Reverse power loop inverter power supply multi-machine parallel power grid and reverse power control method

Abstract

The invention discloses a reverse power loop inverter power supply multi-machine parallel power grid and a reverse power control method, and relates to the field of ship electrical engineering, the power grid comprises n inverter power supplies of which alternating current output ends are connected in parallel, and each inverter power supply comprises an inverter module and a reverse power control module; the inversion module converts a direct current input voltage into a three-phase alternating current voltage; the reverse power control module comprises a reverse thyristor and a control driving circuit thereof, generates different control instructions based on a comparison result of the acquired direct current bus voltage and the input voltage, and controls the reverse thyristor when the comparison result exceeds a preset threshold value and the duration exceeds a preset anti-shake time; the generated control instruction enables a reverse thyristor connected in series on a positive pole direct current bus to be conducted, and excessive energy on the direct current bus is conducted back to the input end to prevent the direct current bus from being pumped too high; and when the conduction time of the reverse thyristor reaches a preset maximum time limit value, the reverse power control module terminates conduction and enters a reset process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship electricity, in particular to a multi-machine parallel grid of an inverter power supply in an inverse power loop and an inverse power control method. BACKGROUND

[0002] As an important part of the ship power system, the inverter power supply plays a key role in meeting the daily AC power demand of the ship and ensuring the power supply of important loads. With the development of the ship power system towards large capacity, high reliability and intelligence, the multi-machine parallel technology of the inverter power supply has become a key solution to improve the power supply capacity and redundancy of the ship AC grid. However, in actual operation, due to the characteristics of the closed nature of the ship grid, large load impact and high complexity of synchronous control of the inverter power supply, the inverse power problem caused by the difference in output voltage phase and amplitude in the multi-machine parallel system of the inverter power supply not only causes the DC bus voltage to pump up and accelerates the aging of key devices such as IGBT, but also causes the shutdown of multiple inverter power supplies and power loss in the whole grid, which has become a core factor restricting the safe and stable operation of the ship power system.

[0003] Traditional research techniques usually adopt the passive tripping protection mode of disconnecting the relays or circuit breakers of the inverter power supply, which can avoid further expansion of the power loss failure. Existing new research schemes focus on optimizing the control strategy (such as droop control, parallel synchronous control, etc.) of the multi-machine parallel inverter power supply to improve the power distribution accuracy, thereby achieving active suppression of inverse power.

[0004] However, the passive tripping protection scheme may cause some key loads in the power system to lose power, which is not conducive to improving the reliability of ship power supply. The active suppression scheme of control strategy optimization still has a small inverse power due to a small phase difference in the output voltage under the no-load parallel working condition of the inverter power supply, which may still induce overvoltage of the input DC bus of the inverter power supply and cause fault shutdown over time. SUMMARY

[0005] The purpose of the present application is to provide a multi-machine parallel grid of an inverter power supply in an inverse power loop.

[0006] The technical solution of the present application is to provide a multi-machine parallel grid of an inverter power supply in an inverse power loop, which includes n inverter power supplies with AC output ends connected in parallel, wherein n is an integer greater than or equal to 2.

[0007] Each inverter power supply includes a signal acquisition module, an inverter module and an inverse power control module.

[0008] The signal acquisition module acquires the DC bus voltage, the input voltage, the output voltage and the output inductance current of the inverter, and sends the acquired data to the inverter module and the inverse power control module.

[0009] The inverter module includes a three-phase bridge DC / AC inverter unit and a control circuit thereof, which converts a direct current input voltage into a three-phase alternating current voltage;

[0010] The reverse power control module includes a reverse thyristor and a control driving circuit thereof, and generates different control instructions based on a comparison result of the collected direct current bus voltage and the input voltage; when the comparison result exceeds a preset threshold value and the duration exceeds a preset anti-shake time, the generated control instruction makes the reverse thyristor connected in series on the positive direct current bus conduct, so as to guide the excess energy on the direct current bus back to the input end to prevent the direct current bus voltage from being pumped too high; when the reverse thyristor conduction time reaches a preset maximum limit value, the reverse power control module terminates the conduction and enters a reset process.

[0011] In any of the above technical solutions, further, the power grid further comprises a soft start module and a filter module;

[0012] The soft start module precharges the direct current bus capacitor when the direct current input switch is closed and powered on, and suppresses the peak voltage at the power-on instant through the thyristor buffer board to prevent the large current impact at the power-on instant;

[0013] The filter module suppresses interference signals, the input filter of the filter module suppresses high-frequency interference on the direct current input side, the LC filter circuit composed of the direct current filter inductor and the direct current bus capacitor filters out low-frequency interference on the direct current input side, and the output filter filters out harmonic components of the output voltage and current.

[0014] In any of the above technical solutions, further, the control circuit of the inverter module performs Clark transformation and Park transformation on the sampled output three-phase alternating current voltage and output three-phase inductor current to obtain DQ axis components, compares the DQ axis components with DQ axis reference voltage and current, obtains a duty cycle signal through double PI closed-loop control, generates a PWM signal through modulation technology, and sends the PWM signal to the corresponding switch tube in the inverter circuit after amplification by the driving board.

[0015] A reverse power control method applied to the reverse power circuit inverter power supply multi-machine parallel grid in any of the above technical solutions is also provided, and the possibility of reverse power exists only in the P6 mode in the working state of the grid, the P6 mode is a parallel no-load state, and after two or more inverter power supplies enter single-machine no-load state, the corresponding AC distribution board is closed by closing the switch, the parallel connection of the AC output ports of the multiple inverter power supplies is realized, but there is no load.

[0016] The reverse power control is realized by controlling the opening of the reverse thyristor, and the following steps are continuously executed:

[0017] S1, parameter initialization: the determination time T s and the opening time T onInitialize to 0, and customize the stabilization time T. d , Upper limit of the operating voltage U limit and the maximum activation time T set Among them, the image stabilization time T d satisfy Activation voltage upper limit U limit satisfy Maximum activation time T set satisfy Where Δt represents the execution period of the voltage judgment function, U buslimit Indicates the rated voltage of the bus capacitor;

[0018] S2, Voltage Judgment: The collected input voltage U in With bus voltage U bus In contrast, if U bus - U in ≥ U limit If the condition is met, then execute S3; otherwise, jump to S7.

[0019] S3, Accumulate the anti-shake judgment time, for Accumulation Each time an addition is made, a subsequent step is evaluated.

[0020] S4. Anti-shake time judgment, if T s ≥ T d If the condition is met, then execute S5; otherwise, jump to S2.

[0021] S5. Turn on the reverse thyristor, and provide a drive signal to the reverse thyristor VT1n through the control drive circuit, while simultaneously... Accumulation Each time an addition is made, a subsequent step is evaluated.

[0022] S6. Activation time determination: If T on ≥ T set If the condition is met, proceed to S7; otherwise, jump to S5.

[0023] S7. Turn off the reverse thyristor and block the drive signal. It will automatically turn off when the reverse thyristor current decays to the turn-off current.

[0024] In any of the above technical solutions, the inverter power supply is further divided into 7 operating modes, the remaining operating modes besides P6 include:

[0025] P1 mode is the shutdown state. At this time, both the input switch and the output switch are in the open state, the DC input voltage is 0, and the main circuit is not energized. Closing the input switch in P1 mode will switch to P2 mode.

[0026] In P2 mode, the power-on state is reached. At this time, the input switch is closed, the DC bus capacitor has completed pre-charging, but the inverter module's switching transistor is in the off state, and the AC output voltage is 0. In P2 mode, turning on the inverter module's switching transistor switches the system to switch to P3 mode. In P3, P4, P5, P6, and P7 modes, turning off the inverter module's switching transistor switches the system back to P2 mode.

[0027] In P3 mode, the inverter module starts working and outputs three-phase AC power, but the output switch is not closed. In P3 mode, closing the output switch will turn off the load switch and enter P4 mode. Closing the load switch will directly enter P5 mode. In P4, P6, and P7 modes, turning off the output switch will return to P3 mode.

[0028] P4 mode is a single unit no-load state. At this time, the output switch is closed and the corresponding AC distribution board is powered on, but there is no load. In P4 mode, closing the load switch will enter P5 mode. After two or more inverters enter P4 mode, closing the corresponding AC distribution board's interconnection switch will enter P6 mode.

[0029] P5 mode is a single-unit load state, in which the load switch is closed and the inverter power supply supplies AC load; after two or more inverter power supplies enter P5 mode, they enter P7 mode by closing the corresponding AC distribution board's interconnection switch.

[0030] In P7 mode, the load is connected in parallel. At this time, the load switch in the AC power grid is closed, and the inverters connected in parallel supply power to the AC load.

[0031] In any of the above technical solutions, the switching paths related to P6 mode further include paths P62, P63, P64, P67, and P76, and the inverse power control strategies for these paths include:

[0032] For the P62 path, when switching from P6 to P2, the drive signals of all switching transistors and thyristors are immediately blocked.

[0033] For path P63, when switching from P6 to P3, the reverse thyristor is immediately turned on, and the turn-on time is T. set To balance the bus voltage and the input voltage;

[0034] For the P64 path, when switching from P6 to P4, the reverse thyristor is immediately turned on to dissipate the energy of the bus capacitor.

[0035] For the P67 path, when switching from P6 to P7, the reverse thyristor does not need to be turned on, but the PI parameter of the inverter module current inner loop should be appropriately reduced, and then slowly restored to the original value according to the control cycle.

[0036] For the P76 path, when switching from P7 to P6, appropriately reduce the PI parameter of the inner current loop, and then slowly restore it.

[0037] The beneficial effects of this invention are:

[0038] The technical solution in this invention introduces a reverse power control module into the inverter power supply and combines it with software algorithms to perform targeted control on the P6 parallel no-load mode and related mode switching paths. This achieves effective reverse power distribution and dynamic management, avoiding the critical load power loss problem caused by traditional passive trip protection schemes, and preventing DC bus overvoltage fault shutdowns caused by the accumulation of small phase differences under no-load parallel conditions in optimized control strategies. Specifically, the combination of hardware-level reverse thyristor on / off control and software-level anti-jitter judgment and turn-on time limitation ensures real-time balance between bus voltage and input voltage, preventing accelerated aging of critical components such as IGBTs. At the same time, the reverse thyristor is actively turned on to conduct energy in mode switching paths such as P63 and P64, and PI parameters are adjusted in P67 and P76 paths to reduce circulating current and impact, effectively improving the power distribution accuracy and output power quality of the multi-machine parallel system. Attached Figure Description

[0039] The advantages of the above and additional aspects of the present invention will become apparent and readily understood in the description of the embodiments in conjunction with the following drawings, wherein:

[0040] Figure 1 This is a schematic diagram of the structure of a multi-machine parallel grid of an inverter power supply with a reverse power loop according to an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the hardware architecture of a multi-machine parallel grid inverter power supply according to an embodiment of the present invention.

[0042] Figure 3 This is a diagram showing the switching path of the inverter operating mode in a multi-machine parallel grid of an inverter with a reverse power loop according to an embodiment of the present invention.

[0043] Figure 4 This is a flowchart of reverse power control under no-load parallel operation mode of a multi-machine parallel grid of reverse power circuit inverter power supply according to an embodiment of the present invention. Detailed Implementation

[0044] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0045] In the following description, many specific details are set forth in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0046] like Figure 1 As shown, this embodiment provides a multi-unit parallel grid of inverter power supplies with reverse power loops. The grid includes n inverter power supplies with their AC output terminals connected in parallel, where n is an integer greater than or equal to 2.

[0047] The hardware architecture of each inverter is as follows: Figure 2 As shown, the solid gray line represents the direction of power flow, and the dashed black line represents the direction of information flow. Each inverter power supply includes a soft-start module, a filtering module, an inverter module, a signal acquisition module, and a reverse power control module in terms of hardware. Taking inverter power supply 1 as an example, its soft-start module includes a soft-start resistor R1, a diode module D1, a thyristor buffer board P1, a forward thyristor VT1p and its driving circuit; the filtering module includes an input filter Z11, a DC filter inductor L1, a DC bus capacitor C1 and an output filter Z12; the inverter module includes a three-phase bridge DC / AC inverter unit and its control circuit; the reverse power control module includes a reverse thyristor VT1n and its control and driving circuit; the signal acquisition module includes DC voltage Hall effect sensors M11 and M12, a three-phase AC Hall effect sensor, and a matching sampling circuit board.

[0048] The soft-start module is used to suppress the voltage spike at the moment of power-on through the thyristor buffer plate P1 when the DC input switch is closed and powered on. The soft-start resistor R1 and the diode module D1 pre-charge the DC bus capacitor C1 to prevent the large current surge at the moment of power-on of the inverter, thereby protecting the power devices and filter components.

[0049] The filtering module is used to suppress interference signals. The input filter Z11 suppresses high-frequency interference on the DC input side, the LC filter circuit composed of DC filter inductor L1 and DC bus capacitor C1 filters out low-frequency interference on the DC input side, and the output filter Z12 filters out harmonic components of the output voltage and current to improve the power quality of the output voltage.

[0050] As the core component of the inverter power supply, the inverter module is used to convert the DC input voltage into a three-phase AC voltage. Specifically, its control circuit performs Clark and Park transformations on the sampled output three-phase AC voltage and output three-phase inductor current to obtain the DQ axis components. These components are compared with the DQ axis reference voltage and current, and the duty cycle signal is obtained through dual PI closed-loop control. Then, a PWM signal is generated through modulation technology, amplified by the driver board, and sent to the corresponding switching transistor in the inverter circuit.

[0051] The inverse power control module is used to implement inverse power control. Its working principle is to determine the input voltage U. in and DC bus voltage U bus The size and system operating mode control the switching on and off of the reverse thyristor VT1n to prevent DC bus voltage U bus Pump rise is too high; This module is a hardware improvement over traditional multi-unit parallel inverter systems, designed to enhance the stability and reliability of the AC power grid.

[0052] The reverse power control module includes a reverse thyristor and its control drive circuit. Based on the comparison result of the collected DC bus voltage and the input voltage, it generates different control commands. When the comparison result exceeds a preset threshold and the duration exceeds a preset anti-jitter time, the generated control command turns on the reverse thyristor connected in series on the positive DC bus, and guides the excess energy on the DC bus back to the input terminal to prevent the DC bus voltage from being pumped too high. When the reverse thyristor conduction time reaches the preset maximum time limit, the reverse power control module terminates conduction and enters the reset process.

[0053] The signal acquisition module is used to acquire voltage signals. The DC voltage Hall M11 acquires the input voltage Uin, the DC voltage Hall M12 acquires the DC bus voltage Ubus, and the three-phase AC Hall acquires the output voltage and output inductor current. These signals are then sent to the inverter module and the reverse power control module via the sampling circuit board.

[0054] In this invention, the inverter power supply with reverse power control is divided into 7 operating modes, namely P1 to P7, and the switching paths between the modes are as follows: Figure 3 As shown, specifically:

[0055] P1 is the shutdown state. At this time, both the input and output switches of the inverter power supply are in the open state, the DC input voltage is 0, and the main circuit is not energized. Closing the input switch in P1 mode switches to P2 mode.

[0056] In P2 mode, the input switch is closed and the DC bus capacitor is pre-charged, but the inverter module's switching transistor is in a closed state, and the AC output voltage is 0. In P2 mode, turning on the inverter module's switching transistor switches the circuit to P3 mode. In P3, P4, P5, P6, and P7 modes, turning off the inverter module's switching transistor switches the circuit back to P2 mode.

[0057] In P3 mode, the inverter module starts working and outputs three-phase AC power, but the output switch is not closed. In P3 mode, closing the output switch will turn off the load switch and enter P4 mode. Closing the load switch will directly enter P5 mode. In P4, P6, and P7 modes, turning off the output switch will return to P3 mode.

[0058] P4 is the single-unit no-load state. At this time, the output switch is closed and the corresponding AC distribution board is powered on, but there is no load. In P4 mode, closing the load switch will enter P5 mode. After two or more inverters enter P4 mode, closing the corresponding AC distribution board's connection switch will enter P6 mode.

[0059] P5 is the single-unit load state, where the load switch is closed and the inverter supplies power to the AC load. After two or more inverters enter P5 mode, they enter P7 mode by closing the corresponding AC distribution board's interconnection switch.

[0060] P6 is the parallel no-load state. After two or more inverters enter the P4 state, the AC output ports of multiple inverters can be connected in parallel without load by closing the corresponding AC distribution board's closing switch.

[0061] P7 is in parallel load condition. At this time, the load switch in the AC power grid is closed, and the parallel inverters supply power to the AC load together.

[0062] Figure 3 The dashed line with an arrow indicates the working mode switching path. The "Pmn" label next to the path indicates switching from mode Pm to Pn. For example, "P12" indicates switching from P1 to P2. The switching condition is that the input switch is closed.

[0063] Under normal operating conditions, only the P6 parallel no-load mode has the possibility of reverse power. The DC bus voltage rise caused by reverse power is a common cause of inverter overvoltage shutdown. In the ship AC power grid, multiple inverters need to be in P6 mode to prepare for the input of large-capacity loads. Therefore, the reverse power smoothing in P6 mode and related mode switching is crucial to the reliability of the power grid.

[0064] In the P6 parallel no-load mode, the core of reverse power control is to control the switching on of the reverse thyristor VT1n, and the process is as follows: Figure 4 As shown, the following steps are continuously performed during the operation of the power grid:

[0065] S1, Parameter initialization. Set the decision time T... s and opening time T on Initialize to 0, and customize the stabilization time T. d , Upper limit of the operating voltage U limit and the maximum activation time T set Among them, the image stabilization time T d satisfy Activation voltage upper limit U limit satisfy Maximum activation time T set satisfy Where Δt represents the execution period of the voltage judgment function, Ubuslimit This indicates the rated voltage of the bus capacitor.

[0066] S2, Voltage Judgment: The collected input voltage U in With bus voltage U bus In contrast, if U bus - U in ≥ U limit If the condition is met, proceed to S3; otherwise, jump to S7.

[0067] S3, Accumulate the anti-shake judgment time, for Accumulation Each time an addition is made, a subsequent step is evaluated.

[0068] S4. Anti-shake time judgment, if T s ≥ T d If the condition is met, then execute S5; otherwise, jump to S2.

[0069] S5. Turn on the reverse thyristor, and provide a drive signal to the reverse thyristor VT1n through the control drive circuit, while simultaneously... Accumulation Each time an addition is made, a subsequent step is evaluated.

[0070] S6. Activation time determination: If T on ≥ T set If the condition is met, proceed to S7; otherwise, jump to S5.

[0071] S7. Turn off the reverse thyristor and block the drive signal. It will automatically turn off when the reverse thyristor current decays to the turn-off current.

[0072] for Figure 3 The switching paths related to P6 and the inverse power control strategies include:

[0073] For path P62, it means that the inverter power supply switches from P6 to P2 due to a fault. At this time, the inverter module stops working. In order to facilitate fault diagnosis, the drive signals of all switching transistors and thyristors should be blocked immediately.

[0074] For path P63, it indicates that the output switch tripped from P6 to P3. Since the inverter module is still operating, the reverse thyristor VT1n should be turned on immediately for a time T. set This is to balance the bus voltage and the input voltage, and reduce voltage fluctuations during the next closing.

[0075] For path P64, it means that the switch is switched from P6 to P4 due to the tripping of the combined switch. Similar to P63, the reverse thyristor VT1n should be turned on immediately to dissipate the energy of the bus capacitor.

[0076] For path P67, it means that the load switch is switched from P6 to P7 due to the closing of the load switch. At this time, the reverse thyristor does not need to be turned on, and the bus energy flows to the load. However, in order to ensure power balance and reduce load impact, when the switch is detected, the PI parameter of the inverter module current inner loop is appropriately reduced, and then slowly restored to the original value according to the control cycle.

[0077] For path P76, it means that the load switch tripped and switched from P7 to P6. In order to reduce the circulating current at the moment of switching, the PI parameter of the inner current loop was appropriately reduced, and then slowly restored.

[0078] The aforementioned hardware improvements and software algorithms have enabled effective control of reverse power, avoiding the problem of inverter power supply overvoltage shutdown in traditional solutions, and improving the stability of the ship's AC power grid and the reliability of load power supply.

[0079] In summary, this invention proposes a multi-unit parallel grid of inverter power supplies with reverse power loops. The grid includes n inverter power supplies with their AC output terminals connected in parallel, where n is an integer greater than or equal to 2.

[0080] Each inverter power supply includes a signal acquisition module, an inverter module, and an inverter power control module.

[0081] The signal acquisition module collects the DC bus voltage, the inverter's input voltage, output voltage, and output inductor current, and sends the collected data to the inverter module and the inverter power control module.

[0082] The inverter module includes a three-phase bridge DC / AC inverter unit and its control circuit, which converts the DC input voltage into a three-phase AC voltage.

[0083] The reverse power control module includes a reverse thyristor and its control drive circuit. Based on the comparison result of the collected DC bus voltage and the input voltage, it generates different control commands. When the comparison result exceeds a preset threshold and the duration exceeds a preset anti-jitter time, the generated control command turns on the reverse thyristor connected in series on the positive DC bus, and guides the excess energy on the DC bus back to the input terminal to prevent the DC bus voltage from being pumped too high. When the reverse thyristor conduction time reaches the preset maximum time limit, the reverse power control module terminates conduction and enters the reset process.

[0084] A reverse power control method for the aforementioned power grid was also proposed. In the power grid operation state, the possibility of reverse power exists only in P6 mode. P6 mode is a parallel no-load state. After two or more inverters enter the single-unit no-load state, the AC output ports of multiple inverters are connected in parallel by closing the corresponding AC distribution board's closing switch, but there is no load.

[0085] Inverse power control is achieved by controlling the switching on of the reverse thyristor, and the following steps are continuously executed:

[0086] S1. Parameter initialization: Set the decision time T s and opening time T on Initialize to 0, and customize the stabilization time T. d , Upper limit of the operating voltage U limit and the maximum activation time T set Among them, the image stabilization time T d satisfy Activation voltage upper limit U limit satisfy Maximum activation time T set satisfy Where Δt represents the execution period of the voltage judgment function, U buslimit This indicates the rated voltage of the bus capacitor.

[0087] S2, Voltage Judgment: The collected input voltage U in With bus voltage U bus In contrast, if U bus - U in ≥ U limit If the condition is met, proceed to S3; otherwise, jump to S7.

[0088] S3, Accumulate the anti-shake judgment time, for Accumulation Each time an addition is made, a subsequent step is evaluated.

[0089] S4. Anti-shake time judgment, if T s ≥ T d If the condition is met, then execute S5; otherwise, jump to S2.

[0090] S5. Turn on the reverse thyristor, and provide a drive signal to the reverse thyristor VT1n through the control drive circuit, while simultaneously... Accumulation Each time an addition is made, a subsequent step is evaluated.

[0091] S6. Activation time determination: If T on ≥ T set If the condition is met, proceed to S7; otherwise, jump to S5.

[0092] S7. Turn off the reverse thyristor and block the drive signal. It will automatically turn off when the reverse thyristor current decays to the turn-off current.

[0093] The steps in this invention can be adjusted, combined, or deleted according to actual needs.

[0094] The units in the device of the present invention can be merged, divided, or reduced according to actual needs.

[0095] In this invention, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention according to the specific circumstances.

[0096] The shapes of the components in the accompanying drawings are schematic and may differ from their actual shapes. The drawings are only used to illustrate the principles of the present invention and are not intended to limit the present invention.

[0097] Although the invention has been disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and not intended to limit the application of the invention. The scope of protection of the invention is defined by the appended claims and may include various modifications, alterations, and equivalents made to the invention without departing from the scope and spirit of the invention.

Claims

1. A multi-machine parallel grid of an inverse power loop inverter power supply, characterized in that, The power grid comprises n inverter power supplies with AC output terminals connected in parallel, wherein n is an integer greater than or equal to 2; Each inverter power supply comprises a signal acquisition module, an inverter module and an inverter power control module; The signal acquisition module acquires DC bus voltage, input voltage, output voltage and output inductance current of the inverter, and sends the acquired data to the inverter module and the inverter power control module; The inverter module comprises a three-phase bridge DC / AC inverter unit and a control circuit thereof, and converts the DC input voltage into three-phase AC voltage; The inverter power control module comprises a reverse thyristor and a control and driving circuit thereof, generates different control instructions based on the comparison result of the acquired DC bus voltage and input voltage, and when the comparison result exceeds a preset threshold and the duration exceeds a preset anti-shake time, the generated control instruction makes the reverse thyristor connected in series on the positive DC bus conduct, and the excess energy on the DC bus is guided back to the input end to prevent the DC bus voltage from being pumped too high; when the reverse thyristor conduction time reaches a preset maximum limit value, the inverter power control module terminates the conduction and enters a reset process.

2. The inverse power circuit inverter power supply multi-machine parallel grid of claim 1, wherein, The power grid further comprises a soft start module and a filter module; The soft start module pre-charges the DC bus capacitor when the DC input switch is closed, and suppresses the peak voltage at the power-on instant through a thyristor buffer board to prevent large current impact at the power-on instant; The filter module suppresses interference signals, the input filter of the filter module suppresses high-frequency interference on the DC input side, the LC filter circuit composed of the DC filter inductance and the DC bus capacitor filters out low-frequency interference on the DC input side, and the output filter filters out harmonic components of the output voltage and current.

3. The inverse power circuit inverter power supply multi-machine parallel grid of claim 1, wherein, The control circuit of the inverter module performs Clark transformation and Park transformation on the sampled output three-phase AC voltage and output three-phase inductance current to obtain DQ axis components, compares the DQ axis components with DQ axis reference voltage and current, obtains duty cycle signals through double PI closed-loop control, generates PWM signals through modulation technology, and sends the PWM signals to the corresponding switching tubes in the inverter circuit after amplification by the driving board.

4. A method for controlling the reverse power of a reverse power loop inverter power supply multi-machine parallel power grid as claimed in any one of claims 1-3, characterized in that, The possibility of inverter power exists only in P6 mode in the working state of the power grid, P6 mode is a parallel no-load state, and two or more inverter power supplies enter single-machine no-load state, realize parallel connection of the AC output ports of the multiple inverter power supplies by closing the combined switch of the corresponding AC distribution board, but there is no load; The inverter power control is realized by controlling the opening of the reverse thyristor, and the following steps are continuously executed: S1, parameter initialization: the determination time T s and the opening time T on are initialized to 0, and the anti-shake time T d , the upper limit of the opening voltage U limit and the upper limit of the opening time T set are set by the user; wherein the anti-shake time T d satisfies , the upper limit of the opening voltage U limit satisfies , and the upper limit of the opening time T set satisfies ; wherein Δt represents the execution period of the voltage determination function, U buslimit represents the rated voltage of the bus capacitor; S2, voltage determination: the input voltage U in and the bus voltage U bus In contrast, if U bus - U in ≥ U limit S3 is executed, otherwise jump to S7; S3, anti-shake determination time accumulation, against accumulation each time the subsequent step is performed once S4, judgment of anti-shake time, if T s ≥ T d , then execute S5, otherwise jump to S2; S5, open the reverse thyristor, through the control drive circuit for reverse thyristor VT1n provides driving signal, while the accumulation , each time the next step is performed once the judgment; S6, open time judgment, if T on ≥ T set , then execute S7, otherwise jump to S5; S7, close the reverse thyristor and block the driving signal, and automatically close when the reverse thyristor current decays to the off current.

5. The reverse power control method of claim 4, wherein, The working modes of the inverter power supply are divided into seven modes, and the remaining working modes except P6 include: P1 mode is a shutdown state, at this time the input switch and the output switch are both in the open state, the DC input voltage is 0, and the main circuit is not electrified; closing the input switch in P1 mode switches to P2 mode. The P2 mode is a power-on state, in which the input switch is closed, the DC bus capacitor is pre-charged, but the switch tube of the inverter module is in an off state, and the AC output terminal voltage is 0; the switch tube of the inverter module is turned on in the P2 mode, i.e., switching to the P3 mode; the switch tube of the inverter module is turned off in the P3, P4, P5, P6 and P7 modes, i.e., returning to the P2 mode; The P3 mode is a standby state, in which the inverter module starts to work to realize three-phase AC output, but the output switch is not closed; the output switch is closed in the P3 mode, in which case the load switch is turned off to enter the P4 mode, and the load switch is closed to directly enter the P5 mode; the output switch is turned off in the P4, P6 and P7 modes, i.e., returning to the P3 mode; The P4 mode is a single-machine no-load state, in which the output switch is closed, the corresponding AC distribution board is powered on, but there is no load; the load switch is closed in the P4 mode to enter the P5 mode; two or more inverter power sources enter the P4 mode, and then enter the P6 mode by closing the combined switch of the corresponding AC distribution board; The P5 mode is a single-machine load state, in which the load switch is closed, and the inverter power source supplies power to the AC load; two or more inverter power sources enter the P5 mode, and then enter the P7 mode by closing the combined switch of the corresponding AC distribution board; The P7 mode is a parallel load state, in which the load switch of the AC power grid is closed, and the parallel inverter power sources supply power to the AC load together.

6. The inverse power circuit inverter power supply multi-machine parallel grid of claim 5, wherein, The switching paths related to the P6 mode include P62, P63, P64, P67 and P76 paths, and the inverse power control strategies of these paths include: For the P62 path, when switching from P6 to P2, the driving signals of all switch tubes and thyristors are immediately blocked; For the P63 path, the reverse thyristor is turned on immediately when switching from P6 to P3, with a turn-on time of T set to balance the bus voltage and the input voltage; For the P64 path, when switching from P6 to P4, the reverse thyristor is immediately turned on to dissipate the bus capacitor energy; For the P67 path, when switching from P6 to P7, the reverse thyristor does not need to be turned on, but the inverter module current inner loop PI parameters are appropriately reduced, and then slowly restored to the original value according to the control period; For the P76 path, when switching from P7 to P6, the current inner loop PI parameters are appropriately reduced, and then slowly restored.

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