Long-distance offshore wind power low-frequency combined power transmission system and operation mode thereof

Abstract

The present application relates to the offshore wind power technical field, especially to a kind of medium and long distance offshore wind power low-frequency combination power transmission system and its operating mode, system includes: M3C converter and its control system, M3C converter operating state conversion switch group, and M3C converter energy consumption switch and energy consumption resistance R1;Electric motor and generator coaxial M-G equipment and its control system, M-G equipment operating state conversion switch group, and M-G equipment energy consumption switch and energy consumption resistance R2;By switching M3C converter operating state conversion switch group, M3C converter energy consumption switch, M-G equipment operating state conversion switch group and M-G equipment energy consumption switch, realize including at least maintenance, cold standby, hot standby, connection, operation, energy consumption Multiple operating states, to switch between operating states according to grid and new energy access situation.The present application can provide stable support capability for grid, help to solve offshore wind power grid connection and efficient consumption problem.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of offshore wind power technology, and in particular to a medium and long distance offshore wind power low-frequency combined power transmission system and its operation mode. BACKGROUND

[0002] In recent years, the global energy transformation has been accelerating, and offshore wind power, with its clean, stable and efficient characteristics, has become one of the important directions of new energy development. Compared with onshore wind power, offshore wind power has higher wind speed, more stable weather conditions and more developable space. With the exhaustion of nearshore wind power resources, offshore wind power is gradually developing towards medium and long distances.

[0003] The economic efficiency of power frequency alternating current and flexible DC power transmission grid connection mode is low, which is difficult to meet the demand of medium and long distance wind power grid connection and transmission. Low-frequency power transmission technology reduces the line reactance, enhances the line transmission capacity by reducing the transmission frequency, and is suitable for 80~180km distance transmission scenarios. However, the existing low-frequency power transmission technology uses a large number of power electronic devices, which leads to the fact that the active support capacity of the grid-connected wind turbine cannot be effectively utilized, the inertia support capacity is insufficient, and the frequency control capacity is lacking.

[0004] In order to meet the economic and reliable grid connection demand of large-scale medium and long distance offshore wind power, it is urgent to innovate the medium and long distance offshore wind power low-frequency combined power transmission technology, which can not only realize the safe, economic and efficient transmission of offshore wind energy resources to the onshore power grid, but also provide independent synchronization and stability support capacity for the power grid.

[0005] The information disclosed in this BACKGROUND section is only intended to enhance the understanding of the general background of the application, and should not be considered as recognition or suggestion that this information forms the prior art known by those skilled in the art. SUMMARY

[0006] The present application provides a medium and long distance offshore wind power low-frequency combined power transmission system and its operation mode, thereby effectively solving the problems in the background art.

[0007] In order to achieve the above purpose, the technical solution adopted by the present application is as follows: a medium and long distance offshore wind power low-frequency combined power transmission system, comprising:

[0008] M3C converter and its control system, M3C converter operating state conversion switch group, and M3C converter energy consumption switch and energy consumption resistor R1;

[0009] Motor and generator coaxial M-G device and its control system, M-G device operating state conversion switch group, and M-G device energy consumption switch and energy consumption resistor R2;

[0010] By switching the M3C converter operating status switching group, the M3C converter energy consumption switch, the MG equipment operating status switching group, and the MG equipment energy consumption switch, multiple operating states, including at least maintenance, cold standby, hot standby, connection, operation, and energy consumption, can be achieved, and switching between these operating states can be made according to the grid and new energy access situation.

[0011] Furthermore, the M3C converter adopts a 3×3 matrix bridge arm structure, and each bridge arm is composed of modular multilevel cascaded components. By controlling the sub-converters on the power frequency side and the low frequency side and superimposing them according to the bridge arm relationship, frequency conversion control between low frequency and power frequency can be achieved.

[0012] Furthermore, the MG device is a coaxial connection structure of a motor M and a generator G, which realizes the conversion between low-frequency current and power-frequency current based on the number of pole pairs of the motor and the generator, that is:

[0013] ;

[0014] In the formula, f1 represents the wind turbine side frequency, f2 represents the grid side frequency, and p M p represents the number of pole pairs of the electric motor. G This indicates the number of pole pairs of the generator.

[0015] Furthermore, the M3C converter operating state switching switch group includes: QF11, QF12, QS11, and QS12;

[0016] The QF11 is located at the incoming line position between the M3C converter and the low-frequency bus, and is used to control the connection / disconnection between the M3C converter and the low-frequency bus;

[0017] The QF12 is located at the outgoing line position between the M3C converter and the power frequency bus, and is used to control the connection / disconnection between the M3C converter and the power grid.

[0018] One end of QS11 is located between the M3C converter and QF11, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter.

[0019] One end of QS12 is located between the M3C converter and QF12, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter.

[0020] The MG device operating status conversion switch group includes QF21, QF22, QS21, and QS22;

[0021] The QF21 is located at the inlet position between the MG device and the low-frequency bus, and is used to control the connection / disconnection between the MG device and the low-frequency bus;

[0022] The QF22 is located at the outgoing line position between the MG device and the power frequency bus, and is used to control the connection / disconnection between the MG device and the power grid.

[0023] One end of QS21 is located between the MG device and QF21, and the other end is directly grounded. It is used to control the power outage / maintenance of the MG device.

[0024] One end of the QS22 is located between the MG device and the QF22, and the other end is directly grounded. It is used to control the power outage / maintenance of the MG device.

[0025] Furthermore, QF11, QF12, QS11, QS12 and QF21, QF22, QS21, QS22 have the ability to directly interrupt current, and QF11 and QF21 have an interlocking function.

[0026] Furthermore, the selection parameters for QF11 and QF12 are as follows:

[0027] ;

[0028] In the formula, P1 represents the rated power of the wind farm, U1 represents the rated voltage on the high-voltage side of the offshore substation, and U e11 Indicates the rated voltage of switches QF11 and QF12, I e11 Indicates the rated current of switches QF11 and QF12, I m11 Indicates the rated short-circuit breaking current of switches QF11 and QF12;

[0029] The selection parameters for QF21 and QF22 are as follows:

[0030] ;

[0031] In the formula, U e21 Indicates the rated voltage of switches QF21 and QF22, I e21 Indicates the rated current of switches QF21 and QF22, I m21 Indicates the rated short-circuit breaking current of switches QF21 and QF22;

[0032] The selection parameters for QS11 and QS12 are as follows:

[0033] ;

[0034] In the formula, U e12 Indicates the rated voltage of switches QS11 and QS12, I e12 Indicates the rated current of switches QS11 and QS12, I m12 Indicates the rated short-circuit breaking current of switches QS11 and QS12;

[0035] The selection parameters for QS21 and QS22 are as follows:

[0036] ;

[0037] In the formula, U e22 Indicates the rated voltage of switches QS21 and QS22, I e22 Indicates the rated current of switches QS21 and QS22, I m22 This indicates the rated short-circuit breaking current of switches QS21 and QS22.

[0038] Furthermore, the selection parameters for the power dissipation resistor R1 of the M3C converter are as follows:

[0039] ;

[0040] In the formula, U e13 This indicates the rated voltage of the energy-consuming resistor R1, R R1 This indicates the resistance value of the energy-consuming resistor R1;

[0041] The selection parameters for the energy-consuming resistor R2 of the MG equipment are as follows:

[0042] ;

[0043] In the formula, U e23 This indicates the rated voltage of the energy-consuming resistor R2, R R2 This indicates the resistance value of the energy-consuming resistor R2.

[0044] Furthermore, the selection parameters for the M3C converter power dissipation switch QF13 are as follows:

[0045] ;

[0046] In the formula, U e14 Indicates the rated voltage of switch QF13, I e14 Indicates the rated current of switch QF13, I m14 This indicates the rated short-circuit breaking current of switch QF13;

[0047] The selection parameters for the MG equipment energy dissipation switch QF23 are as follows:

[0048] ;

[0049] In the formula, U e24 Indicates the rated voltage of switch QF23, I e24 Indicates the rated current of switch QF23, I m24 This indicates the rated short-circuit breaking current of switch QF23.

[0050] Furthermore, the M3C converter includes the following operating states:

[0051] M3C converter maintenance status: QF11, QF12, and QF13 are open, QS11 and QS12 are closed, and the M3C converter is locked and depressurized.

[0052] M3C converter cold standby state: QF11, QF12, QF13 are disconnected, QS11, QS12 are disconnected, M3C converter is locked and unpressurized;

[0053] M3C converter hot standby status: QF11 and QF13 are open, QF12 is closed, QS11 and QS12 are open, and the M3C converter is unlocked for voltage regulation.

[0054] M3C converter connection status: QF11 and QF13 are disconnected, QF12 is closed, QS11 and QS12 are disconnected, and the M3C converter is unlocked for reactive power control.

[0055] M3C converter operating status: QF11 and QF12 are closed, QF13 is open, QS11 and QS12 are open, and the M3C converter unlocks the frequency conversion control.

[0056] M3C converter power consumption state: QF11 and QF13 are closed, QF12 is open, QS11 and QS12 are open, the M3C converter unlocks the frequency conversion control, and power is consumed through resistor R1.

[0057] Furthermore, the MG device includes the following operating states:

[0058] MG equipment maintenance status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are closed, and the MG equipment is stopped.

[0059] MG equipment in cold standby status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are disconnected, and the MG equipment is shut down;

[0060] MG equipment hot standby status: QF21 and QF23 are open, QF22 is closed, QS21 and QS22 are open, the generator of the MG equipment is running in power generation mode, and the motor is running at low frequency synchronous speed.

[0061] MG device connection status: QF21 and QF23 are disconnected, QF22 is closed, QS21 and QS22 are disconnected. The MG device is operating in synchronous condenser mode to achieve reactive power control.

[0062] MG equipment operating status: QF21 and QF22 are closed, QF23 is open, QS21 and QS22 are open, the MG equipment is operating normally, and frequency conversion control is achieved by different pole pairs;

[0063] MG device energy consumption status: QF21 and QF23 are closed, QF22 is open, QS21 and QS22 are open, the MG device is operating normally and consumes energy through resistor R2.

[0064] Furthermore, the system is configured to perform at least one of the following operating modes:

[0065] M3C converter in operation, MG equipment in hot standby;

[0066] MG equipment is running, M3C converter is in hot standby;

[0067] M3C converter is running, MG device is connected;

[0068] The MG device is running, and the M3C converter is connected.

[0069] The M3C converter consumes energy, and the MG equipment is in cold standby mode.

[0070] MG equipment consumes energy, and the M3C converter is in cold standby mode;

[0071] M3C converter under maintenance, MG equipment in operation;

[0072] MG equipment under maintenance, M3C converter in operation;

[0073] M3C converter hot standby, MG equipment hot standby;

[0074] M3C converter connection, MG device connection;

[0075] M3C converter repair, MG equipment repair;

[0076] Each method triggers and executes corresponding switching actions based on the grid's rotational inertia support capacity, reactive power support capacity, new energy access ratio, grid faults, and equipment faults to achieve state switching.

[0077] This invention also includes an operation mode for a medium-to-long-distance offshore wind power low-frequency combined transmission system, wherein operating the system as described above includes the following steps:

[0078] Monitor the grid-side rotational inertia support capacity, reactive power support capacity, wind turbine-side output status, grid status, and the proportion of new energy access;

[0079] Based on the monitoring results, the operating status of the M3C converter and the MG device is selected and switched according to the preset strategy;

[0080] By controlling the connection / disconnection of the corresponding M3C converter operating status switching group, M3C converter energy consumption switch, MG device operating status switching group, and MG device energy consumption switch, the system can switch between multiple operating modes.

[0081] Furthermore, the preset strategy includes:

[0082] When the grid has strong rotational inertia support capability, the M3C converter should be put into operation first.

[0083] When the power grid's rotational inertia support capacity is weak, the MG equipment should be put into operation first.

[0084] When the reactive power support capability is strong, the M3C converter or / and MG equipment should be put in hot standby mode first.

[0085] When the reactive power support capability is weak, the M3C converter or / and MG equipment should be kept in the connected state first.

[0086] When a fault occurs on the grid side that prevents the transmission of power, the M3C converter or MG equipment should be put into a power-consuming state first to protect the equipment and achieve orderly shutdown or state switching in a short time.

[0087] And in the event of equipment failure or maintenance, the switching is completed in accordance with the interlocking and safety sequence.

[0088] The present invention also includes a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the manner described above.

[0089] The present invention also includes a storage medium having a computer program stored thereon, which, when executed by a processor, implements the manner described above.

[0090] The beneficial effects of this invention are as follows: By controlling the operating status of the M3C converter and MG equipment, it effectively ensures the safe, economical, and efficient transmission of offshore wind energy resources into the onshore power grid, while also providing the power grid with autonomous synchronization and stability support capabilities, thus helping to solve the problems of friendly grid connection and efficient consumption of offshore wind power. Through switching between multiple operating modes, it can be applied to different power grid scenarios, expanding its application scope; by adopting a low-frequency combined transmission system based on the M3C converter and MG equipment, offshore wind power can still be reliably transmitted even when a single M3C converter or MG equipment fails, reducing wind curtailment and ensuring the safety and stability of the power grid. Attached Figure Description

[0091] 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.

[0092] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0093] Figure 2 This is a schematic diagram illustrating various operating modes;

[0094] Figure 3 This is a flowchart illustrating the operation mode of the present invention;

[0095] Figure 4 A flowchart for a preset strategy;

[0096] Figure 5 This is a schematic diagram of the structure of the computer device of the present invention. Detailed Implementation

[0097] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0098] Example 1:

[0099] like Figure 1 As shown: A medium-to-long-distance offshore wind power low-frequency combined transmission system, comprising:

[0100] M3C converter and its control system, M3C converter operating status switching group, and M3C converter power consumption switch and power consumption resistor R1;

[0101] The coaxial motor and generator MG equipment and its control system, the MG equipment operation status conversion switch group, and the MG equipment energy consumption switch and energy consumption resistor R2;

[0102] By switching the M3C converter operating status switching group, the M3C converter energy consumption switch, the MG equipment operating status switching group, and the MG equipment energy consumption switch, multiple operating states, including at least maintenance, cold standby, hot standby, connection, operation, and energy consumption, can be achieved, so as to switch between operating states according to the grid and new energy access situation.

[0103] By controlling the operating status of the M3C converter and MG equipment, the system effectively ensures the safe, economical, and efficient transmission of offshore wind energy resources into the onshore power grid. It also provides the grid with autonomous synchronization and stability support capabilities, helping to solve the challenges of friendly grid connection and efficient absorption of offshore wind power. Through switching between multiple operating modes, it can be applied to different grid scenarios, expanding its application scope. Using a low-frequency combined transmission system based on the M3C converter and MG equipment, even if only one of the M3C converter or MG equipment fails, offshore wind power can still be reliably transmitted, reducing wind curtailment and ensuring grid security and stability.

[0104] The M3C converter adopts a 3×3 matrix bridge arm structure, and each bridge arm is composed of modular multilevel cascaded components. By controlling the sub-converters on the power frequency side and the low frequency side and superimposing them according to the bridge arm relationship, frequency conversion control between low frequency and power frequency can be achieved.

[0105] The MG device is a coaxial connection structure between a motor M and a generator G. It converts low-frequency current to power-frequency current based on the number of pole pairs of the motor and generator.

[0106] ;

[0107] In the formula, f1 represents the wind turbine side frequency, f2 represents the grid side frequency, and p M p represents the number of pole pairs of the electric motor. G This indicates the number of pole pairs of the generator.

[0108] In this embodiment, the M3C converter operating state switching switch group includes: QF11, QF12, QS11, and QS12;

[0109] QF11 is located at the incoming line position between the M3C converter and the low-frequency bus, and is used to control the connection / disconnection between the M3C converter and the low-frequency bus;

[0110] QF12 is located at the outgoing line position between the M3C converter and the power frequency bus, and is used to control the connection / disconnection between the M3C converter and the power grid.

[0111] One end of QS11 is located between the M3C converter and QF11, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter.

[0112] One end of QS12 is located between the M3C converter and QF12, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter.

[0113] The MG equipment operating status conversion switch group includes QF21, QF22, QS21, and QS22;

[0114] QF21 is located at the incoming line position between the MG equipment and the low-frequency bus, and is used to control the connection / disconnection between the MG equipment and the low-frequency bus;

[0115] QF22 is located at the outgoing line position between the MG equipment and the power frequency bus, and is used to control the connection / disconnection between the MG equipment and the power grid;

[0116] One end of QS21 is located between the MG device and QF21, and the other end is directly grounded. It is used to control the power outage / maintenance of the MG device.

[0117] One end of QS22 is located between the MG device and QF22, and the other end is directly grounded. It is used to control the MG device for power outages / maintenance.

[0118] Among them, QF11, QF12, QS11, QS12 and QF21, QF22, QS21, QS22 have the ability to directly interrupt current, and QF11 and QF21 have interlocking function.

[0119] The selection parameters for QF11 and QF12 are as follows:

[0120] ;

[0121] In the formula, P1 represents the rated power of the wind farm, U1 represents the rated voltage on the high-voltage side of the offshore substation, and U e11 Indicates the rated voltage of switches QF11 and QF12, I e11 Indicates the rated current of switches QF11 and QF12, I m11 Indicates the rated short-circuit breaking current of switches QF11 and QF12;

[0122] The selection parameters for QF21 and QF22 are as follows:

[0123] ;

[0124] In the formula, U e21 Indicates the rated voltage of switches QF21 and QF22, I e21 Indicates the rated current of switches QF21 and QF22, I m21 Indicates the rated short-circuit breaking current of switches QF21 and QF22;

[0125] The selection parameters for QS11 and QS12 are as follows:

[0126] ;

[0127] In the formula, U e12 Indicates the rated voltage of switches QS11 and QS12, I e12 Indicates the rated current of switches QS11 and QS12, I m12 Indicates the rated short-circuit breaking current of switches QS11 and QS12;

[0128] The selection parameters for QS21 and QS22 are as follows:

[0129] ;

[0130] In the formula, U e22 Indicates the rated voltage of switches QS21 and QS22, I e22 Indicates the rated current of switches QS21 and QS22, I m22This indicates the rated short-circuit breaking current of switches QS21 and QS22.

[0131] The selection parameters for the power dissipation resistor R1 of the M3C converter are as follows:

[0132] ;

[0133] In the formula, U e13 This indicates the rated voltage of the energy-consuming resistor R1, R R1 This indicates the resistance value of the energy-consuming resistor R1;

[0134] The selection parameters for the energy-consuming resistor R2 of the MG equipment are as follows:

[0135] ;

[0136] In the formula, U e23 This indicates the rated voltage of the energy-consuming resistor R2, R R2 This indicates the resistance value of the energy-consuming resistor R2.

[0137] The selection parameters for the M3C converter power dissipation switch QF13 are as follows:

[0138] ;

[0139] In the formula, U e14 Indicates the rated voltage of switch QF13, I e14 Indicates the rated current of switch QF13, I m14 This indicates the rated short-circuit breaking current of switch QF13;

[0140] The selection parameters for the MG equipment energy dissipation switch QF23 are as follows:

[0141] ;

[0142] In the formula, U e24 Indicates the rated voltage of switch QF23, I e24 Indicates the rated current of switch QF23, I m24 This indicates the rated short-circuit breaking current of switch QF23.

[0143] The M3C converter includes the following operating states:

[0144] M3C converter maintenance status: QF11, QF12, and QF13 are open, QS11 and QS12 are closed, and the M3C converter is locked and depressurized.

[0145] M3C converter cold standby state: QF11, QF12, QF13 are disconnected, QS11, QS12 are disconnected, M3C converter is locked and unpressurized;

[0146] M3C converter hot standby status: QF11 and QF13 are open, QF12 is closed, QS11 and QS12 are open, and the M3C converter is unlocked for voltage regulation.

[0147] M3C converter connection status: QF11 and QF13 are disconnected, QF12 is closed, QS11 and QS12 are disconnected, and the M3C converter is unlocked for reactive power control.

[0148] M3C converter operating status: QF11 and QF12 are closed, QF13 is open, QS11 and QS12 are open, and the M3C converter unlocks the frequency conversion control.

[0149] M3C converter power consumption state: QF11 and QF13 are closed, QF12 is open, QS11 and QS12 are open, the M3C converter unlocks the frequency conversion control, and power is consumed through resistor R1.

[0150] The MG device includes the following operating states:

[0151] MG equipment maintenance status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are closed, and the MG equipment is stopped.

[0152] MG equipment in cold standby status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are disconnected, and the MG equipment is shut down;

[0153] MG equipment hot standby status: QF21 and QF23 are open, QF22 is closed, QS21 and QS22 are open, the generator of the MG equipment is running in power generation mode, and the motor is running at low frequency synchronous speed.

[0154] MG device connection status: QF21 and QF23 are disconnected, QF22 is closed, QS21 and QS22 are disconnected. The MG device is operating in synchronous condenser mode to achieve reactive power control.

[0155] MG equipment operating status: QF21 and QF22 are closed, QF23 is open, QS21 and QS22 are open, the MG equipment is operating normally, and frequency conversion control is achieved by different pole pairs;

[0156] MG device energy consumption status: QF21 and QF23 are closed, QF22 is open, QS21 and QS22 are open, the MG device is operating normally and consumes energy through resistor R2.

[0157] like Figure 2 As shown, in this embodiment, the system is configured and can implement at least one of the following operating modes:

[0158] M3C converter in operation, MG equipment in hot standby;

[0159] MG equipment is running, M3C converter is in hot standby;

[0160] M3C converter is running, MG device is connected;

[0161] The MG device is running, and the M3C converter is connected.

[0162] The M3C converter consumes energy, and the MG equipment is in cold standby mode.

[0163] MG equipment consumes energy, and the M3C converter is in cold standby mode;

[0164] M3C converter under maintenance, MG equipment in operation;

[0165] MG equipment under maintenance, M3C converter in operation;

[0166] M3C converter hot standby, MG equipment hot standby;

[0167] M3C converter connection, MG device connection;

[0168] M3C converter repair, MG equipment repair;

[0169] Each method triggers and executes corresponding switching actions based on the grid's rotational inertia support capacity, reactive power support capacity, new energy access ratio, grid faults, and equipment faults to achieve state switching.

[0170] like Figure 3 As shown, this embodiment also includes an operation mode for a medium-to-long-distance offshore wind power low-frequency combined transmission system. Operating the system as described above includes the following steps:

[0171] Monitor the grid-side rotational inertia support capacity, reactive power support capacity, wind turbine-side output status, grid status, and the proportion of new energy access;

[0172] Based on the monitoring results, the operating status of the M3C converter and the MG device is selected and switched according to the preset strategy;

[0173] Control the connection / disconnection of the corresponding M3C converter operating status switching group, M3C converter energy consumption switch, MG equipment operating status switching group and MG equipment energy consumption switch to realize the system switching between multiple operating modes.

[0174] like Figure 4 As shown, the preset strategies include:

[0175] When the grid has strong rotational inertia support capability, the M3C converter should be put into operation first.

[0176] When the power grid's rotational inertia support capacity is weak, the MG equipment should be put into operation first.

[0177] When the reactive power support capability is strong, the M3C converter or / and MG equipment should be put in hot standby mode first.

[0178] When the reactive power support capability is weak, the M3C converter or / and MG equipment should be kept in the connected state first.

[0179] When a fault occurs on the grid side that prevents the transmission of power, the M3C converter or MG equipment should be put into a power-consuming state first to protect the equipment and achieve orderly shutdown or state switching in a short time.

[0180] And in the event of equipment failure or maintenance, the switching is completed in accordance with the interlocking and safety sequence.

[0181] Example 2:

[0182] In this embodiment, the long-distance offshore wind power low-frequency combined transmission system is as follows: Figure 1 As shown.

[0183] The low-frequency combined transmission system includes an M3C converter and its control system, M3C converter operation status switching switches QF11, QF12, QS11, and QS12, M3C converter energy dissipation switch QF13 and energy dissipation resistor R1, MG equipment and its control system, MG equipment operation status switching switches QF21, QF22, QS21, and QS22, MG equipment energy dissipation switch QF23 and energy dissipation resistor R2.

[0184] The M3C converter adopts a 3×3 matrix bridge arm structure. Each bridge arm is composed of modular multilevel cascaded components. Its basic principle is to control the sub-converters on the power frequency and low frequency sides and superimpose them according to the bridge arm relationship to realize the frequency conversion control of M3C.

[0185] The MG device adopts a coaxial connection structure between a motor (M) and a generator (G). Its basic principle is to convert low-frequency current to power-frequency current based on the number of pole pairs of the motor and generator, that is:

[0186] ;

[0187] In the formula, f1 represents the wind turbine side frequency, f2 represents the grid side frequency, and p M p represents the number of pole pairs of the electric motor. G This indicates the number of pole pairs of the generator.

[0188] The M3C converter operation status switching switches QF11, QF12, QS11, and QS12, and the MG equipment operation status switching switches QF21, QF22, QS21, and QS22 have direct current interruption capability. QF11 and QF21 have interlocking functionality. The selection parameters for QF11 and QF12 are as follows:

[0189] ;

[0190] In the formula, P1 represents the rated power of the wind farm, U1 represents the rated voltage on the high-voltage side of the offshore substation, and U e11 Indicates the rated voltage of switches QF11 and QF12, I e11 Indicates the rated current of switches QF11 and QF12, I m11 This indicates the rated short-circuit breaking current of switches QF11 and QF12.

[0191] The selection parameters for QF21 and QF22 are as follows:

[0192] ;

[0193] In the formula, U e21 Indicates the rated voltage of switches QF21 and QF22, I e21 Indicates the rated current of switches QF21 and QF22, I m21 This indicates the rated short-circuit breaking current of switches QF21 and QF22.

[0194] The selection parameters for QS11 and QS12 are as follows:

[0195] ;

[0196] In the formula, U e12 Indicates the rated voltage of switches QS11 and QS12, I e12 Indicates the rated current of switches QS11 and QS12, I m12 This indicates the rated short-circuit breaking current of switches QS11 and QS12.

[0197] The selection parameters for QS21 and QS22 are as follows:

[0198] ;

[0199] In the formula, U e22 Indicates the rated voltage of switches QS21 and QS22, I e22 Indicates the rated current of switches QS21 and QS22, I m22 This indicates the rated short-circuit breaking current of switches QS21 and QS22.

[0200] The selection parameters for the power dissipation resistor R1 of the M3C converter are as follows:

[0201] ;

[0202] In the formula, U e13 This indicates the rated voltage of the energy-consuming resistor R1, R R1 This indicates the resistance value of the energy-consuming resistor R1.

[0203] The selection parameters for the energy-consuming resistor R2 of the MG device are as follows:

[0204] ;

[0205] In the formula, U e23 This indicates the rated voltage of the energy-consuming resistor R2, R R2 This indicates the resistance value of the energy-consuming resistor R2.

[0206] The selection parameters for the M3C converter power dissipation switch QF13 are as follows:

[0207] ;

[0208] In the formula, U e14 Indicates the rated voltage of switch QF13, I e14 Indicates the rated current of switch QF13, I m14 This indicates the rated short-circuit breaking current of switch QF13.

[0209] The selection parameters for the MG equipment energy dissipation switch QF23 are as follows:

[0210] ;

[0211] In the formula, U e24 Indicates the rated voltage of switch QF23, I e24 Indicates the rated current of switch QF23, I m24 This indicates the rated short-circuit breaking current of switch QF23.

[0212] The low-frequency combined power transmission system has 11 operating modes, including six states for the M3C converter and MG equipment: maintenance, cold standby, hot standby, connection, operation, and energy consumption.

[0213] The six states of the M3C converter are:

[0214] (1) M3C converter under maintenance status: QF11, QF12, and QF13 are open, QS11 and QS12 are closed, and the M3C converter is locked and depressurized;

[0215] (2) M3C converter cold standby state: QF11, QF12, QF13 are disconnected, QS11, QS12 are disconnected, and the M3C converter is locked without pressure;

[0216] (3) M3C converter hot standby state: QF11 and QF13 are open, QF12 is closed, QS11 and QS12 are open, and the M3C converter is unlocked and regulated.

[0217] (4) M3C converter connection status: QF11 and QF13 are disconnected, QF12 is closed, QS11 and QS12 are disconnected, and the M3C converter is unlocked for reactive power control;

[0218] (5) M3C converter operating status: QF11 and QF12 are closed, QF13 is open, QS11 and QS12 are open, and the M3C converter unlocks the frequency conversion control;

[0219] (6) M3C converter power consumption state: QF11 and QF13 are closed, QF12 is open, QS11 and QS12 are open, the M3C converter unlocks the frequency conversion control, and power is consumed through resistor R1.

[0220] The six states of an MG device are:

[0221] (1) MG equipment maintenance status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are closed, and the MG equipment is shut down;

[0222] (2) MG equipment in cold standby state: QF21, QF22, QF23 are disconnected, QS21, QS22 are disconnected, and the MG equipment is shut down;

[0223] (3) MG equipment hot standby status: QF21 and QF23 are open, QF22 is closed, QS21 and QS22 are open, the generator of the MG equipment is running in power generation mode, and the motor is running at low frequency synchronous speed;

[0224] (4) MG equipment connection status: QF21 and QF23 are disconnected, QF22 is closed, QS21 and QS22 are disconnected, the MG equipment is running in the synchronous condenser state to realize reactive power control;

[0225] (5) MG equipment operating status: QF21 and QF22 are closed, QF23 is open, QS21 and QS22 are open, the MG equipment is operating normally, and frequency conversion control is achieved by different pole pairs;

[0226] (6) Energy consumption status of MG equipment: QF21 and QF23 are closed, QF22 is open, QS21 and QS22 are open, the MG equipment is operating normally and consumes energy through resistor R2.

[0227] The operation mode of the low-frequency combined transmission system is as follows:

[0228] Method 1: When the proportion of new energy sources such as photovoltaic and wind power is relatively small, the grid rotational inertia support capacity is strong, the reactive power support capacity is strong, and the grid side, wind turbine side, M3C converter and MG equipment are all normal, the M3C converter is in the running state and the MG equipment is in the hot standby state; when the MG equipment needs maintenance or fails, the MG equipment is switched to the maintenance state.

[0229] Method 2: When the proportion of new energy sources such as photovoltaic and wind power is relatively large, the grid rotational inertia support capacity is relatively weak, the reactive power support capacity is relatively strong, and the grid side, wind turbine side, M3C converter and MG equipment are all normal, the MG equipment is in the running state and the M3C converter is in the hot standby state; when the M3C converter needs maintenance or fails, the M3C converter is switched to the maintenance state.

[0230] Method 3: When the proportion of new energy sources such as photovoltaic and wind power is relatively small, the grid rotational inertia support capacity is strong, the reactive power support capacity is insufficient, and the grid side, wind turbine side, M3C converter and MG equipment are all normal, the M3C converter is in the running state and the MG equipment is in the connected state; when the MG equipment needs maintenance or malfunctions, the MG equipment is switched to the maintenance state.

[0231] Method 4: When the proportion of new energy sources such as photovoltaic and wind power is large, the grid rotational inertia support capacity is weak, the reactive power support capacity is insufficient, and the grid side, wind turbine side, M3C converter and MG equipment are all normal, the MG equipment is in the running state and the M3C converter is in the connected state; when the M3C converter needs maintenance or fails, the M3C converter is switched to the maintenance state.

[0232] Method 5: When the proportion of new energy sources such as photovoltaic and wind power is relatively small, and the grid rotational inertia support capacity is strong, regardless of the strength of reactive power support capacity, if a grid-side fault occurs and power cannot be transmitted, and the wind turbine side, M3C converter, and MG equipment are all normal, the M3C converter is in a power consumption state, and the MG equipment is in a cold standby state; when the grid-side fault cannot be restored in a short time, the wind turbine stops operating, and the M3C converter is switched to a cold standby state.

[0233] Method 6: When the proportion of new energy sources such as photovoltaic and wind power is large, the grid's rotational inertia support capacity is weak. Regardless of whether the reactive power support capacity is strong, if a grid-side fault occurs and power cannot be transmitted, and the wind turbine, M3C converter, and MG equipment are all normal, the MG equipment is in an energy-consuming state, and the M3C converter is in a cold standby state. When the grid fault cannot be restored in a short time, the wind turbine stops operating, and the MG equipment is switched to a cold standby state.

[0234] Method 7: When the proportion of new energy sources such as photovoltaic and wind power is small and the grid rotational inertia support capability is strong, regardless of whether the reactive power support capability is strong, if the M3C converter sends a fault, and the grid side, wind turbine side and MG equipment are all normal, the M3C converter is in maintenance state and the MG equipment is in operation state.

[0235] Method 8: When the proportion of new energy sources such as photovoltaic and wind power is large and the grid rotational inertia support capacity is weak, regardless of whether the reactive power support capacity is strong, if the MG equipment fails and the grid side, wind turbine side and M3C converter are all normal, the MG equipment is in maintenance state and the M3C converter is in operation state.

[0236] Method 9: Regardless of the proportion of new energy sources such as photovoltaics and wind power, regardless of whether the grid rotational inertia support capability is strong or weak, whether the reactive power support capability is strong, when there is a fault on the wind turbine side or the wind speed is too low and the output power cannot be stable, and when the grid side, M3C converter and MG equipment are all normal, the M3C converter is in hot standby state and the MG equipment is in hot standby state.

[0237] Method 10: Regardless of the proportion of new energy sources such as photovoltaic and wind power, regardless of whether the grid rotational inertia support capacity is strong or weak, the reactive power support capacity is insufficient, the wind turbine side has a transmission fault or the wind speed is too low and cannot output power stably, and the grid side, M3C converter and MG equipment are all normal, the M3C converter is in the connected state and the MG equipment is in the connected state.

[0238] Method 11: When both the M3C converter and the MG device need maintenance or are faulty, the M3C converter is in maintenance mode and the MG device is in maintenance mode.

[0239] By controlling the operating status of the M3C converter and MG equipment, the system effectively ensures the safe, economical, and efficient transmission of offshore wind energy resources into the onshore power grid. It also provides the grid with autonomous synchronization and stability support capabilities, helping to solve the challenges of friendly grid connection and efficient absorption of offshore wind power. Through switching between multiple operating modes, it can be applied to different grid scenarios, expanding its application scope. Using a low-frequency combined transmission system based on the M3C converter and MG equipment, even if only one of the M3C converter or MG equipment fails, offshore wind power can still be reliably transmitted, reducing wind curtailment and ensuring grid security and stability.

[0240] Please see Figure 5 The diagram shows a structural schematic of a computer device provided in an embodiment of this application. An embodiment of this application provides a computer device 400, including a processor 410 and a memory 420. The memory 420 stores a computer program executable by the processor 410, and the computer program, when executed by the processor 410, performs the above-described manner.

[0241] This application embodiment also provides a storage medium 430, on which a computer program is stored, which is executed by a processor 410 in the manner described above.

[0242] The storage medium 430 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0243] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0244] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0245] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0246] Any process or manner described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0247] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered 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-included 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. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), 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). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since 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 a computer memory.

[0248] 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.

[0249] Those skilled in the art will understand that all or part of the steps carried out in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the embodiments.

[0250] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A medium-to-long-distance offshore wind power low-frequency combined transmission system, characterized in that, include: M3C converter and its control system, M3C converter operating status switching group, and M3C converter power consumption switch and power consumption resistor R1; The coaxial motor and generator MG equipment and its control system, the MG equipment operation status conversion switch group, and the MG equipment energy consumption switch and energy consumption resistor R2; By switching the M3C converter operating status switching switch group, the M3C converter energy consumption switch, the MG equipment operating status switching switch group, and the MG equipment energy consumption switch, multiple operating states, including at least maintenance, cold standby, hot standby, connection, operation, and energy consumption, can be achieved, so as to switch between the operating states according to the grid and new energy access situation. The M3C converter operating state switching switch group includes: QF11, QF12, QS11, and QS12; The QF11 is located at the incoming line position between the M3C converter and the low-frequency bus, and is used to control the connection / disconnection between the M3C converter and the low-frequency bus; The QF12 is located at the outgoing line position between the M3C converter and the power frequency bus, and is used to control the connection / disconnection between the M3C converter and the power grid. One end of QS11 is located between the M3C converter and QF11, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter. One end of QS12 is located between the M3C converter and QF12, and the other end is directly grounded. It is used to control the power outage / maintenance of the M3C converter. The MG device operating status conversion switch group includes QF21, QF22, QS21, and QS22; The QF21 is located at the inlet position between the MG device and the low-frequency bus, and is used to control the connection / disconnection between the MG device and the low-frequency bus; The QF22 is located at the outgoing line position between the MG device and the power frequency bus, and is used to control the connection / disconnection between the MG device and the power grid. One end of QS21 is located between the MG device and QF21, and the other end is directly grounded. It is used to control the power outage / maintenance of the MG device. One end of the QS22 is located between the MG device and the QF22, and the other end is directly grounded. It is used to control the power outage / maintenance of the MG device. QF11, QF12, QS11, QS12 and QF21, QF22, QS21, QS22 have the ability to directly interrupt current, and QF11 and QF21 have an interlocking function.

2. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 1, characterized in that, The M3C converter adopts a 3×3 matrix bridge arm structure, and each bridge arm is composed of modular multilevel cascaded components. By controlling the sub-converters on the power frequency side and the low frequency side and superimposing them according to the bridge arm relationship, frequency conversion control between low frequency and power frequency can be achieved.

3. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 1, characterized in that, The MG device is a coaxial connection structure of a motor M and a generator G. It converts low-frequency current to power-frequency current based on the number of pole pairs of the motor and generator. ； In the formula, f1 represents the wind turbine side frequency, f2 represents the grid side frequency, and p M p represents the number of pole pairs of the electric motor. G This indicates the number of pole pairs of the generator.

4. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 1, characterized in that, The selection parameters for QF11 and QF12 are as follows: ； In the formula, P1 represents the rated power of the wind farm, U1 represents the rated voltage on the high-voltage side of the offshore substation, and U e11 Indicates the rated voltage of switches QF11 and QF12, I e11 Indicates the rated current of switches QF11 and QF12, I m11 Indicates the rated short-circuit breaking current of switches QF11 and QF12; The selection parameters for QF21 and QF22 are as follows: ； In the formula, U e21 Indicates the rated voltage of switches QF21 and QF22, I e21 Indicates the rated current of switches QF21 and QF22, I m21 Indicates the rated short-circuit breaking current of switches QF21 and QF22; The selection parameters for QS11 and QS12 are as follows: ； In the formula, U e12 Indicates the rated voltage of switches QS11 and QS12, I e12 Indicates the rated current of switches QS11 and QS12, I m12 Indicates the rated short-circuit breaking current of switches QS11 and QS12; The selection parameters for QS21 and QS22 are as follows: ； In the formula, U e22 Indicates the rated voltage of switches QS21 and QS22, I e22 Indicates the rated current of switches QS21 and QS22, I m22 This indicates the rated short-circuit breaking current of switches QS21 and QS22.

5. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 1, characterized in that, The selection parameters for the power dissipation resistor R1 of the M3C converter are as follows: ； In the formula, U e13 This indicates the rated voltage of the energy-consuming resistor R1, R R1 This indicates the resistance value of the energy-consuming resistor R1; The selection parameters for the energy-consuming resistor R2 of the MG device are as follows: ； In the formula, U e23 This indicates the rated voltage of the energy-consuming resistor R2, R R2 This indicates the resistance value of the energy-consuming resistor R2.

6. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 5, characterized in that, The selection parameters for the M3C converter power dissipation switch QF13 are as follows: ； In the formula, U e14 Indicates the rated voltage of switch QF13, I e14 Indicates the rated current of switch QF13, I m14 This indicates the rated short-circuit breaking current of switch QF13; The selection parameters for the MG device energy consumption switch QF23 are as follows: ； In the formula, U e24 Indicates the rated voltage of switch QF23, I e24 Indicates the rated current of switch QF23, I m24 This indicates the rated short-circuit breaking current of switch QF23.

7. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 1, characterized in that, The M3C converter includes the following operating states: M3C converter maintenance status: QF11, QF12, and QF13 are open, QS11 and QS12 are closed, and the M3C converter is locked and depressurized. M3C converter cold standby state: QF11, QF12, QF13 are disconnected, QS11, QS12 are disconnected, M3C converter is locked and unpressurized; M3C converter hot standby status: QF11 and QF13 are open, QF12 is closed, QS11 and QS12 are open, and the M3C converter is unlocked for voltage regulation. M3C converter connection status: QF11 and QF13 are disconnected, QF12 is closed, QS11 and QS12 are disconnected, and the M3C converter is unlocked for reactive power control. M3C converter operating status: QF11 and QF12 are closed, QF13 is open, QS11 and QS12 are open, and the M3C converter unlocks the frequency conversion control. M3C converter power consumption state: QF11 and QF13 are closed, QF12 is open, QS11 and QS12 are open, the M3C converter unlocks the frequency conversion control, and power is consumed through resistor R1.

8. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 7, characterized in that, The MG device includes the following operating states: MG equipment maintenance status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are closed, and the MG equipment is stopped. MG equipment in cold standby status: QF21, QF22, and QF23 are disconnected, QS21 and QS22 are disconnected, and the MG equipment is shut down; MG equipment hot standby status: QF21 and QF23 are open, QF22 is closed, QS21 and QS22 are open, the generator of the MG equipment is running in power generation mode, and the motor is running at low frequency synchronous speed. MG device connection status: QF21 and QF23 are disconnected, QF22 is closed, QS21 and QS22 are disconnected. The MG device is operating in synchronous condenser mode to achieve reactive power control. MG equipment operating status: QF21 and QF22 are closed, QF23 is open, QS21 and QS22 are open, the MG equipment is operating normally, and frequency conversion control is achieved by different pole pairs; MG device energy consumption status: QF21 and QF23 are closed, QF22 is open, QS21 and QS22 are open, the MG device is operating normally and consumes energy through resistor R2.

9. The medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 8, characterized in that, The system is configured to perform at least one of the following operating modes: M3C converter in operation, MG equipment in hot standby; MG equipment is running, M3C converter is in hot standby; M3C converter is running, MG device is connected; The MG device is running, and the M3C converter is connected. The M3C converter consumes energy, and the MG equipment is in cold standby mode. MG equipment consumes energy, and the M3C converter is in cold standby mode; M3C converter under maintenance, MG equipment in operation; MG equipment under maintenance, M3C converter in operation; M3C converter hot standby, MG equipment hot standby; M3C converter connection, MG device connection; M3C converter repair, MG equipment repair; Each method triggers and executes corresponding switching actions based on the grid's rotational inertia support capacity, reactive power support capacity, new energy access ratio, grid faults, and equipment faults to achieve state switching.

10. An operation mode for a medium-to-long-distance offshore wind power low-frequency combined transmission system, characterized in that, Operating the system as described in any one of claims 1 to 9 includes the following steps: Monitor the grid-side rotational inertia support capacity, reactive power support capacity, wind turbine-side output status, grid status, and the proportion of new energy access; Based on the monitoring results, the operating status of the M3C converter and the MG device is selected and switched according to the preset strategy; By controlling the connection / disconnection of the corresponding M3C converter operating status switching group, M3C converter energy consumption switch, MG device operating status switching group, and MG device energy consumption switch, the system can switch between multiple operating modes.

11. The operation mode of the medium-to-long-distance offshore wind power low-frequency combined transmission system according to claim 10, characterized in that, The preset strategy includes: When the grid has strong rotational inertia support capability, the M3C converter should be put into operation first. When the power grid's rotational inertia support capacity is weak, the MG equipment should be put into operation first. When the reactive power support capability is strong, the M3C converter or / and MG equipment should be put in hot standby mode first. When the reactive power support capability is weak, the M3C converter or / and MG equipment should be kept in the connected state first. When a fault occurs on the grid side that prevents the transmission of power, the M3C converter or MG equipment should be put into a power-consuming state first to protect the equipment and achieve orderly shutdown or state switching in a short time. And in the event of equipment failure or maintenance, the switching is completed in accordance with the interlocking and safety sequence.

12. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the manner described in any one of claims 10-11.

13. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the manner described in any one of claims 10-11.

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