Hybrid valve multiplexing storage and regeneration conversion control method and system

Abstract

This invention relates to the field of high-voltage direct current (HVDC) transmission technology, and particularly to a hybrid valve multiplexing energy storage and dissipation converter control method and system. The method includes: constructing a bridge converter structure, comprising a converter branch and an auxiliary branch, and an energy storage and dissipation module, all housed within a hybrid valve module; during normal system operation, controlling the converter branch to conduct, and controlling the auxiliary branch and energy storage and dissipation module to shut down or bypass; upon detecting an AC-side fault, controlling the bridge arm current to transfer from the converter branch to the auxiliary branch, and controlling the energy storage and dissipation module to establish an auxiliary commutation voltage; during branch transfer, controlling the energy storage and dissipation module to operate in different modes based on the relationship between the system's surplus power and a specified limit; upon detecting a DC-side fault, controlling the bridge arm current to transfer from the converter branch to the auxiliary branch, and controlling the energy storage and dissipation module to operate in discharge mode. This invention effectively solves the problems of traditional LCC-HVDC systems being unable to withstand commutation failure and power suppression.

Description

Technical Field

[0001] This invention relates to the field of high voltage direct current transmission technology, and in particular to a hybrid valve multiplexing storage and converter control method and system. Background Technology

[0002] With the rapid development of large-capacity, long-distance inter-regional power transmission projects, the power grid is exhibiting complex characteristics of large-scale AC / DC hybrid interconnection. Traditional line-commutated converters dominate the field of high-voltage direct current transmission due to their advantages such as large capacity and low cost.

[0003] However, due to its commutation mechanism's inherent reliance on the receiving-end AC grid voltage, the system's operational resilience is limited, facing the following main challenges: First, commutation failure is the most frequent and damaging fault in LCC-HVDC system operation. The essence of commutation failure lies in the thyristor valve group failing to obtain a sufficient turn-off angle to complete carrier recombination after commutation. If disturbances occur in the receiving-end grid causing AC voltage drops or distortion, the commutation margin will be significantly reduced, causing the thyristors to prematurely bear forward bias before restoring blocking, thus re-conducting. Second, large-scale renewable energy integration places higher demands on the system's power balance. In cases where renewable energy is transmitted via DC, receiving-end AC faults often lead to a reduction in the converter station's active power absorption capacity. Due to the fluctuating and lag-responding output of renewable energy at the sending end, energy surplus is easily generated on the DC link, triggering DC bus overvoltage. Current improvement measures mainly focus on optimizing control strategies, such as predictive turn-off angle control and adaptive current deviation control, or increasing the commutation area by enhancing AC-side strength. While these methods reduce the probability of commutation failure to some extent, they still fall under the category of passive defense and cannot eliminate faults under extremely harsh operating conditions. In summary, existing technologies struggle to simultaneously resist commutation failure and address power fluctuations in both directions.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a method and system for controlling the reuse of hybrid valves for energy storage and commutation, which can effectively solve the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling the multiplexing of storage and loss switching in a hybrid valve, the method comprising: Construct a bridge converter structure, and set up a converter branch and an auxiliary branch in the hybrid valve module of the bridge converter structure, and set up a switchable energy storage and consumption module between the bridge arms; During normal system operation, the converter branch is turned on, and the auxiliary branch and the energy storage and energy consumption module are turned off or bypassed to complete steady-state converter operation. When an AC-side fault is detected that restricts commutation in the converter branch, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to establish an auxiliary commutation voltage. During branch transfer, the energy storage and energy consumption module is controlled to operate in energy storage mode or energy storage and energy consumption coordination mode based on the relationship between the system surplus power and the limit value Pmax. When a DC-side fault is detected that causes insufficient power in the DC system, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to operate in discharge mode to release the stored energy to the DC system. After the fault is cleared, the energy storage and energy consumption module is controlled to exit the fault support state and the converter branch is restored to conduction, so that the system returns to normal operation.

[0007] Furthermore, a bridge converter structure is constructed, including: A three-phase bridge inverter structure is constructed, consisting of multiple identical hybrid valve modules. The commutation branch and the auxiliary branch are connected in parallel in each of the mixing valve modules; The energy storage and energy consumption module is connected between the upper and lower bridge arms of the three-phase bridge inverter structure.

[0008] Furthermore, the commutation branch and the auxiliary branch are connected in parallel in each of the mixing valve modules, including: thyristor and The auxiliary branch is formed by reverse series connection; thyristor and controlled switching transistor The converter branch is formed by connecting them in series; The values ​​i = 1, 2, 3 and j = 1, 2, 3, 4, 5, 6 are set to characterize the device positions of each phase arm in the three-phase bridge inverter structure.

[0009] Furthermore, the energy storage and energy consumption module is configured as follows: The energy storage and energy consumption module includes an energy storage branch, an energy consumption branch, and a switching switch. The switching switch is connected in parallel at the output end of the energy storage branch to control the access state or bypass state of the energy storage consumption module. The energy storage branch is connected to the energy consumption branch to form a functional unit for energy storage, discharge and energy consumption regulation.

[0010] Furthermore, the energy storage branch is configured as follows: Energy storage battery Filter inductor First controlled switch transistor Second controlled switch transistor and DC capacitor ; The first controlled switch transistor With the second controlled switch After being connected in series, it is then connected in parallel to the DC capacitor. Both ends; The energy storage battery via the filter inductor Connect to the first controlled switch transistor With the second controlled switch The midpoint.

[0011] Furthermore, the energy-consuming branch is configured as follows: Energy-consuming resistor Third controlled switch tube and the fourth controlled switch ; The energy-consuming resistor One end is connected to the third controlled switch transistor The other end is connected to the DC side negative busbar; The third controlled switch transistor With the fourth controlled switch tube The midpoint of the bridge arm is connected to the energy storage and energy consumption module.

[0012] Furthermore, the actions to complete steady-state commutation include: During normal system operation, the thyristors and controlled switches in the converter branch are synchronously triggered to conduct. When the thyristor and the controlled switch are turned on, the auxiliary branch and the remaining power devices in the energy storage and energy consumption module are kept off or bypassed. The current is controlled in turn by controlling each arm of the bridge converter structure in turn according to the conduction sequence of 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

[0013] Furthermore, the actions taken upon detecting an AC-side or DC-side fault include: When an AC side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristor in the auxiliary branch and the energy storage and dissipation module are triggered to establish the auxiliary commutation voltage. When the branch is transferred and the system surplus power is less than the limit value Pmax, the control switch is turned off and the first controlled switch tube and the second controlled switch tube are turned on, so that the energy storage and energy consumption module works in the energy storage mode. When the branch is transferred and the system surplus power is greater than the limit value Pmax, the fourth controlled switch and the switching switch are turned off, and the third controlled switch, the first controlled switch and the second controlled switch are turned on, so that the energy storage and energy consumption module works in the energy storage and energy consumption cooperative mode. When a DC-side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristor and the fourth controlled switch in the auxiliary branch are triggered, the switching switch is turned off, and the first and second controlled switches are turned on, so that the energy storage and energy consumption module operates in the discharge mode.

[0014] A hybrid valve multiplexing storage and switching control system, the system comprising: The bridge converter module constructs a bridge converter structure, and sets up converter branches and auxiliary branches in the mixing valve module of the bridge converter structure, and sets up switchable energy storage and consumption modules between the bridge arms. The operation control module controls the conduction of the converter branch and controls the shutdown or bypass of the auxiliary branch and energy storage module during normal system operation to complete steady-state conversion. When the AC detection module detects an AC-side fault that restricts commutation in the converter branch, it controls the arm current to be transferred from the converter branch to the auxiliary branch and controls the energy storage module to establish the auxiliary commutation voltage. The mode switching module controls the energy storage and energy consumption module to work in energy storage mode or energy storage and energy consumption co-operation mode based on the relationship between the system surplus power and the limit value Pmax when the branch is transferred. When the DC detection module detects a DC-side fault that causes insufficient power in the DC system, it controls the bridge arm current to be transferred from the converter branch to the auxiliary branch, and controls the energy storage and consumption module to operate in discharge mode to release the stored energy to the DC system. The fault exit module controls the energy storage and energy consumption module to exit the fault support state and restore the converter branch conduction after the fault is cleared, so that the system returns to normal operation.

[0015] Furthermore, the operation control module includes: The commutation triggering unit synchronously triggers the thyristors and controlled switches in the commutation branch to conduct during normal system operation. The shutdown control unit controls the auxiliary branch and the remaining power devices in the energy storage and energy consumption module to remain off or bypassed when the thyristor and the controlled switch are turned on. The sequential conduction unit controls the current flow of each bridge arm of the bridge converter structure in turn according to the conduction sequence of 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

[0016] The technical solution of this invention can achieve the following technical effects: By setting up the converter branch and auxiliary branch in parallel in the hybrid valve module of the bridge converter structure and integrating switchable energy storage and energy dissipation modules between the bridge arms, the system can complete steady-state commutation by the converter branch under normal operating conditions. In the event of an AC side fault, the current is transferred to the auxiliary branch and an auxiliary commutation voltage is established by energy storage or energy storage and energy dissipation in a coordinated manner to suppress commutation failure. In the event of a DC side fault, the bus voltage is supported by the discharge of the energy storage module. This effectively solves the problem that traditional LCC-HVDC DC systems cannot resist commutation failure and power suppression.

[0017] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a hybrid valve reuse storage and commutation control method. Figure 2 This is a schematic diagram of the topology of a bridge converter structure. Figure 3 This is a schematic diagram of the topology of a mixing valve; Figure 4 This is a schematic diagram of the topology of the energy storage and energy consumption module; Figure 5 The DC voltage waveform when the system power is insufficient; Figure 6 This is the DC voltage waveform when the system has excess power. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0022] Example 1; like Figure 1 As shown, this application provides a hybrid valve multiplexing storage and loss commutation control method, the method comprising: S10: Construct a bridge converter structure, and set up converter branches and auxiliary branches in the hybrid valve module of the bridge converter structure, and set up switchable energy storage and energy consumption modules between the bridge arms; S20: During normal system operation, control the conduction of the converter branch and control the shutdown or bypass of the auxiliary branch and energy storage module to complete steady-state converter. S30: When an AC side fault is detected that causes limited commutation in the converter branch, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to establish the auxiliary commutation voltage. S40: When the branch is transferred, the energy storage and energy consumption module is controlled to work in energy storage mode or energy storage and energy consumption co-operation mode according to the relationship between the system surplus power and the limit value Pmax. S50: When a DC-side fault is detected that causes insufficient power in the DC system, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to operate in discharge mode to release the stored energy to the DC system. S60: After the fault is cleared, control the energy storage and energy consumption module to exit the fault support state and restore the converter branch to conduction, so that the system returns to normal operation.

[0023] Specifically, a three-phase bridge inverter structure consisting of six identical hybrid valve modules is first constructed. Each hybrid valve module contains a converter branch and an auxiliary branch connected in parallel, and a switchable energy storage and dissipation device is connected between the upper and lower bridge arms. The converter branch preferably uses thyristors connected in series with controlled switching devices to form the main current path, ensuring that the system maintains an operating mode similar to that of a conventional line-commutated converter under normal operating conditions. The auxiliary branch preferably uses thyristors connected in reverse series to handle the bridge arm current transferred from the converter branch during faults. The energy storage and dissipation device preferably includes an energy storage branch, a dissipation branch, and a switching switch for switching between connected and bypass states. The energy storage branch can use a battery or filter. The system consists of an inductor, a bidirectional controlled switch, and a DC-side capacitor. The energy-consuming branch can be constructed using an energy-consuming resistor and a controlled switch, enabling the energy storage and energy-consuming device to simultaneously absorb surplus power, release stored power, and rapidly dissipate excess energy. During normal system operation, the preferred control strategy is to trigger only the commutator branch to conduct, allowing the bridge arm current to flow along the commutator branch. The auxiliary branches and the energy storage and energy-consuming device remain off or bypassed. Each bridge arm takes turns flowing current according to a preset commutation sequence, thus completing steady-state power conversion. At this time, the energy storage and energy-consuming device does not participate in main power transmission, balancing operational economy and structural reusability. When a voltage drop, distortion, or other disturbance occurs on the AC side of the receiving end, causing commutation limitation, it is preferable to first activate the controlled switch in the commutator branch. The switching device implements turn-off control, diverting the bridge arm current originally flowing through the commutator branch to the auxiliary branch. Simultaneously, the energy storage device is activated, creating a reverse support voltage on the valve side. This reverse support voltage directly acts on the thyristors involved in commutation, compensating for the reduction in commutation area caused by AC side faults. This ensures the thyristors maintain reliable reverse blocking conditions even with a short turn-off margin, thereby reducing or even preventing commutation failures. Furthermore, after the bridge arm current has been diverted, it is preferable to monitor the system's surplus power in real time and compare it with a pre-set limit value Pmax. When the surplus power is less than Pmax, it is preferable to control the energy storage branch to enter energy storage mode, preventing power loss during faults. Excess energy sent to the AC side is preferentially stored in energy storage elements. This method is suitable for short-term or moderate power surplus scenarios and can improve energy utilization while suppressing DC bus voltage rise. When the surplus power is greater than the limit value Pmax, it is preferable to connect the energy dissipation path while maintaining the energy absorption of the energy storage branch, so that some of the excess energy is quickly consumed by the energy dissipation resistor, so as to avoid the DC side overvoltage from further expanding due to the rapid accumulation of energy during the fault. For example, when the AC fault at the receiving end is more serious and the sending end still maintains a high power transmission capacity, the surplus power can be layered and absorbed by energy storage and energy dissipation in parallel, which can reduce the capacity pressure brought by simple energy storage and improve the stability of DC voltage during the fault.When a fault occurs on the DC side, causing insufficient power supply from the DC system to the AC side, it is preferable to transfer the control arm current from the converter branch to the auxiliary branch, and switch the energy storage branch from standby to discharge mode. The energy storage elements release pre-stored energy to the DC system to dynamically support the DC bus voltage and quickly compensate for active power deficits. Under this condition, the energy storage branch's focus shifts from energy absorption to energy supply, thereby suppressing bus voltage drops and oscillations caused by power imbalances. For example, when a sudden increase in load at the receiving end or a transient disturbance on the DC side causes a significant drop in bus voltage, the energy storage branch can output power in a short time, gradually restoring the bus voltage to its nominal range. Nearby, the system's fault ride-through capability is improved; after the AC-side or DC-side fault is cleared, the system preferentially exits the fault support state of the energy storage and energy consumption device gradually according to the predetermined recovery logic, so that the auxiliary branch stops carrying the fault transfer current, the converter branch resumes to bear the main current path, and the entire bridge converter structure returns to the normal steady-state converter state. This achieves reuse of the same device under three operating conditions: normal operation, AC fault defense, and DC fault support. It solves the problem of commutation failure that easily occurs in traditional line-commutated converters under AC faults, and also takes into account the bidirectional adjustment needs of surplus power absorption, excess energy dissipation, and power deficit compensation during fault periods.

[0024] The technical solution of this invention sets up a converter branch and an auxiliary branch in parallel in the hybrid valve module of the bridge converter structure, and integrates a switchable energy storage and energy consumption module between the bridge arms. Under normal operating conditions, the system completes steady-state commutation by the converter branch. In the event of an AC side fault, the current is transferred to the auxiliary branch and an auxiliary commutation voltage is established by energy storage or energy storage and energy consumption in a coordinated manner to suppress commutation failure. In the event of a DC side fault, the bus voltage is supported by the discharge of the energy storage module. This effectively solves the problem that traditional LCC-HVDC DC systems cannot resist commutation failure and power suppression.

[0025] Furthermore, such as Figure 2 As shown, the bridge converter structure is constructed, including: Construct a three-phase bridge inverter structure consisting of multiple hybrid valve modules with the same structure; In each mixing valve module, a commutation branch and an auxiliary branch are connected in parallel. An energy storage and energy consumption module is connected between the upper and lower arms of a three-phase bridge inverter structure.

[0026] As a preferred embodiment of the above, the bridge converter structure adopts a three-phase bridge inverter topology. Specifically, multiple identical hybrid valve units are respectively arranged on the upper and lower arms of the three-phase bridge to form a valve-side main circuit that meets the requirements of line-commutated inverter operation. Preferably, each hybrid valve unit adopts the same circuit configuration and connection form to facilitate device selection, control coordination, and engineering layout, and to ensure consistent electrical behavior of each phase arm during normal and fault operation. Furthermore, within each hybrid valve unit, the converter branch and auxiliary branch are preferably connected in parallel, with both branches connected to the two ends of the same arm current channel. The converter branch is used to handle the current under normal operating conditions. The main current-carrying branch is used to take over the bridge arm current transferred from the converter branch when the original converter conditions deteriorate due to AC or DC side anomalies. Since the converter branch and the auxiliary branch are connected in parallel, a smooth transition between the normal converter path and the fault support path can be achieved by controlling the branch switching without changing the basic topology of the original bridge converter main circuit. At the same time, an energy storage and energy dissipation device is preferably connected between the upper and lower bridge arms of the three-phase bridge inverter structure. This device does not directly carry the steady-state main power transmission for a long time, but is selectively activated according to control commands under fault conditions, so as to provide additional voltage support and surplus energy to the valve side when the bridge arm commutation is restricted or the DC bus power is unbalanced. The absorption and compensation of energy deficit are preferably achieved by distributing energy storage devices between each phase bridge arm, so that each bridge arm of the three-phase bridge has independent and coordinated support conditions when local or overall disturbances occur. For example, when the AC system at the receiving end experiences a voltage drop, the main current path in the bridge arm no longer has sufficient natural commutation conditions. At this time, since the auxiliary branch and the energy storage device are pre-integrated into the bridge converter structure, the bridge arm current can be transferred within the original topology, and the energy storage device forms additional support between the bridge arms, thereby avoiding the response lag and structural dispersion problems caused by the need to add independent energy dissipation equipment or external support devices in traditional solutions. For another example, when the DC... When a power deficit occurs on the DC side, the energy storage and energy dissipation device is located between the upper and lower arms of the three-phase bridge inverter structure. The stored energy it releases can directly act on the power transmission path corresponding to the bridge converter structure, which is more conducive to maintaining the stability of the DC side voltage. Therefore, by constructing a three-phase bridge inverter structure composed of multiple hybrid valve units with the same structure, setting up a converter branch and an auxiliary branch in parallel in each hybrid valve unit, and connecting the energy storage and energy dissipation device between the upper and lower arms, it is possible to achieve the integration of normal converter function and fault support function while maintaining the basic function of bridge converter. This provides a unified hardware foundation for auxiliary commutation under AC side faults and energy storage discharge support under DC side faults.

[0027] Furthermore, such as Figure 3As shown, each mixing valve module is equipped with a commutation branch and an auxiliary branch connected in parallel, including: thyristor and Reverse series connection forms an auxiliary branch; thyristor and controlled switching transistor The series connection forms the converter branch; The values ​​i = 1, 2, 3 and j = 1, 2, 3, 4, 5, 6 are set to characterize the device positions of each phase arm in the three-phase bridge inverter structure.

[0028] As a preferred embodiment, each mixing valve unit adopts a branch configuration of parallel connection of commutation branch and auxiliary branch, so as to achieve the integrated configuration of normal commutation channel and fault transfer channel without changing the basic flow port of the bridge arm. The auxiliary branch is preferably composed of thyristors. and The configuration is a reverse series connection, where two thyristors are connected end-to-end with opposite conduction directions. This ensures that the branch provides a corresponding conduction path for current transfer when the direction of the bridge arm current changes or the commutation conditions change. The advantage of this structure is that it retains the high voltage withstand capability and suitability for high-voltage scenarios of thyristors, while also allowing the auxiliary branch to adapt to bidirectional voltage constraints and fault transients that may occur in the bridge arm. This ensures that when the original commutation path is limited due to AC or DC side faults, the bridge arm current can be smoothly transferred to the auxiliary branch. Accordingly, the commutation branch is preferably composed of thyristors. and controlled switching transistor It is connected in series, in which the thyristor Controlled switching transistors used to handle the main current flow and commutation process under normal operating conditions. This is used to perform rapid shutdown control in the event of a fault, actively cutting off the continuous current flow conditions of the commutator branch and causing the bridge arm current to transfer to the auxiliary branch. Because the thyristors and controlled switching devices are connected in series in the same branch, it maintains conductivity characteristics close to those of a traditional line-commutated converter during normal operation, while also providing the active shutdown capability that a traditional pure thyristor branch lacks during a fault. This combination is the foundation for achieving active current transfer and establishing auxiliary commutation conditions. Furthermore, to clarify the arrangement of each branch device in the three-phase bridge inverter structure, it is preferable to use subscript parameters i and j to represent each device. The components are identified, where i takes the values ​​1, 2, and 3, preferably corresponding to the three phases in a three-phase bridge inverter structure, and j takes the values ​​1, 2, 3, 4, 5, and 6, preferably corresponding to the six arms or six mixing valve positions in the three-phase bridge. This identification method clearly expresses the distribution relationship of the same structural unit in the three-phase bridge, facilitating the explanation of the installation and control correspondence of each device in different phases and arms. For example, when i is 1, it can represent the set of devices in the corresponding arm of the first phase; when j is 1 to 6, it can further distinguish the specific mixing valve unit at the corresponding position in the upper or lower arm of that phase, thereby... , , and To ensure a one-to-one correspondence between each bridge arm and its corresponding arm, in engineering implementation, it is preferable to use the same branch topology and device connection sequence for all hybrid valve units to reduce design complexity and improve the symmetry of three-phase operation. For example, under normal operating conditions, the bridge arm current mainly flows through the thyristors. and controlled switching transistor The commutator branch formed by series connection flows through the thyristors. and The auxiliary branch formed by the reverse series connection remains in standby mode. When the AC voltage at the receiving end drops, causing a reduction in the commutation margin, the controlled switch is turned off. This allows the current that originally flowed through the converter branch to exit the main branch and enter the auxiliary branch, creating conditions for establishing additional reverse voltage and completing fault support.

[0029] Furthermore, such as Figure 4 As shown, an energy storage and energy consumption module is set up, including: The energy storage and energy consumption module includes energy storage branches, energy consumption branches, and switching switches; The switching switch is connected in parallel at the output end of the energy storage branch to control the access or bypass status of the energy storage consumption module. The energy storage branch is connected to the energy consumption branch to form a functional unit for energy storage, discharge and energy consumption regulation.

[0030] In a preferred embodiment, the energy storage and energy dissipation device is disposed between the bridge arms of the bridge converter structure and configured as a multiplexing unit participating in energy regulation and voltage support under fault conditions. Specifically, the energy storage and energy dissipation device preferably includes an energy storage branch, an energy dissipation branch, and a switching switch. The energy storage branch is used to absorb excess energy when a power surplus is caused by an AC-side fault and to release pre-stored energy when a power deficiency is caused by a DC-side fault. The energy dissipation branch is used to rapidly consume the remaining energy when the surplus power exceeds the preferred absorption capacity of the energy storage branch. The switching switch is used to control the access state or bypass state of the energy storage and energy dissipation device in the bridge converter structure, thereby enabling the same device to operate under different conditions. Under normal operating conditions, the system can perform energy storage, discharge, and energy consumption regulation functions respectively. Furthermore, the switching switch is preferably connected in parallel at the output end of the energy storage branch. Its function is to form a bypass channel through the switching switch when the system is in normal steady-state converter operation, allowing the energy storage branch to exit the main circuit's operating range, thereby avoiding the energy storage branch's long-term participation in steady-state main power transmission and reducing additional losses. When an AC-side fault or DC-side fault is detected, the connection state of the energy storage branch can be changed by controlling the switching switch, allowing the energy storage branch to quickly engage in the bridge arm energy regulation process. Since the switching switch is located at the output end of the energy storage branch, it can directly determine the connection between the energy storage branch and the bridge converter. The energy exchange relationship between the structures is improved, thereby enhancing the response speed and control flexibility of the fault switching process. Simultaneously, the energy storage branch and the energy consumption branch are preferably connected as an integrated energy storage, discharge, and energy consumption regulation unit. This allows for both independent and coordinated operation in control. Specifically, when the power surplus is small, the energy storage branch preferentially absorbs energy; when the power surplus is large and exceeds the preferred energy storage range, the energy storage branch and the energy consumption branch work together, with some energy temporarily stored and others consumed. When the DC power is insufficient, the energy storage branch releases electrical energy while the energy consumption branch does not participate in the energy consumption process. This achieves bidirectional power fluctuations under different fault conditions using the same circuit structure. For example, when a short-term fault occurs in the AC system at the receiving end and there is an energy surplus on the DC side, the switching switch switches from the bypass state to the access control state, and the energy storage branch is put into the energy absorption process first to slow down the rise of the DC bus voltage. When the fault duration is prolonged or the surplus power further increases, the energy consumption branch can be put into operation simultaneously to quickly dissipate the energy exceeding the preferred energy storage capacity to prevent the DC side overvoltage from expanding. As another example, when a transient power deficit occurs on the DC side, the switching switch cuts off the bypass and connects the energy storage branch to the energy support circuit between the bridge arms, and the energy storage branch releases the stored electrical energy to the DC system to support the recovery of the bus voltage.

[0031] Furthermore, such as Figure 4 As shown, an energy storage branch is set up, including: Energy storage battery Filter inductor First controlled switch transistor Second controlled switch transistor and DC capacitor ; The first controlled switch transistor With the second controlled switch After being connected in series, it is then connected in parallel to the DC capacitor. Both ends; Energy storage battery via filter inductor Connect the first controlled switch transistor With the second controlled switch The midpoint.

[0032] As a preferred embodiment of the above, the energy storage branch uses an energy storage battery. Filter inductor First controlled switch transistor Second controlled switch transistor and DC capacitor Composition, including energy storage batteries As an energy storage element, it is used to absorb electrical energy when the system has a power surplus due to an AC side fault and to release electrical energy when the system has a power deficiency due to a DC side fault; the filter inductor Connected in series with energy storage battery With the first controlled switch Second controlled switch transistor Between the midpoints, its preferred function is to limit the rate of current change during the charging and discharging process of the energy storage battery, reduce the current surge caused by switching action, and improve the energy exchange stability between the energy storage branch and the bridge converter structure. The first controlled switch tube With the second controlled switch Preferably, it is connected in series and then in parallel to a DC capacitor. At both ends, a switching path capable of bidirectional energy regulation is formed, and the DC capacitor... On the one hand, it is used to maintain the stability of the voltage at the connection point of the energy storage branch; on the other hand, it is used to absorb transient fluctuations during fault switching and energy exchange, so as to improve the continuity and response speed of the energy storage branch. Furthermore, it integrates energy storage batteries... via filter inductor Connect the first controlled switch transistor With the second controlled switch The midpoint makes the energy storage battery Able to pass through the first controlled switch transistor Second controlled switch Controlled charging and controlled discharging are achieved through different conduction states. The advantage of this midpoint connection method is that it allows for a bidirectional energy exchange channel between the energy storage battery and the DC side without altering the basic connection relationship of the main circuit of the bridge arm. It also facilitates the switching of the energy storage branch under different fault conditions in conjunction with upper-level control strategies. Preferably, when an AC side fault leads to commutation limitation and the system has surplus power, the first controlled switch can be controlled. Second controlled switch Entering the corresponding conduction state allows energy to flow through the DC capacitor. Side-mounted energy storage battery Transfer, filter inductor During this process, the charging current is smoothed to reduce the impact on the energy storage battery and improve the stability of the energy absorption process; when a DC-side fault leads to insufficient DC system power, the first controlled switch can be controlled. Second controlled switch Switch to the corresponding discharge state to enable the energy storage battery The pre-stored electrical energy passes through the filter inductor The controlled switch path is released to the support circuit to improve the DC bus voltage recovery capability; for example, when a disturbance occurs in the receiving-end AC system and the DC side voltage shows an upward trend, the energy storage branch preferably first enters the energy absorption state, and the energy storage battery By using filter inductors DC capacitor absorbs excess electrical energy Used to suppress voltage fluctuations during charging, thereby improving the controllability of the energy storage process; for example, when a short-term active power deficit occurs on the DC side due to a fault, the energy storage battery... Through the first controlled switch transistor Second controlled switch The formed controlled path rapidly releases electrical energy, and the filter inductor... Used to suppress sudden changes in current during discharge.

[0033] Furthermore, such as Figure 4 As shown, an energy-consuming branch is set up, including: Energy-consuming resistor Third controlled switch tube and the fourth controlled switch ; Energy-consuming resistor One end is connected to the third controlled switch transistor The other end is connected to the DC side negative busbar; The third controlled switch With the fourth controlled switch The bridge arm is connected to the energy storage and energy consumption module at its midpoint.

[0034] As a preferred embodiment of the above, the energy-consuming branch uses an energy-consuming resistor. Third controlled switch tube and the fourth controlled switch Composition, including energy-consuming resistors As an actuator that rapidly consumes surplus electrical energy during a fault, it is used when a fault on the AC side causes a large power surplus on the DC side, and the energy storage branch alone cannot absorb all the excess energy in time. It converts the surplus electrical energy into heat energy for release, thereby suppressing further increases in the DC bus voltage. The third controlled switch... and the fourth controlled switch The optimal controlled switching path that together constitutes the energy-consuming branch is selected to flexibly control the timing and duration of the energy-consuming branch's activation based on the fault severity, surplus power, and the operating status of the energy storage branch; specifically, the energy-consuming resistor... One end is connected to the third controlled switch transistor The other end is connected to the DC side negative bus, making the energy-consuming resistor When the conduction conditions are met, a clear energy discharge loop can be formed with the DC side. The advantage of this connection method lies in the energy dissipation resistor. The released energy path is clear and the action is direct, enabling the rapid establishment of energy dissipation channels during system transients, thereby shortening the duration of fault energy accumulation; furthermore, the third controlled switch... With the fourth controlled switch The bridge arm is connected at its midpoint to the energy storage and dissipation device, enabling the dissipation branch to work in conjunction with the energy storage branch. Specifically, when needed, the energy storage branch preferentially absorbs some surplus energy, while the dissipation branch rapidly dissipates any remaining energy exceeding the optimal energy storage capacity. This allows the same device to possess both energy storage and energy release capabilities, moving beyond the traditional approach of passively dissipating energy with a separate energy-dissipating resistor. Preferably, during normal system operation, the third controlled switch... and the fourth controlled switch The circuit remains off, and the power-consuming branch does not participate in the main power transmission to reduce additional losses and avoid interference with the normal commutation process. However, when an AC-side fault occurs and the system's surplus power exceeds a certain limit, the fourth controlled switch can be controlled. The relevant switching devices switch according to a predetermined logic, causing the third controlled switch transistor to... Conduction occurs, thereby establishing a circuit through the energy-dissipating resistor. A pathway for discharging energy to the DC-side negative bus is provided to rapidly consume excess energy. For example, when the receiving-end AC system experiences a severe fault while the sending-end maintains a high power transmission capacity, a large surplus power will accumulate on the DC side in a short period. In this case, relying solely on the energy storage branch to absorb energy is easily limited by the energy storage capacity and energy absorption rate. However, by activating the energy-consuming branch, energy exceeding the optimal energy storage range can be immediately introduced into the energy-consuming resistor. In addition, in scenarios where the fault lasts for a long time, the energy-consuming branch can work in conjunction with the energy storage branch. The former is responsible for quickly reducing the peak surplus power, while the latter is responsible for absorbing the remaining usable energy, so as to balance the voltage suppression effect and energy utilization efficiency.

[0035] Furthermore, the actions required to complete steady-state commutation include: During normal system operation, the thyristors and controlled switches in the converter branch are synchronously triggered to conduct; When the thyristor and the controlled switch are turned on, the remaining power devices in the control auxiliary branch and the energy storage and energy consumption module are kept off or bypassed. The current is controlled in turn by controlling the current through each arm of the bridge converter structure in turn according to the 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

[0036] As a preferred embodiment of the above embodiments, when the system is in normal operation, the bridge converter structure completes steady-state commutation in a manner consistent with conventional line-commutated inverter operation. Specifically, only the converter branch carries the main current path, while the auxiliary branches and energy storage devices do not participate in normal power transmission. Preferably, the thyristors and controlled switches in the converter branch are synchronously triggered to conduct, so that they jointly form the main current path of the bridge arm within the same conduction interval, thereby ensuring that the bridge arm current can flow stably through the converter branch and maintain the normal commutation relationship of the bridge converter structure. The power devices in the auxiliary branches and the related power devices in the energy storage and energy consumption devices are preferably always kept off or bypassed to avoid forming additional parallel current loops or introducing additional energy exchange processes under steady-state conditions. This arrangement has the advantage of maintaining a conduction mode and loss level similar to traditional line-commutated converters under normal operating conditions, while also reserving electrical conditions for the rapid commissioning of auxiliary branches and energy storage and energy consumption devices under fault conditions. Furthermore, each arm of the bridge converter structure is preferably turned on at a 120° electrical angle. Sequential current flow ensures that at any given moment, the main current path is carried by the commutator branch in the corresponding bridge arm, and the commutation process between each phase is completed sequentially. Under this conduction sequence, the conduction and turn-off relationships of each bridge arm can maintain the symmetry and continuity of three-phase operation, thereby ensuring smooth steady-state energy conversion between the DC and AC sides. For example, when a bridge arm enters the conduction range, the thyristors and controlled switches in the corresponding commutator branch can be simultaneously triggered to conduct, while the corresponding auxiliary branches remain untriggered. The energy storage branch, energy dissipation branch, and... Its related switching devices remain off or are in a bypass state via switching devices. After the conduction interval of the bridge arm ends, it switches to the next bridge arm in a predetermined 120° electrical angle sequence, thereby ensuring that the main current is always transferred sequentially along the converter branch. For example, during the entire normal operation phase, although the auxiliary branch and energy storage and consumption device are integrated into the bridge converter structure, they do not participate in the steady-state main power transmission, so they do not change the basic mechanism of conventional steady-state converter. They are only put into operation according to control requirements when a subsequent AC side fault or DC side fault occurs.

[0037] Furthermore, such as Figure 5 and Figure 6 As shown, the actions taken when an AC or DC side fault is detected include: When an AC side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristors and energy storage modules in the auxiliary branch are triggered to establish the auxiliary commutation voltage. When the branch is transferred and the system surplus power is less than the limit value Pmax, the control switch is turned off and the first and second controlled switches are turned on so that the energy storage module works in energy storage mode. When the branch is transferred and the system surplus power is greater than the limit value Pmax, the fourth controlled switch and the switching switch are turned off, and the third controlled switch, the first controlled switch and the second controlled switch are turned on, so that the energy storage and energy consumption module works in the energy storage and energy consumption collaborative mode. When a DC-side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristor and the fourth controlled switch in the auxiliary branch are triggered, the switching switch is turned off, and the first and second controlled switches are turned on, so that the energy storage and energy consumption module operates in discharge mode.

[0038] As a preferred embodiment of the above, when the system detects an AC-side or DC-side fault, the control strategy no longer maintains the normal operating condition where the converter branch alone bears the main current flow. Instead, it uses coordinated control of the controlled switching devices in the converter branch, auxiliary branch, and energy storage device to enable the arm current to be rapidly transferred within the original bridge converter structure and enter the corresponding fault handling state. Specifically, when an AC-side fault is detected, it is preferable to first turn off the controlled switching transistors in the converter branch, causing the arm current that originally flowed through the converter branch to lose its continuous flow condition and transfer to the auxiliary branch. At the same time, the thyristors in the auxiliary branch and the relevant paths of the energy storage device are triggered, thereby establishing an auxiliary commutation voltage on the arm side. The commutation voltage is preferably applied directly to the two ends of the thyristor involved in commutation to compensate for the reduction in commutation area caused by AC voltage drop or distortion at the receiving end. This ensures that the thyristor can still obtain reliable reverse blocking conditions under a short turn-off margin, thereby reducing the possibility of commutation failure. After the bridge arm current completes the branch transfer, it is preferable to further determine the relationship between the system surplus power during the fault and the limit value Pmax. When the system surplus power is less than the limit value Pmax, the switching switch is turned off and the first and second controlled switches are turned on, allowing the energy storage branch to connect to the energy absorption channel and enter the energy storage state. At this time, the excess power is preferentially absorbed by the energy storage battery, which is suitable for faults with short durations or relatively high surplus power. In smaller scenarios, this approach can improve energy utilization while suppressing DC bus voltage rise. When the system surplus power exceeds the limit Pmax, it is preferable to control the fourth controlled switch and the switching switch to turn off, and control the third, first, and second controlled switches to turn on, so that the energy storage branch and the energy consumption branch work together. Part of the surplus power is absorbed by the energy storage battery, and the other part of the surplus power is quickly consumed through the energy consumption resistor. This forms a fault handling method that coordinates energy storage and energy consumption. This method is particularly suitable for situations where the AC side fault is severe and the sending end still maintains a high power transmission capacity, resulting in rapid energy accumulation on the DC side. It can prevent the DC bus from being overloaded due to limited energy absorption capacity when relying solely on the energy storage branch. The voltage continues to rise; furthermore, when a DC-side fault is detected, it is preferable to first turn off the controlled switch in the converter branch and transfer the bridge arm current to the auxiliary branch, while triggering the thyristor and the fourth controlled switch in the auxiliary branch, and controlling the switching switch to turn off and the first and second controlled switches to turn on, so that the energy storage branch switches from standby state to discharge state, and the energy storage battery releases the pre-stored energy to the DC system to provide rapid support for the DC bus voltage and compensate for the active power deficit during the fault. Under this condition, the control focus changes from absorbing and consuming surplus power during AC-side faults to releasing stored energy and supporting the bus voltage, thereby realizing bidirectional power regulation of the same circuit in different fault directions;For example, when a voltage drop occurs in the receiving-end AC system and the fault duration is short, only the energy storage mode can be activated to absorb surplus power. However, when the duration of the same fault is prolonged or the surplus power further increases, the energy consumption channel can be activated simultaneously to enhance voltage suppression capability. As another example, when the DC bus voltage drops rapidly due to sudden load changes or fault disturbances, the energy storage branch can immediately enter the discharge state after the bridge arm current has completed its transfer, allowing the bus voltage to recover and be supported within a short time.

[0039] Example 2; Based on the same inventive concept as the hybrid valve multiplexing storage-loss commutation control method in the foregoing embodiments, the present invention also provides a hybrid valve multiplexing storage-loss commutation control system, the system comprising: The bridge converter module constructs a bridge converter structure, and sets up converter branches and auxiliary branches in the mixing valve module of the bridge converter structure, and sets up switchable energy storage and consumption modules between the bridge arms. The operation control module controls the conduction of the converter branch and controls the shutdown or bypass of the auxiliary branch and energy storage module during normal system operation to complete steady-state conversion. When the AC detection module detects an AC-side fault that restricts commutation in the converter branch, it controls the arm current to be transferred from the converter branch to the auxiliary branch and controls the energy storage module to establish the auxiliary commutation voltage. The mode switching module controls the energy storage and energy consumption module to work in energy storage mode or energy storage and energy consumption co-operation mode based on the relationship between the system surplus power and the limit value Pmax when the branch is transferred. When the DC detection module detects a DC-side fault that causes insufficient power in the DC system, it controls the bridge arm current to be transferred from the converter branch to the auxiliary branch, and controls the energy storage and consumption module to operate in discharge mode to release the stored energy to the DC system. The fault exit module controls the energy storage and energy consumption module to exit the fault support state and restore the converter branch conduction after the fault is cleared, so that the system returns to normal operation.

[0040] The adjustment system described above in this invention can effectively realize a hybrid valve multiplexing storage and commutation control method, and the technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0041] Furthermore, the operation control module includes: The commutation triggering unit synchronously triggers the thyristors and controlled switches in the commutation branch to conduct during normal system operation. The shutdown control unit controls the auxiliary branch and the remaining power devices in the energy storage and energy consumption module to remain off or bypassed when the thyristor and the controlled switch are turned on. The sequential conduction unit controls the current flow of each bridge arm of the bridge converter structure in turn according to the conduction sequence of 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

[0042] Similarly, the above-mentioned optimization schemes for the system can also achieve the optimization effects corresponding to the methods in Embodiment 1, which will not be repeated here.

[0043] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A hybrid valve multiplexing storage-inversion conversion control method characterized by, The method includes: Construct a bridge converter structure, and set up a converter branch and an auxiliary branch in the hybrid valve module of the bridge converter structure, and set up a switchable energy storage and consumption module between the bridge arms; During normal system operation, the converter branch is turned on, and the auxiliary branch and the energy storage and energy consumption module are turned off or bypassed to complete steady-state converter operation. When an AC-side fault is detected that restricts commutation in the converter branch, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to establish an auxiliary commutation voltage. During branch transfer, the energy storage and energy consumption module is controlled to operate in energy storage mode or energy storage and energy consumption coordination mode based on the relationship between the system surplus power and the limit value Pmax. When a DC-side fault is detected that causes insufficient power in the DC system, the control arm current is transferred from the converter branch to the auxiliary branch, and the energy storage module is controlled to operate in discharge mode to release the stored energy to the DC system. After the fault is cleared, the energy storage and energy consumption module is controlled to exit the fault support state and the converter branch is restored to conduction, so that the system returns to normal operation.

2. The method for controlling the reuse of storage and loss switching in a hybrid valve according to claim 1, characterized in that, Constructing a bridge converter structure includes: A three-phase bridge inverter structure is constructed, consisting of multiple identical hybrid valve modules. The commutation branch and the auxiliary branch are connected in parallel in each of the mixing valve modules; The energy storage and energy consumption module is connected between the upper and lower bridge arms of the three-phase bridge inverter structure.

3. The method for controlling the reuse of storage and loss switching in a hybrid valve according to claim 2, characterized in that, The commutation branch and the auxiliary branch are connected in parallel in each of the mixing valve modules, including: thyristor and The auxiliary branch is formed by reverse series connection; thyristor and controlled switching transistor The converter branch is formed by connecting them in series; The values ​​i = 1, 2, 3 and j = 1, 2, 3, 4, 5, 6 are set to characterize the device positions of each phase arm in the three-phase bridge inverter structure.

4. The method for controlling the reuse of storage and loss switching in a hybrid valve according to claim 1, characterized in that, The energy storage and energy consumption module is configured as follows: The energy storage and energy consumption module includes an energy storage branch, an energy consumption branch, and a switching switch. The switching switch is connected in parallel at the output end of the energy storage branch to control the access state or bypass state of the energy storage consumption module. The energy storage branch is connected to the energy consumption branch to form a functional unit for energy storage, discharge and energy consumption regulation.

5. The method for controlling the reuse of storage and commutation of a hybrid valve according to claim 4, characterized in that, Setting up the energy storage branch includes: Energy storage battery Filter inductor First controlled switch transistor Second controlled switch transistor and DC capacitor ; The first controlled switch transistor With the second controlled switch After being connected in series, it is then connected in parallel to the DC capacitor. Both ends; The energy storage battery via the filter inductor Connect to the first controlled switch transistor With the second controlled switch The midpoint.

6. The method for controlling the reuse of storage and loss switching in a hybrid valve according to claim 4, characterized in that, Setting up the energy-consuming branch includes: Energy-consuming resistor Third controlled switch tube and the fourth controlled switch ; The energy-consuming resistor One end is connected to the third controlled switch transistor The other end is connected to the DC side negative busbar; The third controlled switch transistor With the fourth controlled switch tube The midpoint of the bridge arm is connected to the energy storage and energy consumption module.

7. The method for controlling the reuse of storage and commutation of a hybrid valve according to claim 1, characterized in that, The actions required to complete steady-state commutation include: During normal system operation, the thyristors and controlled switches in the converter branch are synchronously triggered to conduct. When the thyristor and the controlled switch are turned on, the auxiliary branch and the remaining power devices in the energy storage and energy consumption module are kept off or bypassed. The current is controlled in turn by controlling each arm of the bridge converter structure in turn according to the conduction sequence of 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

8. The method for controlling the reuse of storage and loss switching in a hybrid valve according to claim 1, characterized in that, Actions taken when an AC or DC fault is detected include: When an AC side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristor in the auxiliary branch and the energy storage and dissipation module are triggered to establish the auxiliary commutation voltage. When the branch is transferred and the system surplus power is less than the limit value Pmax, the control switch is turned off and the first controlled switch tube and the second controlled switch tube are turned on, so that the energy storage and energy consumption module works in the energy storage mode. When the branch is transferred and the system surplus power is greater than the limit value Pmax, the fourth controlled switch and the switching switch are turned off, and the third controlled switch, the first controlled switch and the second controlled switch are turned on, so that the energy storage and energy consumption module works in the energy storage and energy consumption cooperative mode. When a DC-side fault is detected, the controlled switch in the converter branch is turned off and the bridge arm current is transferred to the auxiliary branch. At the same time, the thyristor and the fourth controlled switch in the auxiliary branch are triggered, the switching switch is turned off, and the first and second controlled switches are turned on, so that the energy storage and energy consumption module operates in the discharge mode.

9. A hybrid valve multiplexing storage and switching control system, characterized in that, The system includes: The bridge converter module constructs a bridge converter structure, and sets up converter branches and auxiliary branches in the mixing valve module of the bridge converter structure, and sets up switchable energy storage and consumption modules between the bridge arms. The operation control module controls the conduction of the converter branch and controls the shutdown or bypass of the auxiliary branch and energy storage module during normal system operation to complete steady-state conversion. When the AC detection module detects an AC-side fault that restricts commutation in the converter branch, it controls the arm current to be transferred from the converter branch to the auxiliary branch and controls the energy storage module to establish the auxiliary commutation voltage. The mode switching module controls the energy storage and energy consumption module to work in energy storage mode or energy storage and energy consumption co-operation mode based on the relationship between the system surplus power and the limit value Pmax when the branch is transferred. When the DC detection module detects a DC-side fault that causes insufficient power in the DC system, it controls the bridge arm current to be transferred from the converter branch to the auxiliary branch, and controls the energy storage and consumption module to operate in discharge mode to release the stored energy to the DC system. The fault exit module controls the energy storage and energy consumption module to exit the fault support state and restore the converter branch conduction after the fault is cleared, so that the system returns to normal operation.

10. The hybrid valve multiplexing storage and switching control system according to claim 9, characterized in that, The operation control module includes: The commutation triggering unit synchronously triggers the thyristors and controlled switches in the commutation branch to conduct during normal system operation. The shutdown control unit controls the auxiliary branch and the remaining power devices in the energy storage and energy consumption module to remain off or bypassed when the thyristor and the controlled switch are turned on. The sequential conduction unit controls the current flow of each bridge arm of the bridge converter structure in turn according to the conduction sequence of 120° electrical angle, so that the converter branch carries the main current path and completes steady-state commutation.

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