Bypass switch monitoring and control system and method for flexible dc transmission modules

Abstract

This invention belongs to the field of DC power transmission technology and relates to a bypass switch monitoring and control system for a flexible DC power transmission module. It includes a trigger circuit, a state feedback circuit, a voltage divider circuit, an amplifier circuit, a comparator circuit, an information processing circuit, and a main control board. The trigger circuit includes an energy storage capacitor, a trigger thyristor, and a photoelectric converter. The closing coil is connected in series with the trigger thyristor and then in parallel with the energy storage capacitor. The voltage divider circuit is connected in parallel across the energy storage capacitor. The comparator circuit compares the voltage value of the energy storage capacitor with a set voltage threshold to obtain a comparison result. The state feedback circuit converts the opening and closing status of the bypass switch into a level signal. The information processing circuit summarizes the acquired comparison result and opening / closing status and transmits them to the main control board. The main control board determines the operating status of the bypass switch and executes the corresponding control logic. This invention solves the problem that existing technologies cannot achieve state monitoring and control of the bypass switch.

Description

Technical Field

[0001] This invention belongs to the field of DC power transmission technology, specifically relating to a bypass switch monitoring and control system and method for a flexible DC power transmission module. Background Technology

[0002] Against the backdrop of "dual carbon" (carbon and energy), energy and industrial structures will face low-carbon transformation, and energy technology will become the driving force for energy industry transformation and innovation-driven development. Currently, my country's installed capacity of photovoltaic, wind power, and hydropower each accounts for one-third of the global total. To achieve "dual carbon" goals, the clean and green energy industry has enormous development potential, which also presents significant opportunities and challenges for flexible DC transmission. Flexible DC transmission systems, depending on voltage level, consist of hundreds or thousands of... Figure 1 The sub-modules shown are designed to ensure the continuous and stable operation of the system. When a single sub-module fails, it needs to be disconnected from the system in a timely manner. The bypass switch is the only mechanical component in the sub-module that performs this action. Therefore, the monitoring and control of the bypass switch is particularly important for the reliability of the entire system.

[0003] Regarding the monitoring and control of bypass switches for flexible DC power transmission modules, the patent publication number CN113746311A, "A Drive System for Bypass Switch of Flexible DC Submodule," describes a drive system suitable for bypass switches of flexible DC submodules. This system has dual power supply and dual energy storage circuits, and has multiple drive circuits. However, the BOD triggering method set in this drive system can only operate when the submodule capacitor voltage is high, which poses a certain risk. At the same time, this drive system does not have the function of monitoring the status of the bypass switch.

[0004] The patent publication number CN 114094614 A, entitled "A Redundant Control Device and Method for Bypass Switch of MMC Flexible DC Transmission Converter Valve Submodule", describes a redundant control device and method for bypass switch of MMC flexible DC transmission converter valve submodule. It focuses on describing the coordination between the submodule and adjacent submodules and the upper-level valve control, but does not involve the status monitoring and control logic of the bypass switch in the submodule.

[0005] The patent publication number CN 110137902 B, entitled "A Circuit and Method for Preventing the Bypass Switch of a Flexible DC Power Module from Failing to Close," describes a circuit and method for preventing the bypass switch of a flexible DC power module from failing to close. In the event that the bypass switch of the power module fails to close, a trigger command is issued through a redundant trigger circuit, ignoring a series of bypass mode failures caused by faults in the bypass switch or bypass trigger system. Summary of the Invention

[0006] The purpose of this invention is to provide a bypass switch monitoring and control system and method for a flexible DC power transmission module, which solves the problem that the existing technology cannot realize the status monitoring and control of the bypass switch.

[0007] This invention is achieved through the following technical solution:

[0008] A bypass switch monitoring and control system for a flexible DC power transmission module includes a trigger circuit, a status feedback circuit, a voltage divider circuit, an amplifier circuit, a comparator circuit, an information processing circuit, and a main control board.

[0009] The trigger circuit includes energy storage capacitor C S Trigger thyristor T k and photoelectric converter, trigger thyristor T k The photoelectric converter connects to the main control board; the closing coil in the bypass switch K is connected to the trigger thyristor T. k After being connected in series, it is then connected to the energy storage capacitor C. S in parallel;

[0010] The voltage divider circuit is connected in parallel to the energy storage capacitor C. S Both ends;

[0011] The voltage divider circuit, amplifier circuit, and comparator circuit are connected in sequence. The amplifier circuit is used to convert the energy storage capacitor C... S The voltage value is amplified; the comparator circuit is used to amplify the voltage value of the energy storage capacitor C. S The voltage value is compared with the set voltage threshold to obtain the comparison result, and the comparison result is transmitted to the information processing circuit.

[0012] The status feedback circuit is used to convert the opening and closing status of the bypass switch into a level signal and transmit it to the information processing circuit.

[0013] The information processing circuit is used to summarize the acquired comparison results and opening / closing status and transmit them to the main control board; at the same time, it receives instructions from the main control board and executes the triggering action of the bypass switch K.

[0014] The main control board is used to determine the working status of the bypass switch and execute the corresponding control logic.

[0015] Furthermore, the trigger circuit also includes an anti-misoperation circuit. The anti-misoperation circuit is used to change the anti-misoperation detection time by adjusting the hardware parameters of the anti-misoperation circuit according to different application conditions, so as to avoid the bypass switch failing to close during the startup phase.

[0016] Furthermore, the anti-misoperation circuit and the photoelectric converter are connected to the trigger thyristor T after passing through a logic gate circuit. k connect.

[0017] Furthermore, the voltage divider circuit includes voltage divider resistors R1 and R2 connected in series, and the input port of the amplifier circuit is connected between voltage divider resistors R1 and R2.

[0018] Furthermore, the comparator circuit is configured with V... th1 and V th2 The two threshold voltages;

[0019] V th1 The minimum energy storage capacitor voltage at which the bypass switch can operate is the threshold value obtained through actual triggering tests of the bypass switch.

[0020] V th2 Energy storage capacitor C S The maximum voltage it can withstand;

[0021] The operating states of a bypass switch include sleep state, ready state, alarm state, and overload state;

[0022] When the energy storage capacitor C S The voltage value is less than V th1 At this time, the bypass switch does not have the ability to be triggered and is in a dormant state.

[0023] When the energy storage capacitor C S The voltage value is greater than V th2 At this time, the bypass switch is in an overload state.

[0024] When the energy storage capacitor C S The voltage value in V th1 When there are fluctuations in the vicinity, the bypass switch is in a warning state.

[0025] The state between the alert state and the overload state is the ready state.

[0026] Furthermore, V th1 The fluctuation range in the vicinity is ±5%.

[0027] Furthermore, the main control board executes corresponding control logic based on the operating status of the bypass switch, as follows:

[0028] (1) When in hibernation mode, the trigger command of the main control board is not executed;

[0029] (2) When in the ready state, it executes various instructions of the main control board normally;

[0030] (3) When in an overload state, the main control board will trigger the controllable switching device T1 in the flexible DC transmission module in a timely manner in combination with the T1 state of the controllable switching device.

[0031] (4) When in alert state, if the alert state is converted to ready state within a preset time, the various instructions of the main control board will be executed normally.

[0032] If the alert state transitions to the sleep state within a preset time, the main control board will trigger the appropriate action based on the state of the controllable switching device T1 within the flexible DC power transmission module.

[0033] Furthermore, the information processing circuit includes a bypass switch that allows the energy storage capacitor C to operate normally. S Rated voltage value V rate The voltage value at which the information processing circuit starts working is denoted as the startup voltage V. start This moment is denoted as t1, and the energy storage capacitor C S The voltage reaches V th1 The time is denoted as t2, and the difference between t2 and t1 is Δt;

[0034] According to the capacitor charging formula, V th1 V rate Substituting into the following formula, we obtain t3:

[0035]

[0036] Where τ is the capacitor charging time constant;

[0037] The energy storage capacitor C is obtained by comparing Δt and t3. S Given a fixed charging circuit resistance, the smaller the capacitance value Δt, the greater the capacitance decay of the energy storage capacitor.

[0038] This invention also discloses a bypass switch monitoring and control method based on the aforementioned flexible DC transmission module, comprising the following steps:

[0039] The amplifier circuit will use the energy storage capacitor C S The voltage value is processed and then transmitted to the comparison circuit;

[0040] The comparator circuit amplifies the energy storage capacitor C. S The voltage value is compared with the set voltage threshold to obtain the comparison result, which is then transmitted to the information processing circuit. At the same time, the status feedback circuit converts the opening and closing status of the bypass switch into a level signal and transmits it to the information processing circuit.

[0041] The information processing circuit summarizes the acquired comparison results and the opening and closing status, and transmits them to the main control board.

[0042] The main control board determines the operating status of the bypass switch and executes the corresponding control logic:

[0043] (1) When in hibernation mode, the trigger command of the main control board is not executed;

[0044] (2) When in the ready state, it executes various instructions of the main control board normally;

[0045] (3) When in an overload state, the main control board will trigger the controllable switching device T1 in the flexible DC transmission module in a timely manner in combination with the T1 state of the controllable switching device.

[0046] (4) When in alert state, if the alert state is converted to ready state within a preset time, the various instructions of the main control board will be executed normally.

[0047] If the alert state transitions to the sleep state within a preset time, the main control board will trigger the appropriate action based on the state of the controllable switching device T1 within the flexible DC power transmission module.

[0048] Compared with the prior art, the present invention has the following beneficial technical effects:

[0049] This invention discloses a bypass switch monitoring and control system for a flexible DC power transmission module, comprising a trigger circuit, a status feedback circuit, a voltage divider circuit, an amplifier circuit, a comparator circuit, an information processing circuit, and a main control board; the trigger circuit includes an energy storage capacitor C. S Trigger thyristor T k The photoelectric converter, the main control board sends a trigger command, the trigger command is an optical signal, which is sent to the trigger thyristor T after passing through the photoelectric converter. k The closing coil inside the bypass switch K and the trigger thyristor T k After being connected in series, it is then connected to the energy storage capacitor C. S Parallel connection; the comparator circuit connects the energy storage capacitor C. S The voltage value is compared with the set voltage threshold to obtain the comparison result, which is then transmitted to the information processing circuit. The status feedback circuit converts the open / close state of the bypass switch into a level signal and transmits it to the information processing circuit. The information processing circuit summarizes the acquired comparison result and open / close state and transmits it to the main control board. The main control board determines the operating state of the bypass switch and executes the corresponding control logic. Since the operating energy of the bypass switch of the flexible DC power transmission module comes from the energy storage capacitor C in the trigger circuit... SThe action command originates from the main control board. If only additional circuitry is added without configuring a corresponding monitoring and control system, the bypass switch may still malfunction. For example, in the event of a power failure in the energy storage circuit or the main control board, the bypass switch will fail to operate. To address these issues, this invention avoids the bypass switch lacking the energy required for operation by adding a status monitoring function to the energy storage capacitor. This invention also allows for flexible control based on different states of the energy storage capacitor, enabling bypass triggering even in the event of a main control board power failure. This system can monitor the status of the bypass switch of the flexible DC submodule in real time and execute corresponding control logic based on different states. In the event of a fault, it can promptly control the bypass switch to close, disconnecting the faulty submodule from the system and ensuring long-term stable and reliable continuous operation.

[0050] Furthermore, the bypass switch has operating states including sleep state, ready state, alarm state, and overload state, and can execute corresponding control logic according to different operating states of the bypass switch.

[0051] Furthermore, the control commands issued by the main control board are in four forms: main control board not working, bypass switch not triggered, bypass switch triggered, and bypass switch strongly triggered. These four control commands cover all operating conditions, ensuring that the bypass switch can complete its operation.

[0052] Furthermore, it can obtain the capacitance status of the energy storage capacitor, improving the operational reliability of the flexible DC transmission module. This function can obtain the health status of the energy storage capacitor in the bypass switch monitoring and control system. If there is a capacitance decay problem, it can be replaced during converter valve maintenance, ensuring that the submodule has normal bypass capability during operation. Attached Figure Description

[0053] Figure 1 This is a topology diagram of a flexible DC transmission module;

[0054] Figure 2 This is a schematic diagram showing the overall connection between the bypass switch and the bypass switch monitoring and control system.

[0055] Figure 3 This is an illustration of the different operating states of the bypass switch corresponding to different voltage values ​​of the energy storage capacitor in this invention. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the present invention clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0057] The components described and illustrated in the accompanying drawings and embodiments of this invention can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely to illustrate one selected embodiment of the invention. All other embodiments obtained by those skilled in the art based on the accompanying drawings and embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0058] It should be noted that the terms “comprising,” “including,” or any other variations are intended to cover non-exclusive inclusion, such that a process, element, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to the process, element, method, article, or apparatus.

[0059] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0060] like Figure 1 As shown, the flexible DC power transmission module includes components such as power semiconductors, DC capacitors, and bypass switches. The power semiconductor devices include controllable switching devices (IGBTs, IGCTs, or other controllable switching devices) T1 and T2, D1 and D2 are anti-parallel diodes, and the DC capacitor C... DC As the energy support component of the submodule, the bypass switch K is connected in parallel at the output terminal of the submodule.

[0061] like Figure 2 As shown, the present invention discloses a bypass switch monitoring and control system for a flexible DC power transmission module, including a trigger circuit, a status feedback circuit, a voltage divider circuit, an amplifier circuit, a comparator circuit, and an information processing circuit.

[0062] like Figure 2 As shown, the trigger circuit includes the closing coil inside the bypass switch K and the energy storage capacitor C. S Trigger thyristor T k And photoelectric converter, where the trigger signal is an optical signal from the main control board.

[0063] Even better, the trigger circuit also includes a fault-prevention circuit. This circuit can adjust the fault-prevention detection time by adjusting hardware parameters according to different application conditions. Figure 2 Chinese R f and C f The value is guaranteed to be within 5×R. f ×C f Within a certain time, the energy storage capacitor C S Having sufficient energy to trigger the bypass switch greatly avoids the situation where the bypass switch cannot be closed during the startup phase of flexible DC transmission projects.

[0064] Even better, the trigger circuit also includes a strong trigger circuit. The energy of the strong trigger circuit comes from the DC capacitor of the power module, which can still issue the trigger command of the bypass switch even when the main control board loses power.

[0065] like Figure 2 As shown, the anti-misoperation circuit and the photoelectric converter are connected to the trigger thyristor T after passing through the logic gate circuit. k connect.

[0066] The number of closing coils, energy storage capacitors, and trigger thyristors in the trigger circuit can be increased according to the degree of redundancy.

[0067] Generally, photoelectric converters are fiber optic transceivers.

[0068] like Figure 2 As shown, the status feedback circuit can convert the opening and closing status of the bypass switch into a level signal and transmit it to the information processing circuit.

[0069] like Figure 2 As shown, the voltage divider circuit includes voltage divider resistors R1 and R2, with a total resistance value in the megaohm range.

[0070] like Figure 2 As shown, the voltage divider circuit, amplifier circuit, and comparator circuit are connected in sequence. The amplifier circuit is used to convert the energy storage capacitor C... S The voltage value is amplified; the comparator circuit amplifies the energy storage capacitor C. S The voltage value is compared with the set voltage threshold to determine the working status of the bypass switch.

[0071] like Figure 2 As shown, the information processing circuit receives control commands from the main control board. These control commands have four states:

[0072] 00: The main control board is not working;

[0073] 01: Do not trigger the bypass switch;

[0074] 10: Trigger the bypass switch;

[0075] 11: Strong trigger bypass switch.

[0076] like Figure 2 As shown, the information processing circuit summarizes the acquired bypass switch status and sends it to the main control board via optical fiber.

[0077] The comparator circuit has two threshold voltages V. th1 and V th2 ,in:

[0078] V th1The minimum energy storage capacitor voltage at which the bypass switch can operate is the threshold value obtained through actual triggering tests of the bypass switch.

[0079] V th2 This is the maximum voltage that the energy storage capacitor can withstand.

[0080] like Figure 3 As shown, when the energy storage capacitor voltage is less than V th1 At this time, the bypass switch does not have the capability to be triggered. When the voltage of the energy storage capacitor is greater than V... th2 At that time, the energy storage capacitor is in an overload state.

[0081] like Figure 3 As shown, the information processing circuit has a bypass switch, and the energy storage capacitor C can operate normally. S Rated voltage value V rate V start The start-up voltage refers to the voltage value at which the information processing circuit in the bypass switch monitoring and control system begins to operate. This moment is denoted as time t1, when the energy storage capacitor voltage reaches V. th1 The time t1 is denoted as t2, and the difference between t2 and t1 is Δt. According to the capacitor charging formula, V... th1 V rate Substituting these values, we can calculate t3.

[0082]

[0083] Where τ is the capacitor charging time constant.

[0084] The capacitance value of the energy storage capacitor can be obtained by comparing Δt and t3. Given a fixed charging circuit resistance, the smaller Δt is, the greater the capacitance value decay of the energy storage capacitor.

[0085] The monitoring and control system is equipped with a CPLD chip, which is used to calculate t3 and compare Δt and t3 to obtain the capacitance value of the energy storage capacitor.

[0086] like Figure 3 As shown, the main control board can determine the operating status of the bypass switch by monitoring the voltage of the energy storage capacitor, which mainly includes sleep state, ready state, alarm state, and overload state. Figure 3 As shown, the bypass switch monitoring and control system of the flexible DC power transmission module executes corresponding control logic by determining the operating state of the bypass switch:

[0087] (1) When in sleep mode, the trigger circuit does not execute the trigger command of the main control board;

[0088] (2) When in the ready state, the trigger circuit normally executes various instructions of the main control board;

[0089] (3) When in an overload state, the triggering circuit is triggered in a timely manner by the main control board in combination with the state of the controllable switching device T1 in the flexible DC power transmission module;

[0090] (4) When in the alert state, if the alert state is converted to the ready state within a preset time, the trigger circuit will execute the various instructions of the main control board normally.

[0091] If the alert state transitions to the sleep state within a preset time, the trigger circuit will be triggered in a timely manner by the main control board in conjunction with the state of the controllable switching device T1 in the flexible DC transmission module.

[0092] In addition to the triggering function during normal operation, the main control board also has a strong triggering circuit. The triggering circuit and the information processing circuit work together to complete the triggering action of the bypass switch under extreme conditions.

[0093] Existing technical solutions improve the reliability of bypass switches in flexible DC power transmission modules by adding additional triggering circuits and power supply and energy storage circuits, but the addition of additional circuits is not conducive to the compact design of flexible DC power transmission modules.

[0094] Meanwhile, since the bypass switch of the flexible DC transmission module has the energy to operate from the energy storage capacitor in the trigger circuit and the operation command comes from the main control board, if only additional circuitry is added without configuring a corresponding monitoring and control system, the bypass switch may still fail to work properly. For example, if the energy storage circuit or the main control board loses power, the bypass switch will not be able to operate.

[0095] To address the above issues, this invention avoids the bypass switch lacking the energy required for operation by adding a state monitoring function to the energy storage capacitor. This invention can also flexibly control the bypass based on different states of the energy storage capacitor, and can automatically trigger the bypass even when the main control board loses power.

[0096] 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.

Claims

1. A bypass switch monitoring and control system for a flexible DC power transmission sub-module, characterized in that, It includes trigger circuits, status feedback circuits, voltage divider circuits, amplifier circuits, comparator circuits, information processing circuits, and main control board; The trigger circuit includes energy storage capacitor C S Trigger thyristor T k and photoelectric converter, trigger thyristor T k The photoelectric converter connects to the main control board; the closing coil in the bypass switch K is connected to the trigger thyristor T. k After being connected in series, it is then connected to the energy storage capacitor C. S in parallel; The voltage dividing circuit is connected in parallel to the energy storage capacitor C S Both ends; The voltage value of the energy storage capacitor C S is amplified by the amplification circuit. The comparison circuit is configured to compare the voltage value of the energy storage capacitor C S with a set voltage threshold to obtain a comparison result, and transmit the comparison result to the information processing circuit. The status feedback circuit is used to convert the opening and closing status of the bypass switch into a level signal and transmit it to the information processing circuit. The information processing circuit is used to summarize the acquired comparison results and opening / closing status and transmit them to the main control board; at the same time, it receives instructions from the main control board and executes the triggering action of the bypass switch K. The main control board is used to determine the working status of the bypass switch and execute the corresponding control logic; The comparison circuit is provided with two threshold voltages of V th1 and V th2 respectively. V th1 the minimum energy storage capacitor voltage at which the bypass switch is able to act, which threshold is obtained by actual trigger testing of the bypass switch; V th2 for the energy storage capacitor C S the maximum voltage that can be withstood; The operating states of a bypass switch include sleep state, ready state, alarm state, and overload state; When the energy storage capacitor C S The voltage value is less than V th1 At this time, the bypass switch does not have the ability to be triggered and is in a dormant state. When the voltage value of the energy storage capacitor C S is greater than V th2 , the working state of the bypass switch is in an overload state. When the voltage value of the energy storage capacitor C S fluctuates around V th1 the bypass switch is in an alert state of operation. The state between the alert state and the overload state is the ready state.

2. The monitoring and control system of a bypass switch of a flexible DC power transmission sub-module according to claim 1, characterized in that, The trigger circuit also includes an anti-misoperation circuit, which is used to change the anti-misoperation detection time by adjusting the hardware parameters of the anti-misoperation circuit according to different application conditions, so as to avoid the bypass switch failing to close during the startup phase.

3. The monitoring and control system of a bypass switch of a flexible DC power transmission sub-module according to claim 2, characterized in that, The anti-misoperation circuit and the photoelectric converter are connected with the logic gate circuit and the trigger thyristor T k connection.

4. The monitoring and control system for a bypass switch of a flexible DC power transmission sub-module according to claim 1, wherein, The voltage divider circuit includes voltage divider resistors R1 and R2 connected in series, and the input port of the amplifier circuit is connected between voltage divider resistors R1 and R2.

5. The monitoring and control system for a bypass switch of a flexible DC power transmission sub-module according to claim 1, wherein, V th1 The fluctuation range in the vicinity is ±5%.

6. The monitoring and control system for a bypass switch of a flexible DC power transmission sub-module according to claim 1, wherein, The main control board executes corresponding control logic based on the operating status of the bypass switch, as follows: (1) When in sleep mode, the trigger circuit does not execute the trigger command of the main control board; (2) When in the ready state, the trigger circuit normally executes various instructions of the main control board; (3) When in an overload state, the triggering circuit is triggered in a timely manner by the main control board in combination with the state of the controllable switching device T1 in the flexible DC transmission module; (4) When in the alert state, if the alert state is converted to the ready state within a preset time, the trigger circuit will execute the various instructions of the main control board normally. If the alert state transitions to the sleep state within a preset time, the trigger circuit will be triggered in a timely manner by the main control board in conjunction with the state of the controllable switching device T1 in the flexible DC transmission module.

7. The monitoring and control system for a bypass switch of a flexible DC power transmission sub-module according to claim 1, wherein, The information processing circuit is equipped with a bypass switch, and the energy storage capacitor C can operate normally. S Rated voltage value V rate The voltage value at which the information processing circuit starts working is recorded as the startup voltage. V start This moment is recorded as t At time 1, the energy storage capacitor C S The voltage reached V th1 The time is recorded as t At time 2, t 2 and t The difference of 1 is Δ t ; According to the formula for capacitive charging, we have V th1 , V rate Substituting into the following equation gives t 3: ； Where τ is the capacitor charging time constant; By comparing Δ t and t 3. Obtain the energy storage capacitor C S Given a fixed resistance in the charging circuit, the capacitance value Δ t The smaller the value, the greater the capacitance decay of the energy storage capacitor.

8. The bypass switch monitoring and control method of the bypass switch monitoring and control system of the flexible DC power transmission sub-module according to any one of claims 1-7, characterized in that, Includes the following steps: The amplification circuit processes the voltage value of the energy storage capacitor C S and transmits it to the comparison circuit. The comparator circuit amplifies the energy storage capacitor C. S The voltage value is compared with the set voltage threshold to obtain the comparison result, and the comparison result is transmitted to the information processing circuit. At the same time, the status feedback circuit converts the opening and closing status of the bypass switch into a level signal and transmits it to the information processing circuit. The information processing circuit summarizes the acquired comparison results and the opening and closing status, and transmits them to the main control board. The main control board determines the operating status of the bypass switch and executes the corresponding control logic: (1) When in sleep mode, the trigger circuit does not execute the trigger command of the main control board; (2) When in the ready state, the trigger circuit normally executes various instructions of the main control board; (3) When in an overload state, the triggering circuit is triggered in a timely manner by the main control board in combination with the state of the controllable switching device T1 in the flexible DC transmission module; (4) When in the alert state, if the alert state is converted to the ready state within a preset time, the trigger circuit will execute the various instructions of the main control board normally. If the alert state transitions to the sleep state within a preset time, the trigger circuit will be triggered in a timely manner by the main control board in conjunction with the state of the controllable switching device T1 in the flexible DC transmission module.

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