Hybrid active filter ground switch trip protection method

Abstract

The application provides a hybrid active filter grounding switch stolen trip protection method, which is used for judging two conditions of an active filter (APF) not starting and starting. In the condition of the active filter (APF) not starting, when the grounding switch is in a closed position and normally operates, the opening / closing position signal of the grounding switch and the current value flowing through the grounding switch are detected in real time, when the grounding switch is in an opening position and the current is less than a set value, it is judged that the grounding switch is stolen tripped, the grounding switch stolen trip protection sends a grounding switch closing command, and the grounding switch is closed. The application can avoid accidents such as overvoltage damage of primary equipment caused by the stolen trip of the grounding switch during the operation of the hybrid active filter, and ensures the safety of the hybrid active filter equipment.

Description

Technical Field

[0001] This invention relates to the field of high-voltage direct current transmission technology in power systems, and in particular to a method for protecting a hybrid active filter grounding switch from tripping unexpectedly. Background Technology

[0002] Hybrid active filters, which consist of passive and active filters connected in series, have excellent harmonic filtering capabilities and will have broad application prospects in the field of high-voltage direct current transmission.

[0003] A hybrid active power filter consists of a passive filter and an active filter connected in series. A bypass switch is connected in parallel with the active filter, serving as a grounding switch for the passive filter to operate alone when the active filter fails. This grounding switch provides a current path for the passive filter. When only the passive filter in the hybrid active power filter is operating through the grounding switch, if the grounding switch trips unexpectedly, the passive filter will be subjected to a large overvoltage, causing frequent operation of the surge arrester, and even damage to the passive filter, affecting the stable operation of the high-voltage direct current transmission system.

[0004] In the existing technology, most of the research focuses on the topology and control and protection technology of hybrid active filters. In addition, the high-voltage direct current transmission project using hybrid active filters is still in its infancy. Therefore, there is no protection technology related to the grounding switch tripping. Summary of the Invention

[0005] In view of the gaps and deficiencies in existing technologies, the purpose of this invention is to propose a hybrid active power filter (APF) grounding switch tripping protection method, which distinguishes between two cases: the APF is not activated and activated. When the APF is not activated, and the grounding switch is operating normally in the closed position, the open / close position signal of the grounding switch and the current flowing through the grounding switch are monitored in real time. When the grounding switch is in the open position and the current is less than a set value, it is determined that the grounding switch has tripped, and the grounding switch tripping protection issues a grounding switch closing command to close the grounding switch. After the grounding switch tripping protection issues the grounding switch closing command, if after a time delay the grounding switch is still in the open position and the current is less than the set value, it is determined that the grounding switch closing has failed, and the grounding switch tripping protection issues a hybrid active power filter stop command to disconnect the hybrid active power filter. When the active power filter (APF) is running, if the grounding switch is tripped by a command from the APF, the grounding switch trip protection will not detect it as a trip. However, if the APF does not issue a tripping command but the grounding switch trips, then if the grounding switch is in the open position and the current is less than a set value, it is determined that a trip has occurred. The grounding switch trip protection will then issue a closing command to close the grounding switch. If closing fails, the grounding switch trip protection will issue a stop command for the hybrid active power filter, disconnecting it. This invention can prevent accidents such as overvoltage damage to primary equipment caused by grounding switch tripping during the operation of the hybrid active power filter, ensuring the safety of the hybrid active power filter equipment.

[0006] The present invention specifically adopts the following technical solution:

[0007] A hybrid active filter grounding switch tripping protection method, characterized in that:

[0008] The judgment is made based on two cases: active filter not activated and activated.

[0009] When the active filter is not activated and the grounding switch is operating normally in the closed position, the open / close position signal of the grounding switch and the current value flowing through the grounding switch are monitored in real time. When the grounding switch is in the open position and the current is less than the set value, it is determined that the grounding switch has tripped. The grounding switch trip protection issues a grounding switch closing command to close the grounding switch. After the grounding switch trip protection issues the grounding switch closing command, after a time delay, if the grounding switch is still in the open position and the current is less than the set value, it is determined that the grounding switch closing has failed. The grounding switch trip protection issues a hybrid active filter stop command to disconnect the hybrid active filter.

[0010] When the active filter is activated, if the grounding switch is tripped by a command from the active filter, the grounding switch trip protection will not detect the grounding switch tripping. If the active filter does not issue a grounding switch tripping command but the grounding switch trips, then when the grounding switch is in the tripped position and the current is less than the set value, it is determined that the grounding switch has tripped. The grounding switch trip protection will issue a grounding switch closing command to close the grounding switch. If the grounding switch closing fails, the grounding switch trip protection will issue a hybrid active filter stop command to disconnect the hybrid active filter.

[0011] Furthermore, let the main switch of the hybrid active filter be Q0, the grounding switch of the passive filter be Q1, and the switch of the active filter be Q2;

[0012] Specifically, the following steps are included:

[0013] Step 1: Determine whether the hybrid active filter is in operation based on the open / closed position status of switches Q0 and Q1;

[0014] Step 2: Determine whether the active filter has been started based on whether there is a start command for the active filter;

[0015] Step 3: When the active filter has no start command, only the passive filter is running in the hybrid active filter. When the active filter is not running, determine whether the grounding switch Q1 has tripped unexpectedly based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0016] Step 4: When there is no start command for the active filter, only the passive filter is running in the hybrid active filter. When the active filter is not running, after determining that the grounding switch Q1 has tripped, a Q1 closing command is issued.

[0017] Step 5: When the active filter has no start command, the hybrid active filter only has the passive filter running, and the active filter is not running. After it is determined that the grounding switch Q1 has tripped and a Q1 closing command is issued, it is determined whether Q1 has successfully closed based on the open position of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0018] Step 6: When the active filter has no start command, only the passive filter is running in the hybrid active filter. When the active filter is not running, it is determined that the grounding switch Q1 has tripped and a Q1 closing command is issued. If Q1 closing fails, a switch Q0 trip command is issued to stop the operation of the hybrid active filter.

[0019] Step 7: When the active filter receives a start command and the active filter issues a grounding switch Q1 trip command, it is determined that the grounding switch Q1 tripping is a normal tripping, and the hybrid active filter is operating normally with the active filter.

[0020] Step 8: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, determine whether the grounding switch Q1 has tripped unexpectedly based on the trip position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0021] Step 9: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped, issue a Q1 closing command and an active filter shutdown command.

[0022] Step 10: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped and issued a Q1 closing command, determine whether Q1 has successfully closed based on the tripped position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0023] Step 11: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, determine that the grounding switch Q1 has tripped and issue a Q1 closing command. If Q1 closing fails, issue a switch Q0 trip command to stop the operation of the hybrid active filter.

[0024] Furthermore, the criterion for determining whether the hybrid active filter is in operation in step 1 is: switches Q0 and Q1 are in the closed position.

[0025] Further, in step 3, the step of determining whether the grounding switch Q1 has tripped illegally is as follows: if the grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the delay time for Q1 to trip illegally, then it is determined that the grounding switch Q1 has tripped illegally; the expression for the tripping criterion is:

[0026]

[0027] In the formula, I1set is the no-current criterion for switch Q1; T1 is the delay time for switch Q1 to trip, which mainly considers the anti-jitter time of the position signal of switch Q1.

[0028] Furthermore, in step 4, after determining that the grounding switch Q1 has tripped unexpectedly, a command to close Q1 is issued.

[0029] Further, in step 5, the step of determining whether Q1 has successfully closed is as follows: if the grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the holding time is greater than the closing delay time of Q1, then the grounding switch Q1 is determined to have failed to close. The expression for the closing failure criterion is:

[0030]

[0031] In the formula, I1set is the no-current criterion for switch Q1; T2 is the closing delay time of switch Q1.

[0032] Furthermore, if Q1 fails to close in step 6, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

[0033] Furthermore, in step 7, when the active filter receives a start command and the active filter issues a grounding switch Q1 trip command, it is determined that the grounding switch Q1 tripping is a normal tripping, and the hybrid active filter is operating normally with the active filter.

[0034] Furthermore, in step 8, when the active filter receives a start command but does not issue a tripping command for grounding switch Q1, the system determines whether grounding switch Q1 has tripped unexpectedly based on its tripping position and the magnitude of the current I1 flowing through Q1. The steps for determining whether grounding switch Q1 has tripped unexpectedly in step 8 are as follows: if grounding switch Q1 is in the tripped position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the delay time for Q1 to trip unexpectedly, then grounding switch Q1 is determined to have tripped unexpectedly. The expression for the tripping criterion is:

[0035]

[0036] In the formula, I1set is the no-current criterion for switch Q1; T3 is the delay time for switch Q1 to trip.

[0037] Furthermore, in step 9, after determining that the grounding switch Q1 has tripped unexpectedly, a Q1 closing command and an active filter shutdown command are issued;

[0038] In step 10, based on the open position of grounding switch Q1 and the magnitude of the current I1 flowing through Q1, it is determined whether Q1 has successfully closed. The steps are as follows: if grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the closing delay time of Q1, then it is determined that grounding switch Q1 has failed to close. The closing failure criterion expression is:

[0039]

[0040] In the formula, I1set is the no-current criterion for switch Q1; T4 is the closing delay time of switch Q1.

[0041] If Q1 fails to close in step 11, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

[0042] Compared with existing technologies, the present invention and its preferred solutions can avoid accidents such as overvoltage damage to primary equipment caused by the grounding switch tripping during the operation of hybrid active filters, thus ensuring the safety of hybrid active filter equipment. Attached Figure Description

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0044] Figure 1 This is a schematic diagram of a hybrid active filter system.

[0045] Figure 2 The flowchart illustrates the control process for the grounding switch tripping protection of the hybrid active filter implemented in this invention.

[0046] Figure 3 This is a schematic diagram showing the position and current of the grounding switch during normal operation of a hybrid active filter.

[0047] Figure 4 This is a schematic diagram showing the position and current of the grounding switch when a hybrid active filter trips unexpectedly. Detailed Implementation

[0048] In the following, specific embodiments of this application will be described in detail with reference to the accompanying drawings. Based on these detailed descriptions, those skilled in the art will be able to clearly understand and implement this application. Without departing from the principles of this application, features from various embodiments can be combined to obtain new implementations, or certain features from some embodiments can be substituted to obtain other preferred implementations.

[0049] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0050] To make the features and advantages of this patent more apparent and understandable, specific embodiments are provided below for detailed explanation:

[0051] The following is a specific application example to further illustrate the solution of the present invention:

[0052] In such Figure 1In the hybrid active filter system shown, the AC side voltage is 525kV, and the passive filter capacity is 140Mvar. Therefore, the rated current I1e of I1 is 154A (140*1000000 / (525*1000*1.732)). During normal operation, the position and current of the grounding switch Q1 are as follows... Figure 3 As shown. When Q1 trips unexpectedly, Q1 is in the open position, and I1 is 0, as... Figure 4 As shown, Q1 skips a jump at time t0.

[0053] To achieve the purpose of this invention, such as Figure 2 As shown, this invention provides a method for protecting a hybrid active filter grounding switch from tripping unexpectedly, which includes the following steps:

[0054] Step 1: Determine whether the hybrid active filter is in operation based on the open / closed position status of switches Q0 and Q1.

[0055] Step 2: Determine whether the Active Power Filter (APF) is started based on whether there is a start command.

[0056] Step 3: When the active power filter (APF) has no start command, the hybrid active power filter only has the passive filter running while the active power filter (APF) is not running. Based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1, determine whether the grounding switch Q1 has tripped unexpectedly.

[0057] Step 4: When the active power filter (APF) has no start command, and only the passive filter is running in the hybrid active power filter, while the active power filter (APF) is not running, after determining that the grounding switch Q1 has tripped, a Q1 closing command is issued.

[0058] Step 5: When the active power filter (APF) has no start command, the hybrid active power filter only has the passive filter running, and the active power filter (APF) is not running. After it is determined that the grounding switch Q1 has tripped and a Q1 closing command has been issued, it is determined whether Q1 has successfully closed based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0059] Step 6: When the active power filter (APF) has no start command, only the passive filter is running in the hybrid active power filter, and the active power filter (APF) is not running. After determining that the grounding switch Q1 has tripped and issuing a Q1 closing command, if Q1 closing fails, issue a switch Q0 trip command to stop the operation of the hybrid active power filter.

[0060] Step 7: When the active power filter (APF) receives a start command and issues a command to open ground switch Q1, it is determined that the opening of ground switch Q1 is a normal opening, and the hybrid active power filter with APF is operating normally.

[0061] Step 8: When the active power filter (APF) has a start command, but the active power filter (APF) does not issue a command to open the grounding switch Q1, determine whether the grounding switch Q1 has tripped unexpectedly based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0062] Step 9: When the active power filter (APF) has a start command, but the active power filter (APF) does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped, issue a Q1 closing command and an APF shutdown command.

[0063] Step 10: When the active power filter (APF) has a start command, but the active power filter (APF) does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped and issued a Q1 closing command, determine whether Q1 has successfully closed based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1.

[0064] Step 11: When the active power filter (APF) has a start command, but the active power filter (APF) does not issue a grounding switch Q1 trip command, it is determined that the grounding switch Q1 has tripped and a Q1 closing command is issued. If the Q1 closing fails, a switch Q0 trip command is issued to stop the operation of the hybrid active power filter.

[0065] Specifically, the criterion for determining whether the hybrid active filter is in operation in step 1 is: switches Q0 and Q1 are in the closed position.

[0066] The step in step 3 to determine whether the grounding switch Q1 has tripped illegally is as follows: if the grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this condition is greater than the delay time for Q1 to trip illegally, then it is determined that the grounding switch Q1 has tripped illegally. The expression for the tripping criterion is as follows.

[0067]

[0068] In the formula, I1set is the no-current criterion for switch Q1, which is generally taken as 0.5*I1e, and I1e is the rated current of I1. In this embodiment, I1e is 154 amperes (A); T1 is the delay time for switch Q1 to trip, which mainly considers the anti-jitter time of the position signal of switch Q1. It is generally taken as 1 to 2 times the power frequency period (20ms). In this embodiment, T1 is taken as 40ms.

[0069] In step 4, after determining that the grounding switch Q1 has tripped unexpectedly, a command to close Q1 is issued.

[0070] Step 5, determining whether Q1 successfully closed, involves the following steps: if grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the closing delay time of Q1, then grounding switch Q1 is determined to have failed to close. The expression for the closing failure criterion is as follows.

[0071]

[0072] In the formula, I1set is the no-current criterion for switch Q1, which is generally taken as 0.5*I1e, and I1e is the rated current of I1. In this embodiment, I1e is 154 A; T2 is the closing delay time of switch Q1, which mainly considers the anti-jitter time of the position signal of switch Q1. It is generally taken as 1 to 2 times the power frequency period (20ms). In this embodiment, it is taken as 40ms.

[0073] If Q1 fails to close in step 6, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

[0074] In step 7, when the active power filter (APF) receives a start command and the active power filter (APF) issues a command to open the grounding switch Q1, it is determined that the opening of the grounding switch Q1 is a normal opening, and the hybrid active power filter with APF is operating normally.

[0075] In step 8, when the active power filter (APF) receives a start command but does not issue a tripping command for grounding switch Q1, the system determines whether grounding switch Q1 has tripped unexpectedly based on its tripped position and the magnitude of the current I1 flowing through Q1. The steps for determining whether grounding switch Q1 has tripped unexpectedly in step 8 are as follows: if grounding switch Q1 is in the tripped position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the delay time for Q1 to trip unexpectedly, then grounding switch Q1 is determined to have tripped unexpectedly. The expression for the tripping criterion is as follows.

[0076]

[0077] In the formula, I1set is the no-current criterion for switch Q1, which is generally taken as 0.5*I1e, and I1e is the rated current of I1, which is 154 A in this embodiment; T3 is the delay time for switch Q1 to trip, which mainly considers the anti-jitter time of the position signal of switch Q1, and is generally taken as 1~2 times the power frequency period (20ms), which is taken as 40ms in this embodiment.

[0078] In step 9, after determining that the grounding switch Q1 has tripped unexpectedly, a Q1 closing command and an APF shutdown command are issued.

[0079] In step 10, based on the open position of grounding switch Q1 and the magnitude of the current I1 flowing through Q1, it is determined whether Q1 has successfully closed. The steps are as follows: if grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the closing delay time of Q1, then it is determined that grounding switch Q1 has failed to close. The expression for the closing failure criterion is as follows.

[0080]

[0081] In the formula, I1set is the no-current criterion for switch Q1, which is generally taken as 0.5*I1e, and I1e is the rated current of I1, which is 154 A in this embodiment; T4 is the closing delay time of switch Q1, which mainly considers the anti-jitter time of the position signal of switch Q1, and is generally taken as 1~2 times the power frequency period (20ms), which is taken as 40ms in this embodiment.

[0082] If Q1 fails to close in step 11, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

[0083] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

[0084] The system and method provided in this embodiment can be stored in a computer-readable storage medium in the form of code, implemented as a computer program, and the basic parameter information required for calculation can be input through computer hardware, and the calculation results can be output.

[0085] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0086] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0087] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0088] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

[0090] This patent is not limited to the above-described preferred embodiment. Anyone can derive other forms of hybrid active filter grounding switch tripping protection methods based on the guidance of this patent. All equivalent changes and modifications made within the scope of this patent application shall fall within the scope of this patent.

Claims

1. A method for preventing the grounding switch from tripping in a hybrid active filter, characterized in that: The judgment is made based on two cases: active filter not activated and activated. When the active filter is not activated and the grounding switch is in the closed position and operating normally, the open / close position signal of the grounding switch and the current value flowing through the grounding switch are detected in real time. When the grounding switch is in the open position and the current is less than the set value, it is determined that the grounding switch has tripped. The grounding switch trip protection issues a grounding switch closing command to close the grounding switch. After the grounding switch trip protection issues a grounding switch closing command, if the grounding switch is still in the open position and the current is less than the set value after a time delay, it is determined that the grounding switch closing has failed. The grounding switch trip protection then issues a hybrid active filter stop command to disconnect the hybrid active filter. When the active filter is activated, if the grounding switch is tripped by a command from the active filter, the grounding switch trip protection will not detect the grounding switch tripping. If the active filter does not issue a grounding switch tripping command but the grounding switch trips, then when the grounding switch is in the tripped position and the current is less than the set value, it is determined that the grounding switch has tripped. The grounding switch trip protection will issue a grounding switch closing command to close the grounding switch. If the grounding switch closing fails, the grounding switch trip protection will issue a hybrid active filter stop command to disconnect the hybrid active filter. Let Q0 be the main switch of the hybrid active filter, Q1 be the grounding switch of the passive filter, and Q2 be the switch of the active filter; Specifically, the following steps are included: Step 1: Determine whether the hybrid active filter is in operation based on the open / closed position status of switches Q0 and Q1; Step 2: Determine whether the active filter has been started based on whether there is a start command for the active filter; Step 3: When the active filter has no start command, only the passive filter is running in the hybrid active filter. When the active filter is not running, determine whether the grounding switch Q1 has tripped unexpectedly based on the open position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1. Step 4: When there is no start command for the active filter, only the passive filter is running in the hybrid active filter. When the active filter is not running, after determining that the grounding switch Q1 has tripped, a Q1 closing command is issued. Step 5: When the active filter has no start command, the hybrid active filter only has the passive filter running, and the active filter is not running. After it is determined that the grounding switch Q1 has tripped and a Q1 closing command is issued, it is determined whether Q1 has successfully closed based on the open position of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1. Step 6: When the active filter has no start command, only the passive filter is running in the hybrid active filter. When the active filter is not running, it is determined that the grounding switch Q1 has tripped and a Q1 closing command is issued. If Q1 closing fails, a switch Q0 trip command is issued to stop the operation of the hybrid active filter. Step 7: When the active filter receives a start command and the active filter issues a grounding switch Q1 trip command, it is determined that the grounding switch Q1 tripping is a normal tripping, and the hybrid active filter is operating normally with the active filter. Step 8: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, determine whether the grounding switch Q1 has tripped unexpectedly based on the trip position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1. Step 9: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped, issue a Q1 closing command and an active filter shutdown command. Step 10: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, after determining that the grounding switch Q1 has tripped and issued a Q1 closing command, determine whether Q1 has successfully closed based on the tripped position status of the grounding switch Q1 and the magnitude of the current I1 flowing through Q1. Step 11: When the active filter has a start command, but the active filter does not issue a grounding switch Q1 trip command, determine that the grounding switch Q1 has tripped and issue a Q1 closing command. If Q1 closing fails, issue a switch Q0 trip command to stop the operation of the hybrid active filter. The criterion for determining whether the hybrid active filter is in operation in step 1 is: the state of switches Q0 and Q1 in the closed position; Step 3, determining whether grounding switch Q1 has tripped illegally, involves the following steps: If grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this condition is greater than the delay time for Q1 to trip illegally, then grounding switch Q1 is determined to have tripped illegally. The expression for the tripping criterion is: In the formula, I1set is the no-current criterion for switch Q1; T1 is the delay time for switch Q1 to trip, which mainly considers the anti-jitter time of the position signal of switch Q1.

2. The hybrid active filter grounding switch tripping protection method according to claim 1, characterized in that: In step 4, after determining that the grounding switch Q1 has tripped unexpectedly, a command to close Q1 is issued.

3. The hybrid active filter grounding switch tripping protection method according to claim 2, characterized in that: Step 5, determining whether Q1 successfully closed, involves the following steps: if grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the closing delay time of Q1, then grounding switch Q1 is determined to have failed to close. The closing failure criterion expression is as follows: In the formula, I1set is the no-current criterion for switch Q1; T2 is the closing delay time of switch Q1.

4. The hybrid active filter grounding switch tripping protection method according to claim 3, characterized in that: If Q1 fails to close in step 6, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

5. The hybrid active filter grounding switch tripping protection method according to claim 4, characterized in that: In step 7, when the active filter receives a start command and the active filter issues a command to open grounding switch Q1, it is determined that the opening of grounding switch Q1 is a normal opening, and the hybrid active filter is operating normally with the active filter.

6. The hybrid active filter grounding switch tripping protection method according to claim 5, characterized in that: In step 8, when the active filter receives a start command but does not issue a trip command for grounding switch Q1, the system determines whether grounding switch Q1 has tripped unexpectedly based on its tripped position and the magnitude of the current I1 flowing through Q1. The steps for determining whether grounding switch Q1 has tripped unexpectedly are as follows: if grounding switch Q1 is in the tripped position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the delay time for Q1 to trip unexpectedly, then grounding switch Q1 is determined to have tripped unexpectedly. The expression for the tripping criterion is: In the formula, I1set is the no-current criterion for switch Q1; T3 is the delay time for switch Q1 to trip.

7. The hybrid active filter grounding switch tripping protection method according to claim 6, characterized in that: In step 9, after determining that the grounding switch Q1 has tripped unexpectedly, a Q1 closing command and an active filter shutdown command are issued. In step 10, based on the open position of grounding switch Q1 and the magnitude of the current I1 flowing through Q1, it is determined whether Q1 has successfully closed. The steps are as follows: if grounding switch Q1 is in the open position, the current I1 flowing through Q1 is less than the no-current criterion for switch Q1, and the duration of this criterion is greater than the closing delay time of Q1, then it is determined that grounding switch Q1 has failed to close. The closing failure criterion expression is: In the formula, I1set is the no-current criterion for switch Q1; T4 is the closing delay time of switch Q1. If Q1 fails to close in step 11, a trip command is issued to switch Q0 to stop the operation of the hybrid active filter.

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