Chain type high-voltage static var generator with power unit on-line bypass function and method

Abstract

The invention discloses a chained high-voltage static reactive power generation device and method with a power unit online bypass function, and relates to the technical field of electric energy quality control and reactive power compensation device.The chained high-voltage static reactive power generation device comprises power units, each power unit comprises a direct-current side loop and an alternating-current side loop, and the multiple power units in the same phase are sequentially connected in series in the phase; forming an in-phase power unit chain; the three-phase in-phase power unit chain is connected to the three-phase alternating current access end in a star-shaped connection mode; the bypass switches are connected in parallel with the alternating current side loops of the corresponding power units; a sub-case is arranged, bypass control circuits corresponding to the power units are integrated in the sub-case, and the bypass control circuits are electrically connected with bypass switches of the corresponding power units respectively; according to the method, a single power unit can be quickly bypassed and isolated when an abnormal state occurs, and normal operation of other power units in the same phase is not affected.

Description

Technical Field

[0001] This invention relates to the field of power quality control and reactive power compensation devices, specifically to a chain-type high-voltage static var generator and method with an online bypass function for power units. Background Technology

[0002] With the continuous expansion of power system scale and the increasing complexity of power grid structure, the importance of power quality in power transmission and distribution systems is constantly increasing. Among these, dynamic regulation and compensation of reactive power has become one of the key technologies to ensure the safe and stable operation of the power grid. Static Var Generators (SVG), as reactive power compensation devices based on power electronics technology, have been widely used in high-voltage and ultra-high-voltage power systems due to their fast response speed, high regulation accuracy, and wide operating range. For high-voltage applications, existing SVG devices typically adopt a chain topology with multiple power units cascaded. This involves connecting multiple power units in series within the same phase and using a three-phase star connection to the AC system to achieve high-voltage output and modular expansion.

[0003] However, in the engineering applications of existing chain-type high-voltage static var generators, when a single power unit needs to be taken out of operation due to device aging, abnormal operating conditions, or faults, it is usually necessary to shut down the entire power unit chain within the phase, or rely on manual switching for bypass operation, thus affecting the continuity and availability of the overall system operation. Although some existing solutions have introduced bypass structures, they mostly focus on simple parallel bypass at the electrical level, lacking a complete bypass control system that matches the power unit control, electrical isolation, and system-level control structure, making it difficult to achieve online bypass of power units without affecting the normal operation of other power units. In addition, the existing technology lacks a unified and clear structural design for the arrangement of bypass control circuits, control levels, and communication relationships with the main control system, which easily leads to complex system structure and difficult maintenance. Summary of the Invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the technical problem solved by this invention is that existing chain-type high-voltage static var generators usually require overall shutdown or manual switching for bypass processing when the power unit malfunctions or needs to be taken out of operation. This results in poor system operation continuity, complex maintenance operations, and unclear coupling between bypass control and system structure. The problem is how to achieve online bypass of the power unit and ensure the continuous operation of the remaining power units while keeping the chain-type high-voltage topology unchanged.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a chain-type high-voltage static var generator with online bypass function of power unit, comprising a power unit, wherein the power unit includes a DC side circuit and an AC side circuit, and multiple power units in the same phase are connected in series along the phase to form a power unit chain within the phase.

[0007] The three-phase power unit chains are connected to the three-phase AC input terminal in a star configuration.

[0008] The bypass switch is connected in parallel to the AC side circuit of the corresponding power unit.

[0009] A sub-chassis is provided, which integrates a bypass control circuit corresponding to the power unit. The bypass control circuit is electrically connected to the bypass switch of the corresponding power unit.

[0010] A main unit chassis is provided, and the main unit chassis is communicatively connected to the sub-chassis.

[0011] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit according to the present invention, the power unit further includes a power conversion circuit, the power conversion circuit adopts an H-bridge topology, the DC side is connected to the DC side circuit, and the AC side is connected to the AC side circuit.

[0012] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit as described in this invention, the three-phase AC access terminal includes an electrical connection to the end of the three-phase power unit chain within the phase, used to realize the electrical connection between the three-phase power unit chain within the phase and the external three-phase AC system.

[0013] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit according to the present invention, the bypass switch includes a bypass control circuit and is arranged in parallel on the AC side circuit of the corresponding power unit.

[0014] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit according to the present invention, the bypass switch further includes a mechanical locking structure, which is mechanically linked with the switching actuator of the power conversion circuit of the power unit to limit the synchronous operation of the bypass switch and the power conversion circuit in a predetermined state.

[0015] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit according to the present invention, the bypass control circuit includes an integrated circuit disposed in the sub-chassis, electrically connected to the bypass switch of the corresponding power unit, for controlling the bypass switch.

[0016] As a preferred embodiment of the chain-type high-voltage static var generator with online bypass function of power unit according to the present invention, the main chassis includes a communication link connected to the sub-chassis, and the main chassis does not directly form an electrical connection with the DC side circuit and AC side circuit of the power unit.

[0017] Another objective of this invention is to provide a chain-type high-voltage static var generator with online bypass function for power units. This method can isolate the abnormal power unit from the power unit chain by performing blocking control and driving the bypass switch to close when the power unit is in an abnormal state. This solves the problem that current chain-type high-voltage static var generators require overall shutdown or manual switching in the event of power unit abnormality, and the system's continuous operation capability is insufficient.

[0018] As a preferred embodiment of the chain-type high-voltage static var generator method with online bypass function of power unit described in this invention, the method includes: when an abnormal state occurs in the power unit, the bypass control circuit performs blocking control on the power conversion circuit of the abnormal power unit, reports the abnormal information to the main control system, and simultaneously drives the bypass switch to close, so that the abnormal power unit is bypassed and isolated from the power unit chain within the phase.

[0019] After the power unit is bypassed and isolated, the main control system redistributes and coordinates the output of the remaining power units in the same phase to maintain the continuous operation of the chain-type high-voltage static var generator.

[0020] The beneficial effects of the present invention are as follows: The chain-type high-voltage static var generator with online bypass function of power unit provided by the present invention sets an online bypass unit in the AC side circuit of the power unit, and with the layered structure design of bypass control circuit, sub-chassis and main chassis, the individual power unit can be quickly bypassed and isolated when an abnormal state occurs, without affecting the normal operation of other power units in the same phase; it achieves better results in terms of system operation continuity, device maintenance convenience and modular structural design. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a chain SVG circuit topology diagram of a chain-type high-voltage static var generator with online bypass function of power unit provided in Embodiment 1 of the present invention.

[0023] Figure 2 This is a schematic diagram of the power unit online bypass technology of a chain-type high-voltage static var generator with power unit online bypass function provided in Embodiment 1 of the present invention. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0025] Example 1, referring to Figure 1 As one embodiment of the present invention, a chain-type high-voltage static var generator with online bypass function of power unit is provided, comprising: Power unit 100 includes a DC side circuit and an AC side circuit. Multiple power units 100 in the same phase are connected in series along the phase to form a power unit chain within the phase.

[0026] The power unit 100 also includes a power conversion circuit 101, which adopts an H-bridge topology, with the DC side connected to the DC side circuit and the AC side connected to the AC side circuit.

[0027] It should be noted that in a chain-type high-voltage static var generator, multiple power units 100 within the same phase are connected in series within the phase to form a power unit chain, such as... Figure 1 As shown, the power unit 100 adopts a common H-bridge topology, such as... Figure 2 As shown, its DC side is connected to the DC side circuit, and its AC side is connected to the corresponding AC side circuit to realize the cascaded output structure of the power unit 100 in the phase.

[0028] It should also be noted that by connecting multiple power units 100 within the same phase in series to form a power unit chain, and using a universal H-bridge topology within each power unit 100, the DC side of the power unit 100 is connected to the DC side circuit, and the AC side is connected to the corresponding AC side circuit, thus forming a multi-level cascaded output structure within the phase. This structural design allows for high-voltage output requirements to be met without relying on a single high-voltage power device, reducing the voltage stress on individual power units and improving the engineering adaptability of the device in high-voltage application scenarios. The universal H-bridge topology for each power unit 100 ensures consistency in structure and interface, facilitating modular design and standardized configuration of the power units 100, and simplifying expansion, replacement, and maintenance within the chain structure. The power unit chain formed by series connection within the phase allows for flexible voltage level configuration by increasing or decreasing the number of power units 100, thereby improving the adaptability of the chain-type high-voltage static var generator under different voltage levels and capacity requirements.

[0029] The three-phase power unit chain is connected to the three-phase AC input terminal 200 via a star connection.

[0030] The three-phase AC access terminal 200 includes an end electrically connected to the three-phase intra-phase power unit chain, used to realize the electrical access of the three-phase intra-phase power unit chain to an external three-phase AC system.

[0031] It should be noted that the three-phase intra-phase power unit chains are connected to the three-phase AC system via a star connection. Each of the three-phase intra-phase power unit chains constitutes an output branch for its corresponding phase, and its ends are electrically connected to the three-phase AC input terminal 200, thereby realizing the electrical connection between the intra-phase power unit chains and the external three-phase AC system. Figure 1 As shown.

[0032] It should also be noted that by constructing the corresponding output branches of the three-phase power unit chains into their respective phases and connecting them to the three-phase AC input terminal 200 in a star configuration, each phase power unit chain can independently correspond to a phase of the external three-phase AC system, achieving a clear and symmetrical electrical connection between the phase power unit chains and the external three-phase AC system. This structure helps ensure the consistency and symmetry of the three-phase output structure and reduces the impact of inter-phase coupling on the system layout.

[0033] The bypass switch 300 is connected in parallel to the AC side circuit of the corresponding power unit 100.

[0034] The bypass switch 300 includes a bypass control circuit 401 connected in parallel to the AC side circuit of the corresponding power unit 100.

[0035] The bypass switch 300 also includes a mechanical locking structure 301, which is mechanically linked to the switching actuator of the power conversion circuit 101 of the power unit 100 to limit the synchronous operation of the bypass switch 300 and the power conversion circuit 101 in a predetermined state.

[0036] It should be noted that the bypass switch 300 is connected in parallel in the AC side circuit of the corresponding power unit. The bypass switch 300 is connected to the bypass control circuit 401, which controls the on / off state of the bypass switch 300. When the power unit needs to perform bypass operation, the bypass switch 300 forms a bypass path in the AC side circuit, thereby achieving bypass isolation of the corresponding power unit. The bypass switch 300 is provided with a mechanical locking structure 301. The mechanical locking structure 301 forms a mechanical linkage relationship with the switching actuator of the power conversion circuit 101 in the power unit 100. The mechanical locking structure 301 restricts the synchronous operation of the bypass switch 300 and the power conversion circuit 101 in a predetermined state, so as to achieve mechanical interlocking between the bypass switch and the power conversion circuit.

[0037] It should also be noted that by setting the bypass switch 300 in parallel in the AC side circuit of the corresponding power unit, and controlling the on / off state of the bypass switch 300 by the bypass control circuit 401, the power unit can form an independent bypass path through the AC side when it needs to perform bypass operation. This achieves electrical isolation between the power unit and the power unit chain within the phase, avoiding any impact on the structural connection of other power units within the phase. The bypass switch 300 is equipped with a mechanical interlocking structure 301 that forms a mechanical linkage with the switching actuator of the power conversion circuit. The mechanical interlocking structure 301 restricts the synchronous operation of the bypass switch 300 and the power conversion circuit in a predetermined state, forming a clear mechanical interlocking relationship between the bypass switch 300 and the power conversion circuit. This helps to avoid the two being in a mismatched working state at the structural level, enhancing the coordination of the bypass structure and the power conversion structure and the structural reliability.

[0038] A sub-chassis 400 is provided, and a bypass control circuit 401 corresponding to the power unit 100 is integrated inside the sub-chassis 400. The bypass control circuit 401 is electrically connected to the bypass switch 300 of the corresponding power unit 100.

[0039] The bypass control circuit 401 includes an integrated sub-chassis 400, which is electrically connected to the bypass switch 300 of the corresponding power unit 100 and is used to control the bypass switch 300.

[0040] It should be noted that a preferred embodiment of the bypass control circuit 401 includes a control core module. The control core module executes bypass control logic and exception handling logic, and can be implemented using a microcontroller (MCU), digital signal processor (DSP), programmable logic device (FPGA), or other control chip with logic operation and control output capabilities. The control core module receives status signals from the power unit 100 and generates a blocking control signal and a bypass drive signal according to preset control logic. A status sampling module collects operating status signals of the power unit 100, including but not limited to fault status signals, voltage status signals, or other operating status identification signals of the power conversion circuit 101. The status sampling module is electrically connected to the control core module and provides status input signals to the control core module. A blocking control interface module is used to communicate with the power unit 100. The power conversion circuit 101 establishes a control connection and outputs a blocking control signal to the power conversion circuit 101 when an abnormal state is detected. The blocking control interface module may include an isolation circuit or a drive interface circuit to achieve electrical isolation between the control signal and the power loop. The bypass drive module is used to output a drive signal to the bypass switch 300 to control the closing or opening of the bypass switch 300. The bypass drive module may include a drive chip, an isolation drive circuit, or a relay drive circuit to achieve signal matching between the control signal and the bypass switch actuator. The communication interface module is used to establish a communication connection between the bypass control circuit 401 and the main chassis 500 or the main control system, and is used to report abnormal state information of the power unit 100. The communication interface module may be implemented using a serial communication interface, an electrically isolated communication interface, or a bus communication interface structure. It also includes a control power module, which provides working power to the control core module, status sampling module and drive module. The control power module is isolated from the main power circuit of the power unit 100. The bypass control circuit 401 only participates in control signal processing and drive signal output, and does not directly participate in the energy transmission of the DC side circuit and AC side circuit of the power unit 100.

[0041] The bypass control circuit 401 is installed and fixed inside the sub-chassis 400 and is electrically connected to the bypass switch 300 of the corresponding power unit 100. The bypass control circuit 401 controls the on / off state of the bypass switch 300 to realize the bypass control operation of the corresponding power unit 100. By integrating the bypass control circuit 401 into the sub-chassis 400 and directly connecting it to the bypass switch 300 of the corresponding power unit 100, the control loop of the bypass switch 300 is centrally arranged in the sub-chassis 400, thereby completing the unified wiring and control configuration of the bypass switches 300 of each power unit 100 in the sub-chassis 400.

[0042] It should also be noted that by integrating the bypass control circuit 401 corresponding to the power unit 100 into the sub-chassis 400, and by directly electrically connecting the bypass control circuit 401 to the bypass switch 300 of the corresponding power unit 100, the control circuit of the bypass switch 300 is centrally arranged in the sub-chassis 400. This makes the bypass control structure of each power unit 100 clearer and more unified in terms of physical location and electrical connection. Through the one-to-one electrical connection between the bypass control circuit 401 and the bypass switch 300, the bypass control of each power unit 100 does not interfere with each other. This facilitates the unified wiring and centralized management of the bypass switches 300 of multiple power units 100 in the sub-chassis 400, reduces the need for scattered wiring between the power unit 100 and the external control circuit, and improves the regularity of the overall structural layout of the device and the convenience of engineering implementation.

[0043] A main unit chassis 500 is provided, which is connected to the sub-chassis 400 via communication.

[0044] The main chassis 500 is connected to the sub-chassis 400 via a communication link, and the main chassis 500 is not directly electrically connected to the DC side circuit and AC side circuit of the power unit 100.

[0045] Example 2, an embodiment of the present invention, provides a chain-type high-voltage static var generator with online bypass function of power unit, including real-time acquisition of the operating status signal of power unit 100, and generating an abnormality identification signal when the power unit 100 is detected to be in an abnormal state.

[0046] After receiving the abnormality flag signal, the bypass control circuit 401 performs a blocking control on the power conversion circuit 101 of the abnormal power unit 100, stopping its PWM pulse output.

[0047] After the power conversion circuit 101 completes the blocking, the bypass control circuit 401 sends an abnormality reporting signal to the main control system.

[0048] The bypass control circuit 401 drives the bypass switch 300 to close, forming a bypass path in the AC side circuit of the corresponding power unit 100, so that the abnormal power unit 100 is bypassed and isolated from the power unit chain within the phase.

[0049] After confirming that the abnormal power unit 100 has been bypassed and isolated, the main control system redistributes and coordinates the output of the remaining power units 100 in the same phase to maintain the continuous operation of the chain-type high-voltage static var generator.

[0050] The reallocation includes, after confirming that the abnormal power unit 100 has been bypassed and isolated, the main control system updates the effective cascade unit quantity parameter of the current phase based on the number of remaining normal power units 100 in the current phase.

[0051] Based on the effective cascade unit quantity parameter and the target output voltage amplitude of the current phase, the reference output voltage allocation value of each remaining normal power unit 100 is recalculated.

[0052] The voltage components originally allocated to the abnormal power unit 100 are proportionally redistributed to the remaining normal power units 100, and an updated voltage reference command for the power units 100 is generated.

[0053] The coordinated control includes the main control system regenerating the PWM modulation control signal for each remaining normal power unit 100 according to the updated voltage reference command, and sending it to the corresponding power conversion circuit 101 through the power unit control circuit to adjust the output voltage amplitude of the H bridge.

[0054] Simultaneously, the three-phase output voltage is sampled in real time, and the amplitude and phase of the three-phase voltage are balanced and corrected based on the sampling results to keep the output voltage symmetrical under the three-phase star connection structure.

[0055] After the voltage amplitude recovers to the set operating range, the updated modulation parameters are maintained for continuous operation.

[0056] Specifically, when a power unit 100 malfunctions and is isolated by the bypass switch 300, the number of effective power units participating in cascaded output within the same phase decreases. The main control system first receives the malfunction indicator signal reported by the bypass control circuit 401 through the communication connection with the sub-chassis 400, and confirms that the power unit 100 has stopped outputting and that a bypass path has been formed on the AC side. Subsequently, based on the number of remaining normal power units 100 in the current phase, the main control system recalculates the voltage distribution parameters for that phase, and proportionally redistributes the voltage components originally allocated to the malfunctioning power unit 100 to the remaining normal power units 100, thereby increasing or readjusting the reference output voltage values ​​of each remaining power unit 100 accordingly. Based on the current target phase voltage amplitude and the number of effective cascaded units, the main control system regenerates the modulation reference signal for each power conversion circuit 101, and sends new PWM modulation commands to each normal power unit 100 through the power unit control circuit to adjust the amplitude and polarity of its H-bridge output voltage, thereby realizing the re-superposition of cascaded voltages within the phase. At the same time, the main control system synchronously samples the three-phase output voltage and corrects the adjusted phase voltage amplitude and phase to ensure that the output of each phase remains balanced under the three-phase star connection structure. After the output voltage recovers to the set operating range, the main control system maintains the updated modulation parameters and continues to operate, thereby completing the output redistribution and coordinated control under the power unit bypass isolation condition.

[0057] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0058] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-including system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0059] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0060] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0061] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A chain-type high-voltage static var generator with online bypass function of power unit, characterized in that, include: A power unit (100) includes a DC side circuit and an AC side circuit. Multiple power units (100) in the same phase are connected in series along the phase to form a power unit chain within the phase. The three-phase power unit chain is connected to the three-phase AC access terminal (200) in a star connection manner. A bypass switch (300) is connected in parallel to the AC side circuit of the corresponding power unit (100); A sub-chassis (400) is provided, and a bypass control circuit (401) corresponding to the power unit (100) is integrated in the sub-chassis (400). The bypass control circuit (401) is electrically connected to the bypass switch (300) of the corresponding power unit (100). A main chassis (500) is provided, and the main chassis (500) is communicatively connected to the sub-chassis (400).

2. The chain-type high-voltage static var generator with online bypass function of power unit as described in claim 1, characterized in that: The power unit (100) further includes a power conversion circuit (101) internally configured. The power conversion circuit (101) adopts an H-bridge topology, with its DC side connected to the DC side circuit and its AC side connected to the AC side circuit.

3. The chain-type high-voltage static var generator with online bypass function of power unit as described in claim 1 or 2, characterized in that: The three-phase AC access terminal (200) includes an electrical connection to the end of the three-phase power unit chain, used to realize the electrical access of the three-phase power unit chain to an external three-phase AC system.

4. The chain-type high-voltage static var generator with online bypass function of power unit as described in claim 3, characterized in that: The bypass switch (300) includes a bypass control circuit (401) connected in parallel to the AC side circuit of the corresponding power unit (100).

5. The chain-type high-voltage static var generator with online bypass function of power unit as described in any one of claims 1, 2, and 4, characterized in that: The bypass switch (300) further includes a mechanical locking structure (301), which is mechanically linked with the switching actuator of the power conversion circuit (101) of the power unit (100) to limit the synchronous operation of the bypass switch (300) and the power conversion circuit (101) in a predetermined state.

6. The chain-type high-voltage static var generator with online bypass function of power unit as described in claim 2 or 4, characterized in that: The bypass control circuit (401) includes an integrated sub-chassis (400) that is electrically connected to the bypass switch (300) of the corresponding power unit (100) and is used to control the bypass switch (300).

7. The chain-type high-voltage static var generator with online bypass function of power unit as described in claim 6, characterized in that: The main chassis (500) includes a communication link connected to the sub-chassis (400), and the main chassis (500) is not directly electrically connected to the DC side circuit and AC side circuit of the power unit (100).

8. A chain-type high-voltage static var generator with online bypass function of power unit, comprising a chain-type high-voltage static var generator with online bypass function of power unit as described in any one of claims 1 to 7, characterized in that: This includes real-time acquisition of the operating status signal of the power unit (100), and generating an abnormality identification signal when the power unit (100) is detected to be in an abnormal state; After receiving the abnormal identification signal, the bypass control circuit (401) performs a blocking control on the power conversion circuit (101) of the abnormal power unit (100) and stops its PWM pulse output; After the power conversion circuit (101) completes the blocking, the bypass control circuit (401) sends an abnormality reporting signal to the main control system; The bypass control circuit (401) drives the bypass switch (300) to close, forming a bypass path in the AC side circuit of the corresponding power unit (100), so that the abnormal power unit (100) is bypassed and isolated from the power unit chain within the phase. After confirming that the abnormal power unit (100) has been bypassed and isolated, the main control system redistributes and coordinates the output of the remaining power units (100) in the same phase to maintain the continuous operation of the chain-type high-voltage static var generator.

9. The chain-type high-voltage static var generator method with online bypass function of power unit as described in claim 8, characterized in that: The reallocation includes, after confirming that the abnormal power unit (100) has been bypassed and isolated, the main control system updates the effective cascade unit quantity parameter of the current phase according to the number of remaining normal power units (100) in the current phase; Based on the effective cascade unit quantity parameter and the target output voltage amplitude of the current phase, the reference output voltage allocation value of each remaining normal power unit (100) is recalculated; The voltage components originally allocated to the abnormal power unit (100) are proportionally redistributed to the remaining normal power units (100), and an updated voltage reference command is generated for the power units (100).

10. The chain-type high-voltage static var generator method with online bypass function of power unit as described in claim 8 or 9, characterized in that: The coordination control includes the main control system regenerating the PWM modulation control signal of each remaining normal power unit (100) according to the updated voltage reference command, and sending it to the corresponding power conversion circuit (101) through the power unit control circuit to adjust the output voltage amplitude of the H bridge. Simultaneously, the three-phase output voltage is sampled in real time, and the amplitude and phase of the three-phase voltage are balanced and corrected based on the sampling results to keep the output voltage symmetrical under the three-phase star connection structure. After the voltage amplitude recovers to the set operating range, the updated modulation parameters are maintained for continuous operation.

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