Offshore wind power direct current transmission simulation system and method, computer equipment and medium

Abstract

The invention relates to the technical field of power electronics, and discloses an offshore wind power direct current transmission simulation system and method, computer equipment and a medium, the system comprises a first fan simulator, a first sending end converter valve, a direct current submarine cable simulator, a receiving end converter valve and a power grid simulator; the first sending end converter valve is connected with a first fan simulator through a first alternating current bus component and is also connected with a receiving end converter valve through a direct current submarine cable simulator; the receiving end converter valve is connected with the power grid simulator through the receiving end transformer component. According to the system, a first diode valve component, a second diode valve component, a plurality of isolation switch components and a plurality of bypass switch components are arranged in a first sending end converter valve, and the states of different switches are controlled, so that a test based on a diode converter valve power transmission scheme can be realized; control strategies, operation characteristics and the like of various offshore wind power direct current transmission systems are fully verified, and a foundation is laid for subsequent engineering application.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to an offshore wind power DC transmission simulation system, method, computer equipment, and medium. Background Technology

[0002] Deep-sea wind power is becoming an inevitable trend in offshore wind power development. Due to the capacitive effect of AC submarine cables, AC transmission schemes are not suitable for transmitting deep-sea wind power, making DC transmission the only option. To analyze the application effect of offshore power transmission schemes in practical engineering, the schemes need to be fully verified before application. Dynamic model experiments are an important means of scheme verification.

[0003] Currently, DC transmission schemes for offshore wind power typically employ flexible DC transmission based on Modular Multilevel Converters (MMCs). MMC-based flexible DC transmission offers advantages such as flexible control, bidirectional active power flow, and decoupling of active and reactive power. Therefore, dynamic model testing systems for offshore wind power transmission are generally designed based on MMC-based flexible DC transmission schemes. However, the large size and high cost of MMC converter valves in MMC-based schemes result in large offshore converter station platforms and high construction costs, which is detrimental to grid parity for offshore wind power. To achieve lightweight offshore converter valves and converter station platforms and reduce the cost of offshore wind power transmission systems, diode-based converter valves are generally used at the sending end. However, existing dynamic model testing systems can only verify MMC-based flexible DC transmission schemes and cannot verify diode-based converter valve schemes. Therefore, there is an urgent need to propose a dynamic model testing system capable of verifying diode-based converter valve schemes. Summary of the Invention

[0004] In view of this, the present invention provides an offshore wind power DC transmission simulation system, method, computer equipment and medium to solve the problem that dynamic model testing systems in related technologies cannot perform power transmission schemes based on diode converter valves.

[0005] In a first aspect, the present invention provides an offshore wind power DC transmission simulation system, comprising: a first wind turbine simulator, a first sending-end converter valve, a DC submarine cable simulator, a receiving-end converter valve, and a power grid simulator; the first sending-end converter valve is connected to the first wind turbine simulator via a first AC bus component and is also connected to the receiving-end converter valve via the DC submarine cable simulator; the receiving-end converter valve is connected to the power grid simulator via a receiving-end transformer component; the first sending-end converter valve includes a first sending-end auxiliary modular multilevel converter valve component, a first diode valve component, and a second diode valve component; the AC side of the first sending-end auxiliary modular multilevel converter valve component is connected to the first AC bus component via a first connecting transformer component, the DC positive terminal is connected to a first terminal via a first disconnecting switch component, and the DC negative terminal is connected via a second disconnecting switch component. The first diode valve component is connected to the second terminal; the AC side of the first diode valve component is connected to the first AC bus component through the first rectifier transformer component, the DC positive terminal is connected to the positive terminal of the DC submarine cable simulator through the third disconnecting switch component, and the DC negative terminal is connected to the first terminal through the fourth disconnecting switch component; the AC side of the second diode valve component is connected to the first AC bus component through the second rectifier transformer component, the DC positive terminal is connected to the second terminal through the fifth disconnecting switch component, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator through the sixth disconnecting switch component; the first terminal is connected to the positive terminal of the DC submarine cable simulator in sequence through the third terminal and the first bypass switch component; the third terminal is connected to the fourth terminal through the second bypass switch component; the second terminal is connected to the negative terminal of the DC submarine cable simulator in sequence through the fourth terminal and the third bypass switch component.

[0006] The offshore wind power DC transmission simulation system provided by this invention includes a first wind turbine simulator, a first sending-end converter valve, a DC submarine cable simulator, a receiving-end converter valve, and a power grid simulator. The first sending-end converter valve is connected to the first wind turbine simulator via a first AC bus component and also connected to the receiving-end converter valve via the DC submarine cable simulator. The receiving-end converter valve is connected to the power grid simulator via a receiving-end transformer component. The first sending-end converter valve includes a first sending-end auxiliary modular multilevel converter valve component, a first diode valve component, and a second diode valve component. The AC side of the first sending-end auxiliary modular multilevel converter valve component is connected to the first AC bus component via a first connecting transformer component, the DC positive terminal is connected to a first terminal via a first disconnecting switch component, and the DC negative terminal is connected via a second disconnecting switch component. The first diode valve component's AC side is connected to the first AC bus component via the first rectifier transformer component, the DC positive terminal is connected to the DC submarine cable simulator via the third isolating switch component, and the DC negative terminal is connected to the first terminal via the fourth isolating switch component; the second diode valve component's AC side is connected to the first AC bus component via the second rectifier transformer component, the DC positive terminal is connected to the second terminal via the fifth isolating switch component, and the DC negative terminal is connected to the DC submarine cable simulator via the sixth isolating switch component; the first terminal is connected to the DC submarine cable simulator sequentially via the third terminal and the first bypass switch component; the third terminal is connected to the fourth terminal via the second bypass switch component; the second terminal is connected to the DC submarine cable simulator sequentially via the fourth terminal and the third bypass switch component. The system provided by this invention, by setting a first diode valve component, a second diode valve component, multiple isolating switch components, and multiple bypass switch components at the first sending-end converter valve, and by controlling the state of different switches, can realize the experiment of a diode converter valve-based power transmission scheme, fully verifying the control strategies and operating characteristics of various offshore wind power DC transmission systems, laying the foundation for subsequent engineering applications.

[0007] In one optional embodiment, the system further includes: a starting device component and a control module; the starting device component is connected to a first AC bus component; the control module is used to control the first disconnecting switch component, the second disconnecting switch component, the third disconnecting switch component, the fourth disconnecting switch component, the fifth disconnecting switch component, and the sixth disconnecting switch component to close when receiving a first simulation command, control the starting device component to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component, and charge the receiving-end converter valve through the grid simulator to start the receiving-end converter valve; the control module is also used to control the first wind turbine simulator to unlock and output electrical energy when the starting of the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve is detected.

[0008] In one optional embodiment, the system further includes: a second sending-end modular multilevel converter valve component and a second wind turbine simulator; the AC side of the second sending-end modular multilevel converter valve component is connected to the second wind turbine simulator in sequence through a second connecting transformer and a second AC bus component, the DC positive terminal is connected to the positive terminal of the DC submarine cable simulator through a seventh disconnecting switch component, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator through an eighth disconnecting switch component; the control module is also used to control the seventh and eighth disconnecting switch components to close when a second simulation command is received, to charge the receiving-end converter valve through the power grid simulator, so as to start the receiving-end converter valve; when the starting of the receiving-end converter valve is detected, the control module controls the receiving-end converter valve to control the voltage of the DC submarine cable simulator, so as to start the second sending-end modular multilevel converter valve component; the control module is also used to control the second wind turbine simulator to unlock and output electrical energy when the starting of the second sending-end modular multilevel converter valve component is detected.

[0009] In an optional implementation, the control module is further configured to, upon receiving a third analog command, control the first disconnecting switch component, the second disconnecting switch component, the third disconnecting switch component, the fourth disconnecting switch component, the fifth disconnecting switch component, the sixth disconnecting switch component, the seventh disconnecting switch component, and the eighth disconnecting switch component to close; control the starting device component to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component; charge the receiving-end converter valve through the power grid simulator to start the receiving-end converter valve; when the starting of the receiving-end converter valve is detected, control the receiving-end converter valve to control the voltage of the DC submarine cable simulator to start the second sending-end modular multilevel converter valve component; when the starting of the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve is detected, control the first wind turbine simulator to unlock and output electrical energy; when the starting of the second sending-end modular multilevel converter valve component is detected, control the second wind turbine simulator to unlock and output electrical energy.

[0010] In an optional implementation, the control module is further configured to, upon receiving a fourth analog command, control the first bypass switch component, the third bypass switch component, the first disconnect switch component, the second disconnect switch component, the seventh disconnect switch component, and the eighth disconnect switch component to close; control the starting device component to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component; control the grid simulator to charge the receiving-end converter valve to start the receiving-end converter valve; when the starting of the receiving-end converter valve is detected, control the voltage of the DC submarine cable simulator through the receiving-end converter valve to start the second sending-end modular multilevel converter valve component; when the starting of the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve is detected, control the first wind turbine simulator to unlock and output electrical energy; when the starting of the second sending-end modular multilevel converter valve component is detected, control the second wind turbine simulator to unlock and output electrical energy.

[0011] In an optional implementation, the control module is further configured to, upon receiving a fifth analog command, control the second bypass switch component, the third disconnect switch component, the fourth disconnect switch component, the fifth disconnect switch component, and the sixth disconnect switch component to close; control the grid simulator to charge the receiving-end converter valve so that the receiving-end converter valve can start; when the starting of the receiving-end converter valve is detected, control the voltage of the DC submarine cable simulator through the receiving-end converter valve; control the first wind turbine simulator to unlock and output electrical energy, and perform grid construction control on the first wind turbine simulator; control the AC side of the first sending-end auxiliary modular multilevel converter valve component to be connected to the first AC bus, and control the first sending-end auxiliary modular multilevel converter valve component to operate as a static synchronous compensator.

[0012] In an optional implementation, the control module is further configured to, upon receiving a sixth analog command, control the second bypass switch component, the third disconnect switch component, the fourth disconnect switch component, the fifth disconnect switch component, the sixth disconnect switch component, the seventh disconnect switch component, and the eighth disconnect switch component to close; charge the receiving-end converter valve and the second sending-end modular multilevel converter valve component through the grid simulator to enable the receiving-end converter valve and the second sending-end modular multilevel converter valve component to start; when the starting of the receiving-end converter valve and the second sending-end modular multilevel converter valve component is detected, control the second wind turbine simulator to unlock and output electrical energy, and perform grid connection control on the first wind turbine simulator; control the AC side of the first sending-end auxiliary modular multilevel converter valve component to be connected to the first AC bus, and control the first sending-end auxiliary modular multilevel converter valve component to operate as a static synchronous compensator.

[0013] Secondly, the present invention provides a method for simulating offshore wind power DC transmission. The method is applied to an offshore wind power DC transmission simulation system according to the first aspect above or any corresponding embodiment thereof. The method includes: acquiring simulation commands; the simulation commands controlling the offshore wind power DC transmission simulation system to cause the offshore wind power DC transmission simulation system to output simulation results.

[0014] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the offshore wind power DC transmission simulation method of the second aspect described above.

[0015] Fourthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the offshore wind power DC transmission simulation method of the second aspect described above.

[0016] Fifthly, the present invention provides a computer program product, including computer instructions for causing a computer to execute the offshore wind power DC transmission simulation method described in the second aspect above. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of an offshore wind power DC transmission simulation system according to an embodiment of the present invention;

[0019] Figure 2 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the first operating mode in the embodiments of this application; Figure 3 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the second operating mode in the embodiments of this application; Figure 4 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the third operating mode in the embodiments of this application; Figure 5 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the fourth operating mode in the embodiments of this application; Figure 6 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the fifth operating mode in the embodiments of this application; Figure 7 This is a schematic diagram of the operation of the offshore wind power DC transmission simulation system in the sixth operating mode in the embodiments of this application; Figure 8 This is a flowchart illustrating the offshore wind power DC transmission simulation method according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In related technologies, dynamic model testing systems for offshore wind power transmission are generally designed based on the MMC (Multi-Converter Capacitor) flexible DC transmission scheme. In the MMC-based flexible DC transmission scheme, the large size and high cost of the MMC converter valve result in a large offshore converter station platform and high construction investment costs, which is highly detrimental to grid parity for offshore wind power. To achieve lightweight offshore converter valves and converter station platforms and reduce the cost of offshore wind power transmission systems, a diode-based converter valve transmission scheme is generally adopted at the sending end. However, the existing dynamic model testing systems can only verify the MMC-based flexible DC transmission scheme and cannot verify the diode-based converter valve transmission scheme. Therefore, there is an urgent need to propose a dynamic model testing system capable of verifying the diode-based converter valve transmission scheme.

[0022] In view of this, the present application provides an offshore wind power DC transmission simulation system. The system provided in this application includes a first wind turbine simulator, a first sending-end converter valve, a DC submarine cable simulator, a receiving-end converter valve, and a power grid simulator. By setting a first diode valve component, a second diode valve component, multiple isolating switch components, and multiple bypass switch components on the first sending-end converter valve, and by controlling the state of different switches, it is possible to realize the test of the diode converter valve-based power transmission scheme, fully verify the control strategies and operating characteristics of various offshore wind power DC transmission systems, and lay the foundation for subsequent engineering applications.

[0023] This embodiment provides a simulation system for offshore wind power DC transmission, such as Figure 1 As shown, the system includes: a first wind turbine simulator 1, a first sending-end converter valve 2, a DC submarine cable simulator 3, a receiving-end converter valve 4, and a power grid simulator 5; The first sending-end converter valve 2 is connected to the first wind turbine simulator 1 through the first AC bus component, and is also connected to the receiving-end converter valve 4 through the DC submarine cable simulator 3; the receiving-end converter valve 4 is connected to the power grid simulator 5 through the receiving-end transformer component. The first sending-end converter valve 2 includes a first sending-end auxiliary modular multilevel converter valve component 6, a first diode valve component 7, and a second diode valve component 8. The AC side of the first sending-end auxiliary modular multilevel converter valve component 6 is connected to the first AC bus component via a first connecting transformer component 9. The DC positive terminal is connected to the first terminal 11 via a first disconnecting switch component 10, and the DC negative terminal is connected to the second terminal 13 via a second disconnecting switch component 12. The AC side of the first diode valve component 7 is connected to the first AC bus component via a first rectifier transformer component. The DC positive terminal is connected to the positive terminal of the DC submarine cable simulator 3 via a third disconnecting switch component 14, and the DC negative terminal is connected to the second terminal 13 via a third disconnecting switch component 14. The fourth isolating switch component 15 is connected to the first terminal 11; the AC side of the second diode valve component 8 is connected to the first AC bus component through the second rectifier transformer component, the DC positive terminal is connected to the second terminal 13 through the fifth isolating switch component 16, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator 3 through the sixth isolating switch component 18; the first terminal 11 is connected to the positive terminal of the DC submarine cable simulator 3 through the third terminal 19 and the first bypass switch component 20 in sequence; the third terminal 19 is connected to the fourth terminal 22 through the second bypass switch component 21; the second terminal 13 is connected to the negative terminal of the DC submarine cable simulator 3 through the fourth terminal 22 and the third bypass switch component 23 in sequence.

[0024] For example, both the first sending-end auxiliary modular multilevel converter (MMC) component 6 and the MMC converter valve component in the receiving-end converter valve 4 adopt a hybrid full-half-bridge or pure full-bridge submodule structure, and have adjustable DC voltage. In terms of capacity configuration, the capacity of the first sending-end auxiliary modular multilevel converter component 6 can be designed according to 50% of the total capacity of the first sending-end converter valve 2, and the capacity of a single diode converter valve can be designed according to 37.5% of the total capacity of the receiving-end converter valve 4. The rated capacity of the first sending-end converter valve 2 is half of the rated capacity of the receiving-end converter valve 4. The MMC converter valve uses fully controlled devices, such as insulated-gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs). There are two methods for handling the reactive power balance and harmonic suppression of the first sending-end converter valve 2: 1) all passive filters handle it; 2) all MMC converter valves handle it, in which case the passive filters are cut off.

[0025] The offshore wind power DC transmission simulation system provided by this invention includes a first wind turbine simulator, a first sending-end converter valve, a DC submarine cable simulator, a receiving-end converter valve, and a power grid simulator. By setting a first diode valve component, a second diode valve component, multiple isolating switch components, and multiple bypass switch components on the first sending-end converter valve, and by controlling the state of different switches, it is possible to conduct tests on the diode converter valve-based power transmission scheme, fully verifying the control strategies and operating characteristics of various offshore wind power DC transmission systems, and laying the foundation for subsequent engineering applications.

[0026] In some alternative implementations, the system further includes: a starting device component 24 and a control module; The starting device component 24 is connected to the first AC bus component; The control module is used to control the first disconnecting switch component 10, the second disconnecting switch component 12, the third disconnecting switch component 14, the fourth disconnecting switch component 15, the fifth disconnecting switch component 16, and the sixth disconnecting switch component 18 to close when receiving the first analog command; control the starting device component 24 to charge the first sending end auxiliary modular multilevel converter valve component 6 so as to start the first sending end auxiliary modular multilevel converter valve component 6; and charge the receiving end converter valve 4 through the power grid simulator 5 so as to start the receiving end converter valve 4. The control module is also used to control the first fan simulator 1 to unlock and output electrical energy when the first sending-end auxiliary modular multilevel converter valve component 6 and the receiving-end converter valve 4 are detected to be activated.

[0027] Exemplarily, the control module can be a controller used to control the operating status of various components in the system. This application embodiment does not limit the specific content of the control module; those skilled in the art can determine it according to their needs. In this application embodiment, the receiving-end converter valve 4 is considered end one, and the first sending-end converter valve 2 is considered end two. When the first simulation command is received, the system operates in the first operating mode, with both end one and end two operating. End two is a DRU-MMC converter valve, controlling the closure of the first isolating switch component 10, the second isolating switch component 12, the third isolating switch component 14, the fourth isolating switch component 15, the fifth isolating switch component 16, and the sixth isolating switch component 18. The starting device component 24 charges the end two MMC converter valve, and after charging, unlocks the MMC converter valve to control the sending-end AC voltage. The end one MMC converter valve is charged through the grid simulator 5, completing the startup process and unlocking to control the DC voltage. The first wind turbine simulator 1 unlocks and begins outputting power. The system operation diagram in the first operating mode is as follows: Figure 2 As shown, the red part is used to represent the operation of both ends of the terminal and the terminal of the terminal in this operating mode. The terminal of the terminal is a DRU-MMC converter valve.

[0028] In some alternative implementations, the system further includes a second feed-end modular multilevel converter valve component 25 and a second fan simulator 26. Exemplarily, the second feed-end modular multilevel converter valve component 25 is terminal three in the system.

[0029] The AC side of the second sending-end modular multilevel converter valve component 25 is connected to the second wind turbine simulator 26 in sequence through the second connecting transformer and the second AC bus component. The DC positive terminal is connected to the positive terminal of the DC submarine cable simulator 3 through the seventh disconnecting switch component 27, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator 3 through the eighth disconnecting switch component 28. The control module is also used to control the seventh disconnecting switch component 27 and the eighth disconnecting switch component 28 to close when a second analog command is received, and to charge the second sending-end auxiliary module of the receiving-end converter valve 4 through the power grid simulator 5 so as to start the receiving-end converter valve 4; when the starting of the receiving-end converter valve 4 is detected, the control module controls the receiving-end converter valve 4 to control the voltage of the DC submarine cable simulator 3 so as to start the second sending-end modular multilevel converter valve component 25; The control module is also used to control the second fan simulator 26 to unlock and output electrical energy when the second sending end modular multilevel converter valve component 25 is detected to be activated.

[0030] Exemplary, the method provided in this application embodiment, when receiving a second simulation command, operates in a second operating mode, with both terminals one and three running. It controls the closing of the seventh disconnecting switch component 27 and the eighth disconnecting switch component 28, charges the terminal one MMC converter valve and the terminal three MMC converter valve via the power grid simulator 5, unlocks the terminal one MMC converter valve to control the DC voltage, unlocks the terminal three MMC converter valve to control the sending-end AC voltage, and the second wind turbine simulator 26 unlocks and begins outputting power. A schematic diagram of the system operation in the first operating mode is shown below. Figure 3 As shown, the red part is used to represent the operation of both ends, Terminal 1 and Terminal 2, in this operating mode.

[0031] In some optional implementations, the control module is also configured to control the first disconnecting switch component 10, the second disconnecting switch component 12, the third disconnecting switch component 14, the fourth disconnecting switch component 15, the fifth disconnecting switch component 16, the sixth disconnecting switch component 18, the seventh disconnecting switch component 27 and the eighth disconnecting switch component 28 to close when a third analog command is received. The control start-up device charges the first sending-end auxiliary modular multilevel converter valve component 6 to start the first sending-end auxiliary modular multilevel converter valve component 6, and charges the receiving-end converter valve 4 through the power grid simulator 5 to start the receiving-end converter valve 4; when the starting of the receiving-end converter valve 4 is detected, the control of the receiving-end converter valve 4 controls the voltage of the DC submarine cable simulator 3 to start the second sending-end modular multilevel converter valve component 25; When the activation of the first sending-end auxiliary modular multilevel converter valve component 6 and the receiving-end converter valve 4 is detected, the first fan simulator 1 is controlled to unlock and output electrical energy; when the activation of the second sending-end modular multilevel converter valve component 25 is detected, the second fan simulator 26 is controlled to unlock and output electrical energy.

[0032] For example, in this embodiment of the application, when the third simulation command is received, the system operates in the third operating mode, with both ends of terminal 1, terminal 2, and terminal 3 operating. The receiving end terminal 1 has an MMC converter valve, and the sending end terminal 2 has a DRU-MMC converter valve and the sending end terminal 3 has an MMC converter valve. The first isolating switch component 10, the second isolating switch component 12, the third isolating switch component 14, the fourth isolating switch component 15, the fifth isolating switch component 16, and the sixth isolating switch component 18 are closed. The starting device component 24 charges the first sending end auxiliary modular multilevel converter valve component 6 of terminal 2. After charging is completed, it is unlocked, and the MMC converter valve of terminal 2 controls the AC voltage of the first AC bus component of the sending end. Terminal 3 closes the seventh isolating switch component 27 and the eighth isolating switch component 28. The grid simulator 5 charges the MMC converter valves of terminal 1 and terminal 3. The MMC converter valve of terminal 1 is unlocked to control the DC voltage, and the MMC converter valve of terminal 3 is unlocked to control the AC voltage of the second AC bus component of the sending end. Then, the second wind turbine simulator 26 is unlocked and starts outputting power. In the third operating mode, the system's operating diagram is as follows: Figure 4 As shown, the red part is used to represent the operation of Terminal 1, Terminal 2 and Terminal 3 in this operating mode.

[0033] In some optional implementations, the control module is also configured to control the first bypass switch component 20, the third bypass switch component 23, the first disconnect switch component 10, the second disconnect switch component 12, the seventh disconnect switch component 27 and the eighth disconnect switch component 28 to close when a fourth analog command is received; The control start-up device component 24 charges the first sending-end auxiliary modular multilevel converter valve component 6 to start the first sending-end auxiliary modular multilevel converter valve component 6, and charges the receiving-end converter valve 4 through the power grid simulator 5 to start the receiving-end converter valve 4; when the starting of the receiving-end converter valve 4 is detected, the control of the receiving-end converter valve 4 controls the voltage of the DC submarine cable simulator 3 to start the second sending-end modular multilevel converter valve component 25; When the activation of the first sending-end auxiliary modular multilevel converter valve component 6 and the receiving-end converter valve 4 is detected, the first fan simulator 1 is controlled to unlock and output electrical energy; when the activation of the second sending-end modular multilevel converter valve component 25 is detected, the second fan simulator 26 is controlled to unlock and output electrical energy.

[0034] For example, in this embodiment of the application, when the fourth simulation command is received, the system operates in the fourth operating mode, with terminals one, two, and three operating simultaneously. The receiving end terminal one MMC converter valve, and the sending end terminal two and terminal three MMC converter valves are all operating. The first bypass switch component 20, the third bypass switch component 23, the first disconnect switch component 10, and the second disconnect switch component 12 are closed. The starting device component 24 charges the terminal two MMC converter valve. After charging is complete, the MMC converter valve is unlocked to control the AC voltage of the first AC bus component. The seventh disconnect switch component 27 and the eighth disconnect switch component 28 charge the terminal one and terminal three MMC converter valves via the power grid simulator. The terminal one MMC converter valve unlocks to control the DC voltage, and the terminal three MMC converter valve unlocks to control the AC voltage of the second AC bus component. The wind turbine simulator unlocks and begins outputting power. In this operating mode, both the MMC converter valve at terminal one and the MMC converter valve at terminal three require reduced voltage operation on their DC sides, matching the DC side voltage of the MMC converter valve at terminal two. The system's operating diagram in the third operating mode is as follows: Figure 5 As shown, the red part is used to represent the operation of Terminal 1, Terminal 2 and Terminal 3 in this operating mode.

[0035] In some alternative implementations, the control module is also configured to control the second bypass switch component 21, the third disconnect switch component 14, the fourth disconnect switch component 15, the fifth disconnect switch component 16 and the sixth disconnect switch component 18 to close when a fifth analog command is received. The control grid simulator 5 charges the receiving-end converter valve 4 to start the receiving-end converter valve 4; when the starting of the receiving-end converter valve 4 is detected, the voltage of the DC submarine cable simulator 3 is controlled through the receiving-end converter valve 4; the control first wind turbine simulator 1 is unlocked and outputs electrical energy, and the grid construction control of the first wind turbine simulator 1 is performed; the control first sending-end auxiliary modular multilevel converter valve component 6 is made to connect the AC side to the first AC bus, and the control first sending-end auxiliary modular multilevel converter valve component 6 is made to operate as a static synchronous compensator.

[0036] For example, in this embodiment of the application, when the fifth simulation command is received, the system operates in the fifth operating mode, with both ends of terminal one and terminal two running. The receiving end terminal one MMC converter valve and the sending end terminal two diode converter valve control the closure of the second bypass switch component 21, the third disconnect switch component 14, the fourth disconnect switch component 15, the fifth disconnect switch component 16, and the sixth disconnect switch component 18. The terminal one MMC converter valve is charged through the grid simulator, completing the startup process and unlocking the control DC voltage. The first wind turbine simulator 1 unlocks and starts outputting power. In this operating mode, the first wind turbine simulator 1 connected to terminal two performs grid control. The DC side of the terminal two MMC converter valve is disconnected from the DC side of the diode converter valve, and the AC side is connected to the first AC bus, which can be selected to operate as a static synchronous compensator (STATCOM). In this operating mode, the DC side of the terminal one MMC converter valve needs to be stepped down to match the DC side voltage of terminal two. The system operation diagram in the fifth operating mode is as follows. Figure 6 As shown, the red part is used to represent the operation of Terminal 1 and Terminal 2 in this operating mode.

[0037] In an optional implementation, the control module is further configured to control the second bypass switch component 21, the third disconnect switch component 14, the fourth disconnect switch component 15, the fifth disconnect switch component 16, the sixth disconnect switch component 18, the seventh disconnect switch component 27 and the eighth disconnect switch component 28 to close when a sixth analog command is received. The receiving-end converter valve 4 and the second sending-end modular multilevel converter valve component 25 are charged by the power grid simulator 5 to start the receiving-end converter valve 4 and the second sending-end modular multilevel converter valve component 25. When the start-up of the receiving-end converter valve and the second sending-end modular multilevel converter valve component is detected, the second fan simulator 26 is unlocked and outputs electrical energy, and the first fan simulator 1 is controlled to form a network; the AC side of the first sending-end auxiliary modular multilevel converter valve component 6 is connected to the first AC bus, and the first sending-end auxiliary modular multilevel converter valve component 6 is controlled to operate as a static synchronous compensator.

[0038] For example, when the fifth simulation command is received, the system operates in the fifth operating mode, with three terminals operating: the receiving end's MMC converter valve 1, and the sending end's diode converter valve 2 and MMC converter valve 3. The second bypass switch component 21, the third disconnect switch component 14, the fourth disconnect switch component 15, the fifth disconnect switch component 16, the sixth disconnect switch component 18, the seventh disconnect switch component 27, and the eighth disconnect switch component 28 are closed. The grid simulator 5 charges the MMC converter valves 1 and 3, unlocks the DC voltage of the MMC converter valve 1, and unlocks the AC voltage of the sending end's second AC bus. The wind turbine simulator unlocks and begins outputting power. In this operating mode, the wind turbine simulator connected to the second terminal performs grid connection control. At this time, the DC side of the MMC converter valve connected to the second terminal is disconnected from the DC side of the diode converter valve, and the AC side is connected to the first AC bus, allowing it to be operated as a STATCOM. In this operating mode, both the MMC converter valve at terminal one and the MMC converter valve at terminal three require reduced voltage operation on their DC sides to match the DC side voltage at terminal two. The system's operating diagram in the sixth operating mode is as follows: Figure 7 As shown, the red part is used to represent the three-terminal operation in this operating mode.

[0039] The system provided in this application embodiment can switch between different topologies and has multiple operating modes. It can not only realize the test verification of traditional MMC-based flexible DC transmission systems, but also realize the test verification of novel diode-based DC transmission systems. At the same time, the dynamic model test system can also realize three-terminal operation test.

[0040] According to an embodiment of the present invention, an embodiment of a method for simulating offshore wind power DC transmission is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0041] This embodiment provides a method for simulating offshore wind power DC transmission, which can be used in the offshore wind power DC transmission simulation system described in the above embodiments. Figure 8 This is a flowchart of a method for simulating offshore wind power DC transmission according to an embodiment of the present invention, such as... Figure 8 As shown, the process includes the following steps: Step S801: Obtain simulation instructions.

[0042] For example, the simulation instructions are used to control the offshore wind power DC transmission simulation system to operate in different simulation modes. The specific content of the simulation instructions in this application is not limited, and those skilled in the art can determine it according to their needs.

[0043] Step S802: Use simulation commands to control the offshore wind power DC transmission simulation system so that the offshore wind power DC transmission simulation system outputs simulation results.

[0044] For example, the specific control process is described in the relevant content of the above embodiments, and will not be repeated here.

[0045] The offshore wind power DC transmission simulation method provided in this embodiment uses simulation commands to control the offshore wind power DC transmission simulation system. It can realize the test of the diode converter valve-based transmission scheme, fully verify the control strategies and operating characteristics of various offshore wind power DC transmission systems, and lay the foundation for subsequent engineering applications.

[0046] This invention also provides a computer device for performing the above-described actions. Figure 8 The method for simulating offshore wind power DC transmission is shown.

[0047] Please see Figure 9 , Figure 9 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 9 As shown, the computer device includes one or more processors 100, memory 200, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system). Figure 9 Take a processor 100 as an example.

[0048] Processor 100 may be a central processing unit, a network processor, or a combination thereof. Processor 100 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GPA), or any combination thereof.

[0049] The memory 200 stores instructions executable by at least one processor 100 to cause the at least one processor 100 to perform the method shown in the above embodiments.

[0050] The memory 200 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device. Furthermore, the memory 200 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 200 may optionally include memory remotely located relative to the processor 10, and these remote memories can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0051] The memory 200 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 200 may also include a combination of the above types of memory.

[0052] The computer device also includes a communication interface 300 for communicating with other devices or communication networks.

[0053] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0054] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0055] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A simulation system for offshore wind power DC transmission, characterized in that, The system includes: a first wind turbine simulator, a first sending-end converter valve, a DC submarine cable simulator, a receiving-end converter valve, and a power grid simulator; The first sending-end converter valve is connected to the first wind turbine simulator via the first AC bus component, and is also connected to the receiving-end converter valve via the DC submarine cable simulator; the receiving-end converter valve is connected to the power grid simulator via the receiving-end transformer component. The first sending-end converter valve includes a first sending-end auxiliary modular multilevel converter valve component, a first diode valve component, and a second diode valve component. The AC side of the first sending-end auxiliary modular multilevel converter valve component is connected to the first AC bus component via a first connecting transformer component, the DC positive terminal is connected to the first terminal via a first disconnecting switch component, and the DC negative terminal is connected to the second terminal via a second disconnecting switch component. The AC side of the first diode valve component is connected to the first AC bus component via a first rectifier transformer component, the DC positive terminal is connected to the positive terminal of the DC submarine cable simulator via a third disconnecting switch component, and the DC negative terminal is connected to the first terminal via a fourth disconnecting switch component. The AC side of the second diode valve component is connected to the first AC bus component via a second rectifier transformer component, the DC positive terminal is connected to the second terminal via a fifth disconnecting switch component, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator via a sixth disconnecting switch component. The first terminal is connected to the positive terminal of the DC submarine cable simulator sequentially via a third terminal and a first bypass switch component. The third terminal is connected to the fourth terminal via a second bypass switch component. The second terminal is connected to the negative terminal of the DC submarine cable simulator sequentially via a fourth terminal and a third bypass switch component.

2. The system according to claim 1, characterized in that, The system also includes: a starting device component and a control module; The starting device component is connected to the first AC bus component; The control module is used to control the first disconnecting switch component, the second disconnecting switch component, the third disconnecting switch component, the fourth disconnecting switch component, the fifth disconnecting switch component, and the sixth disconnecting switch component to close when receiving a first simulation command; control the starting device component to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component; and charge the receiving-end converter valve through the power grid simulator to start the receiving-end converter valve. The control module is also used to control the first wind turbine simulator to unlock and output electrical energy when the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve are detected to be activated.

3. The system according to claim 2, characterized in that, The system also includes: a second feed-end modular multilevel converter valve component and a second fan simulator; The AC side of the second sending-end modular multilevel converter valve component is connected to the second wind turbine simulator in sequence through the second connecting transformer and the second AC bus component. The DC positive terminal is connected to the positive terminal of the DC submarine cable simulator through the seventh disconnecting switch component, and the DC negative terminal is connected to the negative terminal of the DC submarine cable simulator through the eighth disconnecting switch component. The control module is also used to control the seventh and eighth disconnecting switch components to close when a second simulation command is received, and to charge the receiving-end converter valve through the power grid simulator so as to start the receiving-end converter valve; when the starting of the receiving-end converter valve is detected, the control module controls the receiving-end converter valve to control the voltage of the DC submarine cable simulator so as to start the second sending-end modular multilevel converter valve component. The control module is also used to control the second fan simulator to unlock and output electrical energy when the second sending-end modular multilevel converter valve component is detected to be activated.

4. The system according to claim 3, characterized in that, The control module is also used to control the first disconnecting switch component, the second disconnecting switch component, the third disconnecting switch component, the fourth disconnecting switch component, the fifth disconnecting switch component, the sixth disconnecting switch component, the seventh disconnecting switch component, and the eighth disconnecting switch component to close when a third analog command is received; The starting device is controlled to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component. The receiving-end converter valve is charged through the power grid simulator to start the receiving-end converter valve. When the starting of the receiving-end converter valve is detected, the receiving-end converter valve is controlled to control the voltage of the DC submarine cable simulator to start the second sending-end modular multilevel converter valve component. When the activation of the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve is detected, the first wind turbine simulator is controlled to unlock and output electrical energy. When the second-end modular multilevel converter valve component is detected to be activated, the second fan simulator is controlled to unlock and output electrical energy.

5. The system according to claim 3, characterized in that, The control module is also used to control the first bypass switch component, the third bypass switch component, the first disconnect switch component, the second disconnect switch component, the seventh disconnect switch component, and the eighth disconnect switch component to close when a fourth analog command is received; The starting device is controlled to charge the first sending-end auxiliary modular multilevel converter valve component to start the first sending-end auxiliary modular multilevel converter valve component. The receiving-end converter valve is charged through the power grid simulator to start the receiving-end converter valve. When the starting of the receiving-end converter valve is detected, the receiving-end converter valve is controlled to control the voltage of the DC submarine cable simulator to start the second sending-end modular multilevel converter valve component. When the activation of the first sending-end auxiliary modular multilevel converter valve component and the receiving-end converter valve is detected, the first wind turbine simulator is controlled to unlock and output electrical energy. When the second-end modular multilevel converter valve component is detected to be activated, the second fan simulator is controlled to unlock and output electrical energy.

6. The system according to claim 3, characterized in that, The control module is also used to control the second bypass switch component, the third disconnect switch component, the fourth disconnect switch component, the fifth disconnect switch component, and the sixth disconnect switch component to close when a fifth analog command is received. The system controls the grid simulator to charge the receiving-end converter valve, thereby activating the receiving-end converter valve. When the activation of the receiving-end converter valve is detected, the voltage of the DC submarine cable simulator is controlled through the receiving-end converter valve. The system controls the first wind turbine simulator to unlock and output electrical energy, and performs grid construction control on the first wind turbine simulator. The system controls the AC side of the first sending-end auxiliary modular multilevel converter valve component to be connected to the first AC bus, and controls the first sending-end auxiliary modular multilevel converter valve component to operate as a static synchronous compensator.

7. The system according to claim 3, characterized in that, The control module is also used to control the second bypass switch component, the third disconnect switch component, the fourth disconnect switch component, the fifth disconnect switch component, the sixth disconnect switch component, the seventh disconnect switch component, and the eighth disconnect switch component to close when a sixth analog command is received. The receiving-end converter valve and the second sending-end modular multilevel converter valve component are charged by the power grid simulator to start the receiving-end converter valve and the second sending-end modular multilevel converter valve component. When the start-up of the receiving-end converter valve and the second sending-end modular multilevel converter valve component is detected, the second wind turbine simulator is controlled to unlock and output electrical energy, and the first wind turbine simulator is controlled to form a network; the AC side of the first sending-end auxiliary modular multilevel converter valve component is controlled to be connected to the first AC bus, and the first sending-end auxiliary modular multilevel converter valve component is controlled to operate as a static synchronous compensator.

8. A method for simulating offshore wind power DC transmission, characterized in that, The method is applied to the offshore wind power DC transmission simulation system according to any one of claims 1 to 7, and the method includes: Obtain simulation instructions; The simulation command controls the offshore wind power DC transmission simulation system to output simulation results.

9. A computer device, characterized in that, include: The system includes a memory and a processor, which are interconnected. The memory stores computer instructions, and the processor executes the computer instructions to perform the offshore wind power DC transmission simulation method of claim 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to execute the offshore wind power DC transmission simulation method of claim 8.

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