A method for preventing malfunction of zero-sequence current protection when manual tripping of circuit breaker fails

Abstract

A method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to trip manually comprises the following steps: in a high-voltage line with double busbar connection, longitudinal differential protection or longitudinal distance and zero-sequence protection, as well as a circuit breaker phase-splitting operation box, are respectively configured on both sides of each line; the contact states of the manual trip relay, phase trip position relay, and phase closing position relay in the operation box on one side of the line, as well as the other protection action input states of the protection devices, are respectively collected; when it is identified that the circuit breaker on one side of the line is in a state of manual trip failure of one or two phases of the circuit breaker, a remote trip signal, an enabling command signal, or a stop signal is sent to the opposite protection device in the line by means of the other protection action input states and the line longitudinal channel, and the opposite protection device is instructed to perform an action condition determination and trip the opposite circuit breaker. The method of the present invention is simple, low-cost, and overcomes the defect of malfunction of zero-sequence current protection caused by the inability to activate failure protection when a manual trip circuit breaker fails.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and more particularly to a method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails. Background Art

[0002] Currently, manually tripping circuit breakers is a common method for achieving line safety control during high-voltage line outages. However, during this manual tripping operation, one or two phase breakers may fail, resulting in inconsistent three-phase positions.

[0003] In the 3 / 2 circuit breaker connection scheme for 220kV and above lines, since each side of the line has two circuit breakers, if one breaker fails during a manual trip, the zero-sequence current is small and will not affect the zero-sequence current protection. In contrast, in the dual-busbar connection scheme for 220kV and above lines, each side has only one circuit breaker. During a manual trip, if one or two phase breakers fail and the line load current is high, significant zero-sequence and negative-sequence currents will flow, severely impacting the system.

[0004] However, according to existing technical regulations, manual tripping of a circuit breaker does not activate circuit breaker failure protection. If one or two phases of the circuit breaker fail during manual tripping, the failure protection will not operate. In this case, the three-phase inconsistency protection on the circuit breaker itself or the three-phase inconsistency protection for electrical quantities integrated into the line protection device may operate, and the local zero-sequence current protection may operate. However, due to the circuit breaker failure, the local circuit breaker will still not trip. Furthermore, components in the high-voltage line, such as the longitudinal current differential protection, longitudinal distance and zero-sequence protection, and remote tripping, all fail to meet the operating conditions, and the circuit breaker remains in a failed state.

[0005] In existing technology, while the probability is low, one or two phase circuit breakers may fail during an on-site manual trip of a circuit breaker. The current solution to this problem is to delay the backup zero-sequence current protection on the opposite side of the line, removing the load current from the line and eliminating the zero-sequence and negative-sequence currents. However, the zero-sequence current protection on the adjacent line may also malfunction and trigger protection, resulting in an over-tripping and expanding the scope of the accident.

[0006] Therefore, there is an urgent need for a method to prevent the zero-sequence current protection from malfunctioning when the circuit breaker manual trip fails. Summary of the Invention

[0007] In order to address the deficiencies in the prior art, the purpose of the present invention is to provide a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip, detect the failure state of the manually tripped circuit breaker, and when the manually tripped circuit breaker fails, control the tripping state of the opposite side protection device by means of the opening state of other protection actions and the line longitudinal channel.

[0008] The present invention adopts the following technical solutions.

[0009] The present invention relates to a method for preventing malfunction of zero-sequence current protection when manual tripping of a circuit breaker fails, wherein the method comprises the following steps: step 1, in a high-voltage line with double busbar connection, respectively disposing a longitudinal differential protection device or a longitudinal distance and zero-sequence protection device, and a circuit breaker phase-splitting operation box on both sides of each line; step 2, respectively collecting the contact states of a manual tripping relay, a phase-splitting tripping position relay, and a phase-splitting closing position relay in the circuit breaker phase-splitting operation box disposed on one side of the high-voltage line, and the other protection action input states of the protection devices; step 3, when it is identified that the circuit breaker on one side of the high-voltage line is in a one-phase or two-phase circuit breaker manual tripping failure state, by means of the other protection action input states and the line longitudinal connection channel, sending a remote tripping signal, an enabling command signal, or stopping sending a blocking signal to a protection device on the opposite side of the line, and instructing the protection device on the opposite side to perform an action condition judgment and trip the circuit breaker on the opposite side.

[0010] Preferably, in step 2, the contacts of the relay are all normally open contacts; when the phase-splitting operation box is designed with a single jump ring method, the contact status of each phase relay in a group of phase closing position relays is collected; when the phase-splitting operation box is designed with a double jump ring method, the contact status of each phase relay in two groups of phase closing position relays is collected.

[0011] Preferably, after manual tripping is performed on the circuit breaker configured on the high-voltage line, the status of the circuit breaker includes a manual trip failure state in which the protection device outputs other protection action signals when the circuit breaker is manually tripped, and a manual trip normal state in which the protection device does not output other protection action signals when the circuit breaker is manually tripped.

[0012] Preferably, when the contacts of the manual trip relay are closed, any one of the three phase contacts in the phase trip position relay is closed, and any one of the three phase contacts in the phase closing position relay is closed simultaneously, the current state is determined to be a manual trip failure state, and at this time other protection action inputs are in the on state.

[0013] Preferably, when the phase-splitting operating box adopts a double-tripping ring design, if any contact in the two sets of phase closing position relays is closed, then based on the closure of the contact of the manual trip relay and the closure of any contact in the three phases of the phase-splitting tripping position relay, it is determined that the current state is a manual tripping failure state. At this time, other protection action inputs are in the on state.

[0014] Preferably, the types of longitudinal channels of the line where the protection device is located include optical fiber channels and power line carrier channels; wherein the power line carrier channels also include locked power line carrier channels and permissive power line carrier channels.

[0015] Preferably, for a fiber optic channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in an on state, the protection device immediately sends a remote trip signal to the opposite side protection device.

[0016] Preferably, for a permissive power line carrier channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in the on state, the protection device sends a permissive command signal to the opposite protection device; for a locked power line carrier channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in the on state, it stops sending a locking signal to the opposite protection device.

[0017] Preferably, for the optical fiber channel, when the protection device on the opposite side receives the remote trip signal, it determines the remote trip action condition and quickly trips the circuit breaker on the opposite side when the remote trip action condition is met.

[0018] Preferably, for a permissive power line carrier channel, if the opposite side protection device receives a permissive command signal, the opposite side circuit breaker is tripped when the pilot distance and zero sequence protection action conditions are met.

[0019] Preferably, for a locked power line carrier channel, if the opposite protection device fails to receive a locking signal, the opposite circuit breaker is tripped when the pilot distance and zero-sequence protection action conditions are met.

[0020] The present invention has the beneficial effect of preventing malfunction of zero-sequence current protection when a circuit breaker fails due to manual tripping, compared to the prior art. The present invention can detect the failure state of a manually tripped circuit breaker and, when the manually tripped circuit breaker fails, control the tripping state of the opposite protection device by utilizing the opening states of other protection actions and the line pilot channel. The present method is simple, inexpensive to implement, and effectively overcomes the drawback of the prior art that failure protection cannot be activated when a manually tripped circuit breaker fails.

[0021] The beneficial effects of the present invention also include:

[0022] 1. In the prior art, when a fault occurs on the current line, the backup zero-sequence current protection on the opposite side is activated. Although it can cut off the load current of the current line and avoid abnormal zero-sequence current and negative-sequence current, it cannot avoid abnormal zero-sequence current on the adjacent line, thereby causing the line protection device on the adjacent line to trip. However, in the present invention, when the line protection device recognizes that the manual tripping fails, it can quickly execute the operation of tripping the circuit breaker on the opposite side by turning on other protection actions of the line protection on this side. The method of the present invention can effectively avoid the impact of the current line fault on the adjacent line, prevent the adjacent line protection from malfunctioning, and minimize the scope of the accident to the greatest extent.

[0023] 2. The method of the present invention provides relatively rapid line protection action, requiring no modifications to existing protection devices, no software upgrades, no changes to protection logic, and no modifications to protection settings. This method can be implemented by pre-connecting the trip relay contacts, closed relay contacts, and manual trip relay contacts in the circuit breaker operating box to other protection action inputs of the line protection device in the secondary circuit, in accordance with the specific combinations specified in the present invention. This method is inexpensive, low-cost, and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic flow chart of the steps of a method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to the present invention;

[0025] Figure 2 A schematic diagram of a high-voltage circuit in a double-busbar wiring mode in a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip in the present invention;

[0026] Figure 3 A wiring diagram of other protection actions in a method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to the present invention;

[0027] Figure 4 The present invention is a schematic diagram of a manual trip circuit breaker A phase failure state in a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip. DETAILED DESCRIPTION

[0028] The present application will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present application.

[0029] Figure 1 This is a flow chart of the steps of a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip. Figure 1 As shown, a method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails, wherein the method comprises the following steps:

[0030] Step 1: In a high-voltage line with double busbar connection, a longitudinal differential protection device or a longitudinal distance and zero-sequence protection device, as well as a circuit breaker phase operation box are respectively configured on both sides of each line.

[0031] The circuit breaker's phase-splitting operation box is equipped with a manual trip relay, the contacts of which are hereinafter represented by the symbol STJ. The operation box is also equipped with phase-splitting trip position relays and phase-splitting closing position relays. The phase-splitting trip position relays include the A-phase trip position relay TWJa, the B-phase trip position relay TWJb, and the C-phase trip position relay TWJc. The phase-splitting closing position relays include the first-group trip ring A-phase closing position relay 1HWJa, the first-group trip ring B-phase closing position relay 1HWJb, the first-group trip ring C-phase closing position relay 1HWJc, the second-group trip ring A-phase closing position relay 2HWJa, the second-group trip ring B-phase closing position relay 2HWJb, and the second-group trip ring C-phase closing position relay 2HWJc.

[0032] For the phase-split operation box of the circuit breaker with a single trip ring, only the closing position relays 1HWJa, 1HWJb and 1HWJc of the first group of trip rings are configured; for the phase-split operation box of the circuit breaker with a double trip ring, the closing position relays 1HWJa, 1HWJb, 1HWJc of the first group of trip rings and the closing position relays 2HWJa, 2HWJb, 2HWJc of the second group of trip rings are configured.

[0033] The trip position relay monitors whether the corresponding circuit breaker is in the tripped position, while the closed position relay monitors whether the corresponding circuit breaker is in the closed position. When the corresponding circuit breaker is in the tripped position, the trip position relay contacts are closed, while the closed position relay contacts are open. When the corresponding circuit breaker is in the closed position, the trip position relay contacts are open, while the closed position relay contacts are closed.

[0034] For example, for a single-trip circuit breaker, if the A-phase circuit breaker is in the tripped position and the B-phase and C-phase circuit breakers are in the closed position, the TWJa contact is closed, the TWJb and TWJc contacts are open, the 1HWJa contact is open, and the 1HWJb and 1HWJc contacts are closed. For a double-trip circuit breaker, for example, if the A-phase circuit breaker is in the tripped position and the B-phase and C-phase circuit breakers are in the closed position, the TWJa contact is closed, the TWJb and TWJc contacts are open, the 1HWJa and 2HWJa contacts are open, and the 1HWJb, 1HWJc, 2HWJb, and 2HWJc contacts are closed. As described in the background technology section, when a circuit breaker manual trip failure occurs in a line, the impact of this situation on a 3 / 2 circuit breaker connection method for lines with voltage levels of 220kV and above is relatively small, and will not cause protection malfunction unless both circuit breakers fail at the same time. However, for dual-busbar wiring systems of 220kV and above, each line has only one circuit breaker at one end. Therefore, if one or two phases of the circuit breaker fail, not only will the current line be affected, but adjacent lines may also be affected. To prevent this, the present invention provides a preventive measure for high-voltage lines with dual-busbar wiring.

[0035] Figure 2 This is a schematic diagram of a high-voltage circuit with a double busbar connection method in a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip. Figure 2 As shown, in the present invention, the circuit formed by the double busbar connection method can be simplified as shown in FIG. Figure 2 As shown in the schematic diagram, two lines, line 1 and line 2, are connected across busbars M and N, and line 3 is connected to the downstream side of line 1 and line 2.

[0036] In the prior art, when one or two phases of manually tripped circuit breaker 1 fail, line 1 enters a state of partial phase operation. In this case, zero-sequence current and voltage will also appear on line 2 for an extended period. When a certain level of zero-sequence current flows through line 2, circuit breakers 2 and 4 on line 2 may malfunction due to the zero-sequence current protection. Similarly, in this situation, zero-sequence current and voltage will inevitably appear on line 3 for an extended period, potentially causing the zero-sequence current protection of circuit breakers 5 and 6 to malfunction. Due to this malfunction, both lines 2 and 3 cannot operate normally, amplifying the fault.

[0037] To prevent this from happening, in the present invention, a longitudinal differential protection device or a longitudinal distance and zero-sequence protection device, as well as a circuit breaker phase-splitting operation box, are respectively configured on both sides of each line. This allows for rapid transmission of fault information to the other side when a fault occurs on one side of each line. The fault is then cleared based on the status of the other side using the methods in steps 2 and 3, thereby avoiding malfunctions of protection on other lines.

[0038] Step 2: respectively collect the contact states of the manual trip relay, phase trip position relay and phase closing position relay in the phase operation box of the circuit breaker configured on one side of the high-voltage line, as well as the other protection action input states of the protection device.

[0039] It is understood that in the present invention, by collecting the relay status and protective device operation status on one side of the high-voltage line, it is possible to accurately determine whether a manual trip failure has occurred on the line. If such a problem occurs, the manual trip failure in the present invention can be resolved by the protective device on the other side of the high-voltage line. In the present invention, both sides of the line are equipped with protective devices and circuit breaker phase control boxes, and one side can disconnect the line based on the manual trip failure status of the other side.

[0040] Preferably, the contacts of the relay are all normally open contacts; when the circuit breaker phase operation box is designed with a single jump ring method, the contact status of each phase relay in one group of phase closing position relays is collected; when the circuit breaker phase operation box is designed with a double jump ring method, the contact status of each phase relay in two groups of phase closing position relays is collected.

[0041] To ensure reliability during relay tripping, conventional techniques employ either a single-trip or double-trip circuit design. Depending on the design of the single-trip or double-trip circuit, the relay contact acquisition method also differs. Preferably, after manually tripping the circuit breaker on the high-voltage line, the circuit breaker states include a manual trip failure state, in which the protection device outputs other protection action signals when the circuit breaker is manually tripped, and a manual trip normal state, in which the protection device does not output other protection action signals when the circuit breaker is manually tripped.

[0042] During a manual tripping circuit breaker operation, the circuit breaker manually trips based on remote control information, thereby opening the circuit breaker. However, after receiving this remote control information, the circuit breaker may experience a fault, causing the circuit breaker to malfunction. Therefore, even when the line has received the manual trip remote control information, there are two states: the actual normal manual tripping state and the actual circuit breaker malfunction state, namely the manual trip failure state. The method of the present invention provides subsequent safety protection measures for this manual trip failure state.

[0043] After collecting the above information, you can proceed to the next step.

[0044] Step 3: When it is identified that the circuit breaker on one side of the high-voltage line is in a one-phase or two-phase manual trip failure state, with the help of other protection action input status information and line longitudinal channel, a remote trip signal, an enabling command signal or a stop sending blocking signal is sent to the opposite side protection device in the line, and the opposite side protection device is instructed to perform trip condition judgment and trip the opposite side circuit breaker.

[0045] In the present invention, when it is identified that the circuit breaker is in a manual trip failure state, that is, a manual trip failure state, the information will be sent to the protection device on the opposite side with the help of other protection action opening states, so that the protection device on the opposite side can trip and perform work normally, and the circuit breaker on the opposite side is not in an abnormal state.

[0046] Preferably, when the contacts of the manual trip relay are closed, any one of the three phase contacts in the phase trip position relay is closed, and any one of the three phase contacts in the phase closing position relay is closed simultaneously, the current state is determined to be a manual trip failure state, and at this time other protection action inputs are in the on state.

[0047] It is understandable that when the contacts of the manual trip relay are closed, it can ensure that any one of the three phase contacts in the phase trip position relay is closed. When any one of the three phase contacts in the phase closing position relay is closed simultaneously, it can be determined that the current state is a manual trip failure state, and at this time, other protection action inputs are in the on state. It is understandable that the manual trip failure state described here is identified by a specific combination of the states of the hand trip relay contacts, the phase trip position relay contacts, and the phase closing position relay contacts. If the current state is a manual trip failure state, at this time, other protection action inputs are in the on state, which can enable the protection device to receive the other protection action input states, start the remote trip function, and trip the opposite side circuit breaker.

[0048] Figure 3 This is a wiring diagram of other protection actions in a method for preventing malfunction of zero-sequence current protection when a circuit breaker fails to manually trip. Figure 3 As shown, a circuit breaker in the present invention may include a trip position relay, a closing position relay and a normally open contact of a manual trip relay connected in series.

[0049] Furthermore, for the trip position relay, corresponding to the three phases A, B, and C in the line are the phase-splitting relay contacts TWJa, TWJb, and TWJc. For the closed position relay, corresponding to the three phases A, B, and C in the line are the phase-splitting relay contacts 1HWJa, 1HWJb, 1HWJc and 2HWJa, 2HWJb, and 2HWJc. Specifically, the three-phase relay contacts of the trip position relay are internally connected in parallel, and the three phases of the closed position are also internally connected in parallel. All of the relay contacts mentioned above are normally open contacts.

[0050] Preferably, when the circuit breaker phase-splitting operation box adopts a double-tripping ring design, if any contact in the two sets of phase closing position relays is closed, then based on the contact closure of the manual trip relay and the closure of any contact in the three phases of the phase-splitting tripping position relay, it is determined that the current state is a manual tripping failure state, and at this time, other protection action inputs are in the on state.

[0051] Figure 4 This diagram illustrates a manual trip circuit breaker in the A-phase failure state, according to a method for preventing malfunction of zero-sequence current protection during manual trip failure of a circuit breaker according to the present invention. During a manual trip, the STJ contact in the operating box closes. When the A-phase circuit breaker fails, the TWJa contact opens, the TWJb and TWJc contacts close, the 1HWJa contact closes, and the 1HWJb and 1HWJc contacts open. For a double trip circuit, this also includes the 2HWJa contact closing and the 2HWJb and 2HWJc contacts opening.

[0052] When a manual trip failure occurs, the STJ contacts in the phase-splitting operating box of the circuit breaker are closed. If one or two phases of the circuit breaker fail, there will be inconsistencies in the three-phase positions. In other words, when it is determined that the manual trip relay contacts are closed, at least one position contact of the three-phase circuit breaker in the trip position is closed, and at least one position contact of the three-phase circuit breaker in the closing position is closed simultaneously, it can be determined that the current state must be in a manual trip failure state. After the manual trip failure state is determined, other protection action signals will be output. In the present invention, this signal is connected to the other existing protection action input circuits in the protection device, and other protection action logics are executed, thereby starting the remote tripping function and tripping the opposite circuit breaker.

[0053] It is understood that in the present invention, the circuit breaker can be configured as either a single-trip circuit or a double-trip circuit. When using different circuit breaker configurations, the number of circuit breaker switch contacts also varies. Regardless of the configuration, the switch contacts all utilize normally open contacts. When a phase circuit breaker trips, the trip position relay contacts for the corresponding phase close, and the closed position relay contacts for the corresponding phase open. When a phase circuit breaker is not tripped, the trip position relay contacts for the corresponding phase open, and the closed position relay contacts for the corresponding phase close.

[0054] Preferably, the types of longitudinal channels of the line where the protection device is located include optical fiber channels and power line carrier channels; wherein the power line carrier channels also include locked power line carrier channels and permissive power line carrier channels.

[0055] Similar to existing power line channels, the line channels in the present invention can be modern fiber-optic channels with fully automated control, or traditional power line carrier channels. Power line carrier channels are further divided into blocking power line carrier channels and permissive power line carrier channels. Preferably, for fiber-optic channels, when a protection device detects a manual trip failure (i.e., when it detects that other protection action inputs are in the on state), the protection device immediately sends a remote trip signal to the opposite protection device.

[0056] It can be understood that in the present invention, for the optical fiber channel and the permissive power line carrier channel, after the manual trip failure is identified, a remote trip signal and a permission command signal can be sent to the opposite protection device respectively. For the optical fiber channel, when the protection device identifies the manual trip failure state, that is, when it identifies that other protection action inputs are in the on state, the protection device immediately sends a remote trip signal to the opposite protection device. For the permissive power line carrier channel, when the protection device identifies the manual trip failure state, that is, when it identifies that other protection action inputs are in the on state, the protection device sends a permission command signal to the opposite protection device; for the locked power line carrier channel, when the protection device identifies the manual trip failure state, that is, when it identifies that other protection action inputs are in the on state, it stops sending the locking signal to the opposite protection device. If the current device does not identify that other protection action inputs are in the on state, the above signal will not be sent.

[0057] At the same time, for the locked power line carrier channel, since this carrier channel locks the opposite side protection tripping by sending a locking signal, when the manual trip fails, the locking signal is stopped from being sent to the opposite side protection, thereby allowing the opposite side protection to trip.

[0058] Preferably, for the optical fiber channel, when the protection device on the opposite side receives the remote trip signal, it determines the remote trip action condition and quickly trips the circuit breaker on the opposite side when the remote trip action condition is met.

[0059] Specifically, the present invention optimizes the wiring design of the secondary circuit outside the protection device. Using other protection action input terminals, the protection device can receive the aforementioned manual trip failure status and transmit the other protection action input status signal via the line's longitudinal connection channel. The opposite protection device can receive this signal in a specific format and, based on it, determine whether to trip the local circuit breaker where the opposite protection device is located.

[0060] Specifically, the remote tripping action condition of the fiber optic channel refers to querying whether the starting element is locked through the control word "remote trip controlled by the starting element" of the protection device. If the protection device meets the set conditions of the control word, it can be driven to trip.

[0061] Preferably, for a permissive power line carrier channel, if the opposite side protection device receives a permissive command signal, the opposite side circuit breaker is tripped when the pilot distance and zero sequence protection action conditions are met.

[0062] Preferably, for a locked power line carrier channel, if the opposite protection device fails to receive a locking signal, the opposite circuit breaker is tripped when the pilot distance and zero-sequence protection action conditions are met.

[0063] Unlike fiber optic channels, the power line carrier channel in the present invention utilizes pilot protection, including both distance protection and zero-sequence protection. Before tripping the opposite-side circuit breaker, the operating conditions for the distance and zero-sequence protections must be determined. This determination requires that the pilot protection is within the distance protection zone or the zero-sequence protection zone. As long as the pilot protection is within either of these protection zones, the pilot protection operating conditions are considered met.

[0064] Starting with the manually tripped circuit breaker, for the fiber optic channel, the time required for the line protection to confirm the activation of other protections is 20ms (debounce time) + 1ms (fiber optic channel transmission time) + 10ms (confirmation time for the opposite-side pilot protection) + 60ms (typical circuit breaker trip time) = 91ms. For the power line carrier channel, the time required for the power line distance and zero-sequence protection to confirm the activation of other protections is 5ms (debounce time) + 1ms (carrier channel transmission time) + 30ms (operation time for the opposite-side pilot distance and zero-sequence protection group) + 60ms (typical circuit breaker trip time) = 96ms. In both channel modes, the tripping time of the opposite-side circuit breaker is less than 0.1s, significantly shorter than the operating delay of zero-sequence overcurrent stages II and III, ensuring that the zero-sequence current protection of adjacent lines does not malfunction.

[0065] According to the method of the present invention, when a manual trip circuit breaker fails and three-phase positions are inconsistent, the typical time for tripping the opposite circuit breaker is less than 0.1s, and the shortest time required for the zero-sequence current protection to operate is 0.3s, thereby effectively avoiding the false operation of the zero-sequence current protection of adjacent lines.

[0066] The present invention has the beneficial effect of preventing malfunction of zero-sequence current protection when a circuit breaker fails due to manual tripping, compared to the prior art. The present invention can detect the failure state of a manually tripped circuit breaker and, when the manually tripped circuit breaker fails, control the tripping state of the opposite protection device by utilizing the opening states of other protection actions and the line pilot channel. The present method is simple, inexpensive to implement, and effectively overcomes the drawback of the prior art that failure protection cannot be activated when a manually tripped circuit breaker fails.

[0067] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation plans of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, and is not a limitation on the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for preventing malfunction of zero-sequence current protection when manual tripping of a circuit breaker fails, characterized in that: The method comprises the following steps: Step 1: In a high-voltage line with double busbar connection, a longitudinal differential protection device or a longitudinal distance and zero-sequence protection device, as well as a circuit breaker phase operation box, are respectively configured on both sides of each line; Step 2, respectively collecting the contact states of the manual trip relay, the phase trip position relay and the phase closing position relay in the phase operation box of the circuit breaker configured on one side of the high-voltage line, and the other protection action input states of the protection device; Step 3: When it is identified that the circuit breaker on one side of the high-voltage line is in a manual trip failure state of one or two phases, a remote trip signal, an enabling command signal, or a stop signal is sent to the opposite side protection device in the line by means of the other protection action switching-in state and the line pilot channel, and the opposite side protection device is instructed to perform an action condition determination and trip the opposite side circuit breaker; When the contacts of the manual trip relay are closed, any one of the three phase contacts in the phase trip position relay is closed, and any one of the three phase contacts in the phase closing position relay are closed simultaneously, it is determined that the current state is a manual trip failure state, and at this time other protection action inputs are in the on state.

2. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 1, characterized in that: In step 2, the contacts of the relay are all normally open contacts; When the phase-splitting operation box is designed in a single-jump loop mode, the contact state of each phase relay in a group of phase closing position relays is collected; When the phase-splitting operation box is designed in a double-jump ring manner, the contact state of each phase relay in the two groups of phase closing position relays is collected.

3. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 1, characterized in that: After manual tripping is performed on the circuit breaker configured on the high-voltage line, the status of the circuit breaker includes a manual trip failure state in which the protection device outputs other protection action signals when the circuit breaker is manually tripped, and a manual trip normal state in which the protection device does not output other protection action signals when the circuit breaker is manually tripped.

4. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 3, characterized in that: When the phase-splitting operating box adopts a double-tripping ring design, if any contact in the two groups of phase closing position relays is closed, then based on the closure of the contact of the manual tripping relay and the closure of any contact in the three phases of the phase-splitting tripping position relay, it is determined that the current state is a manual tripping failure state. At this time, other protection action inputs are in the on state.

5. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 1, characterized in that: The types of the pilot channel of the line where the protection device is located include optical fiber channel and power line carrier channel; The power line carrier channel further includes a locked power line carrier channel and a permissive power line carrier channel.

6. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 5, characterized in that: For a fiber optic channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in an on state, the protection device immediately sends a remote trip signal to the opposite side protection device.

7. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 5, characterized in that: For a permissive power line carrier channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in the on state, the protection device sends a permissive command signal to the opposite side protection device; For a locked power line carrier channel, when the protection device identifies a manual trip failure state, that is, identifies that other protection action inputs are in the on state, it stops sending a locking signal to the opposite side protection device.

8. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 6, characterized in that: For the optical fiber channel, when the opposite-side protection device receives the remote trip signal, it determines the remote trip action condition and quickly trips the opposite-side circuit breaker when the remote trip action condition is met.

9. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 7, characterized in that: For a permissive power line carrier channel, if the opposite protection device receives the permissive command signal, the opposite circuit breaker is tripped when the pilot distance and zero-sequence protection action conditions are met.

10. The method for preventing malfunction of zero-sequence current protection when a circuit breaker manual trip fails according to claim 7, characterized in that: For a locked power line carrier channel, if the opposite protection device fails to receive the locked signal, the opposite circuit breaker will be tripped when the pilot distance and zero-sequence protection action conditions are met.

Images