current flowing out of the busbar to positive. If the sum of the currents of all switches in the ring network is greater than the set value, and the busbar zero-sequence voltage is greater than the set value and remains greater than the set value for a certain period of time, then all switches in the ring network will be tripped. Among them, the current setting value and the time limit setting value are adjusted to have sufficient sensitivity to the ring network busbar fault.

[0051] Step 1.2: Configure overcurrent or zero-sequence overcurrent protection on the ring network switch and the user demarcation point switch. Set the current setting to be sensitive enough to line faults. Ensure the time limit is one level different from the time limit in step 1.1, and activate the protection signal alarm function.

[0052] Step 1.3: Configure overcurrent or zero-sequence overcurrent protection on the switches in the substation. Set the current setting to be sensitive enough to line faults. Ensure that the time limit is one level different from the time limit in step 1.2. Enable the protection signal alarm function and the protection action tripping function.

[0053] As a prominent substantive feature of the present invention and one of the significant improvements it brings to the prior art, on the basis of adopting centralized feeder automation, the impact of faults is fully taken into consideration. By configuring three levels of ring network protection, ring network switch protection and substation switch protection, dead zone faults can be effectively identified to avoid problems such as the expansion of power outage scope.

[0054] Step 2: When a permanent fault occurs in the cable between the H1 ring network and the H2 ring network, line protection is activated.

[0055] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0056] In step 2.1, the current in the substation outgoing line switch exceeds the overcurrent threshold preset in step 1.2, causing protection action and tripping.

[0057] In step 2.2, the current in the ring network protection does not reach the action threshold set in step 1.1, so the circuit breaker does not trip.

[0058] Step 3: Identify and isolate the fault area

[0059] In a preferred but non-limiting embodiment of the present invention, step 3 specifically comprises:

[0060] By searching for switch protection signals on the line, it was found that K1 and K2 had protection alarm signals, and the fault area was determined to be between switches K2 and K3. Then, switches K2 and K3 on each side of the fault area were remotely separated to isolate the fault area.

[0061] As a prominent substantive feature of the present invention and one of the significant advances it brings to the prior art, through the three-level coordination of ring network protection, ring network switch protection and substation switch protection, the fault area can be accurately identified. When a dead zone fault occurs, the power outage range will not be expanded, and the impact range of the power outage can be minimized.

[0062] Step 4: After isolating the faulty area in step 3, restore power to the non-faulty areas.

[0063] In a preferred but non-limiting embodiment of the present invention, step 4 specifically comprises:

[0064] Step 4.1: Retrieve the line topology and form the power supply path topology from switch K2 to substation outgoing switch Q1 and switch K3 to substation outgoing switch Q2.

[0065] Step 4.2: Remotely close the substation outgoing line switch Q1 and the tie switch K7 to restore power supply to the non-fault area.

[0066] As a prominent substantive feature of the present invention and one of the significant advances it brings to the prior art, the present invention can achieve accurate fault identification, most importantly, it can identify dead zone faults; when a dead zone fault occurs, the fault can be quickly isolated and power supply restored.

[0067] Example 2

[0068] Reference Figure 4 The second embodiment of the present invention provides a method for improving power supply reliability when a fault occurs between the ring network switch K3 and the current transformer. In this embodiment, it is assumed that a dead zone fault occurs at the H2 ring network switch K3. Based on the operation of the protection measures, the fault area is determined and isolated, and power supply to the non-fault area is restored.

[0069] 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.

[0070] Step 2: When a dead zone fault occurs at the H2 ring network switch K3, the line protection is activated.

[0071] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0072] In step 2.1, the sum of the switch currents in the H2 ring network exceeds the set value in step 1, and the bus zero-sequence voltage exceeds the set value in step 1 and remains there for a period of time. The ring network protection is activated, causing switches K3 and K4 to trip.

[0073] In step 2.2, the current in the switch Q1 in the substation exceeds the current setting configured in step 1, Q1 trips due to protection, and the upper-level switch K2 of the H2 ring network issues a protection alarm.

[0074] Step 3: Determine the fault location and isolate it. Based on the protection alarm information obtained in Step 2, determine that a dead zone fault has occurred in the incoming line switch K3 of the H2 ring network. Remotely disconnect the upper-level switch K2 of the H2 ring network to isolate the fault point.

[0075] Step 4: Restore power to the non-faulty areas.

[0076] In a preferred but non-limiting embodiment of the present invention, step 4 specifically comprises:

[0077] Step 4.1: After isolating the fault area in step 3, retrieve the line topology to form the power supply path topology from switch K2 to substation outgoing switch Q1 and from switch K4 to the opposite substation outgoing switch Q2 of tie switch K7, and build a link structure.

[0078] Step 4.2: Close the substation outgoing line switch Q1, tie switch K7, H2 ring network switch K4, and H2 ring network switch L2 by remote control, thereby restoring power supply to the non-fault area.

[0079] Reference Figure 5 As a third embodiment of the present invention, a method for improving power supply reliability in the event of a fault between the K4 switch and the current transformer is provided.

[0080] 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.

[0081] Step 2: When a dead zone fault occurs at the switch K4 of the ring network H2, the ring network protection action occurs.

[0082] In a preferred but non-limiting embodiment of the present invention, step 2 specifically comprises:

[0083] In step 2.1, the substation switch protection does not trip. At this time, the sum of the ring network current and the bus voltage exceed the set value in step 1.1, and both exceed the set value in step 1.1 for a period of time. The ring network protection trips. Open switches K3, K4, and L2.

[0084] Step 2.2: Retrieve the line topology to form the power supply path topology from the switch K4 on each side of the fault area to the substation outgoing switch Q2 on the opposite side of the tie switch K7. Construct a link structure from the substation outgoing switch on the opposite side of the tie switch to the switch on the fault area, and identify the upper-level switch K5 on each side of the fault area.

[0085] Step 3: Isolate the fault area.

[0086] In a preferred but non-limiting embodiment of the present invention, step 3 specifically comprises:

[0087] In step 3.1, the protection tripping function of the upper level switch K5 of the switch K4 on each side of the fault area in step 2 is enabled.

[0088] Step 3.2: Close the contact switch K7 in step 2 by remote control

[0089] Step 4: The switch protection in step 3 is activated, and switch K5 trips. It is determined that the tripped ring network switch K4 has a dead zone fault.

[0090] Step 5: Restore power to the non-faulty areas.

[0091] In a preferred but non-limiting embodiment of the present invention, step 5 specifically comprises:

[0092] Step 5.1: Remotely close the tripped power supply side incoming line switch K3 of the tripped ring network in step 2.

[0093] Step 5.2: remotely close the feeder outgoing line switch L2 without a tie switch in the rear section of the tripped ring network in step 2. When restoring power to the rear section of the fault area, the line power supply with a large load margin, a short power supply radius and good line condition is preferably used.

[0094] In step 5.3, the upper level switch protection tripping function of the switches on each side of the fault area in step 3 is exited, and the power supply to the non-fault area is restored.

[0095] Example 4

[0096] Embodiment 4 of the present invention provides a system for improving power supply reliability under dead zone faults of a ring network switch, which executes the method for improving power supply reliability under dead zone faults of a ring network switch according to embodiments 1 to 3. The system comprises:

[0097] Fault protection module, used to configure corresponding protection measures for the distribution network to prevent damage to equipment when a fault occurs;

[0098] Fault isolation module, used to determine the fault location and isolate the fault area based on the action of protection measures when a fault occurs;

[0099] 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.

[0100] 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 method for improving power supply reliability under dead zone fault of a ring network switch, characterized in that: The following steps are involved: The ring network is equipped with overcurrent and ground fault protection; The ring network switch and user demarcation point switch are equipped with overcurrent and ground fault protection; The substation is equipped with overcurrent and ground fault protection; Distribution network failure, switch protection tripping; Based on whether the substation switch protection is activated, whether the ring network protection is activated, and whether the upper-level ring network switch is activated, it is determined whether the fault occurs in a dead zone, the fault area is isolated, and power supply to the non-fault section is restored; If the switch protection in the substation trips, and the ring network protection also trips, the upper switch on the ring network will send out an alarm signal, and it will be determined that the incoming switch of the tripped ring network has a dead zone fault, and the fault point will be isolated, and the power supply to the non-fault area will be restored; If the switch protection in the substation trips but the ring network protection does not, the switch protection signal on the line is searched to determine if the cable between the ring networks is faulty, isolate the faulty area, and restore power to the non-faulty areas. If the switch protection in the substation does not trip, the ring network protection will trip, determine and isolate the fault area, and restore power supply to the non-fault area.

2. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 1, characterized in that: The current and time limit values ​​of the ring network protection are set to have sufficient sensitivity to the ring network bus fault; The current setting of the ring network switch and the user demarcation point switch protection is set to have sufficient sensitivity to line faults, and the time limit is guaranteed to be one level different from the time limit set in the ring network protection; The current setting of the substation switch protection is adjusted to have sufficient sensitivity to line faults, and the time limit is guaranteed to be one level different from the time limit set in the ring network switch.

3. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 1, characterized in that: When a dead zone fault occurs on the incoming switch of the tripping ring network, the specific measures to isolate the fault point include: Retrieve the line topology structure, form the power supply path topology from the switches on each side of the fault area to the substation outgoing switches and the substation outgoing switches on the opposite side of the tie switch, remotely separate the upper-level switches of the tripping ring network, and build the link structure from the substation outgoing switches and the substation outgoing switches on the opposite side of the tie switch to the switches on the fault area.

4. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 2, characterized in that: When a cable fault occurs between ring networks, the following operations are performed to isolate the faulty area: Remotely separate the switches on each side of the fault area and build a link structure from the outgoing line switch of the substation on the opposite side of the tie switch to the switch on the local side of the fault area.

5. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 2, characterized in that: When the switch protection in the substation does not trip and the ring network protection trips, the operation to isolate the fault area is as follows: Retrieve the line topology structure, form the power supply path topology from the switches on each side of the fault area to the outgoing line switches of the substation on the opposite side of the tie switch, build the link structure from the outgoing line switches of the substation on the opposite side of the tie switch to the switches on the fault area, identify the upper-level switches on each side of the fault area and activate the protection action tripping function.

6. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 5, characterized in that: If the upper level switches of the switches on each side of the fault area do not trip, it is determined that the tripped ring network switch has a ring network bus fault. Otherwise, it is determined that a dead zone fault has occurred on the opposite side of the tripped ring network switch.

7. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 2, characterized in that: When a dead zone fault occurs in the incoming switch of the tripped ring network, the specific measures to restore power supply to the non-fault area include: Remotely close the tripped substation switch, tie switch, any feeder outgoing line switch with tie switch in the rear section of the tripped ring network, and any feeder outgoing line switch without tie switch in the rear section of the tripped ring network.

8. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 3, characterized in that: When a dead zone fault occurs in the incoming switch of the tripped ring network, the specific measures to restore power supply to the non-fault area include: Retrieve the line topology structure, form the power supply path topology from the switches on each side of the fault area to the substation outgoing line switches on the opposite side of the tie switch, and remotely close the tie switch and the tripped substation switch.

9. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 4, characterized in that: When a cable fault occurs between ring networks, specific measures to restore power to the non-faulty area include: The interconnecting switch, the incoming line switch on the tripped power supply side of the tripped ring network and the outgoing line switch on the feeder without interconnecting switch in the rear section of the tripped ring network are closed remotely, and the upper level switch protection action tripping function of the switches on each side of the fault area is exited.

10. The method for improving power supply reliability under dead zone fault of a ring network switch according to claim 1, characterized in that: The switch has three remote control functions. If it does not have three remote control functions, the fault area will be expanded.

11. A system for improving power supply reliability under dead zone faults of a ring network switch, which runs the method for improving power supply reliability under dead zone faults of a ring network switch according to any one of claims 1 to 10, characterized in that: include: The fault protection module is used to configure corresponding protection measures for the distribution network to prevent damage to equipment when a fault occurs; 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 the fault occurs; 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.

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