Circuit breaker, multi-power supply system, ring power supply system and protection method of system

Abstract

A circuit breaker, a multi-power supply system, a ring power supply system, and a protection method for the two systems are provided. The circuit breaker can be configured to respond to a current in a forward direction and not respond to a current in a reverse direction. The forward direction is from a busbar or power supply nearest the circuit breaker to a line, and the reverse direction is from the line to the busbar or power supply nearest the circuit breaker.

Description

Technical Field

[0001] This application relates to power distribution systems, and more specifically, to a circuit breaker, a multi-power supply system and its protection method, and a ring power supply system and its protection method. Background Technology

[0002] On one hand, with the increasing integration of new energy sources (such as photovoltaics, wind power, energy storage, and vehicle-to-grid (V2G)), the architecture of the entire power distribution system has undergone tremendous changes, evolving from the traditional single-source (waterfall) network to a new multi-source system. In multi-source systems, the direction of short-circuit current becomes very complex, and traditional protection methods based on three-stage long-time, short-time, and instantaneous (LSI) circuit breakers cannot solve the problem and are no longer suitable for the protection of multi-source systems.

[0003] Therefore, this application provides a protection method for multi-power supply systems. By installing circuit breakers with directional protection in multi-power supply systems, the protection challenges of multi-power supply systems are effectively solved.

[0004] The method of this application has many advantages, including but not limited to: it does not rely excessively on communication, it is implemented on the basis of traditional protection methods based on three-stage circuit breakers, it is low in cost, simple to configure, conforms to the usage habits of system maintenance personnel, and is easy to promote on a large scale.

[0005] On another front, with the integration of new energy sources and the development of new power systems, the architecture of the entire power distribution system has undergone tremendous changes, evolving from the traditional single-source network to a new multi-source architecture. Simultaneously, because parallel connection of multiple sources in DC systems is easier to implement, and the ring power supply architecture significantly reduces system costs and improves power supply reliability, it is increasingly being used. However, the ring power supply architecture also makes the direction of the short-circuit current in the entire system exceptionally complex, making it difficult for traditional protection methods based on three-stage (LSI) circuit breakers to provide effective protection for ring power supply systems.

[0006] To this end, this application also provides a protection method for a ring power supply system. Based on the current three-stage circuit breaker, it introduces the concept of directional protection, provides the optimal configuration for the ring power supply system, and successfully solves the protection problem of the ring power supply system.

[0007] The protection method for the ring power supply system proposed in this application does not rely on complex communication mechanisms, requires minimal modification to existing protection methods based on three-stage circuit breakers, has low implementation cost, is simple to configure, conforms to the usage habits of system maintenance personnel, and is easy to promote on a large scale.

[0008] In another aspect, traditional three-stage protection circuit breakers do not have directional protection functions, cannot determine the direction of different short-circuit currents, and therefore cannot take appropriate protective actions for short-circuit currents in different directions.

[0009] Therefore, this application also provides a circuit breaker with directional protection (function). This circuit breaker with directional protection is applied in the protection method for multi-source systems and the protection method for ring power supply systems of this application. Summary of the Invention

[0010] In one aspect of this application, a circuit breaker is provided. The circuit breaker can be configured to: respond to a current in the positive direction; and not respond to a current in the reverse direction, wherein the positive direction is from the bus or power source nearest to the circuit breaker towards the line, and wherein the reverse direction is from the line towards the bus or power source nearest to the circuit breaker.

[0011] In another aspect of this application, a method for protecting a multi-power supply system is also provided, the multi-power supply system including multiple power sources. The method may include: installing a first circuit breaker and a second circuit breaker at both ends of all lines except for pure load branches, wherein the first circuit breaker and the second circuit breaker are respectively responsive to current in their positive direction and not responsive to current in their reverse direction, wherein the positive direction is from the bus or power source nearest to the corresponding circuit breaker towards the line, and wherein the reverse direction is from the line towards the bus or power source nearest to the corresponding circuit breaker.

[0012] In some embodiments, in a method for protecting a multi-power supply system, when the circuit breaker on the line on which the first circuit breaker and the second circuit breaker are located fails to operate normally, both the first circuit breaker and the second circuit breaker are capable of self-protection against abnormally large short-circuit currents in the opposite direction.

[0013] In some implementations, in a method for protecting a multi-power supply system, the number of the plurality of power supplies can be n, where n can be an integer greater than or equal to 2.

[0014] In some implementations, in a method for protecting a multi-power supply system, the bus to which the multiple power supplies are connected is defined as a primary bus, and there may be m buses between each power supply and the primary bus, where m can be an integer greater than or equal to 0.

[0015] In some implementations, in a method for protecting a multi-power supply system, when the line is short, the first circuit breaker and the second circuit breaker can be the same circuit breaker, which can respond in both directions according to different time delay protection settings.

[0016] In some embodiments, the method for protecting a multi-power supply system may further include: when the power supply has short-circuit fault ride-through capability, omitting the circuit breaker closest to the power supply in the first circuit breaker and the second circuit breaker, and only installing the other circuit breaker in the first circuit breaker and the second circuit breaker, wherein the power supply participates in time delay differential coordination.

[0017] In some embodiments, the method for protecting a multi-power system may further include a pure load branch, and the method may further include: installing a circuit breaker without directional protection on the line of the pure load branch.

[0018] In some embodiments, the method for protecting a multi-power supply system may further include: starting from the short-circuit fault location at the farthest end of the line with the most line levels among all lines in the multi-power supply system, and along all possible short-circuit current paths, performing time delay differential coordination on all circuit breakers that respond to current in the positive direction, so as to ensure that the time delay protection settings of all circuit breakers that respond to current in the positive direction meet the differential coordination requirements.

[0019] In some implementations, in a method for protecting a multi-power supply system, when performing time-delay differential coordination, the location of the short-circuit fault at the farthest end of each of all lines is taken into account, and when a short-circuit fault occurs at the corresponding location, the time-delay protection settings of the circuit breakers that respond to the current in the positive direction in all possible short-circuit current paths meet the differential coordination requirements.

[0020] In some implementations, in methods for protecting multi-power supply systems, when performing time delay differential coordination, it is ensured that the time delay protection settings of all circuit breakers and power supplies are configured, and that the power supplies and circuit breakers responding to positive currents meet the differential coordination requirements on all possible short-circuit current paths.

[0021] In some embodiments, the method for protecting a multi-power supply system may further include: without omitting a circuit breaker located near the power supply, both the circuit breaker and the power supply participate in time delay differential coordination.

[0022] In some embodiments, the method for protecting a multi-power system may further include a bus tie circuit breaker, which may be a circuit breaker with directional protection.

[0023] In some implementations, in methods for protecting multi-power supply systems, the bus tie circuit breaker may occupy a first-level time delay protection setting and may participate in time delay differential coordination.

[0024] In some embodiments, in a method for protecting a multi-power supply system, the time delay protection setting of the bus tie circuit breaker can be set to a first time delay protection setting and a second time delay protection setting, wherein the first time delay protection setting can be for short-circuit current flowing from the first side to the second side of the bus tie circuit breaker, and the first time delay protection setting can be the maximum value among time delay protection settings determined by coordinating time delay levels on all possible short-circuit current paths starting from the farthest end of all lines on the second side of the bus tie circuit breaker; wherein the second time delay protection setting can be for short-circuit current flowing from the second side to the first side of the bus tie circuit breaker, and the second time delay protection setting can be the maximum value among time delay protection settings determined by coordinating time delay levels on all possible short-circuit current paths starting from the farthest end of all lines on the first side of the bus tie circuit breaker.

[0025] In some implementations, in a method for protecting a multi-power supply system, the bus tie circuit breaker may be a circuit breaker without directional protection when the first time delay protection setting is equal to the second time delay protection setting.

[0026] In some embodiments, the method for protecting a multi-power supply system may further include: determining, upon determining a first time delay protection setting, the power supply on the first side of the bus tie circuit breaker and the time delay protection setting of the circuit breaker that responds to positive current by using time delay differential coordination based on the first time delay protection setting of the bus tie circuit breaker; and determining, upon determining a second time delay protection setting, the power supply on the second side of the bus tie circuit breaker and the time delay protection setting of the circuit breaker that responds to positive current by using time delay differential coordination based on the second time delay protection setting of the bus tie circuit breaker.

[0027] In some implementations, in methods for protecting multi-power systems, the delay step difference in the coordination is determined by coordinating the operating time of the circuit breaker.

[0028] In some embodiments, the multi-power system may further include a loop in the method for protecting a multi-power system.

[0029] In another aspect of this application, a method for protecting a ring power supply system is also provided. The ring power supply system may include a power source and a loop, the loop including n distribution cabinets connected to each other by lines to form part of the loop. The method may include: installing a circuit breaker with directional protection at both ends of n+1 lines other than the incoming busbar on the loop, thereby installing a total of 2n+2 circuit breakers on the loop, wherein each of the 2n+2 circuit breakers can respond to current in its positive direction and can not respond to current in its reverse direction, wherein the positive direction is from the busbar nearest to the corresponding circuit breaker to the line, and the reverse direction is from the line to the busbar nearest to the corresponding circuit breaker.

[0030] In some implementations, in a method for protecting a ring power supply system, when the circuit breaker on the line on which the 2n+2 circuit breakers are located fails to operate normally, all 2n+2 circuit breakers are capable of self-protection against abnormally large short-circuit currents in the opposite direction.

[0031] In some embodiments, the method for protecting a ring power supply system may further include an incoming bus tie switch that remains closed during normal operation.

[0032] In some implementations, in a method for protecting a ring power supply system, there are power sources supplying power to the loop on both sides of the incoming bus tie switch.

[0033] In some implementations, the incoming bus tie switch in the method for protecting a ring power supply system does not have a protective function.

[0034] In some embodiments, in a method for protecting a ring power supply system, when a fault occurs on the incoming bus, the incoming bus tie switch, in conjunction with bus differential protection, isolates the fault area of ​​the bus.

[0035] In some embodiments, in the method for protecting a ring power supply system, among the 2n+2 circuit breakers other than the incoming bus tie switch, the n+1 circuit breakers in the clockwise direction form a time delay differential coordination, with the time delay protection setting increasing progressively from the circuit breaker furthest from the power source to meet the differential coordination requirements; and among the 2n+2 circuit breakers other than the incoming bus tie switch, the n+1 circuit breakers in the counterclockwise direction form a time delay differential coordination, with the time delay protection setting increasing progressively from the circuit breaker furthest from the power source to meet the differential coordination requirements.

[0036] In some embodiments, the method for protecting a ring power supply system may further include: installing a circuit breaker with directional protection on the power supply line, the circuit breaker responding to current from the bus, and the circuit breaker having instantaneous protection, or the circuit breaker having a time delay protection setting of T=0.

[0037] In some embodiments, the method for protecting a ring power supply system may further include: installing a circuit breaker without directional protection on the line where the load is located, the circuit breaker having instantaneous protection, or the circuit breaker having a time delay protection setting of T=0.

[0038] In some implementations, in a method for protecting a ring power supply system, a time delay protection setting of T=0 represents the minimum value among all possible time delay protection settings.

[0039] In some embodiments, in a method for protecting a ring power supply system, the power supply may have short-circuit fault ride-through capability, and the method may further include obtaining a time delay protection setting for the power supply by adding to a time delay protection setting determined based on the maximum number of distribution cabinets connected to each other in each loop of the ring power supply system.

[0040] In some embodiments, the method for protecting a ring power supply system may further include: obtaining a time delay protection setting based on the obtained time delay protection setting according to the number of busbars between the power supply and the primary busbar, wherein the busbars commonly connected to the power supply are defined as primary busbars.

[0041] In some implementations, in a method for protecting a ring power supply system, the number of distribution cabinets connected to each other on each ring can be an integer greater than or equal to 1.

[0042] In some implementations, in a method for protecting a ring power supply system, the number of power sources can be n', where n' can be an integer greater than or equal to 1.

[0043] In some implementations, in the method for protecting a ring power supply system, there may be m buses between each power source and the primary bus, where m can be an integer greater than or equal to 0.

[0044] In some implementations, in a method for protecting a ring power supply system, the step difference in the delay step coordination is determined by the operating time of the coordinated circuit breaker.

[0045] In another aspect of this application, a multi-power supply system is also provided, configured to perform the method for protecting a multi-power supply system as described herein.

[0046] In another aspect of this application, a ring power supply system is also provided, configured to perform the method for protecting a ring power supply system as described herein. Attached Figure Description

[0047] This application will be more readily understood through the following detailed description with reference to the accompanying drawings, wherein the same reference numerals designate units of the same structure, and in the drawings:

[0048] Figure 1 This diagram illustrates the problems encountered when traditional protection methods based on three-stage circuit breakers are applied to multi-power supply systems.

[0049] Figure 2 This is a schematic diagram illustrating a protection method for a multi-power supply system without a bus tie circuit breaker according to an embodiment of this application;

[0050] Figure 3 This is a schematic diagram illustrating a protection method for a multi-power supply system with a bus tie circuit breaker according to an embodiment of this application;

[0051] Figure 4 This is a schematic diagram illustrating a protection method for a ring power supply system according to an embodiment of this application;

[0052] Figure 5 This is a schematic structural diagram showing a circuit breaker with directional protection according to an embodiment of this application;

[0053] Figure 6 This is a schematic structural diagram illustrating a multi-power supply system according to an embodiment of this application; and

[0054] Figure 7 This is a schematic structural diagram illustrating a ring power supply system according to an embodiment of this application. Detailed Implementation

[0055] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0056] Furthermore, it should be noted that in this specification, A connected to B can mean "A is directly connected to B" or "A is connected to B via other middleware". A connected between B and C can mean "A is directly connected to both A and B" or "A is connected to both B and C via other middleware".

[0057] In multi-source systems, traditional protection methods based on three-stage circuit breakers cannot meet the requirements of selective coordination. The resulting problems are discussed in the following sections. Figure 1 A more detailed description.

[0058] This application provides a circuit breaker (with directional protection). The circuit breaker with directional protection in this application is based on a traditional three-stage circuit breaker, with the addition of directional protection function, enabling the circuit breaker to determine different short-circuit current directions and then take different protective actions for short-circuit currents in different directions.

[0059] Specifically, according to embodiments of this application, a circuit breaker can be configured to respond to current in the forward direction and not to respond to current in the reverse direction. In embodiments, the forward direction can be the direction from the bus or power source nearest to the circuit breaker towards the line. In embodiments, the reverse direction can be the direction from the line towards the bus or power source nearest to the circuit breaker. It should be understood that the terms "forward direction" and "reverse direction" in this application are defined for illustrative purposes only and are not limiting.

[0060] The accompanying drawings of this application use a low-voltage power distribution system as an example for illustration. However, those skilled in the art will understand that the protection methods for multi-power supply systems and ring power supply systems of this application can also be applied to medium-voltage power distribution systems and / or high-voltage power distribution systems.

[0061] The power sources involved in the multi-power supply system and ring power supply system of this application include, but are not limited to, power grids, energy storage, photovoltaics, wind power, V2G, etc.

[0062] The protection methods for multi-source systems and ring power supply systems proposed in this application can be applied to various new power systems, including, for example, DC power distribution, DC microgrids, AC microgrids, etc., but are not limited thereto.

[0063] The number of power sources, loads, lines, their connections, and circuit topologies shown in the accompanying drawings of this application for multi-power systems and ring power supply systems are exemplary, but not limited thereto.

[0064] The time delay protection settings (e.g., T=0 to T=4) in the accompanying drawings of this application represent only the relative magnitudes of the time delay protection settings, not the absolute time magnitudes. In this application, the time represented by the time delay protection setting (T=0) < the time represented by the time delay protection setting (T=1) < the time represented by the time delay protection setting (T=2) < the time represented by the time delay protection setting (T=3) < the time represented by the time delay protection setting (T=4), and so on.

[0065] The time delay protection setting range (T=0 to T=4) shown in the accompanying drawings of this application is given under specific circuit topologies. Those skilled in the art should understand that the time delay protection setting range is not limited to this. For different circuit topologies, there may be higher-level time delay protection settings than the highest time delay protection setting shown (T=4), such as T=5, T=6, etc.

[0066] In the embodiment, the delay level difference in the delay level coordination can be determined in conjunction with the operating time of the circuit breaker.

[0067] The arrows shown in the accompanying drawings of this application indicate the direction of the short-circuit current responded to by the corresponding circuit breaker. The corresponding circuit breaker operates (e.g., disconnects) according to the corresponding time-delay protection setting in response to the short-circuit current in that direction. In this application, "circuit breaker responds to current in the positive direction" means that when the amplitude of the short-circuit current in the positive direction meets the conditions, the circuit breaker responds to the short-circuit current according to the corresponding time-delay protection setting to disconnect the circuit breaker. In this application, "circuit breaker does not respond to current in the reverse direction" means that the circuit breaker allows current in the reverse direction to pass without disconnecting. However, in specific situations, such as when the paired circuit breaker that responds to current in the positive direction fails to disconnect normally, and / or the current in the reverse direction is abnormally large, the circuit breaker that should not respond to current in the reverse direction may also perform self-protection and disconnect.

[0068] In the accompanying drawings of this application, the circuit breaker corresponding to the arrow represents a circuit breaker with directional protection. In a circuit breaker with directional protection, the directional protection can be combined with any one of the three LSI stages. In the accompanying drawings of this application, the circuit breaker not corresponding to the arrow represents a circuit breaker without directional protection.

[0069] Figure 1 This diagram illustrates the problems encountered when traditional protection methods based on three-stage circuit breakers are applied to multi-power supply systems.

[0070] like Figure 1 As shown, the multi-power supply system includes power source #1, power source #2, and loads. Power source #1, power source #2, and loads are connected via lines (including busbars). Figure 1 As shown, the busbar connecting power supply #1 and power supply #2 (the busbar at the top of the diagram) is defined as the primary busbar. There is another busbar between power supply #2 and the primary busbar. Figure 1 As shown, the bus directly connected to power supply #2 is defined as the secondary bus.

[0071] In the traditional protection method based on a three-stage circuit breaker, circuit breaker 101 is installed on the line between the primary busbar and power source #1. Similarly, circuit breakers 101 are installed on the lines between the primary busbar and power source #2, and on the lines between the primary busbar and the load, respectively, as follows: Figure 1Circuit breakers 103, 109, 110 and 104, 111, 112 are installed as shown. Circuit breakers 103, 109, 110 and 104, 111, 112 are all circuit breakers without directional protection.

[0072] In multi-source systems, traditional protection methods based on three-stage circuit breakers cannot meet the requirements for selective coordination. This is because short-circuit faults can occur at different locations within the system, and the direction of the short-circuit current changes with the fault location, making the current path complex. Consequently, when configuring the time-delay protection settings of the circuit breaker, the time-delay protection settings for the same circuit breaker in both forward and reverse directions may be contradictory, thus failing to meet the requirements for selective coordination.

[0073] by Figure 1 For example, when a short-circuit fault occurs at the branch where power source #1 is located, circuit breaker 101 should operate before circuit breaker 103 to meet the selective coordination requirements. However, when a short-circuit fault occurs at the branch where power source #2 is located, circuit breaker 103 should operate before circuit breaker 101 to meet the selective coordination requirements. In this situation, to meet the selective coordination requirements, the order in which circuit breakers 103 and 101 operate contradicts each other for short-circuit currents in both directions. Therefore, it is evident that the traditional protection method based on three-stage circuit breakers cannot meet the selective coordination requirements when applied to multi-power source systems.

[0074] Figure 2 This is a schematic diagram illustrating a protection method for a multi-power supply system without a bus tie circuit breaker according to an embodiment of this application.

[0075] In this embodiment, the number of power sources included in the multi-power system can be n, where n can be an integer greater than or equal to 2. In this embodiment, the busbar to which the multiple power sources are connected is defined as a primary busbar (the busbar at the top of the figure). There can also be m buses between each power source and the primary busbar, where m can be an integer greater than or equal to 0. Figure 2 In the example shown, m is 0 for power supply #1 and 1 for power supplies #2 and #3.

[0076] The method for protecting a multi-power supply system according to this application may include: installing a first circuit breaker and a second circuit breaker at both ends of all other lines except for pure load branches, wherein the first circuit breaker and the second circuit breaker respond to current in the positive direction and do not respond to current in the reverse direction, wherein the positive direction is from the bus or power source nearest to the corresponding circuit breaker to the line, and wherein the reverse direction is from the line to the bus or power source nearest to the corresponding circuit breaker.

[0077] like Figure 2As shown, the multi-power system includes power supply #1, power supply #2, and power supply #3. Furthermore, the multi-power system may also include loads. Similar to... Figure 1 Circuit breaker 101 is installed on the line between the primary busbar and power source #1. Circuit breakers 102, 105, 107, and 108 are installed on the line between the primary busbar and power source #2. Circuit breakers 103, 106, 109, and 110 are installed on the line between the primary busbar and power source #3. Circuit breakers 104, 111, and 112 are installed on the line between the primary busbar and the load. Figure 2 In the diagram, the circuit breakers 101, 102, 105, 107, 108, 103, 106, 109, and 110 are located on circuits other than pure load branches. As shown in the diagram, the busbars connected to power supplies #2 and #3 are defined as secondary busbars.

[0078] According to the method of this application, a first circuit breaker and a second circuit breaker can be respectively installed at both ends of the lines other than the pure load branches (the lines where circuit breakers 101, 102, 105, 107, 108, 103, 106, 109, and 110 are located). (For ease of explanation, only the case where one circuit breaker is installed at each end of the lines where circuit breakers 102 and 105 are located and the lines where circuit breakers 103 and 106 are located is shown, but it is not limited to this. One circuit breaker can also be installed at each end of the lines where circuit breakers 101, 107, 108, 109, and 110 are located.) The first circuit breaker and the second circuit breaker respond to the current in the positive direction and do not respond to the current in the opposite direction. The positive direction is the direction from the bus or power source closest to the corresponding circuit breaker to the line, and the opposite direction is the direction from the line to the bus or power source closest to the corresponding circuit breaker.

[0079] In this embodiment, when the circuit breaker on the line where the first circuit breaker and the second circuit breaker are located fails to operate normally, both the first circuit breaker and the second circuit breaker can self-protect against the abnormally large short-circuit current in the opposite direction.

[0080] For example, according to the method of this application, circuit breakers 102 and 105 are respectively installed at both ends of the line where circuit breakers 102 and 105 are located, and these two circuit breakers 102 and 105 respond to the current in their positive direction (e.g. Figure 2As shown, circuit breaker 102 responds to current in the downward direction but not to current in the upward direction, while circuit breaker 105 responds to current in the upward direction but not to current in the downward direction. The downward direction is the positive direction of circuit breaker 102, which is the direction from the busbar nearest to circuit breaker 102 towards the line; the upward direction is the opposite direction of circuit breaker 102, which is the direction from the line towards the busbar nearest to circuit breaker 102. Similarly, the upward direction is the positive direction of circuit breaker 105, which is the direction from the busbar nearest to circuit breaker 105 towards the line; the downward direction is the opposite direction of circuit breaker 105, which is the direction from the line towards the busbar nearest to circuit breaker 105.

[0081] In embodiments, when the line is short, and / or for cost-saving purposes, circuit breakers 102 and 105 can be the same circuit breaker. In this case, the same circuit breaker responds in both directions according to different time-delay protection settings. For example, in Figure 2 In the case shown, the circuit breaker can respond to a short-circuit current in the downward direction according to the time delay protection setting T=1, and can respond to a short-circuit current in the upward direction according to the time delay protection setting T=2. Those skilled in the art will understand that the configuration of replacing two circuit breakers with the same circuit breaker can also be applied to other lines (e.g., the line where circuit breakers 103 and 106 are located, or the line where the power supply is located).

[0082] In the embodiments, the power supply may have short-circuit fault ride-through capability (i.e., the ability to maintain short-circuit operation for a certain period of time, after which the power supply enters self-protection mode). However, this is not necessary, and the protection method of this application can also be applied to multi-power supply systems or ring power supply systems that include power supplies that do not have short-circuit fault ride-through capability.

[0083] like Figure 2 As shown, power sources #1, #2, and #3 are all marked with time delay protection settings (T=2 and T=3 respectively), indicating that power sources #1, #2, and #3 are all power sources with short-circuit fault ride-through capability. In this case, the circuit breaker closest to the corresponding power source among the two circuit breakers that should be installed at both ends of the line containing power sources #1, #2, and #3 can be omitted; only the other circuit breaker (i.e., the circuit breaker closest to the corresponding busbar) needs to be installed. In this case, power sources #1, #2, and #3 all participate in time delay differential coordination according to their time delay protection settings.

[0084] against Figure 2 The rightmost pure load branch can have one circuit breaker installed on each line, such as circuit breakers 104, 111, and 112. These three circuit breakers can be non-directional protection circuit breakers. The time delay protection settings for circuit breakers 104, 111, and 112 are as follows: Figure 2 As shown.

[0085] According to the embodiments of this application, in a multi-power supply system, for short-circuit faults at different locations, the time delay protection settings of the circuit breakers can be configured in the following way: starting from the short-circuit fault location at the farthest end of the line with the most line levels among all lines in the multi-power supply system, along all possible short-circuit current paths, the time delay levels of all circuit breakers responding to current in the positive direction are coordinated to ensure that the time delay protection settings of all circuit breakers responding to current in the positive direction meet the coordination requirements.

[0086] For example, such as Figure 2 As shown, starting from the short-circuit fault location at the farthest end of the line with the most line levels (the line where power supply #2, power supply #3, and the load are located), along all possible short-circuit current paths (paths where the short-circuit current comes from power supply #1, power supply #2, and power supply #3), time delay differential coordination is performed on all circuit breakers that respond to current in the positive direction to ensure that the time delay protection settings of all circuit breakers that respond to current in the positive direction meet the differential coordination requirements.

[0087] In the embodiment, when a short-circuit fault occurs at the line where circuit breaker 111 is located, circuit breaker 111 operates with a time delay protection setting of T=0; circuit breaker 104 operates with a time delay protection setting of T=1, which is greater than T=0; power supply #1 operates with a time delay protection setting of T=2, which is greater than T=1; on the lines where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time delay protection setting of T=2, which is greater than T=1; power supply #3 operates with a time delay protection setting of T=3, which is greater than T=2; on the lines where circuit breakers 102 and 105 are located, circuit breaker 105 operates with a time delay protection setting of T=2, which is greater than T=1; power supply #2 operates with a time delay protection setting of T=3, which is greater than T=2. Thus, all these circuit breakers and power supplies meet the differential coordination requirements. In the event of a short circuit fault at circuit breaker 111, circuit breakers 101, 102, 103, 107, 108, 109, and 110, which are used to respond to currents in the opposite direction to the short circuit current, will not operate.

[0088] In another embodiment, the situation where a short circuit fault occurs at the line where circuit breaker 112 is located is similar to the situation where a short circuit fault occurs at circuit breaker 111, and will not be described again here.

[0089] In another embodiment, in the event of a short-circuit fault at the line where circuit breaker 107 is located, circuit breaker 107 operates with a time-delay protection setting of T=0; on the lines where circuit breakers 102 and 105 are located, circuit breaker 102 operates with a time-delay protection setting of T=1, which is greater than T=0; power supply #1 operates with a time-delay protection setting of T=2, which is greater than T=1; on the lines where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time-delay protection setting of T=2, which is greater than T=1; power supply #3 operates with a time-delay protection setting of T=3, which is greater than T=2; and on the line where circuit breaker 108 is located, power supply #2 operates with a time-delay protection setting of T=3, which is greater than T=0. Thus, these circuit breakers and power supplies all meet the differential coordination requirements. On the line where the load is located, there is no current flowing towards circuit breaker 107, and circuit breakers 104, 111, and 112 do not operate. In the event of a short circuit fault at circuit breaker 107, circuit breakers 101, 103, 105, 108, 109, and 110, which are used to respond to currents in the opposite direction to the short circuit current, will not operate.

[0090] In another embodiment, the situation where a short circuit fault occurs at the line where circuit breakers 108, 109, and 110 are located is similar to the situation where a short circuit fault occurs at circuit breaker 107, and will not be described again here.

[0091] In another embodiment, in the event of a short circuit fault at the line where circuit breaker 101 is located, circuit breaker 101 operates with a time delay protection setting of T=0; on the lines where circuit breakers 102 and 105 are located, circuit breaker 105 operates with a time delay protection setting of T=2, which is greater than T=0; power supply #2 operates with a time delay protection setting of T=3, which is greater than T=2; on the lines where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time delay protection setting of T=2, which is greater than T=0; power supply #3 operates with a time delay protection setting of T=3, which is greater than T=2, so that these circuit breakers and power supplies also meet the differential coordination requirements. There is no current flowing towards circuit breaker 101 on the line where the load is located, so circuit breakers 104, 111, and 112 do not operate. In the event of a short circuit fault at circuit breaker 101, circuit breakers 102, 103, 107, 108, 109, and 110, which are used to respond to currents in the opposite direction to the short circuit current, do not operate.

[0092] In this way, when performing time delay differential coordination, the location of the short-circuit fault at the farthest end of each of all lines is taken into account, and when a short-circuit fault occurs at the corresponding location, the time delay protection settings of the circuit breakers that respond to the current in the positive direction in all possible short-circuit current paths meet the differential coordination requirements.

[0093] In addition, when performing time delay differential coordination, ensure that the time delay protection settings of all circuit breakers and power supplies are configured, and that the power supply and the circuit breakers that respond to the positive current meet the differential coordination requirements on all possible short-circuit current paths.

[0094] In this embodiment, without omitting the circuit breaker (not shown) located near the power source, both the circuit breaker and the power source participate in time delay differential coordination. In this case, the time delay protection setting of the power source can be one level higher than the time delay protection setting of the circuit breaker located near the power source.

[0095] Figure 3 This is a schematic diagram illustrating a protection method for a multi-power supply system with a bus tie circuit breaker according to an embodiment of this application.

[0096] like Figure 3 As shown, a multi-source system may include power source #1-1, power source #1-2, power source #1-3, power source #2-1, power source #2-2, power source #2-3, and loads. The multi-source system also includes multiple buses, including, for example, bus #1 and bus #2. Bus #1 and bus #2 are defined as primary buses. Similar to... Figure 1 and Figure 2 Circuit breaker 101 is installed on the line between busbar #1 and power source #1-1. Circuit breakers 102, 105, 107, and 108 are installed on the line between busbar #1 and power source #1-2. Circuit breakers 103, 106, 109, and 110 are installed on the line between busbar #1 and power source #1-3. Circuit breakers 104, 111, and 112 are installed on the line between busbar #1 and the load. Circuit breaker 201 is installed on the line between busbar #2 and power source #2-1. Circuit breakers 202, 205, 207, and 208 are installed on the line between busbar #2 and power source #2-2. Circuit breakers 203, 206, 209, and 210 are installed on the line between busbar #2 and power source #2-3. Circuit breakers 204, 211, and 212 are installed on the line between busbar #2 and the load. Busbar #1 and busbar #2 are connected by a bus tie circuit breaker (also known as a bus tie switch) 300.

[0097] In this embodiment, the bus tie circuit breaker 300 may be a circuit breaker with directional protection (e.g., Figure 3 As shown by the green double-headed arrow in the middle, the delay protection settings in the two directions need to be set separately.

[0098] In this embodiment, the bus tie circuit breaker 300 can occupy the first-level time delay protection setting and participate in the time delay differential coordination. In this case, when a short-circuit fault occurs on either side of the bus tie circuit breaker 300, the bus tie circuit breaker can be disconnected to isolate the scope of the fault.

[0099] In this embodiment, the time-delay protection setting of the bus tie circuit breaker 300 can be set to a first time-delay protection setting and a second time-delay protection setting, respectively. In this embodiment, the first time-delay protection setting can be for short-circuit current flowing from the first side to the second side of the bus tie circuit breaker. This first time-delay protection setting can be the maximum value among time-delay protection settings determined by coordinating delay levels across all possible short-circuit current paths, starting from the farthest end of all lines on the second side of the bus tie circuit breaker. In this embodiment, the second time-delay protection setting can be for short-circuit current flowing from the second side to the first side of the bus tie circuit breaker. This second time-delay protection setting can be the maximum value among time-delay protection settings determined by coordinating delay levels across all possible short-circuit current paths, starting from the farthest end of all lines on the first side of the bus tie circuit breaker.

[0100] For example, in Figure 3 In this context, the first time delay protection setting can be for short-circuit current flowing from the left side to the right side of the bus tie circuit breaker 300. The first time delay protection setting (T=2) can be the maximum value (T=2) among the time delay protection settings (T=1 and T=2) determined by coordinating the time delay levels on all possible short-circuit current paths, starting from the farthest end (power supply #2-1, power supply #2-2, power supply #2-3, load) of all lines (power supply #2-1, power supply #2-2, power supply #2-3, load) on the right side of the bus tie circuit breaker. In an embodiment, the second time delay protection setting may be for short-circuit current flowing from the right side to the left side of the bus tie circuit breaker. The second time delay protection setting (T=2) may be the maximum value (T=2) of the time delay protection settings (T=1 and T=2) determined by coordinating the time delay levels on all possible short-circuit current paths, starting from the farthest end (power supply #1-1, power supply #1-2, power supply #1-3, and the load line) of all lines (power supply #1-1, power supply #1-2, power supply #1-3, and the load) on the left side of the bus tie circuit breaker.

[0101] It should be noted that, in Figure 3 In the illustrated case, since the circuits on both sides of the bus tie circuit breaker 300 are symmetrical, the first and second time delay protection settings of the bus tie circuit breaker are equal, both being T=2. In the embodiment, when the first and second time delay protection settings of the bus tie circuit breaker are equal, the bus tie circuit breaker 300 can be a circuit breaker without directional protection.

[0102] Similar to Figure 2 In response to the situation Figure 3For each of the two load branches, a circuit breaker can be installed, namely circuit breakers 104, 111, 112, 204, 211, and 212. These circuit breakers can be non-directional protection circuit breakers. The time delay protection settings for circuit breakers 104, 111, 112, 204, 211, and 212 are as follows: Figure 3 As shown.

[0103] exist Figure 3 In this configuration, a circuit breaker 101 with directional protection is installed on the line containing power source #1-1; circuit breakers 107 and 108 with directional protection are installed on the two lines containing power source #1-2; and circuit breakers 109 and 110 with directional protection are installed on the two lines containing power source #1-3. Similarly, a circuit breaker 201 with directional protection is installed on the line containing power source #2-1; circuit breakers 207 and 208 with directional protection are installed on the two lines containing power source #2-2; and circuit breakers 209 and 210 with directional protection are installed on the two lines containing power source #2-3. These circuit breakers respond to the current in their respective positive directions as follows: Figure 3 The time delay protection setting shown is activated. (Refer to...) Figure 2 The above, Figure 3 Power supplies #1-1, #1-2, #1-3, #2-1, #2-2, and #2-3 shown in the diagram all have short-circuit fault ride-through capability. Therefore, in Figure 3 The diagram shows the case where circuit breakers near the power source are omitted. The time-delay protection settings for each power source are as follows: Figure 3 As shown. Those skilled in the art should understand that this application is not limited to this, that is, a circuit breaker with directional protection can be installed at both ends of the lines containing power supplies #1-1, #1-2, #1-3, #2-1, #2-2, and #2-3, and the circuit breakers and power supplies on the same line need to meet the time delay differential coordination requirements.

[0104] like Figure 3 As shown, for the lines on the left or right side of the bus tie circuit breaker 300, for example... Figure 3 The circuits containing circuit breakers 102, 105, 103, and 106, as well as the circuits containing circuit breakers 202, 205, 203, and 206, can each have directional protection circuit breakers installed at both ends. Each circuit breaker is configured to protect against forward short-circuit currents. The time-delay protection settings for each of circuit breakers 102, 105, 103, 106, and 202, 205, 203, and 206 are as follows: Figure 3As shown. In this embodiment, the time delay protection setting of each of circuit breakers 105, 106, 205, and 206 can be implemented by extending the time delay protection setting of the bus tie circuit breaker 300. For example, if the time delay protection setting of the bus tie circuit breaker 300 is T=2, the time delay protection setting of each of circuit breakers 105, 106, 205, and 206 can be extended from T=2 to T=3.

[0105] and Figure 2 Compared to the protection method for a multi-power supply system without a bus tie circuit breaker, the time-delay protection setting of the power supply itself should also consider the time-delay protection setting of the bus tie circuit breaker 300, and be implemented by sequentially increasing the setting. For example, Figure 3 The time delay protection settings for power supply #1-1 and power supply #2-1 are both increased sequentially to T=3 based on the time delay protection setting T=2 of the bus tie circuit breaker 300. For example, Figure 3 The time delay protection settings for power supplies #1-2, #1-3, #2-2, and #2-3 are all increased sequentially from the time delay protection setting T=2 of the bus tie circuit breaker 300. The time delay protection settings for circuit breakers 105, 106, 205, and 206 are also increased sequentially from the time delay protection setting T=3 to T=4.

[0106] In the embodiment, given that the first time delay protection setting of the bus tie circuit breaker has been determined, the time delay protection setting of the power supply on the first side of the bus tie circuit breaker and the circuit breaker that responds to the positive current is determined by using time delay differential coordination based on the first time delay protection setting of the bus tie circuit breaker.

[0107] In the embodiment, when the second time delay protection setting of the bus tie circuit breaker is determined, the power supply on the second side of the bus tie circuit breaker and the time delay protection setting of the circuit breaker that responds to the positive current are determined by using time delay differential coordination based on the second time delay protection setting of the bus tie circuit breaker.

[0108] In the embodiment, in the event of a short-circuit fault at the line where circuit breaker 111 is located, circuit breaker 111 operates with a time-delay protection setting of T=0; circuit breaker 104 operates with a time-delay protection setting of T=1, which is greater than T=0; bus tie circuit breaker 300 operates with a time-delay protection setting of T=2, which is greater than T=1, to isolate the fault's impact area to its left; power supply #2-1 operates with a time-delay protection setting of T=3, which is greater than T=2; on the lines where circuit breakers 203 and 206 are located, circuit breaker 206 operates with a time-delay protection setting of T=3, which is greater than T=2; power supply #2-3 operates with a time-delay protection setting of T=4, which is greater than T=3; and at circuit breaker 202... On the line where circuit breaker 205 is located, circuit breaker 205 operates with a time delay protection setting T=3 greater than T=2; power supply #2-2 operates with a time delay protection setting T=4 greater than T=3; on the line where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time delay protection setting T=3 greater than T=1; power supply #1-3 operates with a time delay protection setting T=4 greater than T=3; on the line where circuit breakers 102 and 105 are located, circuit breaker 105 operates with a time delay protection setting T=3 greater than T=1; power supply #1-2 operates with a time delay protection setting T=4 greater than T=3, ensuring that all power supplies and circuit breakers meet the differential coordination requirements. There is no current flowing to circuit breaker 111 in the branch where the load is located on the right side of the bus tie circuit breaker 300, so circuit breakers 204, 211, and 212 do not operate; in the event of a short circuit fault at circuit breaker 111, circuit breakers 101, 102, 103, 107, 108, 109, 110, 201, 202, 203, 207, 208, 209, and 210, which are used to respond to currents in the opposite direction to the short circuit current, do not operate.

[0109] In another embodiment, the situation where a short circuit fault occurs at the line where circuit breakers 112, 211, and 212 are located is similar to the situation where a short circuit fault occurs at circuit breaker 111, and will not be described again here.

[0110] In another embodiment, in the event of a short-circuit fault at the line where circuit breaker 107 is located, circuit breaker 107 operates with a time-delay protection setting of T=0; on the lines where circuit breakers 102 and 105 are located, circuit breaker 102 operates with a time-delay protection setting of T=1, which is greater than T=0; power supply #1-1 operates with a time-delay protection setting of T=3, which is greater than T=1; on the lines where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time-delay protection setting of T=3, which is greater than T=1; power supply #1-3 operates with a time-delay protection setting of T=4, which is greater than T=3; and on the branch line where circuit breaker 108 is located, power supply #1-2 operates with a time-delay protection setting of T=4, which is greater than T=0. The following actions are taken: The bus tie circuit breaker 300 operates with a time delay protection setting T=2, greater than T=1, to isolate the affected area to its left; power supply #2-1 operates with a time delay protection setting T=3, greater than T=2; on the lines where circuit breakers 202 and 205 are located, circuit breaker 205 operates with a time delay protection setting T=3, greater than T=2; power supply #2-2 operates with a time delay protection setting T=4, greater than T=3; on the lines where circuit breakers 203 and 206 are located, circuit breaker 206 operates with a time delay protection setting T=3, greater than T=2; power supply #2-3 operates with a time delay protection setting T=4, greater than T=3, ensuring that all circuit breakers and power supplies meet the differential coordination requirements. On the line where the load is located to the left of the bus tie circuit breaker 300, there is no current flowing to the circuit breaker 107, and circuit breakers 104, 111, and 112 do not operate; on the line where the load is located to the right of the bus tie circuit breaker, there is no current flowing to the circuit breaker 107, and circuit breakers 204, 211, and 212 do not operate; in the event of a short circuit fault at circuit breaker 107, circuit breakers 101, 103, 105, 108, 109, 110, 201, 202, 203, 207, 208, 209, and 210, which are used to respond to currents in the opposite direction to the short circuit current, do not operate.

[0111] In another embodiment, the situation where a short circuit fault occurs at the line where circuit breakers 108, 109, and 110 are located is similar to the situation where a short circuit fault occurs at circuit breaker 107, and will not be described again here.

[0112] In another embodiment, in the event of a short circuit fault at the line where circuit breaker 101 is located, circuit breaker 101 operates with a time delay protection setting of T=0; on the lines where circuit breakers 102 and 105 are located, circuit breaker 105 operates with a time delay protection setting of T=3, which is greater than T=0; power supply #1-2 operates with a time delay protection setting of T=4, which is greater than T=3; on the lines where circuit breakers 103 and 106 are located, circuit breaker 106 operates with a time delay protection setting of T=3, which is greater than T=0; power supply #1-3 operates with a time delay protection setting of T=4, which is greater than T=3; and bus tie circuit breaker 300 operates with a time delay setting of T=4, which is greater than T=0. The protection setting T=2 is activated to isolate the affected area to its left; power supply #2-1 is activated with a time delay setting T=3, which is greater than T=2; on the line where circuit breakers 202 and 205 are located, circuit breaker 205 is activated with a time delay setting T=3, which is greater than T=2; power supply #2-2 is activated with a time delay setting T=4, which is greater than T=3; on the line where circuit breakers 203 and 206 are located, circuit breaker 206 is activated with a time delay setting T=3, which is greater than T=2; power supply #2-3 is activated with a time delay setting T=4, which is greater than T=3, so that the power supply and circuit breakers meet the differential coordination requirements. On the line where the load is located to the right of the bus tie circuit breaker, there is no current flowing to circuit breaker 101, and circuit breakers 204, 211, and 212 do not operate; on the line where the load is located to the left of the bus tie circuit breaker, there is no current flowing to circuit breaker 101, and circuit breakers 104, 111, and 112 do not operate; in the event of a short circuit fault at circuit breaker 101, circuit breakers 102, 103, 107, 108, 109, 110, 201, 202, 203, 207, 208, 209, and 210, which are used to respond to currents in the opposite direction to the short circuit current, do not operate.

[0113] The situation where a short circuit fault occurs at different locations on the right side of the bus tie circuit breaker 300 is similar to the aforementioned situation where a short circuit fault occurs at different locations on the left side of the bus tie circuit breaker 300, and will not be repeated here.

[0114] In this way, when performing time-delay differential coordination, with the bus tie circuit breaker, the location of the short-circuit fault at the farthest end of each line in all lines is taken into account, and when a short-circuit fault occurs at the corresponding location, the time-delay protection settings of the circuit breakers that respond to the current in the positive direction in all possible short-circuit current paths meet the differential coordination requirements.

[0115] Furthermore, when implementing time delay differential coordination, in the case of bus tie circuit breakers, ensure that the time delay protection settings of all circuit breakers and power supplies are configured, and that the circuit breakers and power supplies that respond to the positive current in all possible short-circuit current paths meet the differential coordination requirements.

[0116] In the embodiment, the delay step difference in the coordination is determined by the operating time of the coordination circuit breaker.

[0117] exist Figure 3 In the illustrated embodiment, when a bus tie circuit breaker is present, protection of a multi-power supply system with a bus tie circuit breaker can be achieved by configuring the delay protection settings of the bus tie circuit breaker, other circuit breakers, and power supply as described above.

[0118] In a multi-power supply system, the time delay protection setting for a specific power supply is the maximum value among all possible time delay protection settings obtained by coordinating the time delay levels of the power supply and the responding circuit breakers along the short-circuit current path of the power supply (regardless of whether it passes through the bus tie circuit breaker) starting from the farthest short-circuit fault location of each of all lines.

[0119] The time delay protection setting of a circuit breaker that responds to positive current is the maximum value among all possible time delay protection settings obtained by coordinating the time delay levels of the circuit breaker and other responding circuit breakers along the short-circuit current path of the circuit breaker (regardless of whether it passes through the bus tie circuit breaker) starting from the farthest short-circuit fault location of each of all lines.

[0120] Although not shown in the embodiments, the multi-power supply system of this application may also include a loop.

[0121] Another aspect of this application provides a protection method for a ring power supply system.

[0122] Figure 4 This is a schematic diagram illustrating a protection method for a ring power supply system according to an embodiment of this application.

[0123] like Figure 4 As shown, the ring power supply system of this application includes power source #1, power source #2, power source #3, and power source #4, but is not limited thereto. In fact, the ring power supply system of this application may include one or more power sources, and the number of power sources may be n', where n' may be an integer greater than or equal to 1. In the case where the ring power supply system includes only one power source, that single power source can supply power to all loops of the ring power supply system.

[0124] In this embodiment, the ring power supply system may also include multiple loads, such as... Figure 4 The loads shown below. The electrical energy for these loads is distributed via feeders from the corresponding distribution cabinets, such as... Figure 4 As shown, there are 3 distribution cabinets in the left loop and 1 distribution cabinet in the right loop.

[0125] The ring power supply system also considers scenarios with multiple power sources. For example, in addition to power source #1 and power source #2, the system can also include power source #3 and power source #4.

[0126] Those skilled in the art should understand that Figure 4 The number and connection methods of power sources, loads, distribution cabinets, loops, and the topology of the ring power supply system shown are exemplary and not restrictive.

[0127] In this application, a) the positive direction of the current is defined as flowing from the busbar to the line; b) all circuit breakers on the loop respond only to short-circuit currents in the positive direction and do not operate to short-circuit currents in the reverse direction; c) according to the direction of the short-circuit current, the time delay protection settings of all circuit breakers on the loop that respond to short-circuit currents in the positive direction are configured in progressively increasing order to meet the requirements of differential coordination.

[0128] In the embodiments of this application, for loops, circuit breakers with directional protection can be set, and the protection delay setting can be set in both clockwise (indicated by the pink arrow) and counterclockwise (indicated by the blue arrow) directions according to the possible current direction.

[0129] This application provides a method for protecting a ring power supply system, the ring power supply system including a power source and a loop, the loop including n distribution cabinets connected to each other by lines to form part of the loop, the method including: installing a circuit breaker with directional protection at both ends of n+1 lines other than the incoming bus on the loop, thereby installing a total of 2n+2 circuit breakers on the loop, wherein each of the 2n+2 circuit breakers responds to current in its positive direction and does not respond to current in its reverse direction, wherein the positive direction is from the bus closest to the corresponding circuit breaker to the line, and the reverse direction is from the line to the bus closest to the corresponding circuit breaker.

[0130] like Figure 4 As shown, the ring power supply system of this application includes power supply #1, power supply #2, power supply #3, and power supply #4, as well as two loops. Each of the two loops includes a different number (n) of distribution cabinets. Figure 4 The three distribution cabinets on the left form part of the left loop (n=3). Figure 4 A distribution cabinet on the right side forms part of the right-side loop (n=1). In the protection method for the ring power supply system of this application, on the loop, except for the incoming bus ( Figure 4 Besides the incoming busbars #1 and #2 above, each of the other n+1 lines is equipped with a circuit breaker with directional protection at both ends, resulting in a total of 2n+2 circuit breakers in the loop. For example... Figure 4As shown, Figure 4 On the left loop, a circuit breaker with directional protection is installed at both ends of the four lines other than incoming busbar #1 and incoming busbar #2, resulting in a total of eight circuit breakers on the loop. On the right loop, a circuit breaker with directional protection is installed at both ends of the two lines other than incoming busbar #1 and incoming busbar #2, resulting in a total of four circuit breakers on the loop. In this embodiment, Figure 4 The 8 circuit breakers on the left ring road and Figure 4 All four circuit breakers on the right loop respond to current in the positive direction but not to current in the negative direction. In this embodiment, the positive direction is from the busbar nearest to the corresponding circuit breaker towards the line, and the negative direction is from the line towards the busbar nearest to the corresponding circuit breaker.

[0131] In this application, when the circuit breaker on the line containing the 2n+2 circuit breakers that should respond to the current in its positive direction fails to operate normally, all 2n+2 circuit breakers can self-protect against the abnormally large short-circuit current in the opposite direction. In the embodiment, in Figure 4 The 8 circuit breakers on the left ring road and Figure 4 When the four circuit breakers on the right loop, which are supposed to respond to the current in the positive direction, fail to function properly, Figure 4 The 8 circuit breakers on the left ring road and Figure 4 All four circuit breakers on the right loop are capable of self-protection against abnormally large short-circuit currents in the opposite direction.

[0132] In an embodiment, the ring power supply system of this application may further include an incoming bus tie switch 500, which remains closed during normal operation.

[0133] In this embodiment, power supplies (power supply #1, power supply #3, power supply #2, and power supply #4, but not limited to these) supply power to the loop are present on both sides of the incoming bus tie switch 500. In this embodiment, when a fault occurs on the incoming bus, the incoming bus tie switch 500 can cooperate with the bus differential protection to isolate the fault area. Thus, in the event of a short-circuit fault on the incoming bus, the fault area can be isolated by disconnecting the incoming bus tie switch 500, maintaining normal power supply to the unaffected areas and improving the stability of the power distribution system.

[0134] In this embodiment, the incoming bus tie switch 500 may not have a protection function.

[0135] In this embodiment, among the 2n+2 circuit breakers other than the incoming bus tie switch on the loop, the n+1 circuit breakers in the clockwise direction form a time delay differential coordination, and the time delay protection setting increases progressively from the circuit breaker furthest from the power source to meet the differential coordination requirements. Additionally, among the 2n+2 circuit breakers other than the incoming bus tie switch on the loop, the n+1 circuit breakers in the counterclockwise direction form a time delay differential coordination, and the time delay protection setting increases progressively from the circuit breaker furthest from the power source to meet the differential coordination requirements.

[0136] In an embodiment, for example, such as Figure 4 As shown, among the eight circuit breakers (circuit breakers 301, 302, 303, 304, 201, 202, 203, 204) on the left loop excluding the incoming bus tie switch 500, the four circuit breakers (circuit breakers 301, 302, 303, 304) in the clockwise direction form a time-delay tiered coordination. Their time-delay protection settings increase progressively from the circuit breaker 301, which is furthest from the power source (time-delay protection setting T=0 for circuit breaker 301, T=1 for circuit breaker 302, T=2 for circuit breaker 303, and T=3 for circuit breaker 304), to meet the tiered coordination requirements. For example, as... Figure 4 As shown, among the eight circuit breakers (circuit breakers 301, 302, 303, 304, 201, 202, 203, 204) on the left loop excluding the incoming bus tie switch 500, the four circuit breakers (circuit breakers 201, 202, 203, 204) in the counterclockwise direction form a time delay differential coordination. Their time delay protection settings increase progressively from the circuit breaker 201, which is furthest from the power source (the time delay protection setting of circuit breaker 201 is T=0, the time delay protection setting of circuit breaker 202 is T=1, the time delay protection setting of circuit breaker 203 is T=2, and the time delay protection setting of circuit breaker 204 is T=3) to meet the differential coordination requirements.

[0137] In an embodiment, for example, such as Figure 4 As shown, in the right loop, excluding the incoming bus tie switch 500, the other four circuit breakers (circuit breakers 501, 502, 401, and 402) form a time-delay differential coordination between the two circuit breakers (circuit breakers 501 and 502) in the clockwise direction. Their time-delay protection settings increase progressively from the circuit breaker 501, which is furthest from the power source (the time-delay protection setting for circuit breaker 501 is T=0, and the time-delay protection setting for circuit breaker 502 is T=1), to meet the differential coordination requirements. For example, as... Figure 4As shown, among the four circuit breakers (circuit breakers 501, 502, 401, and 402) on the right loop excluding the incoming bus tie switch 500, the two circuit breakers (circuit breakers 401 and 402) in the counterclockwise direction form a time delay differential coordination. Their time delay protection settings increase progressively from the circuit breaker 401, which is furthest from the power source (the time delay protection setting of circuit breaker 401 is T=0, and the time delay protection setting of circuit breaker 402 is T=1), in order to meet the differential coordination requirements.

[0138] In the embodiment, circuit breakers with directional protection (circuit breakers 100, 200, 300, and 400, as shown by the purple arrows) are installed on the lines connected to power supplies #1, #3, #2, and #4. These circuit breakers respond to current from the busbar and have instantaneous protection, or a time-delay protection setting of T=0. Those skilled in the art will understand that, although for illustrative purposes, [the following is unclear due to incomplete text]. Figure 4 The example shown illustrates the installation of a circuit breaker with directional protection on the lines containing power sources #1, #2, #3, and #4, but this application is not limited to this. In fact, similar to the protection method for multi-power source systems, a circuit breaker with directional protection can be installed at each end of the lines containing power sources #1, #2, #3, and #4. The arrangement of these two circuit breakers, the coordination between the corresponding power sources, and the setting of the time-delay protection values ​​have already been explained with reference to the protection method for multi-power source systems, and will not be repeated here.

[0139] In this embodiment, a circuit breaker without directional protection (circuit breaker 601, 602, 701, 702, 801, 802, 901, 902) can be installed on the line where the load is located. This circuit breaker can have instantaneous protection, or the time delay protection setting of the circuit breaker can be T=0.

[0140] In the embodiment, the delay protection setting T=0 represents the minimum value among all possible delay protection settings (e.g., T=0 to T=4).

[0141] In the embodiments, power supplies #1, #3, #2, and #4 can all have short-circuit fault ride-through capability. In the embodiments, the protection method for the ring power supply system of this application may further include: obtaining a time delay protection setting for the power supply by adding to a time delay protection setting determined based on the maximum number of distribution cabinets connected to each other on each loop within the ring power supply system. For example, for... Figure 4As shown, the time delay protection setting (T=4) for this power supply can be obtained by adding to the time delay protection setting (T=3) determined based on the maximum value (n=3) of the number of distribution cabinets connected to each other on each loop (left loop and right loop) in the ring power supply system (n=3 on the left loop and n=1 on the right loop).

[0142] In one embodiment, the number of distribution cabinets connected to each other in each loop can be an integer greater than or equal to 1. In another embodiment, the number of distribution cabinets forming a loop is less than or equal to 3, but this application is not limited thereto.

[0143] In an embodiment, the protection method for the ring power supply system of this application further includes, based on the obtained time delay protection setting (T=4), the number of busbars between the power supply (power supply #1, power supply #3, power supply #2, power supply #4) and the primary busbar (in... Figure 4 In the case of incoming bus #1 and incoming bus #2, which are the common connections of all power supplies #1, #2, #3, and #4, they are defined as primary buses in this application. The delay protection setting (T = 4) for a power supply is obtained by incrementing the number of busbars between power supplies #1, #2, #3, and #4 and incoming bus #1 and #2 (i.e., the number of busbars is 0). In this application, the busbars common to all power supplies are defined as primary buses. For example, both incoming bus #1 and incoming bus #2 are primary buses. Those skilled in the art should understand that when the number of busbars between a power supply and a primary busbar is m, the delay protection setting (T = 4 + m) can be obtained by incrementing the number of busbars m based on the obtained delay protection setting (T = 4).

[0144] In this application, as mentioned above, the bus that all power sources are connected to can be defined as a primary bus. There can also be m buses between each power source and the primary bus, where m can be an integer greater than or equal to 0.

[0145] In the protection method for the loop power supply system of this application, the delay differential coordination is determined by the operating time of the coordinated circuit breaker.

[0146] In this application, protection methods for multi-power supply systems and protection methods for ring power supply systems are described respectively. Those skilled in the art should understand that the technical features described in the embodiments of the protection method for multi-power supply systems can be arbitrarily combined with the technical features described in the protection method for ring power supply systems without departing from the scope of the application.

[0147] Figure 5 This is a schematic structural diagram showing a circuit breaker with directional protection according to an embodiment of this application.

[0148] like Figure 5As shown, circuit breaker 500 may include memory 501 and processor 502. According to embodiments of this application, processor 502 may be coupled to memory 501 and perform the circuit breaker methods described herein.

[0149] Figure 6 This is a schematic structural diagram illustrating a multi-power supply system according to an embodiment of this application.

[0150] A multi-power supply system 600 according to an embodiment of this application includes multiple power sources 601, multiple circuit breakers 602, multiple lines 603, and a load 604. The multiple power sources 601 supply power to the load 604 via lines 603 on which the multiple circuit breakers 602 are installed. The multiple circuit breakers 602 are installed according to the protection method of the multi-power supply system of this application.

[0151] In the embodiments, multiple power supplies 601 and multiple circuit breakers 602 are coordinated by time delay according to the protection method of the multi-power supply system of this application to meet the coordination requirements.

[0152] Optionally, the multi-source system 600 may also include a bus tie circuit breaker (not shown). When the multi-source system 600 includes a bus tie circuit breaker, the bus tie circuit breaker also participates in time delay differential coordination to meet the differential coordination requirements.

[0153] Figure 7 This is a schematic structural diagram illustrating a ring power supply system according to an embodiment of this application.

[0154] A ring power supply system 700 according to an embodiment of this application includes a power source 701, a plurality of circuit breakers 702, a plurality of lines 703, and a load 704. The power source 701 supplies power to the load 704 via lines 703 on which the plurality of circuit breakers 702 are installed. The plurality of circuit breakers 702 are installed according to the protection method of the ring power supply system of this application. The loop of the ring power supply system 700 according to an embodiment of this application includes n distribution cabinets (not shown) that are interconnected by lines to form part of the loop.

[0155] In the embodiment, the power supply 701 and multiple circuit breakers 702 are coordinated with time delay levels according to the protection method of the ring power supply system of this application to meet the coordination requirements.

[0156] In one embodiment, the ring power supply system 700 may further include an incoming bus tie switch (not shown).

[0157] Those skilled in the art will recognize that the units and algorithm steps of the various embodiments described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each embodiment have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0158] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0159] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0160] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0161] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0162] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0163] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A circuit breaker configured as follows: Responding to current in the positive direction; and It does not respond to current in the opposite direction. in, The positive direction is from the busbar or power source closest to the circuit breaker towards the line, and The reverse direction is the direction from the line towards the busbar or power source closest to the circuit breaker.

2. A method for protecting a multi-power supply system, the multi-power supply system comprising multiple power supplies, the method comprising: A first circuit breaker and a second circuit breaker are installed at both ends of all other lines except for the pure load branch. The first circuit breaker and the second circuit breaker respond to current in the positive direction, but do not respond to current in the opposite direction. The positive direction is the direction from the busbar or power source closest to the corresponding circuit breaker towards the line, and The reverse direction is the direction from the line to the bus or power source closest to the corresponding circuit breaker.

3. The method as described in claim 2, wherein, When the circuit breakers on the lines where the first and second circuit breakers are located, which should respond to the current in the positive direction, are not working properly, both the first and second circuit breakers can self-protect against the abnormally large short-circuit current in the opposite direction.

4. The method of claim 2, wherein, The number of the plurality of power sources is n, where n is an integer greater than or equal to 2.

5. The method of claim 2, wherein, The busbar that the multiple power sources are connected to is defined as the primary busbar. There are also m buses between each power source and the primary busbar. Where m is an integer greater than or equal to 0.

6. The method of claim 2, wherein, In the case of a short line, the first circuit breaker and the second circuit breaker are the same circuit breaker, which responds in both directions according to different time delay protection settings.

7. The method of claim 2, further comprising: When the power supply has short-circuit fault ride-through capability, the circuit breaker closest to the power supply in the first and second circuit breakers is omitted, and only the other circuit breaker in the first and second circuit breakers is installed. This power supply participates in the time delay differential coordination.

8. The method of claim 2, wherein, The multi-power supply system also includes a pure load branch, and the method further includes: Circuit breakers without directional protection are installed on the lines of the pure load branch.

9. The method of claim 2, further comprising: Starting from the short-circuit fault location at the farthest end of the line with the most line levels in the multi-power system, along all possible short-circuit current paths, time delay differential coordination is performed on all circuit breakers that respond to current in the positive direction to ensure that the time delay protection settings of all circuit breakers that respond to current in the positive direction meet the differential coordination requirements.

10. The method of claim 9, wherein, When performing time-delay differential coordination, the location of the short-circuit fault at the farthest end of each of all lines is taken into account, and when a short-circuit fault occurs at the corresponding location, the time-delay protection settings of the circuit breakers that respond to the current in the positive direction in all possible short-circuit current paths meet the differential coordination requirements.

11. The method of claim 9, wherein, When performing time delay differential coordination, ensure that the time delay protection settings of all circuit breakers and power supplies are configured, and that the power supply and the circuit breakers responding to the positive current meet the differential coordination requirements on all possible short-circuit current paths.

12. The method of claim 2, further comprising: Without omitting the circuit breaker located near the power source, both the circuit breaker and the power source participate in the time delay differential coordination.

13. The method of claim 2, wherein, The multi-power system also includes a bus tie circuit breaker, which is a circuit breaker with directional protection.

14. The method of claim 13, wherein, The bus tie circuit breaker occupies the first-level time delay protection setting and participates in the time delay differential coordination.

15. The method of claim 14, wherein, The time delay protection settings of the bus tie circuit breaker are respectively set to the first time delay protection setting and the second time delay protection setting. The first time delay protection setting is for the short-circuit current flowing from the first side to the second side of the bus tie circuit breaker. This first time delay protection setting is the maximum value among the time delay protection settings determined by coordinating the time delay levels across all possible short-circuit current paths, starting from the farthest end of all lines on the second side of the bus tie circuit breaker. The second time delay protection setting is for the short-circuit current flowing from the second side of the bus tie circuit breaker to the first side. The second time delay protection setting is the maximum value among the time delay protection settings determined by coordinating the time delay levels on all possible short-circuit current paths, starting from the farthest end of all lines on the first side of the bus tie circuit breaker.

16. The method of claim 15, wherein, When the first time delay protection setting is equal to the second time delay protection setting, the bus tie circuit breaker is a circuit breaker without directional protection.

17. The method of claim 16, further comprising: Given the first time delay protection setting, the time delay protection setting of the power supply on the first side of the bus tie circuit breaker and the circuit breaker that responds to the positive current are determined by using time delay differential coordination based on the first time delay protection setting of the bus tie circuit breaker. as well as Given the second time delay protection setting, the time delay protection setting of the power supply on the second side of the bus tie circuit breaker and the circuit breaker that responds to the positive current are determined by using time delay differential coordination based on the second time delay protection setting of the bus tie circuit breaker.

18. The method according to any one of claims 9, 10, 11, 12, 14, 15, and 17, wherein, The time difference in delay-level coordination is determined by the operating time of the coordinated circuit breaker.

19. The method of claim 2, wherein, The multi-power system also includes a loop.

20. A method for protecting a ring power supply system, the ring power supply system comprising a power source and a loop, the loop comprising n distribution cabinets interconnected by lines to form part of the loop, the method comprising: On the loop, a circuit breaker with directional protection is installed at both ends of each of the n+1 lines other than the incoming bus, resulting in a total of 2n+2 circuit breakers on the loop. In this configuration, each of the 2n+2 circuit breakers responds to current in the positive direction but does not respond to current in the reverse direction. The positive direction is the direction from the busbar closest to the corresponding circuit breaker to the line, and the negative direction is the direction from the line to the busbar closest to the corresponding circuit breaker.

21. The method of claim 20, wherein, When the circuit breaker on the line where the 2n+2 circuit breakers are located fails to operate normally, all 2n+2 circuit breakers can self-protect against the abnormally large short-circuit current in the opposite direction.

22. The method of claim 20, wherein, The ring power supply system also includes an incoming bus tie switch, which remains closed during normal operation.

23. The method of claim 22, wherein, There are power supplies supplying power to the loop on both sides of the incoming bus tie switch.

24. The method of claim 22, wherein, The incoming bus tie switch does not have a protection function.

25. The method of claim 22, wherein, When a fault occurs on the incoming bus, the incoming bus tie switch, in conjunction with the bus differential protection, is used to isolate the fault area of ​​the bus.

26. The method of claim 20, wherein, Of the 2n+2 circuit breakers on the loop (excluding the incoming bus tie switch), the n+1 circuit breakers in the clockwise direction form a time-delay differential coordination. The time-delay protection settings increase progressively from the circuit breaker furthest from the power source to meet the differential coordination requirements. In the loop, apart from the incoming bus tie switch, among the other 2n+2 circuit breakers, the n+1 circuit breakers in the positive direction and the counterclockwise direction form a time delay differential coordination. The time delay protection setting increases step by step from the circuit breaker furthest from the power source to meet the differential coordination requirements.

27. The method of claim 20, further comprising: A circuit breaker with directional protection is installed on the power supply line. This circuit breaker responds to the current from the busbar and has instantaneous protection, or the time delay protection setting of the circuit breaker is T=0.

28. The method of claim 20, further comprising: A circuit breaker without directional protection is installed on the line where the load is located. This circuit breaker has instantaneous protection, or the time delay protection setting of this circuit breaker is T=0.

29. The method of claim 27 or 28, wherein, A time delay protection setting of T=0 indicates the minimum possible time delay protection setting.

30. The method of claim 20, wherein, The power supply has short-circuit fault ride-through capability, and the method further includes: The delay protection setting for this power supply is obtained by adding to the delay protection setting based on the maximum number of distribution cabinets connected to each other in each loop of the ring power supply system.

31. The method of claim 30, further comprising: Based on the obtained delay protection setting, the delay protection setting of the power supply is obtained by increasing the number of busbars between the power supply and the primary busbar. The busbars that the power supply is connected to are defined as the primary busbars.

32. The method of claim 30, wherein, The number of distribution cabinets connected to each other on each loop is an integer greater than or equal to 1.

33. The method of claim 20, wherein, The number of power sources is n', where n' is an integer greater than or equal to 1.

34. The method of claim 31, wherein, There are m buses between each power source and the primary bus, where m is an integer greater than or equal to 0.

35. The method of claim 26, wherein, The time difference in delay-level coordination is determined by the operating time of the coordinated circuit breaker.

36. A multi-power supply system configured to perform the method as described in any one of claims 2-19.

37. A ring power supply system configured to perform the method as described in any one of claims 20-35.

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