Offshore Wind Power Black Start Method, Device and Equipment Based on Self-Powered Source

Abstract

The present invention discloses a black start method, device and equipment for offshore wind power based on self-provided power sources. Based on an offshore wind power DC transmission system including a first offshore wind farm, a second offshore wind farm, 4 first inverters, 2 second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer and an onshore power grid, corresponding first switches, second switches and third switches are configured. A small-capacity inverter is used in cooperation with a certain switching sequence to achieve black start at the sending end and power balance, maintaining the technical advantages of the diode solution in terms of low cost and small volume, and solving the technical problem that the existing offshore wind power black start methods reduce the technical advantages of the diode solution in terms of small volume and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of offshore wind power, and particularly to an offshore wind power black start method, device and equipment based on a self-provided power source. Background Art

[0002] At present, the main transmission methods for offshore wind power are nearshore - AC and far - sea - DC, and the capacity of a single project is about one million kilowatts. With the exhaustion of nearshore offshore wind power development, far - reaching offshore wind power has become the focus of future offshore wind power development. The AC transmission solution cannot meet the needs of large - scale far - reaching offshore wind power development, and the traditional DC transmission solution has a high cost and is difficult to meet the needs of large - scale offshore wind power economic development. It is necessary to explore a new low - cost transmission solution to provide new technical options for far - reaching offshore wind power development. There are AC transmission and various DC transmission commutation solutions for large - scale offshore wind power. At present, the mainstream DC transmission solution in practical applications is the flexible DC transmission technology based on the MMC topology, but the volume and weight of its platform are large and the cost is high. Therefore, the transmission solution for large - scale offshore wind power needs to be further optimized. To adapt to various application scenarios and reduce the cost of transmission projects, various transmission solutions with their own characteristics have been proposed at home and abroad, including sending - end using an uncontrolled rectifier converter of unidirectional current type based on diode elements, DC fan aggregation and step - up transmission, low - frequency power transmission and other transmission solutions.

[0003] Using an uncontrolled rectifier converter of unidirectional current type based on diode elements at the sending - end helps to realize the light weight of the offshore platform, but the existing solutions still have disadvantages. The black start problem is the most difficult problem to solve in the existing diode solutions. The current black start method uses a hybrid converter with series - parallel VSC converters to assist in starting, but this solution uses a certain proportion of VSC structures, reducing the technical advantages of the small - volume and low - cost diode solution. Therefore, for the offshore wind power black start problem, how to maintain the technical advantages of the small - volume and low - cost diode solution is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] The present invention provides an offshore wind power black start method, device and equipment based on a self - provided power source, which is used to solve the technical problem that the existing offshore wind power black start method reduces the technical advantages of the small - volume and low - cost diode solution.

[0005] In view of this, in the first aspect of the present invention, an offshore wind power black start method based on a self - provided power source is provided, which is applied to an offshore wind power DC transmission system. The offshore wind power DC transmission system includes: a first offshore wind farm, a second offshore wind farm, 4 first inverters, 2 second inverters, a back - to - back AC / DC / AC module, a first diode commutation valve, a second diode commutation valve, a diesel generator system, an energy storage system, an onshore commutation valve, an onshore transformer and an onshore power grid;

[0006] The first offshore wind farm is connected to two first inverters and a second inverter respectively through a first busbar. One first inverter connected to the first busbar is connected to one end of a first diode converter valve, and the other end of the first diode converter valve is connected to the second inverter connected to the first busbar. The other first inverter connected to the first busbar is connected to one end of a back-to-back AC / DC / AC module;

[0007] The second offshore wind farm is connected to two first inverters and a second inverter respectively through a second busbar. One first inverter connected to the second busbar is connected to one end of a second diode converter valve, and the other end of the second diode converter valve is connected to the second inverter connected to the second busbar. The other first inverter connected to the second busbar is connected to the other end of the back-to-back AC / DC / AC module;

[0008] The DC side of the back-to-back AC / DC / AC module is connected to an AC / DC module and a diesel generator system in sequence through two first switches, and is connected to an energy storage system through two second switches;

[0009] A third switch is provided at the common end of the first inverter and the second inverter connected to the first diode converter valve on the first busbar, and another third switch is provided at the common end of the first inverter and the second inverter connected to the second diode converter valve on the second busbar;

[0010] The positive extreme of the first diode converter valve is connected to the negative extreme of the second diode converter valve. The negative extreme of the first diode converter valve is connected to the input end of a first DC line, and the output end of the first DC line is connected to one input end of an onshore converter valve. The positive extreme of the second diode converter valve is connected to the input end of a second DC line, and the output end of the second DC line is connected to the other input end of the onshore converter valve. The output end of the onshore converter valve is connected to an onshore transformer, and the onshore transformer is connected to an onshore power grid;

[0011] The capacity of the back-to-back AC / DC / AC module is the total capacity of 3 to 5 wind turbines in the first offshore wind farm and the second offshore wind farm;

[0012] The offshore wind power black start method based on a self-provided power source includes the following steps:

[0013] T1. Control all the first switches, second switches, and third switches to be in the open state, the onshore converter valve to be in the blocked state, and the energy storage system to meet the preset capacity margin;

[0014] T2. Close all the third switches, and connect the first diode converter valve and the second diode converter valve to the first busbar and the second busbar respectively;

[0015] T3. Close all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system;

[0016] T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus and the second bus is 15°;

[0017] T6. Unlock one fan of one of the first offshore wind farm and the second offshore wind farm. After the unlocked fan stably outputs power to charge the energy storage system, unlock one fan of the other offshore wind farm among the first offshore wind farm and the second offshore wind farm, so that the unlocked fan stably outputs power to charge the energy storage system;

[0018] T6. Unlock the onshore converter valve, and adjust the magnitude of the power fed into the DC side of the back-to-back AC / DC / AC module until all the DC side power is transferred to the first diode converter valve and the second diode converter valve, completing the black start.

[0019] Optionally, the first diode converter valve and the second diode converter valve adopt a six-pulse full-bridge structure.

[0020] Optionally, the first inverter is a YY-type transformer, and the second inverter is a YD-type transformer.

[0021] Optionally, in step T3, closing all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system includes:

[0022] When both the diesel generator system and the energy storage system can charge the DC side, use the energy storage system to charge the DC side and close all the second switches;

[0023] When the energy storage system cannot charge the DC side, use the diesel generator system to charge the DC side and close all the first switches.

[0024] Optionally, when the energy storage system cannot charge the DC side and the diesel generator system is used to charge the DC side and all the first switches are closed, it further includes:

[0025] Close all the second switches.

[0026] The second aspect of the present invention provides a black start device for offshore wind power based on self-provided power sources, which is applied to an offshore wind power DC transmission system. The offshore wind power DC transmission system includes: a first offshore wind farm, a second offshore wind farm, 4 first inverters, 2 second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer, and an onshore power grid;

[0027] The first offshore wind farm is connected to two first inverters and a second inverter respectively through a first busbar. One of the first inverters connected to the first busbar is connected to one end of a first diode converter valve, and the other end of the first diode converter valve is connected to the second inverter connected to the first busbar. The other first inverter connected to the first busbar is connected to one end of a back-to-back AC / DC / AC module;

[0028] The second offshore wind farm is connected to two first inverters and a second inverter respectively through a second busbar. One of the first inverters connected to the second busbar is connected to one end of a second diode converter valve, and the other end of the second diode converter valve is connected to the second inverter connected to the second busbar. The other first inverter connected to the second busbar is connected to the other end of the back-to-back AC / DC / AC module;

[0029] The DC side of the back-to-back AC / DC / AC module is connected to an AC / DC module and a diesel generator system in sequence through two first switches, and is connected to an energy storage system through two second switches;

[0030] A third switch is provided at the common end of the first inverter and the second inverter connected to the first diode converter valve on the first busbar, and another third switch is provided at the common end of the first inverter and the second inverter connected to the second diode converter valve on the second busbar;

[0031] The positive terminal of the first diode converter valve is connected to the negative terminal of the second diode converter valve. The negative terminal of the first diode converter valve is connected to the input end of a first DC line. The output end of the first DC line is connected to an input end of an onshore converter valve. The positive terminal of the second diode converter valve is connected to the input end of a second DC line. The output end of the second DC line is connected to another input end of the onshore converter valve. The output end of the onshore converter valve is connected to an onshore transformer, and the onshore transformer is connected to the onshore power grid;

[0032] The capacity of the back-to-back AC / DC / AC module is the total capacity of 3 to 5 wind turbines in the first offshore wind farm and the second offshore wind farm;

[0033] The offshore wind power black start method based on a self-provided power source includes the following steps:

[0034] T1. Control all the first switches, second switches, and third switches to be in the open state, the onshore converter valve to be in the blocked state, and the energy storage system to meet the preset capacity margin;

[0035] T2. Close all the third switches, and connect the first diode converter valve and the second diode converter valve to the first busbar and the second busbar respectively;

[0036] T3. Close all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system;

[0037] T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus and the second bus is 15°.

[0038] T5. Unlock one wind turbine in one of the first offshore wind farm and the second offshore wind farm. After the unlocked wind turbine stably outputs power to charge the energy storage system, unlock one wind turbine in the other offshore wind farm of the first offshore wind farm and the second offshore wind farm, so that the unlocked wind turbine stably outputs power to charge the energy storage system.

[0039] T6. Unlock the onshore converter valve, and adjust the magnitude of the power fed into the DC side of the back-to-back AC / DC / AC module until all the power on the DC side is transferred to the first diode converter valve and the second diode converter valve, completing the black start.

[0040] Optionally, the first diode converter valve and the second diode converter valve adopt a six-pulse full-bridge structure.

[0041] Optionally, the first inverter is a YY-type transformer, and the second inverter is a YD-type transformer.

[0042] Optionally, in step T3, all the first switches and / or the second switches are closed according to the available states of the diesel generator system and the energy storage system, including:

[0043] When both the diesel generator system and the energy storage system can charge the DC side, the energy storage system is used to charge the DC side, and all the second switches are closed;

[0044] When the energy storage system cannot charge the DC side, the diesel generator system is used to charge the DC side, and all the first switches are closed.

[0045] Optionally, when the energy storage system cannot charge the DC side, the diesel generator system is used to charge the DC side, and all the first switches are closed, and it further includes:

[0046] All the second switches are closed.

[0047] The third aspect of the present invention provides an offshore wind power black start device based on a self-provided power source, and the device includes a processor and a memory:

[0048] The memory is used to store program codes and transmit the program codes to the processor;

[0049] The processor is used to execute any one of the offshore wind power black start methods based on a self-provided power source according to the instructions in the program codes.

[0050] A fourth aspect of the present invention provides a computer-readable storage medium for storing program codes for executing any one of the methods for black start of offshore wind power based on self-provided power sources according to the first aspect.

[0051] As can be seen from the above technical solutions, the method for black start of offshore wind power based on self-provided power sources provided by the present invention has the following advantages:

[0052] The method for black start of offshore wind power based on self-provided power sources provided by the present invention is based on an offshore wind power HVDC transmission system including a first offshore wind farm, a second offshore wind farm, four first inverters, two second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer, and an onshore power grid. Corresponding first switches, second switches, and third switches are configured, and a small-capacity inverter is used in cooperation with a certain switching sequence to achieve black start at the sending end and power balance, maintaining the technical advantages of the diode solution in terms of low cost and small size, and solving the technical problem that the existing methods for black start of offshore wind power reduce the technical advantages of the diode solution in terms of small size and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for describing the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other relevant drawings without creative efforts based on these drawings.

[0054] Figure 1 It is a schematic flow chart of a method for black start of offshore wind power based on self-provided power sources provided in an embodiment of the present invention;

[0055] Figure 2 It is a topological wiring diagram of the offshore wind power HVDC transmission system provided in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0057] For ease of understanding, please refer to Figure 1 and Figure 2, an embodiment of a black start method for offshore wind power based on self-provided power is provided in the present invention. This method is applied to an offshore wind power DC transmission system, which includes: the first offshore wind farm F1, the second offshore wind farm F2, 4 first inverters TB1, 2 second inverters TB2, a back-to-back AC / DC / AC module, the first diode converter valve V1, the second diode converter valve V2, a diesel generator system SY1, an energy storage system SY2, an onshore converter valve G, an onshore transformer T, and an onshore power grid;

[0058] The first offshore wind farm F1 is respectively connected to two first inverters TB1 and one second inverter TB2 through the first busbar A. One first inverter TB1 connected to the first busbar A is connected to one end of the first diode converter valve V1, the other end of the first diode converter valve V1 is connected to the second inverter TB2 connected to the first busbar A, and the other first inverter TB1 connected to the first busbar A is connected to one end of the back-to-back AC / DC / AC module;

[0059] The second offshore wind farm F2 is respectively connected to two first inverters TB1 and one second inverter TB2 through the second busbar B. One first inverter TB1 connected to the second busbar B is connected to one end of the second diode converter valve V2, the other end of the second diode converter valve V2 is connected to the second inverter TB2 connected to the second busbar B, and the other first inverter TB1 connected to the second busbar B is connected to the other end of the back-to-back AC / DC / AC module;

[0060] The first diode converter valve V1 and the second diode converter valve V2 adopt a six-pulse full-bridge structure.

[0061] The DC side of the back-to-back AC / DC / AC module is connected to the AC / DC module and the diesel generator system SY1 in sequence through two first switches S1, and is connected to the energy storage system SY2 through two second switches S2;

[0062] A third switch S3 is provided at the common end of the first inverter TB1 and the second inverter TB2 connected to the first diode converter valve V1 on the first busbar B, and another third switch S3 is provided at the common end of the first inverter TB1 and the second inverter TB2 connected to the second diode converter valve V2 on the second busbar B;

[0063] The positive terminal of the first diode commutation valve V1 is connected to the negative terminal of the second diode commutation valve V2. The negative terminal of the first diode commutation valve V1 is connected to the input end of the first DC line L1. The output end of the first DC line L1 is connected to one input end of the onshore commutation valve G. The positive terminal of the second diode commutation valve V2 is connected to the input end of the second DC line L2. The output end of the second DC line L2 is connected to the other input end of the onshore commutation valve G. The output end of the onshore commutation valve G is connected to the onshore transformer T, and the onshore transformer T is connected to the onshore power grid;

[0064] The back-to-back AC / DC / AC module is mainly used to achieve black start. To meet the technical requirements of black start, the capacity of the back-to-back AC / DC / AC module only needs to be set as the total capacity of 3 to 5 wind turbines in the first offshore wind farm F1 and the second offshore wind farm F2;

[0065] The offshore wind power black start method based on self-provided power supply includes the following steps:

[0066] T1. Control all the first switches S1, the second switches S2, and the third switches S3 to be in the open state, and the onshore commutation valve G to be in the blocked state. The energy storage system SY2 needs to meet the preset capacity margin and can absorb at least two wind turbines continuously charging for more than half an hour;

[0067] T2. Close all the third switches S3, and connect the first diode commutation valve V1 and the second diode commutation valve V2 to the first bus A and the second bus B respectively, to avoid the impact of inrush current generated by closing after establishing voltage on the black start system;

[0068] T3. Close all the first switches S1 and / or the second switches S2 according to the available states of the diesel generator system SY1 and the energy storage system SY2. Closing all the first switches S1 and / or the second switches S2 can establish a DC voltage on the DC side. The diesel generator system SY1 and the energy storage system SY2 are in standby for each other. When both the diesel generator system SY1 and the energy storage system SY2 can charge the DC side, the energy storage system SY2 is preferentially used to charge the DC side, and it can be tested by only closing all the second switches S2. If the energy storage system SY2 is unavailable, all the first switches S1 can be closed to use the diesel generator system SY2 to charge the DC side. At this time, all the second switches S2 can also be closed to ensure the real-time availability of the energy storage system SY2.

[0069] T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus A and the second bus B is 15°, so as to ensure the minimum harmonic when the whole system outputs;

[0070] T5. Unlock one wind turbine of one of the first offshore wind farm F1 and the second offshore wind farm F2. After the unlocked wind turbine stably outputs power to charge the energy storage system SY2, unlock one wind turbine of the other offshore wind farm among the first offshore wind farm F1 and the second offshore wind farm F2, so that the unlocked wind turbine stably outputs power to charge the energy storage system SY2;

[0071] T6. Unlock the onshore converter valve G, and adjust the magnitude of the power fed into the DC side of the back-to-back AC / DC / AC module until all the DC side power is transferred to the first diode converter valve V1 and the second diode converter valve V2 to complete black start.

[0072] The offshore wind power black start method based on self-provided power sources provided by the present invention is based on an offshore wind power DC transmission system including a first offshore wind farm, a second offshore wind farm, 4 first inverters, 2 second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer, and an onshore power grid. Corresponding first switches, second switches, and third switches are configured, and a small-capacity inverter is used in cooperation with a certain switching sequence to achieve sending-end black start and power balance, maintaining the technical advantages of the diode solution in terms of low cost and small volume, and solving the technical problem that the existing offshore wind power black start methods reduce the technical advantages of the diode solution in terms of small volume and low cost.

[0073] An embodiment of an offshore wind power black start device based on self-provided power sources is provided in the present invention. The device is applied to an offshore wind power DC transmission system, and the offshore wind power DC transmission system includes: a first offshore wind farm F1, a second offshore wind farm F2, 4 first inverters TB1, 2 second inverters TB2, a back-to-back AC / DC / AC module, a first diode converter valve V1, a second diode converter valve V2, a diesel generator system SY1, an energy storage system SY2, an onshore converter valve G, an onshore transformer T, and an onshore power grid;

[0074] The first offshore wind farm F1 is respectively connected to two first inverters TB1 and one second inverter TB2 through a first busbar A. One of the first inverters TB1 connected to the first busbar A is connected to one end of the first diode converter valve V1, the other end of the first diode converter valve V1 is connected to the second inverter TB2 connected to the first busbar A, and the other first inverter TB1 connected to the first busbar A is connected to one end of the back-to-back AC / DC / AC module;

[0075] The second offshore wind farm F2 is respectively connected to two first inverters TB1 and a second inverter TB2 through the second busbar B. One of the first inverters TB1 connected to the second busbar B is connected to one end of the second diode converter valve V2, and the other end of the second diode converter valve V2 is connected to the second inverter TB2 connected to the second busbar B. The other first inverter TB1 connected to the second busbar B is connected to the other end of the back-to-back AC / DC / AC module;

[0076] The first diode converter valve V1 and the second diode converter valve V2 adopt a six-pulse full-bridge structure.

[0077] The DC side of the back-to-back AC / DC / AC module is sequentially connected to the AC / DC module and the diesel generator system SY1 through two first switches S1, and is connected to the energy storage system SY2 through two second switches S2;

[0078] A third switch S3 is provided at the common end of the first inverter TB1 and the second inverter TB2 connected to the first diode converter valve V1 on the first busbar B, and another third switch S3 is provided at the common end of the first inverter TB1 and the second inverter TB2 connected to the second diode converter valve V2 on the second busbar B;

[0079] The positive terminal of the first diode converter valve V1 is connected to the negative terminal of the second diode converter valve V2. The negative terminal of the first diode converter valve V1 is connected to the input end of the first DC line L1. The output end of the first DC line L1 is connected to one input end of the onshore converter valve G. The positive terminal of the second diode converter valve V2 is connected to the input end of the second DC line L2. The output end of the second DC line L2 is connected to the other input end of the onshore converter valve G. The output end of the onshore converter valve G is connected to the onshore transformer T, and the onshore transformer T is connected to the onshore power grid;

[0080] The back-to-back AC / DC / AC module is mainly used to achieve black start. To meet the requirements of black start technology, the capacity of the back-to-back AC / DC / AC module only needs to be set as the total capacity of 3 to 5 wind turbines in the first offshore wind farm F1 and the second offshore wind farm F2;

[0081] The offshore wind power black start method based on self-provided power source includes the following steps:

[0082] T1. Control all the first switches S1, second switches S2 and third switches S3 to be in the open state, the onshore converter valve G to be in the locked state, and the energy storage system SY2 to meet the preset capacity margin, and can absorb at least two wind turbines continuously charging for more than half an hour;

[0083] T2. Close all the third switches S3, and connect the first diode commutation valve V1 and the second diode commutation valve V2 to the first bus A and the second bus B respectively, so as to avoid the impact of the magnetizing inrush current generated by closing after voltage establishment on the black start system;

[0084] T3. Close all the first switches S1 and / or the second switches S2 according to the available states of the diesel generator system SY1 and the energy storage system SY2. Closing all the first switches S1 and / or the second switches S2 can establish a DC voltage on the DC side. The diesel generator system SY1 and the energy storage system SY2 are backup to each other. When both the diesel generator system SY1 and the energy storage system SY2 can charge the DC side, the energy storage system SY2 is preferentially used to charge the DC side, and it can be tested by only closing all the second switches S2. If the energy storage system SY2 is unavailable, all the first switches S1 can be closed to use the diesel generator system SY2 to charge the DC side. At this time, all the second switches S2 can also be closed to ensure the real-time availability of the energy storage system SY2.

[0085] T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus A and the second bus B is 15°, so as to ensure the minimum harmonic when the whole system outputs;

[0086] T5. Unlock one fan of one of the first offshore wind farm F1 and the second offshore wind farm F2. After the unlocked fan stably outputs power to charge the energy storage system SY2, unlock one fan of the other offshore wind farm among the first offshore wind farm F1 and the second offshore wind farm F2, so that the unlocked fan stably outputs power to charge the energy storage system SY2;

[0087] T6. Unlock the onshore commutation valve G, and adjust the magnitude of the power fed into the DC side of the back-to-back AC / DC / AC module until all the power on the DC side is transferred to the first diode commutation valve V1 and the second diode commutation valve V2, and the black start is completed.

[0088] An embodiment of a black start device for offshore wind power based on self-provided power is also provided in the present invention. The device includes a processor and a memory:

[0089] The memory is used to store program codes and transmit the program codes to the processor;

[0090] The processor is used to execute the black start method for offshore wind power based on self-provided power in the present invention according to the instructions in the program codes.

[0091] The present invention also provides a computer-readable storage medium for storing program codes for executing the method for black start of offshore wind power based on self-provided power source in the present invention.

[0092] The device, equipment and computer-readable storage medium for black start of offshore wind power based on self-provided power source provided in the present invention are used to execute the method for black start of offshore wind power based on self-provided power source provided in the present invention. Their principles and achieved technical effects are the same as those of the method for black start of offshore wind power based on self-provided power source provided in the present invention, and will not be elaborated herein.

[0093] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A black start method for offshore wind power based on self-provided power supply, characterized in that, Applied to the HVDC transmission system for offshore wind power, the HVDC transmission system for offshore wind power includes: the first offshore wind farm, the second offshore wind farm, 4 first inverters, 2 second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer, and an onshore power grid; The first offshore wind farm is respectively connected to two first inverters and a second inverter through the first bus. One of the first inverters connected to the first bus is connected to one end of the first diode converter valve. The other end of the first diode converter valve is connected to the second inverter connected to the first bus. The other first inverter connected to the first bus is connected to one end of the back-to-back AC / DC / AC module; The second offshore wind farm is respectively connected to two first inverters and a second inverter through the second bus. One of the first inverters connected to the second bus is connected to one end of the second diode converter valve. The other end of the second diode converter valve is connected to the second inverter connected to the second bus. The other first inverter connected to the second bus is connected to the other end of the back-to-back AC / DC / AC module; The DC side of the back-to-back AC / DC / AC module is connected to the AC / DC module and the diesel generator system in sequence through two first switches, and is connected to the energy storage system through two second switches; A third switch is provided at the common end of the first inverter and the second inverter connected to the first diode converter valve on the first bus, and another third switch is provided at the common end of the first inverter and the second inverter connected to the second diode converter valve on the second bus; The positive terminal of the first diode converter valve is connected to the negative terminal of the second diode converter valve. The negative terminal of the first diode converter valve is connected to the input end of the first DC line. The output end of the first DC line is connected to one input end of the onshore converter valve. The positive terminal of the second diode converter valve is connected to the input end of the second DC line. The output end of the second DC line is connected to the other input end of the onshore converter valve. The output end of the onshore converter valve is connected to the onshore transformer, and the onshore transformer is connected to the onshore power grid; The capacity of the back-to-back AC / DC / AC module is the total capacity of 3 to 5 wind turbines in the first offshore wind farm and the second offshore wind farm; The offshore wind power black start method based on the self-provided power source includes the following steps: T1. Control all the first switches, second switches, and third switches to be in the open state, the onshore converter valve to be in the blocked state, and the energy storage system to meet the preset capacity margin; T2. Close all the third switches, and connect the first diode converter valve and the second diode converter valve to the first bus and the second bus respectively; T3. Close all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system; T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus and the second bus is 15°; T5. Unlock one wind turbine of one of the first offshore wind farm and the second offshore wind farm. After the unlocked wind turbine stably outputs power to charge the energy storage system, unlock one wind turbine of the other offshore wind farm of the first offshore wind farm and the second offshore wind farm, so that the unlocked wind turbine stably outputs power to charge the energy storage system; T6. Unlock the onshore converter valve, and adjust the power feed-in magnitude on the DC side of the back-to-back AC / DC / AC module until all the power on the DC side is transferred to the first diode converter valve and the second diode converter valve to complete black start.

2. The black start method for offshore wind power based on self-provided power supply according to claim 1, characterized in that, The first diode converter valve and the second diode converter valve adopt a six-pulse full-bridge structure.

3. The black start method for offshore wind power based on self-provided power supply according to claim 1, characterized in that, The first inverter is a YY-type transformer, and the second inverter is a YD-type transformer.

4. The black start method for offshore wind power based on self-provided power supply according to claim 1, characterized in that, In step T3, close all the first switches and / or the second switches according to the available states of the diesel generator system and the energy storage system, including: When both the diesel generator system and the energy storage system can charge the DC side, use the energy storage system to charge the DC side and close all the second switches; When the energy storage system cannot charge the DC side, use the diesel generator system to charge the DC side and close all the first switches.

5. The black start method for offshore wind power based on self-provided power supply according to claim 1, characterized in that, When the energy storage system cannot charge the DC side, use the diesel generator system to charge the DC side and close all the first switches, further including: Close all the second switches.

6. A black start device for offshore wind power based on self-provided power supply, characterized in that, Applied to an offshore wind power DC transmission system, the offshore wind power DC transmission system includes: the first offshore wind farm, the second offshore wind farm, 4 first inverters, 2 second inverters, a back-to-back AC / DC / AC module, a first diode converter valve, a second diode converter valve, a diesel generator system, an energy storage system, an onshore converter valve, an onshore transformer and an onshore power grid; The first offshore wind farm is respectively connected to two first inverters and a second inverter through a first busbar. One first inverter connected to the first busbar is connected to one end of the first diode converter valve. The other end of the first diode converter valve is connected to the second inverter connected to the first busbar. The other first inverter connected to the first busbar is connected to one end of the back-to-back AC / DC / AC module; The second offshore wind farm is respectively connected to two first inverters and a second inverter through a second busbar. One first inverter connected to the second busbar is connected to one end of the second diode converter valve. The other end of the second diode converter valve is connected to the second inverter connected to the second busbar. The other first inverter connected to the second busbar is connected to the other end of the back-to-back AC / DC / AC module; The DC side of the back-to-back AC / DC / AC module is sequentially connected to the AC / DC module and the diesel generator system through two first switches, and is connected to the energy storage system through two second switches; A third switch is provided at the common end of the first inverter and the second inverter connected to the first diode converter valve on the first busbar, and another third switch is provided at the common end of the first inverter and the second inverter connected to the second diode converter valve on the second busbar; The positive terminal of the first diode commutation valve is connected to the negative terminal of the second diode commutation valve. The negative terminal of the first diode commutation valve is connected to the input end of the first DC line. The output end of the first DC line is connected to one input end of the onshore commutation valve. The positive terminal of the second diode commutation valve is connected to the input end of the second DC line. The output end of the second DC line is connected to the other input end of the onshore commutation valve. The output end of the onshore commutation valve is connected to the onshore transformer, and the onshore transformer is connected to the onshore power grid; The capacity of the back-to-back AC / DC / AC module is the total capacity of 3 to 5 wind turbines in the first offshore wind farm and the second offshore wind farm; The offshore wind power black start method based on the self-provided power supply includes the following steps: T1. Control all the first switches, second switches, and third switches to be in the open state, the onshore commutation valve to be in the blocked state, and the energy storage system to meet the preset capacity margin; T2. Close all the third switches, and connect the first diode commutation valve and the second diode commutation valve to the first bus and the second bus respectively; T3. Close all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system; T4. Unlock the back-to-back AC / DC / AC module, and adjust the output AC voltage of the back-to-back AC / DC / AC module so that the phase difference between the first bus and the second bus is 15°; T5. Unlock one wind turbine in one of the first offshore wind farm and the second offshore wind farm. After the unlocked wind turbine stably outputs power to charge the energy storage system, unlock one wind turbine in the other offshore wind farm of the first offshore wind farm and the second offshore wind farm, so that the unlocked wind turbine stably outputs power to charge the energy storage system; T6. Unlock the onshore commutation valve, and adjust the magnitude of the power fed into the DC side of the back-to-back AC / DC / AC module until all the DC side power is transferred to the first diode commutation valve and the second diode commutation valve, completing the black start.

7. The offshore wind power black start device based on self-provided power supply according to claim 6, wherein, The first diode commutation valve and the second diode commutation valve adopt a six-pulse full-bridge structure. The first inverter is a YY-type transformer, and the second inverter is a YD-type transformer.

8. The offshore wind power black start device based on self-provided power supply according to claim 6, wherein, In step T3, closing all the first switches and / or second switches according to the available states of the diesel generator system and the energy storage system includes: When both the diesel generator system and the energy storage system can charge the DC side, use the energy storage system to charge the DC side and close all the second switches; When the energy storage system cannot charge the DC side, use the diesel generator system to charge the DC side and close all the first switches.

9. The offshore wind power black start device based on self-provided power supply according to claim 6, wherein, When the energy storage system cannot charge the DC side, using the diesel generator system to charge the DC side and closing all the first switches further includes: Closing all the second switches.

10. An offshore wind power black start device based on self-provided power supply, the device comprising a processor and a memory: The memory is used for storing program codes and transmitting the program codes to the processor; The processor is used for executing the offshore wind power black start method based on self-provided power supply according to any one of claims 1-5 according to the instructions in the program codes.

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