Failure protection method and failure protection device of circuit breaker

Abstract

The invention discloses a failure protection method and a failure protection device of a circuit breaker. The failure protection method comprises the steps that after a control protection device corresponding to a circuit breaker on a fault line sends out a control protection action or a line protection device sends out a line protection action, whether the composite voltage of the fault line meets a first set condition or not and whether the failure current of the fault line meets a second set condition or not are determined; when the composite voltage meets a first set condition and the failure current meets a second set condition, a circuit breaker on the fault line is tripped off after first set time is delayed; and when the circuit breaker on the faulty line is still in the closed state, tripping off other circuit breakers on a bus connected with the faulty line or tripping off other circuit breakers on a previous-stage line of the faulty line after delaying a second set time. According to the invention, the accuracy of fault identification can be improved, selective tripping can be realized, and the power failure range is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection of power systems, and in particular to a failure protection method and a failure protection device for a circuit breaker. Background Art

[0002] Circuit breaker failure protection is an important protection measure in the power system. Its main purpose is to cut off other related circuit breakers in the same plant and station in a shorter time through specific judgment logic and action process when the relay protection of the faulty electrical equipment issues a tripping command and the circuit breaker refuses to operate, thereby limiting the scope of power outage, ensuring the stable operation of the power grid, and avoiding serious burning of faulty components such as generators and transformers and the collapse of the power grid.

[0003] The existing circuit breaker failure protection method has low fault identification accuracy. Summary of the invention

[0004] The present invention provides a failure protection method and a failure protection device for a circuit breaker, which can improve the accuracy of fault identification and can selectively trip to reduce the scope of power outage.

[0005] In a first aspect, an embodiment of the present invention provides a failure protection method for a circuit breaker, comprising: after a control protection device corresponding to the circuit breaker on the fault line issues a control protection action or a line protection device issues a line protection action, determining whether the composite voltage of the fault line meets a first setting condition and whether the failure current of the fault line meets a second setting condition; when the composite voltage of the fault line meets the first setting condition and the failure current of the fault line meets the second setting condition, tripping the circuit breaker on the fault line after a first setting time delay; when the circuit breaker on the fault line is still in a closed state, tripping other circuit breakers on a bus connected to the fault line or tripping other circuit breakers on a line one level above the fault line after a second setting time delay; the second setting time is greater than the first setting time; wherein the first setting condition is that the negative sequence voltage is greater than the first setting value, the zero sequence voltage is greater than the second setting value, or any one of the voltages of phase A, phase B and phase C is less than the third setting value; the second setting condition is that the failure current is greater than the fourth setting value.

[0006] Optionally, the failure protection method of the circuit breaker also includes: after the control protection action device corresponding to the circuit breaker on the fault line sends a control protection action or the line protection action device sends a line protection action, and when the composite voltage of the fault line meets the first set condition, the failure current of the fault line does not meet the second set condition, the normally open contact of the circuit breaker on the fault line is closed and the normally closed contact of the circuit breaker on the fault line is disconnected, determining whether the detection module of the circuit breaker sends a switch position alarm signal; when the detection module of the circuit breaker does not send a switch position alarm signal, tripping the circuit breaker on the fault line after a first set time delay; when the circuit breaker on the fault line is still in a closed state, tripping other circuit breakers on the bus connected to the fault line or tripping other circuit breakers on the upper level line of the fault line after a second set time delay.

[0007] Optionally, the step of determining whether the detection module of the circuit breaker issues a switch position alarm signal includes: when the normally open contact of the circuit breaker on the fault line and the normally closed contact of the circuit breaker on the fault line are closed at the same time, determining that the detection module of the circuit breaker issues a switch position alarm signal; or, when the normally open contact of the circuit breaker on the fault line and the normally closed contact of the circuit breaker on the fault line are opened at the same time, determining that the detection module of the circuit breaker issues a switch position alarm signal; or, when the circuit breaker on the fault line trips and the current flowing through the circuit breaker on the fault line is greater than zero, determining that the detection module of the circuit breaker issues a switch position alarm signal.

[0008] Optionally, the step of determining whether the detection module of the circuit breaker issues a switch position alarm signal includes: when the time for the normally closed contact of the circuit breaker on the fault line to change from open to closed or the time for the normally open contact of the circuit breaker on the fault line to change from closed to open is greater than a third set time, determining that the detection module of the circuit breaker issues a switch position alarm signal.

[0009] Optionally, the third setting time is 50 ms.

[0010] Optionally, after the control protection device corresponding to the circuit breaker on the fault line sends action information or the line protection action device sends action information, before the step of determining whether the composite voltage of the fault line meets the first set condition and whether the failure current of the fault line meets the second set condition, the circuit breaker failure protection method includes: obtaining control protection action information sent by the control protection device corresponding to the circuit breaker on the fault line and line protection action information sent by the line protection device corresponding to the circuit breaker on the fault line.

[0011] Optionally, the control protection action includes at least overcurrent protection, differential protection and overtemperature protection.

[0012] Optionally, the first set time is 5 ms and the second set time is 10 ms.

[0013] Optionally, the first set value is 2V, the second set value is 4V, and the third set value is 40V.

[0014] In a second aspect, an embodiment of the present invention provides a failure protection device for a circuit breaker, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the failure protection method for a circuit breaker provided in any embodiment of the present invention.

[0015] The technical solution of the embodiment of the present invention simultaneously performs conditional judgment on the composite voltage and failure current of the fault line, that is, the composite voltage is required to meet the first set condition (including the negative sequence voltage being greater than the first set value, the zero sequence voltage being greater than the second set value, or the phase voltage being less than the third set value, etc.), and the failure current is required to meet the second set condition of being greater than the fourth set value, and comprehensively considers the characteristics of various electrical quantities to determine whether a fault situation that requires failure protection action actually occurs, thereby avoiding the problem of misjudgment caused by a single electrical quantity abnormality, and being able to accurately identify the fault scenario that really requires the initiation of failure protection, thereby improving the accuracy of fault judgment. After the corresponding set conditions of the composite voltage and failure current are met, the circuit breaker on the fault line is first tripped after a delay of the first set time. This is a measure to try to remove the fault first, because in many cases the fault may be limited to the line, and directly tripping the circuit breaker can quickly isolate the fault, so that the power system can be restored to normal operation as soon as possible, minimizing the scope and duration of the fault impact. When the circuit breaker on the faulty line is still in the closed state after the first set time delay operation, it means that the circuit breaker has not successfully removed the fault. At this time, after the second set time delay, other circuit breakers on the bus connected to the faulty line or other circuit breakers on the upper level of the faulty line are tripped. This backup protection mechanism can further expand the fault isolation range, prevent the fault from continuing to affect a wider range of power grids, and ensure the safe and stable operation of the entire power system. And because the second set time is greater than the first set time, the rationality of the action sequence is guaranteed, and the faulty line circuit breaker is given enough time to perform the tripping operation first. If it is unsuccessful, the tripping operation of a wider range is started to avoid unnecessary large-scale power outages. Accurate fault judgment and reasonable protection action sequence and time arrangement help to isolate faults in a timely and effective manner, prevent the spread and expansion of faults in the power grid, maintain the continuity of power supply of other normal operating parts in the power grid, and avoid chain reactions caused by the continued existence of faults, such as voltage collapse, line overload and other problems that seriously affect the stability of the power grid, which enhances the stability of the power grid in response to faults as a whole and ensures reliable power supply of the power system.

[0016] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a flow chart of a circuit breaker failure protection method provided by an embodiment of the present invention;

[0019] Figure 2 is a wiring diagram of a power supply system provided by an embodiment of the present invention;

[0020] Figure 3 is a flow chart of another circuit breaker failure protection method provided by an embodiment of the present invention;

[0021] Figure 4 It is a switch position alarm action logic diagram provided by an embodiment of the present invention;

[0022] Figure 5 It is a failure protection action logic diagram provided by an embodiment of the present invention;

[0023] Figure 6 is a flow chart of another circuit breaker failure protection method provided by an embodiment of the present invention;

[0024] Figure 7 It is a structural schematic diagram of a failure protection device for a circuit breaker provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] Figure 1 This is a flow chart of a failure protection method for a circuit breaker provided by an embodiment of the present invention. This embodiment can be applied to the analysis of failure protection of a circuit breaker that refuses to operate in an AC or DC system. The method can be executed by a failure protection device, which can be implemented in the form of hardware and / or software, and can be configured in a power system.

[0028] Figure 2 It is a wiring diagram of a power supply system provided by an embodiment of the present invention. The following is an example of a double bus main wiring method. The double bus wiring has two sets of busbars, and each power supply and each appearance are connected to the two sets of busbars through a circuit breaker and two sets of disconnectors, respectively. Any set of busbars can be used as a working busbar or a standby busbar. The two sets of busbars are connected by a connecting circuit breaker QFL. Among them, the first line 1# and the second line 2# run on the first bus Ⅰ, and the third line 3# and the fourth line 4# run on the second bus Ⅱ. The first circuit breaker DL1 is set on the first line 1# to control the on and off of the first line 1#. The second circuit breaker DL2 is set on the second line 2# to control the on and off of the second line 2#. The third circuit breaker DL3 is set on the third line 3# to control the on and off of the third line 3#. The fourth circuit breaker DL4 is set on the fourth line 4# to control the on and off of the fourth line 4#.

[0029] Optionally, a static synchronous compensator 11 (STATCOM) is also connected to the first bus I. The first bus I is connected to the first end of the fifth circuit breaker DL5, the second end of the fifth circuit breaker DL5 is connected to the high voltage side of the transformer T1, the low voltage side of the transformer T1 is connected to the third bus III, the third bus III is connected to the first end of the sixth circuit breaker DL6, and the second end of the sixth circuit breaker DL6 is connected to the static synchronous compensator 11.

[0030] The static synchronous compensator 11 and the sixth circuit breaker DL6 are connected to the control protection device 12, and the sixth circuit breaker DL6 is also connected to the first failure protection device 13. The first circuit breaker DL1, the second circuit breaker DL2, the third circuit breaker DL3 and the fourth circuit breaker DL4 are connected to the line protection device 14, and the line protection device is connected to the second failure protection device 15.

[0031] Combination Figure 1 and Figure 2 , the failure protection method of the circuit breaker includes:

[0032] S101. After a control protection device corresponding to a circuit breaker on a faulty line issues a control protection action or a line protection device issues a line protection action, determine whether a composite voltage of the faulty line satisfies a first set condition and whether a failure current of the faulty line satisfies a second set condition.

[0033] The first setting condition is that the negative sequence voltage is greater than the first setting value, the zero sequence voltage is greater than the second setting value, or any one of the voltages of phase A, phase B and phase C is less than the third setting value; the second setting condition is that the failure current is greater than the fourth setting value. For example, the first setting value is 2V, the second setting value is 4V, and the third setting value is 40V.

[0034] The control and protection action refers to the control operation and protection action performed on the circuit breaker by the control and protection device 12 corresponding to the circuit breaker. The control and protection device 12 is used to remotely control and locally control the circuit breaker, and monitor the operating status of the circuit breaker. When an abnormal situation is found that may cause harm to the circuit breaker itself or the entire power system, a control and protection action will be issued. Optionally, the control and protection action includes at least overcurrent protection, differential protection and overtemperature protection.

[0035] Control: For example, in normal power system dispatching operations, the remote opening and closing operations of the circuit breaker can be realized through the control protection device 12. The dispatching center sends instructions to the control protection device 12 corresponding to the circuit breaker according to the operation of the power grid, such as load adjustment, line maintenance and other requirements, to control the opening or closing of the circuit breaker. This is a normal control action.

[0036] Protection: When the control protection device 12 detects that the electrical parameters of the circuit breaker are abnormal, it will take protective action. For example, when it is detected that the current of the circuit breaker exceeds a certain multiple of its rated current (such as a short-circuit current) or the temperature of the circuit breaker is too high (possibly due to long-term overload, etc.), the control protection device will immediately issue a trip command to disconnect the circuit breaker to protect the circuit breaker from damage and prevent the fault from further expanding to the entire power system.

[0037] Line protection action refers to the protection action issued by the line protection device 14 which is specially used to protect the transmission line. The line protection device 14 will monitor the electrical parameters of the transmission line in real time, such as current, voltage, phase, etc. When these parameters exceed the normal range, indicating that the line may have a fault, the line protection device 14 will act. Exemplarily, when the current in the line exceeds the set quick-break current value, the line protection device 14 will immediately start the quick-break protection and quickly disconnect the circuit breakers at both ends of the line. This is mainly for short-circuit faults on the line, such as three-phase short circuit, two-phase short circuit, etc. The quick-break protection can cut off the faulty line in a very short time (generally tens of milliseconds) to prevent the fault current from causing serious damage to the line equipment.

[0038] Control protection devices and line protection devices are important components of the power system protection system. Their main function is to quickly detect and respond to line faults and try to limit the faults to the minimum range. When they take action, the failure protection device begins to intervene for further judgment. For example, the line protection device 14 can quickly determine whether a line fault occurs and take preliminary measures (such as tripping), while the failure protection device focuses on whether the circuit breaker successfully performs the tripping operation and whether the fault is truly isolated. Through this division of labor and cooperation, the reliability and effectiveness of the protection of the entire power system are improved.

[0039] When the power system is operating normally, the three-phase voltage is basically symmetrical, and the negative sequence voltage is very small. When an asymmetrical fault occurs in the system, such as single-phase grounding, two-phase short circuit, etc., a large negative sequence voltage will be generated. For example, in a three-phase transmission line, if a ground fault occurs in phase A, the three-phase balance will be broken and a negative sequence voltage component will be generated.

[0040] Zero-sequence voltage is mainly generated when there is a ground fault. For a neutral point direct grounding system, when a ground fault occurs, a zero-sequence current will flow, and a zero-sequence voltage will be generated accordingly. For example, in a neutral point direct grounding system of 110kV and above, once a ground fault occurs, the zero-sequence voltage will increase significantly.

[0041] Failure current refers to the current flowing through the faulty component when the fault still exists after the protection action of the faulty component issues a tripping command when a fault occurs in the power system. For example, when a switching device such as a circuit breaker fails to effectively cut off the fault current due to mechanical failure, control circuit failure, etc., the failure current will continue to exist. When the failure current flowing through the faulty line is greater than the fourth set value, it means that the circuit breaker on the faulty line failed to successfully trip when the fault occurred. At this time, it is necessary to delay the first set time to trip the circuit breaker on the faulty line.

[0042] S102: When the composite voltage of the fault line meets the first set condition and the failure current of the fault line meets the second set condition, trip the circuit breaker on the fault line after a first set time delay.

[0043] Specifically, when the composite voltage of the fault line meets the first set condition and the failure current meets the second set condition, the circuit breaker on the fault line is tripped after the first set time delay. This is because after the fault is detected, the system needs to be given a short stabilization time. At the same time, it is also possible that some instantaneous interference causes the protection device to operate and meet the above conditions. The delay can avoid false tripping.

[0044] S103: When the circuit breaker on the faulty line is still in the closed state, trip other circuit breakers on the bus connected to the faulty line or trip other circuit breakers on the upper level line of the faulty line after a delay of a second set time.

[0045] Specifically, if the circuit breaker on the faulty line is still in the closed state after the first set time, it means that the circuit breaker may fail and fail to cut off the fault current. In this case, in order to prevent the fault from further affecting the entire system, more extensive protection measures need to be taken.

[0046] The delay of the second setting time is set to ensure the accuracy of the action. There may be some short-term interference factors in the power system, causing the circuit breaker to be abnormal in a short period of time. Through the delay, the influence of these accidental factors can be eliminated. For example, when the system is struck by lightning or electromagnetic interference, signal transmission errors may occur, making the circuit breaker temporarily unable to respond to the trip signal normally, but it can return to normal after a short period of time. Without this delay, other circuit breakers may be tripped prematurely, causing unnecessary expansion of the power outage.

[0047] The purpose of tripping other circuit breakers on the bus connected to the faulty line is to prevent the fault from spreading to other normal lines through the bus. The bus is a very critical part of the power system, which connects multiple lines. If the problem of the faulty line cannot be isolated in time, it may cause abnormal bus voltage, which in turn affects all lines connected to the bus. For example, in a double bus system, there are other normally operating lines on the bus connected to the faulty line. When the circuit breaker of the faulty line fails, tripping other circuit breakers on the bus can isolate the fault on this bus and protect the normal operation of the lines on the other bus. Exemplarily, if a fault occurs at point K1 on the first line 1#, the line protection device 14 corresponding to the first line 1# issues a line protection action to control the first circuit breaker DL1 to trip. If the first circuit breaker DL1 refuses to trip due to reasons such as a failure of the operating mechanism, the second failure protection device 15 corresponding to the first circuit breaker DL1 will issue a line protection action to control the circuit breakers on all lines on the second bus II to trip. That is, the connecting circuit breaker QFL, the second circuit breaker DL2 and the fifth circuit breaker DL2 are controlled to trip.

[0048] By tripping other circuit breakers on the upper level of the faulty line, the fault isolation range can be further expanded. By cutting off the upper level of the faulty line, the fault current can be prevented from flowing back, and the fault can be prevented from affecting the power system further upstream. In this way, the fault can be effectively limited to a certain area, reducing the impact of the fault on the entire power system, and ensuring the stable operation of other parts of the power system. Exemplarily, if a fault occurs at point K2, the control protection device 12 corresponding to the sixth circuit breaker DL6 issues a control protection action to control the sixth circuit breaker DL6 to trip. If the sixth circuit breaker DL6 refuses to trip due to reasons such as a failure of the operating mechanism, the first failure protection device 13 corresponding to the sixth circuit breaker DL6 will issue a line protection action to control the fifth circuit breaker DL2 to trip.

[0049] The second set time is greater than the first set time. The circuit breaker on the faulty line is given enough time (the first set time) to perform the tripping operation, and only when it really cannot complete the tripping task will it take more extensive protection measures after a slightly longer time (the second set time). This sequence can minimize the scope of the power outage, try to solve the problem inside the faulty line first, and avoid cutting off a large area of ​​lines related to the faulty line at the beginning. Optionally, the first set time is 5ms and the second set time is 10ms.

[0050] The technical solution of the embodiment of the present invention simultaneously performs conditional judgment on the composite voltage and failure current of the fault line, that is, the composite voltage is required to meet the first set condition (including the negative sequence voltage being greater than the first set value, the zero sequence voltage being greater than the second set value, or the phase voltage being less than the third set value, etc.), and the failure current is required to meet the second set condition of being greater than the fourth set value, and comprehensively considers the characteristics of various electrical quantities to determine whether a fault situation that requires failure protection action actually occurs, thereby avoiding the problem of misjudgment caused by a single electrical quantity abnormality, and being able to accurately identify the fault scenario that really requires the initiation of failure protection, thereby improving the accuracy of fault judgment. After the corresponding set conditions of the composite voltage and failure current are met, the circuit breaker on the fault line is first tripped after a delay of the first set time. This is a measure to try to remove the fault first, because in many cases the fault may be limited to the line, and directly tripping the circuit breaker can quickly isolate the fault, so that the power system can be restored to normal operation as soon as possible, minimizing the scope and duration of the fault impact. When the circuit breaker on the faulty line is still in the closed state after the first set time delay operation, it means that the circuit breaker has not successfully removed the fault. At this time, after the second set time delay, other circuit breakers on the bus connected to the faulty line or other circuit breakers on the upper level of the faulty line are tripped. This backup protection mechanism can further expand the fault isolation range, prevent the fault from continuing to affect a wider range of power grids, and ensure the safe and stable operation of the entire power system. And because the second set time is greater than the first set time, the rationality of the action sequence is guaranteed, and the faulty line circuit breaker is given enough time to perform the tripping operation first. If it is unsuccessful, the tripping operation of a wider range is started to avoid unnecessary large-scale power outages. Accurate fault judgment and reasonable protection action sequence and time arrangement help to isolate faults in a timely and effective manner, prevent the spread and expansion of faults in the power grid, maintain the continuity of power supply of other normal operating parts in the power grid, and avoid chain reactions caused by the continued existence of faults, such as voltage collapse, line overload and other problems that seriously affect the stability of the power grid, which enhances the stability of the power grid in response to faults as a whole and ensures reliable power supply of the power system.

[0051] Figure 3 This is a flow chart of another circuit breaker failure protection method provided by an embodiment of the present invention.

[0052] like Figure 3 As shown, the failure protection method of the circuit breaker also includes:

[0053] S201. After the control protection action device corresponding to the circuit breaker on the fault line issues a control protection action or the line protection action device issues a line protection action, and when the composite voltage of the fault line meets the first set condition, the failure current of the fault line does not meet the second set condition, the normally open contact of the circuit breaker on the fault line is closed and the normally closed contact of the circuit breaker on the fault line is disconnected, determine whether the detection module of the circuit breaker issues a switch position alarm signal.

[0054] When the control protection action device corresponding to the circuit breaker on the faulty line issues a control protection action, or the line protection action device issues a line protection action, it means that the system has detected a fault. These protection devices are used to monitor the status of the line and circuit breaker, and once abnormal conditions such as short circuit, overload, etc. are found, the action signal will be triggered.

[0055] The composite voltage of the faulty line meets the first set condition, which means that the line may be in a fault state from the voltage aspect. For example, the negative sequence voltage is greater than the first set value, the zero sequence voltage is greater than the second set value, or any of the voltages of phase A, phase B and phase C is less than the third set value. These voltage anomalies may be caused by line asymmetry fault or ground fault.

[0056] The failure current of the fault line does not meet the second setting condition, that is, the failure current does not exceed the fourth setting value. This means that although there are signs of fault (compound voltage abnormality), from the perspective of failure current, the circuit breaker has not yet experienced a continuous high current caused by failure.

[0057] The normally open contacts of the circuit breaker on the faulty line are closed and the normally closed contacts of the circuit breaker on the faulty line are opened. This is the contact state change when the circuit breaker is operating normally. The normally open contacts will close when the circuit breaker is closed, and the normally closed contacts will open when the circuit breaker is closed. This state change indicates that the circuit breaker may not have tripped when there is a fault in the system.

[0058] Under the above complex combination of conditions, although the contact state of the circuit breaker seems to change normally, because the composite voltage has signs of fault and the failure current is still normal, it is necessary to determine whether the detection module of the circuit breaker issues a switch position alarm signal. This is to further confirm whether the circuit breaker actually operates as expected, because even if the contact state changes, it may be caused by other factors (such as signal interference, false action caused by mechanical failure, etc.), rather than the correct action in response to the fault condition.

[0059] If the detection module of the circuit breaker sends out a switch position alarm signal, it may mean that the actual position of the circuit breaker is inconsistent with the position believed by the control system. For example, an error occurs during the signal transmission process, and the control system believes that the circuit breaker has not tripped normally, but in fact the circuit breaker has tripped normally. This situation may cause the control system to take unnecessary protection actions. For example, in the subsequent fault handling process, because it is believed that the circuit breaker has not tripped, it may trigger the tripping of other circuit breakers on the bus connected to the faulty line or other circuit breakers on the upper level of the faulty line. This will cause the scope of the power outage to expand unnecessarily, affecting the power supply of other normal lines.

[0060] Figure 4 This is a switch position alarm action logic diagram provided by an embodiment of the present invention. Figure 4 As shown, optionally, when the normally open contact of the circuit breaker on the fault line and the normally closed contact of the circuit breaker on the fault line are closed at the same time, it is determined that the detection module of the circuit breaker sends a switch position alarm signal; or, when the normally open contact of the circuit breaker on the fault line and the normally closed contact of the circuit breaker on the fault line are disconnected at the same time, it is determined that the detection module of the circuit breaker sends a switch position alarm signal; or, when the circuit breaker on the fault line trips and the current flowing through the circuit breaker on the fault line is greater than zero, it is determined that the detection module of the circuit breaker sends a switch position alarm signal.

[0061] Specifically, when the circuit breaker is working normally, the states of the normally open contact and the normally closed contact are mutually exclusive. The normally open contact will only close when the circuit breaker is closed, and the normally closed contact should be open at this time; when the circuit breaker is open, the normally open contact will return to the open state and the normally closed contact will close. This is designed based on the basic working principle and electrical control logic of the circuit breaker to accurately reflect the actual position state of the circuit breaker.

[0062] When the normally open contact and the normally closed contact are closed at the same time, this is contrary to normal electrical logic, indicating that there may be a signal error or contact failure. For example, there may be a short circuit fault in the control circuit, causing the normally open contact and the normally closed contact to receive the closing signal at the same time, causing them to close at the same time; or there may be a mechanical failure in the contact itself, such as contact adhesion, which cannot be separated normally, resulting in this abnormal state. Similarly, when the normally open contact and the normally closed contact are disconnected at the same time, it does not conform to normal working logic. This may be due to reasons such as an open circuit in the control circuit, poor contact, or contact damage, which makes it impossible for both contacts to conduct normally, resulting in a switch position alarm signal of simultaneous disconnection.

[0063] When the circuit breaker trips normally, the fault line should be cut off in theory, and the current flowing through the circuit breaker should be zero at this time. This is because the main function of the circuit breaker is to isolate the circuit in the event of a fault and prevent the current from continuing to flow, so as to protect the safety of equipment and lines.

[0064] If the circuit breaker on the fault line trips and the current flowing through the circuit breaker is greater than zero, this indicates that although the circuit breaker has issued a trip signal and may have an action (such as the contacts have separated), it has not actually completely cut off the circuit and the fault current is still flowing. This situation may be due to the fact that the contacts of the circuit breaker are not completely separated, and there is an arc that continues to conduct current; or the insulating medium inside the circuit breaker is damaged, causing the current to leak through other paths, so that the tripping operation does not achieve the expected effect of cutting off the current. This means that the actual action of the circuit breaker is inconsistent with the tripping action believed by the control system, and the switch position signal cannot accurately reflect the actual state of the circuit breaker, so it is determined that the switch position signal is abnormal, and a switch position alarm signal is issued. If this abnormal situation is not discovered and handled in time, it may cause the fault to persist, further damage the equipment, and even affect the safe and stable operation of the entire power system.

[0065] Optionally, when the time from opening to closing of the normally closed contact of the circuit breaker on the faulty line or the time from closing to opening of the normally open contact of the circuit breaker on the faulty line is greater than a third set time, the detection module of the circuit breaker is determined to send a switch position alarm signal.

[0066] Specifically, in the power system, the action speed of the circuit breaker has certain standards and expectations. From the normally closed contact being opened to the closed contact or the normally open contact being closed to the opened contact, this process should be completed within a reasonable time range. This reasonable time range is defined by the third set time. When the actual action time exceeds this set time, it may mean that the action of the circuit breaker is abnormal, resulting in an abnormal switch position signal. Optionally, the third set time is 50ms.

[0067] For example, for a normally operating circuit breaker, its normally closed contacts should open quickly after receiving a trip signal, and the normally open contacts should close quickly. This process usually takes a few milliseconds to tens of milliseconds (depending on the type and design parameters of the circuit breaker). If this time is too long, it may be due to mechanical jamming, spring fatigue, electromagnetic drive failure, etc. in the operating mechanism of the circuit breaker, resulting in the failure of the contacts to move in time, so that the time for the contact state change exceeds the normal range.

[0068] By monitoring whether the time from opening to closing of the normally closed contact and the time from closing to opening of the normally open contact is greater than the third set time, the action performance and reliability of the circuit breaker can be judged more accurately. If the set time is exceeded, even if the contact state of the circuit breaker finally seems normal (normally closed to normally open, normally open to normally closed), due to the slow action process, the circuit may not be cut off in time when a fault occurs, resulting in a prolonged fault duration and greater harm to the power system.

[0069] For example, when a short circuit occurs in the system, the circuit breaker needs to act quickly to isolate the fault. If the contact action time is too long, the fault current will continue to flow through the faulty equipment during this period, which may cause the equipment to overheat and be damaged, or even cause more serious chain failures. Therefore, when an abnormal contact action time is detected, timely determination of the switch position signal abnormality will help the system take measures in advance, such as issuing a switch position alarm signal to remind operation and maintenance personnel to check and maintain the circuit breaker, or start the backup protection plan when necessary, to ensure the safe and stable operation of the power system.

[0070] Optionally, after determining that the switch position signal sent by the circuit breaker on the faulty line is abnormal, the circuit breaker failure protection method further includes: delaying a fourth set time and sending a switch position alarm signal.

[0071] S202: When the switch position signal is normal, the circuit breaker on the faulty line is tripped after a first set delay time.

[0072] Specifically, when the switch position signal is determined to be normal after a series of previous judgments (such as the judgment of the composite voltage and failure current conditions after the control protection action device or the line protection action device initiates an action, and the judgment of whether the switch position signal is abnormal), this indicates that the feedback information about the circuit breaker position obtained from the control system is accurate and reliable, and the circuit breaker is currently in a state where it can respond normally to the action instruction. At this time, the circuit breaker on the faulty line is tripped after the first set time delay. The purpose of setting this delay is mainly to avoid unnecessary tripping due to some momentary interference factors or misjudgments. Occasionally, short-term electrical parameter fluctuations may occur during the operation of the power system. The delay can give the system time to further confirm that the current fault state is real and continuous, rather than caused by temporary interference, so as to perform the operation of tripping the faulty line circuit breaker more cautiously and accurately, and try to solve the fault at the faulty line level to prevent the fault from further expanding.

[0073] S203: When the circuit breaker on the faulty line is still in the closed state, trip other circuit breakers on the bus connected to the faulty line or trip other circuit breakers on the upper level line of the faulty line after a delay of a second set time.

[0074] Figure 5 This is a failure protection action logic diagram provided by an embodiment of the present invention. Figure 5As shown, the control protection action can be sent by the control protection device 12 to the first failure protection device 13, the line protection action can be sent by the line protection device 14 to the second failure protection device 15, the composite voltage can be obtained by the voltage sensor, and the failure current signal can be obtained by the current sensor and sent to the first failure protection device 13 and the second failure protection device 15. The switch position signal and the switch position alarm signal are detected by the detection module of the circuit breaker.

[0075] The logic of the first failure protection device 13 performing the protection action is as follows: after the control protection device 12 corresponding to the circuit breaker on the faulty line issues a control protection action, and when the composite voltage of the faulty line meets the first set condition and the failure current of the faulty line meets the second set condition, the circuit breaker on the faulty line is tripped after a delay of the first set time, that is, the switch is tripped. When the circuit breaker on the faulty line is still in the closed state, other circuit breakers on the upper level of the faulty line are tripped after a delay of the second set time, that is, other switches are tripped in conjunction.

[0076] Alternatively, after the control protection device 12 corresponding to the circuit breaker on the fault line issues a control protection action, and when the composite voltage of the fault line meets the first set condition and the failure current of the fault line does not meet the second set condition, the normally open contact of the circuit breaker on the fault line is closed and the normally closed contact of the circuit breaker on the fault line is disconnected, that is, when the switch position signal is "1" and the detection module of the circuit breaker does not issue a switch position alarm signal, the first failure protection device 13 trips the circuit breaker on the fault line after a delay of the first set time, that is, trips the switch. When the circuit breaker on the fault line is still in the closed state, the other circuit breakers on the upper level of the fault line are tripped after a delay of the second set time, that is, trips other switches.

[0077] The logic of the second failure protection device 15 performing the protection action is as follows: after the line protection device corresponding to the circuit breaker on the faulty line issues a line protection action, and when the composite voltage of the faulty line meets the first set condition and the failure current of the faulty line meets the second set condition, the circuit breaker on the faulty line is tripped after a delay of the first set time, that is, the switch is tripped. When the circuit breaker on the faulty line is still in the closed state, other circuit breakers on the bus connected to the faulty line are tripped after a delay of the second set time, that is, other switches are tripped.

[0078] Alternatively, after the line protection device corresponding to the circuit breaker on the fault line issues a line protection action, and when the composite voltage of the fault line meets the first set condition and the failure current of the fault line does not meet the second set condition, the normally open contact of the circuit breaker on the fault line is closed and the normally closed contact of the circuit breaker on the fault line is disconnected, that is, when the switch position signal is "1" and the detection module of the circuit breaker does not issue a switch position alarm signal, the second failure protection device 15 trips the circuit breaker on the fault line after a delay of the first set time, that is, trips the switch. When the circuit breaker on the fault line is still in the closed state, the other circuit breakers on the bus connected to the fault line are tripped after a delay of the second set time, that is, other switches are tripped in conjunction.

[0079] Figure 6 This is a flow chart of another circuit breaker failure protection method provided by an embodiment of the present invention.

[0080] like Figure 6 As shown, the failure protection method of the circuit breaker includes:

[0081] S301. Acquire control protection action information sent by a control protection device corresponding to a circuit breaker on a faulty line and line protection action information sent by a line protection device corresponding to a circuit breaker on a faulty line.

[0082] In some embodiments, the control protection device and the line protection device are equipped with Ethernet interfaces, which can be connected to the monitoring system or the failure protection device through an Ethernet switch to form a local area network. When the control protection device sends control protection action information or the line protection device sends line protection action information, these information will be encapsulated into Ethernet data packets, transmitted in the network according to a pre-set communication protocol, and finally received by the failure protection device. For example, in an intelligent substation, each protection device realizes information exchange through the Ethernet network in the station, and the failure protection device can monitor the data packets in the network in real time to obtain relevant action information.

[0083] In some embodiments, the failure protection device can be directly connected to the data output port of the control protection device and the line protection device through a dedicated data acquisition card or communication interface module to read the action information sent by them in real time. This method usually requires understanding the data output format and communication protocol of the protection device in order to correctly parse and obtain relevant information. For example, some protection devices will provide serial port data output, and the failure protection device can be programmed through serial port communication and read the action information from the serial port according to the agreed baud rate, data bit, stop bit and other parameter settings.

[0084] S302: After the control protection device corresponding to the circuit breaker on the faulty line issues a control protection action or the line protection device issues a line protection action, determine whether the composite voltage of the faulty line meets a first set condition and whether the failure current of the faulty line meets a second set condition.

[0085] S303: When the composite voltage of the fault line meets the first set condition and the failure current of the fault line meets the second set condition, trip the circuit breaker on the fault line after a first set delay.

[0086] S304: When the circuit breaker on the faulty line is still in the closed state, trip other circuit breakers on the bus connected to the faulty line or trip other circuit breakers on the upper level line of the faulty line after a delay of a second set time.

[0087] Based on the same inventive concept, an embodiment of the present invention further provides a failure protection device for a circuit breaker. Figure 7 1 is a schematic diagram of the structure of a failure protection device for a circuit breaker provided by an embodiment of the present invention. The failure protection device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The failure protection device may also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0088] like Figure 7 As shown, the failure protection device 2 includes at least one processor 21, and a memory connected to the at least one processor 21, such as a read-only memory (ROM) 22, a random access memory (RAM) 23, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 21 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 22 or the computer program loaded from the storage unit 28 to the random access memory (RAM) 23. In the RAM 23, various programs and data required for the operation of the failure protection device 2 can also be stored. The processor 21, the ROM 22, and the RAM 23 are connected to each other through a bus 24. An input / output (I / O) interface 25 is also connected to the bus 24.

[0089] A number of components in the failure protection device 2 are connected to the I / O interface 25, including: an input unit 26, such as a keyboard, a mouse, etc.; an output unit 27, such as various types of displays, speakers, etc.; a storage unit 28, such as a disk, an optical disk, etc.; and a communication unit 29, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 29 allows the failure protection device 2 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0090] The processor 21 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 21 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 21 executes the various methods and processes described above, such as a failure protection method for a circuit breaker.

[0091] In some embodiments, the failure protection method of the circuit breaker can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 28. In some embodiments, part or all of the computer program can be loaded and / or installed on the failure protection device 2 via the ROM 22 and / or the communication unit 29. When the computer program is loaded into the RAM 23 and executed by the processor 21, one or more steps of the failure protection method of the circuit breaker described above can be performed. Alternatively, in other embodiments, the processor 21 can be configured to execute the failure protection method of the circuit breaker in any other appropriate manner (for example, by means of firmware).

[0092] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0093] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0094] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0095] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A failure protection method for a circuit breaker, characterized in that: include: After the control protection device corresponding to the circuit breaker on the fault line issues a control protection action or the line protection device issues a line protection action, determining whether the composite voltage of the fault line meets a first set condition and whether the failure current of the fault line meets a second set condition; When the composite voltage of the fault line meets a first set condition and the failure current of the fault line meets a second set condition, tripping the circuit breaker on the fault line after a first set time delay; When the circuit breaker on the faulty line is still in the closed state, tripping other circuit breakers on the bus connected to the faulty line or tripping other circuit breakers on the upper level line of the faulty line after a delay of a second set time; the second set time is greater than the first set time; The first setting condition is that the negative sequence voltage is greater than the first setting value, the zero sequence voltage is greater than the second setting value, or any one of the A phase, B phase and C phase voltages is less than the third setting value; the second setting condition is that the failure current is greater than the fourth setting value.

2. The circuit breaker failure protection method according to claim 1, characterized in that: Also includes: After the control protection action device corresponding to the circuit breaker on the fault line issues a control protection action or the line protection action device issues a line protection action, and when the composite voltage of the fault line meets the first set condition, the failure current of the fault line does not meet the second set condition, the normally open contact of the circuit breaker on the fault line is closed, and the normally closed contact of the circuit breaker on the fault line is disconnected, determine whether the detection module of the circuit breaker issues a switch position alarm signal; When the detection module of the circuit breaker does not send out the switch position alarm signal, tripping the circuit breaker on the faulty line after delaying the first set time; When the circuit breaker on the faulty line is still in the closed state, the other circuit breakers on the bus connected to the faulty line or the other circuit breakers on the upper level line of the faulty line are tripped after the second set time delay.

3. The circuit breaker failure protection method according to claim 2, characterized in that: The step of determining whether the detection module of the circuit breaker issues a switch position alarm signal comprises: When the normally open contact of the circuit breaker on the faulty line and the normally closed contact of the circuit breaker on the faulty line are closed at the same time, determining that the detection module of the circuit breaker sends a switch position alarm signal; or, When the normally open contact of the circuit breaker on the faulty line and the normally closed contact of the circuit breaker on the faulty line are disconnected at the same time, determining that the detection module of the circuit breaker sends a switch position alarm signal; or, When the circuit breaker on the faulty line is tripped and the current flowing through the circuit breaker on the faulty line is greater than zero, a detection module for determining the circuit breaker sends a switch position alarm signal.

4. The circuit breaker failure protection method according to claim 2, characterized in that: The step of determining whether the detection module of the circuit breaker issues a switch position alarm signal comprises: When the time from opening to closing of the normally closed contact of the circuit breaker on the faulty line or the time from closing to opening of the normally open contact of the circuit breaker on the faulty line is greater than a third set time, it is determined that the detection module of the circuit breaker sends a switch position alarm signal.

5. The circuit breaker failure protection method according to claim 4, characterized in that: The third set time is 50ms.

6. The circuit breaker failure protection method according to claim 1, characterized in that: After the control protection device corresponding to the circuit breaker on the faulty line sends action information or the line protection action device sends action information, before the step of determining whether the composite voltage of the faulty line meets the first set condition and whether the failure current of the faulty line meets the second set condition, the circuit breaker failure protection method includes: The control protection action information sent by the control protection device corresponding to the circuit breaker on the faulty line and the line protection action information sent by the line protection device corresponding to the circuit breaker on the faulty line are obtained.

7. The circuit breaker failure protection method according to claim 1, characterized in that: The control protection action includes at least overcurrent protection, differential protection and overtemperature protection.

8. The circuit breaker failure protection method according to claim 1, characterized in that: The first setting time is 5 ms, and the second setting time is 10 ms.

9. The circuit breaker failure protection method according to claim 1, characterized in that: The first set value is 2V, the second set value is 4V, and the third set value is 40V.

10. A failure protection device for a circuit breaker, characterized in that: include: at least one processor; as well as A memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the circuit breaker failure protection method according to any one of claims 1 to 9.

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