Distributed energy storage assisted black start method and system for doubly-fed wind farm and electronic device

Abstract

This invention discloses a distributed energy storage-assisted black start method and system for doubly-fed induction generator (DFIG) wind farms, relating to the field of offshore wind farm start-up control technology. The method connects a distributed energy storage system to the DC bus of the grid-side converter of some DFIG wind turbine units. When the energy storage capacity of the DFIG units meets the black start energy requirements and the wind speed meets the cut-in conditions, the turbine-side start-up mode is executed. The distributed energy storage establishes the DC bus voltage and provides excitation to the rotor side, achieving stator voltage build-up and active power output to start the units without energy storage. When the wind speed is insufficient but the units without energy storage meet the conditions, the grid-side start-up mode is executed. The grid-side converter constructs the AC bus voltage to provide black start energy for the units without energy storage. The system includes DFIG units, units without energy storage, a diode rectifier unit, and a control unit. It can flexibly select the start-up mode according to operating conditions, is suitable for DRU-HVDC transmission systems, and features high efficiency, low cost, and strong adaptability.

Description

Technical Field

[0001] This application relates to the field of offshore wind power transmission and control technology, specifically a distributed energy storage-assisted doubly-fed wind farm black start method and system, and electronic equipment. Background Technology

[0002] Offshore wind power, with its abundant wind energy resources, more stable wind speeds, and fewer land restrictions compared to onshore wind power, has become an important component of renewable energy in the global energy transition. Doubly-fed induction generators (DFIGs) are gaining increasing attention for offshore deployment due to their lower converter capacity, lower investment costs, and mature engineering practices. To economically and efficiently transmit offshore power to onshore grids, the industry has proposed high-voltage direct current (HVDC) transmission systems based on diode rectifier units (DRUs). Compared to traditional HVDC systems based on modular multilevel converters (MMCs), the offshore platform volume of the DRU-HVDC transmission system is only one-fifth that of the traditional system, and its weight is only one-third. Therefore, combining DFIGs with DRU-HVDC transmission systems constitutes a highly economical large-scale offshore power transmission solution.

[0003] However, this combination faces the challenge of enabling offshore wind farms to black start independently. As an uncontrolled rectifier, the DRU cannot independently establish offshore AC voltage, thus requiring grid-connected control of the offshore wind turbines. Furthermore, since the DRU only has unidirectional power transmission capability, it cannot provide the necessary power for the black start of offshore wind farms. Therefore, an additional black start power source must be introduced to meet the turbine startup requirements.

[0004] To address this issue, existing technologies have proposed various solutions. For example, some solutions use diesel generators as external power sources, but these suffer from insufficient compatibility with grid-connected wind turbines in terms of power characteristics and synchronization control, and also increase system operation and maintenance complexity. Other solutions involve paralleling auxiliary converters with DRUs to provide the power required for black start, but their large-capacity design significantly increases system investment costs. Additionally, some solutions employ large-scale centralized energy storage systems connected to the AC bus, requiring high-power three-phase inverters, which not only complicate the system structure but also increase costs.

[0005] In summary, existing black start solutions generally suffer from problems such as high cost, complex structure, or incompatibility with wind turbine control. There is an urgent need for a new black start strategy that can balance economy, reliability, and start-up efficiency. Summary of the Invention

[0006] Given that existing black-start strategies in DRU-HVDC transmission systems generally suffer from high costs, complex structures, or low startup efficiency, this application provides a distributed energy storage-assisted black-start method, system, and electronic equipment for doubly-fed induction generator (DFIG) wind farms. This method is based on the connection of a distributed energy storage system (ESS) to the DC bus of the back-to-back converter of the DFIG wind turbine. It combines a dual-path startup strategy with both turbine-side and grid-side startup modes, enabling flexible switching between different wind speed conditions and energy storage states, thereby significantly improving the black-start success rate and overall startup efficiency of the wind farm.

[0007] According to a first aspect of the embodiments of this application, a distributed energy storage-assisted black start method for a doubly-fed induction generator (DFIG) wind farm is provided, wherein a distributed energy storage system is connected to the DC bus of the grid-side converter of some DFIG wind turbine units, and the method includes:

[0008] The modular multilevel converter (MMC) controls the DC-side voltage of the DRU converter to its rated value.

[0009] During the black start of a wind farm, the energy storage capacity of the energy storage units with storage capacity, the current wind speed, and the operating status of the units without storage capacity are collected.

[0010] Based on the energy storage capacity of the aforementioned power storage unit and the current wind speed, select either "unit-side start-up mode" or "grid-side start-up mode":

[0011] 1) When the energy storage capacity of the distributed energy storage unit meets the black start energy requirements of the distributed energy storage unit and the current wind speed of the unit is between the cut-in wind speed and the cut-out wind speed, the unit-side start-up mode is executed. The unit-side start-up mode is to establish the DC bus voltage on the grid side through the distributed energy storage system and provide excitation to the rotor side, so as to realize the stator voltage building and grid-connected output of the distributed energy storage unit.

[0012] 2) When the current wind speed of the distributed energy storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the undistributed energy storage unit meets the start-up condition, the grid-side start-up mode is executed. The grid-side start-up mode is to establish the offshore AC bus voltage through the distributed energy storage system and the grid-side converter to provide black start energy for the undistributed energy storage unit.

[0013] 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side.

[0014] 4) When the energy storage capacity of the wind turbine is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started unit will charge its energy storage system as the energy source for subsequent start-up.

[0015] Furthermore, the machine-side startup mode includes:

[0016] A1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units;

[0017] A2: After the DC bus voltage stabilizes, the rotor-side converter of the power distribution unit is controlled by a grid-type control. The AC bus voltage amplitude is adjusted according to the active power-voltage amplitude characteristic, and the AC system frequency is adjusted according to the reactive power-frequency characteristic. Alternatively, when using virtual synchronous control with air gap flux closed loop, the air gap flux amplitude is adjusted according to the active power to stabilize the AC voltage.

[0018] A3: After the stator terminal of the energy storage unit successfully establishes AC voltage, the grid-side converter selects the conventional vector control mode and achieves DC bus voltage stability through the cascade control of the DC bus voltage outer loop and the current inner loop. That is, the function of maintaining DC bus voltage stability is transferred from the DC side energy storage to the grid-side converter control. At this time, the energy storage equipment is disconnected, and the energy storage unit has been successfully started and is transmitting power.

[0019] A4: After the storage unit is successfully started, the non-storage unit is controlled to establish its DC bus voltage by absorbing the active power output of the started unit, thereby completing rotor excitation, no-load start-up and grid-connected power generation.

[0020] Furthermore, the network-side startup mode includes:

[0021] B1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units;

[0022] B2: After the DC bus voltage stabilizes, the distributed energy storage system is controlled to establish the offshore AC bus voltage through the grid-side converter of the energy storage unit. The grid-side converter selects the grid-type control mode.

[0023] B3: The offshore AC bus voltage directly constructed through the distributed energy storage system provides black start energy for the un-storage-equipped generator units and completes their startup.

[0024] Furthermore, the grid-side converter of the power generation and storage unit is also equipped with a dual-mode control switching switch, which is used to select the conventional vector control mode in the generator-side startup mode and the grid-type control mode in the grid-side startup mode.

[0025] Furthermore, before grid connection, non-storage-equipped generating units need to perform pre-synchronization control of stator voltage and common coupling point voltage, including phase pre-synchronization and amplitude pre-synchronization, in order to reduce grid connection current surges.

[0026] According to a second aspect of the embodiments of this application, a distributed energy storage-assisted black start system for doubly-fed wind farms is provided, wherein a distributed energy storage system is connected to the DC bus of the grid-side converter of some doubly-fed wind turbine units, and the system includes:

[0027] The control module is used to control the modular multilevel converter (MMC) to control the DC-side voltage of the DRU converter to the rated value;

[0028] The data acquisition module is used to collect data on the energy storage capacity of the turbine units with energy storage, the current wind speed, and the operating status of the turbine units without energy storage during the black start of the wind farm.

[0029] The mode selection execution module is used to select either "generator-side start-up mode" or "grid-side start-up mode" based on the energy storage capacity of the power storage unit and the current wind speed.

[0030] 1) When the energy storage capacity of the distributed energy storage unit meets the black start energy requirements of the distributed energy storage unit and the current wind speed of the unit is between the cut-in wind speed and the cut-out wind speed, the unit-side start-up mode is executed. The unit-side start-up mode is to establish the DC bus voltage on the grid side through the distributed energy storage system and provide excitation to the rotor side, so as to realize the stator voltage building and grid-connected output of the distributed energy storage unit.

[0031] 2) When the current wind speed of the distributed energy storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the undistributed energy storage unit meets the start-up condition, the grid-side start-up mode is executed. The grid-side start-up mode is to establish the offshore AC bus voltage through the distributed energy storage system and the grid-side converter to provide black start energy for the undistributed energy storage unit.

[0032] 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side.

[0033] 4) When the energy storage capacity of the wind turbine is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started unit will charge its energy storage system as the energy source for subsequent start-up.

[0034] According to a third aspect of the embodiments of this application, an electronic device is provided, comprising:

[0035] One or more processors;

[0036] Memory, used to store one or more programs;

[0037] When the one or more programs are executed by the one or more processors, the one or more processors perform the method as described in the first aspect.

[0038] According to a third aspect of the embodiments of this application, a computer-readable storage medium is provided that stores computer instructions thereon, which, when executed by a processor, implement the steps of the method as described in the first aspect.

[0039] The technical solutions provided by the embodiments of this application may include the following beneficial effects:

[0040] As can be seen from the above embodiments, this invention proposes a dual-path startup strategy on both the turbine side and the grid side, which can be flexibly switched according to energy storage capacity and wind speed conditions, significantly improving the black start efficiency of wind farms. This invention proposes that the grid-side converter of the wind turbine with energy storage supports dual-mode control, ensuring the stability of DC bus voltage under conventional vector control, and realizing the establishment of AC voltage and frequency under grid-connected control. The system structure proposed by this invention does not require large-scale centralized energy storage or high-capacity auxiliary converters, reducing system investment and operating costs, and providing a solution for the black start of offshore doubly-fed wind farms via DRU transmission systems.

[0041] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0042] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0043] Figure 1 This is a topology of a distributed power generation and storage offshore doubly fed wind farm connected to an onshore power grid via a DRU-HVDC transmission system, according to an exemplary embodiment.

[0044] Figure 2 This is a schematic diagram of a dual-path black start strategy for a power distribution and storage unit on the grid side, according to an exemplary embodiment.

[0045] Figure 3 This is a flowchart illustrating a distributed energy storage-assisted doubly-fed wind farm black start method according to an exemplary embodiment;

[0046] Figure 4 This is a block diagram illustrating a control strategy for a storage and distribution unit according to an exemplary embodiment;

[0047] Figure 5 This is a block diagram illustrating a control strategy for an unequipped storage unit according to an exemplary embodiment.

[0048] Figure 6 The following is a simulation waveform diagram of pre-synchronization of an unequipped storage unit according to an exemplary embodiment, wherein (a) shows the simulation result of pre-synchronization of voltage amplitude of the unequipped storage unit; and (b) shows the simulation result of pre-synchronization of voltage phase of the unequipped storage unit.

[0049] Figure 7 This is a simulation result of the offshore AC bus voltage when a storage-equipped unit drives an unequipped wind turbine in a black-start mode on the turbine side, according to an exemplary embodiment.

[0050] Figure 8This is a simulation result diagram of the AC bus voltage on the stator side of the storage unit when the storage unit drives the non-storage unit to start in the black start mode on the generator side, according to an exemplary embodiment.

[0051] Figure 9 This is a simulation result diagram of the AC bus voltage on the stator side of the un-equipped storage unit when the storage unit drives the unequipped storage unit to start in the black start mode on the generator side according to an exemplary embodiment.

[0052] Figure 10 This is a simulation result diagram of the DC bus voltage of the back-to-back converter of the un-storage-equipped unit when the storage-equipped unit drives the un-storage-equipped unit to start in the black start mode on the generator side, according to an exemplary embodiment.

[0053] Figure 11 The diagram shows the simulation results of the active power of the wind turbine when the storage unit drives the start-up of the non-storage unit in the black start mode on the turbine side, according to an exemplary embodiment.

[0054] Figure 12 The figure shows the simulation results of the reactive power of the wind turbine when the storage unit drives the start-up of the non-storage unit in the black start mode on the turbine side, according to an exemplary embodiment.

[0055] Figure 13 The figure shows the simulation results of the offshore AC bus voltage when the distributed storage unit drives the non-distributed storage unit to start up in the grid-side black start mode according to an exemplary embodiment.

[0056] Figure 14 This is a simulation result diagram of the AC bus voltage on the stator side of the un-distributed storage unit when the distributed storage unit drives the undistributed storage unit to start up in the grid-side black start mode according to an exemplary embodiment.

[0057] Figure 15 This is a simulation result diagram of the DC bus voltage of the back-to-back converter of the un-distributed storage unit when the distributed storage unit drives the un-distributed storage unit to start up in the grid-side black start mode according to an exemplary embodiment.

[0058] Figure 16 This is a simulation result diagram of the active and reactive power of a wind turbine when a distributed storage unit drives the start-up of an undistributed storage unit in a grid-side black start mode, according to an exemplary embodiment. Detailed Implementation

[0059] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of systems and methods consistent with some aspects of this application as detailed in the appended claims.

[0060] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0061] It should be understood that although the terms first, second, third, etc., may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0062] Figure 1This diagram illustrates a topology of a distributed energy storage offshore doubly-fed induction generator (DFIG) wind farm connected to an onshore power grid via a DRU-HVDC transmission system, according to an exemplary embodiment. The wind farm consists of five wind turbine clusters, each with four radial feeders. Each feeder connects to five 10MW rated capacity DFIGs via a 66kV AC array cable, ultimately converging to the PCC bus. In some wind turbines, an energy storage unit (ESS) is connected to the DC bus of its back-to-back converter, mounted on one or more turbines within a feeder. These energy storage units power the auxiliary system, starting the converters and turbines, thus enabling autonomous startup. The ESS-equipped turbines will start first, establishing the initial AC voltage for the offshore wind farm and providing startup energy for turbines without ESS, achieving a black start for the entire wind farm. The offshore converter platform integrates a 12-pulse diode rectifier unit, consisting of two 6-pulse rectifier bridges connected in series on the DC side and in parallel on the AC side via Y / Y and Y / Δ transformers. The platform is also equipped with key equipment such as AC filters, reactive power compensation devices, converter transformers, and circuit breakers. The land-based converter station adopts a modular multilevel converter (MMC) topology to achieve DC voltage regulation and reactive power control. During normal operation, the MMC stably controls the DC bus voltage within the nominal value of ±320kV, providing reliable support for long-distance power transmission.

[0063] Figure 2 This is a schematic diagram of the dual-path black start strategy for the power generation and grid sides of the power generation and storage unit. This means that, depending on the wind speed conditions and energy storage capacity of the power generation and storage unit, the black start process can be completed through two different start paths: one on the generator side and one on the grid side. When the energy storage capacity meets the unit's black start energy requirements and the wind speed is between the cut-in and cut-out wind speeds, the generator side start mode is executed. When the energy storage capacity is insufficient to meet the black start requirements or the wind speed does not meet the cut-in conditions but the wind speed of the power generation and storage unit meets the start conditions, the grid side start mode is executed.

[0064] Figure 3 This is a flowchart illustrating a distributed energy storage-assisted doubly-fed wind farm black start method according to an exemplary embodiment, such as... Figure 3 As shown, a distributed energy storage system is connected to the DC bus of the grid-side converter of some doubly-fed wind turbine units. This method may include the following steps:

[0065] Step 1: Control the modular multilevel converter (MMC) to control the DC-side voltage of the DRU converter to the rated value;

[0066] Specifically, after black start is triggered, the onshore MMC first operates in voltage source mode to boost the DC side of the DRU-HVDC transmission system, gradually increasing the DC bus voltage from zero to the rated value (e.g., ±320 kV). A cascaded control of the DC voltage outer loop and current inner loop ensures a smooth voltage rise. This step guarantees stable DC support for the offshore DRU converter, thus establishing a foundational voltage platform for subsequent power transmission from the wind farm.

[0067] Step 2: During the black start of the wind farm, collect data on the energy storage capacity of the turbine units with energy storage, the current wind speed, and the operating status of the turbine units without energy storage.

[0068] Specifically, once the DC-side voltage of the DRU is controlled to its rated value, the offshore wind turbines gradually enter the initialization state, and the black start process officially begins. Through the wind farm's monitoring and data acquisition system, as well as the turbine's own sensors, the available capacity of the energy storage system for each turbine with integrated energy storage is acquired in real time. Simultaneously, the current wind speed of the turbine is collected and compared with the turbine's cut-in and cut-out wind speed thresholds to determine if start-up conditions are met. For turbines without integrated energy storage, their converter status, whether the blades are in standby / operable condition, and the current wind speed conditions are monitored. This step provides a basis for subsequent mode selection.

[0069] Step 3: Select either "generator-side start-up mode" or "grid-side start-up mode" based on the energy storage capacity of the power storage unit and the current wind speed;

[0070] Specifically, the machine-side startup mode includes:

[0071] A1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units;

[0072] Specifically, after determining the start-up mode on the generator side, the distributed energy storage system (ESS) first connects to the DC bus of the back-to-back converter of the energy storage unit. A dual closed-loop voltage and current system gradually increases the DC bus voltage from zero and stabilizes it at a preset reference value (e.g., 1.0 pu). During the voltage boosting process, the energy storage converter controls the bus voltage amplitude through the outer DC voltage loop and adjusts the output current through the inner current loop, achieving a rapid dynamic response and preventing overshoot or oscillation of the bus voltage. This process is equivalent to the energy storage system creating the DC bus voltage for the back-to-back converter of the energy storage unit, providing the necessary conditions for subsequent rotor excitation and stator voltage build-up.

[0073] A2: After the DC bus voltage stabilizes, the rotor-side converter of the power distribution unit is controlled by a grid-type control. The AC bus voltage amplitude is adjusted according to the active power-voltage amplitude characteristic, and the AC system frequency is adjusted according to the reactive power-frequency characteristic. Alternatively, when using virtual synchronous control with air gap flux closed loop, the air gap flux amplitude is adjusted according to the active power to stabilize the AC voltage.

[0074] Specifically, when an offshore wind farm starts up, the wind turbines with integrated storage and energy storage, due to their self-starting capability, can be started first and are responsible for establishing the AC voltage of the offshore wind farm. Therefore, the integrated storage and energy storage units should adopt grid-based control. Their control block diagram is as follows: Figure 3 As shown. Existing research indicates that in offshore wind power transmission systems based on grid-connected wind turbines and diode rectifier units, the active power of the wind turbines is closely related to the amplitude of the AC bus voltage, while the reactive power of the wind turbines is closely related to the system frequency.

[0075] Therefore, the RSC of the storage wind turbine can be controlled by using active power to control the AC voltage amplitude and reactive power to control the AC system frequency, based on the characteristics of PU and Qf. For virtual synchronous control using a closed-loop air-gap flux linkage, active power is used to control the air-gap flux linkage amplitude. The expression for the active power minus air-gap flux linkage amplitude control loop is:

[0076] (1)

[0077] in, This represents the amplitude reference of the DFIG air gap flux linkage. and These represent the air gap flux reference values ​​for the d-axis and q-axis in the virtual synchronous coordinate system, respectively; k Pp k Pi These are the proportional and integral coefficients of the active power-air gap flux linkage amplitude control loop, respectively; P * P represents the reference value for the active power of the wind turbine stator. S This represents the actual value of the active power of the wind turbine stator.

[0078] For the reactive power-frequency control loop, a droop controller can be used to achieve self-synchronization of the wind turbine frequency in the wind farm. Its expression is:

[0079] (2)

[0080] in, This serves as the frequency reference for the air gap flux linkage in the DFIG. Set the frequency value; and For droop controller parameters; Q * Indicates the reference value for stator reactive power; Q S This represents the actual value of the stator reactive power.

[0081] A3: After the stator terminal of the energy storage unit successfully establishes AC voltage, the grid-side converter selects the conventional vector control mode and achieves DC bus voltage stability through the cascade control of the DC bus voltage outer loop and the current inner loop. That is, the function of maintaining DC bus voltage stability is transferred from the DC side energy storage to the grid-side converter control. At this time, the energy storage equipment is disconnected, and the energy storage unit has been successfully started and is transmitting power.

[0082] Specifically, once the stator voltage amplitude and frequency of the distributed energy storage unit stabilize and meet grid connection requirements, the grid-side converter adopts conventional vector control mode. At this point, the grid-side converter uses the DC bus voltage as the control target and employs a cascaded control strategy of "outer voltage loop + inner current loop": the outer loop generates active current commands based on the bus voltage deviation, while the inner loop rapidly adjusts current tracking, thereby achieving dynamic support and stable regulation of the DC bus voltage. During this process, the DC bus voltage stabilization function, originally undertaken by the distributed energy storage system, is gradually transferred to the grid-side converter. After completing its startup task, the energy storage device can be decommissioned. Thus, the distributed energy storage unit can now generate electricity autonomously using wind power and stably transmit the power to the AC bus via the grid-side converter, providing startup support for subsequent units without distributed energy storage.

[0083] A4: After the storage unit is successfully started, the non-storage unit is controlled to establish its DC bus voltage by absorbing the active power output of the started unit, thereby completing rotor excitation, no-load start-up and grid-connected power generation.

[0084] Specifically, after the distributed energy storage unit enters a stable power generation condition, its grid-side converter feeds a portion of its active power into the offshore AC bus. The grid-side converter of the non-distributed energy storage unit, upon detecting a stable AC voltage on the bus, switches to rectification mode, converting AC bus power into DC power through rectification, thereby gradually establishing its own DC bus voltage. Once the DC voltage reaches the set value, the controller injects excitation current into the rotor-side converter to achieve rotor excitation. At this time, when the blade wind speed meets the cut-in conditions, the non-distributed energy storage unit's turbine-side converter control strategy is the same as that of the distributed energy storage unit, thus completing the stator voltage process. When the amplitude and phase of the unit's output voltage are pre-synchronized with the common coupling point voltage, the control system executes grid connection, enabling the non-distributed energy storage unit to smoothly start operation and begin outputting power. This completes the entire process of the distributed energy storage unit successfully starting the non-distributed energy storage unit through the turbine-side start-up mode.

[0085] The network-side startup mode includes:

[0086] B1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units;

[0087] Specifically, during black start and transition to grid-side startup mode, the distributed energy storage system first controls the bus voltage to gradually rise from zero to its rated value through a dual closed-loop control system of voltage and current. This process is achieved through cascaded regulation of the outer voltage loop and inner current loop of the energy storage system to suppress overshoot and fluctuations during voltage rise. The establishment of the DC bus voltage not only provides the necessary DC support conditions for the subsequent grid-side converter's grid-connected operation but also ensures a stable energy source for subsequent voltage establishment on the offshore AC bus side, thus laying the foundation for the startup of units without energy storage.

[0088] B2: After the DC bus voltage stabilizes, the distributed energy storage system is controlled to establish the offshore AC bus voltage through the grid-side converter of the energy storage unit. The grid-side converter selects the grid-type control mode.

[0089] Specifically, once the DC bus voltage reaches a stable value, the grid-side converter of the distributed energy storage unit switches to grid-connected mode. The distributed energy storage system establishes an AC bus voltage with rated amplitude and frequency at sea via the grid-side converter. This process provides a stable voltage and power base for the startup of undistributed energy storage units.

[0090] B3: The offshore AC bus voltage directly constructed through the distributed energy storage system provides black start energy for the un-storage-equipped generator units and completes their startup.

[0091] Specifically, once the offshore AC bus voltage stabilizes, the grid-side converter of the unconnected energy storage unit detects a stable AC voltage signal on the bus and switches to rectification mode to convert the AC power from the bus into DC power, gradually establishing its own DC bus voltage. After the DC voltage reaches a set value, the controller injects excitation current into the rotor-side converter to excite the rotor. Subsequently, the unconnected energy storage unit starts under no-load conditions when the blade wind speed meets the cut-in requirements, and the stator voltage gradually builds up. Once the voltage amplitude and phase of the unconnected energy storage unit are pre-synchronized with the offshore bus voltage, grid connection is performed, allowing the unit to smoothly start operation and output power. Through this process, the energy provided by the distributed energy storage system is fully utilized, while ensuring the safe and stable connection of the unconnected energy storage unit to the offshore bus during black start-up.

[0092] Based on the energy storage capacity of the aforementioned power storage unit and the current wind speed, the "unit-side start-up mode" or "grid-side start-up mode" will be selected.

[0093] 1) When the energy storage capacity of the distribution and storage unit meets the black start energy requirements of the distribution and storage unit and the current wind speed of the unit is between the unit's cut-in wind speed and cut-out wind speed, the unit-side start-up mode is executed.

[0094] Specifically, when it is confirmed that the capacity of the distributed energy storage system can meet the energy requirements for the start-up of the distributed energy storage unit, and the wind speed is within the allowable operating range, the turbine-side start-up mode is selected first. At this time, the distributed energy storage system establishes the DC bus voltage and drives the turbine-side converter to complete the excitation and stator voltage establishment. Then, the grid-side converter controls the DC bus voltage to realize the black start and independent operation of the unit.

[0095] 2) When the current wind speed of the storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the non-storage unit meets the start-up condition, the grid-side start-up mode is executed;

[0096] Specifically, when the wind speed of the energy storage unit does not meet the cut-in wind speed requirements, while the wind speed of the non-energy storage unit does, the energy storage system directly constructs the offshore AC bus voltage through the grid-side converter. The grid-side converter of the non-energy storage unit operates in rectification mode, absorbing the bus power to establish its own DC bus voltage, completing excitation, no-load start-up, and grid-connected power generation, thus achieving black start.

[0097] 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side.

[0098] Specifically, when the energy storage capacity is insufficient to complete the black start process independently, if the current wind speed meets the unit's start-up requirements, the successfully started units will provide active power support to the units waiting to be started via the offshore AC bus. The grid-side converter of the unit waiting to be started initially operates in rectification mode, absorbing electrical energy from the bus to gradually establish its DC bus voltage. Once the DC bus voltage stabilizes, the generator-side converter is controlled to inject excitation current to excite the rotor and drive the stator to establish AC voltage. Finally, the unit waiting to be started is put into operation when the voltage amplitude and phase meet the grid connection conditions, completing the generator-side startup and grid-connected power generation.

[0099] 4) When the energy storage capacity of the wind turbine is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started units will charge its energy storage system as the energy source for subsequent start-up.

[0100] Specifically, when the energy storage capacity is insufficient and the wind speed does not meet the startup requirements, the startup of the unit with energy storage is temporarily suspended. After other units have successfully started and are running, the energy storage system of this unit is charged through the offshore AC bus. When the energy storage capacity is replenished and the wind speed conditions are met, a black start is then performed according to the turbine-side startup mode, thereby realizing a phased startup strategy.

[0101] This dual-path black-start mechanism significantly improves the system's adaptability and startup flexibility under complex marine conditions.

[0102] Figure 4 This is a block diagram illustrating a control strategy for a storage and distribution unit according to an exemplary embodiment. For example... Figure 4 As shown, the control strategy is divided into two parts: generator-side converter control and grid-side converter control. The grid-side converter of the power generation and storage unit is equipped with a dual-mode control switch, used to select the conventional vector control mode in generator-side startup mode and the grid-based control mode in grid-side startup mode. The following will combine... Figure 4 The control strategy is explained, and the black start process of the distribution and storage wind turbine on the grid side based on the control strategy is further introduced.

[0103] 1) Black start path on the machine side

[0104] When the wind turbine is started in black-start mode on the turbine side, the dual-mode switch K is set to position 1, and the grid-side converter performs conventional vector control to stabilize the DC bus voltage. The startup process is as follows:

[0105] C1: When switch S0 is closed, the energy storage system charges the busbar of the energy storage wind turbine, controlling the DC voltage to rise to the rated value;

[0106] C2: Keep switch K in position 1, then sequentially close switches S1, S2, S3, S4, and S5, placing G1 and G2 in position 2. Subsequently, the rotor-side converter (RSC) starts, controlling the air gap flux linkage amplitude to linearly increase from 0 to the reference value Ψ. m0 The AC voltage generated during this stage should be lower than the DC voltage of the DRU rectifier bridge to ensure it remains off.

[0107] C3: Switch G1 and G2 to position 1, engage the active-voltage control loop of RSC, DRU starts to conduct, AC side voltage amplitude rises to near the rated value, and voltage establishment is completed;

[0108] C4: When the wind turbine is equipped with storage, it enters the power generation stage. When the wind turbine without storage is not equipped starts up, it can absorb the active power generated by the unit to establish the DC bus voltage of its converter, realize rotor excitation and complete grid-connected startup.

[0109] 2) Network-side black boot path

[0110] When the wind turbine is started in grid-side black start mode, the switch K is set to position 2, and the grid-side converter switches to grid-connected control mode to actively establish AC bus voltage. The startup steps are as follows:

[0111] D1: The energy storage system controls the DC bus voltage to rise to the rated value;

[0112] D2: With switch K in position 2, close switches S3 and S4. The grid-side converter (GSC) starts, and the controller linearly increases the AC bus voltage amplitude from 0 to the reference value U. gd0 ;

[0113] D3: After the AC voltage is established, the energy storage system can provide starting energy for the unequipped wind turbine. After the unequipped wind turbine completes its black start, switch S0 can be disconnected to disconnect the energy storage system. Switches S3 and S4 can then be disconnected. At this time, the wind turbine equipped with the energy storage system is in standby start-up mode and will complete its self-start after the wind speed is suitable.

[0114] Figure 5 This is a block diagram illustrating a control strategy for an unequipped storage unit according to an exemplary embodiment. Figure 5 As shown, since wind turbines without storage need to be charged by the DC bus capacitor from the offshore AC grid via the grid-side converter to achieve excitation and black start of the turbines, the grid-side converter control for wind turbines without storage can still use conventional vector control, while the turbine-side converter control is the same as that for wind turbines with storage.

[0115] To reduce the instantaneous current surge during DFIG grid connection, the stator terminal voltage U needs to be adjusted before grid connection. sabc With PCC bus voltage U sabc0 Pre-synchronization control. Considering that the PCC voltage amplitude is basically fixed, this invention focuses on the voltage phase synchronization method. This method is based on the voltage vector orientation principle, transforming the stator voltage into a synchronous rotating coordinate system with the grid voltage as a reference, and adopting a d-axis orientation strategy. When there is a phase difference between the stator voltage and the grid voltage, it generates a component on the q-axis. This q-axis component is adjusted by PI regulation to adjust the stator voltage frequency, so that its phase gradually approaches the grid voltage. Finally, when the q-axis component approaches zero, the synchronization of voltage amplitude, frequency, and phase is completed, achieving shockless grid connection. After completing the pre-synchronization control strategy, the startup process without storage wind turbines is described below, with the specific steps as follows:

[0116] E1: Before the start-up of the storage wind turbine, the storage wind turbine has already established a 66kV AC bus voltage through the turbine side or grid side;

[0117] E2: Close the grid-side AC circuit breakers S6 and S7 to precharge the DC bus capacitor through the grid-side converter.

[0118] E3: The grid-side converter is started under control, and the DC capacitor is charged in a controllable manner to control the bus voltage to 1200V.

[0119] E4: The generator-side converter is started. S8 is closed, and G3 and G4 are both in position 2. The generator-side converter uses Uf control to linearly raise the stator side voltage to the reference value. During this process, pre-synchronization control is introduced to gradually synchronize the stator side voltage of the wind turbine with the AC bus voltage of the PCC, preparing for the wind turbine to be successfully connected to the grid.

[0120] E5: Pre-synchronization switch S9 closes, and the wind turbine is successfully connected to the grid. At this point, since no storage turbine has been installed, it has successfully started and is capable of grid connection.

[0121] E6: Switches G3 and G4 are switched to position 1, the wind turbine starts to output active power, and the unit enters a stable operating state.

[0122] Before grid connection, non-storage-equipped generator units need to perform pre-synchronization control of stator voltage and common coupling point voltage, including phase pre-synchronization and amplitude pre-synchronization, in order to reduce grid connection current surges. Figure 6 (a) in the figure is a waveform diagram of the pre-synchronization process of the stator terminal voltage of a single-phase unequipped generator unit and the AC bus voltage of the PCC. Figure 6 (b) in the diagram shows the waveform of the stator terminal voltage of a single-phase, unequipped gas turbine unit and the phase pre-synchronization process with the PCC AC bus. Figure 6 It can be seen that there is a large phase difference and amplitude difference between the stator voltage and the grid voltage in the initial stage of pre-synchronization. As the pre-synchronization process proceeds, the phase difference and amplitude difference gradually decrease. At 4.30s, the phases basically coincide, and at 5s, the amplitudes basically coincide, indicating that both the amplitude and phase can reach the synchronization state, which meets the grid connection requirements and verifies the effectiveness of the pre-synchronization control.

[0123] Figures 7-12 The simulation results of a storage-equipped unit driving the start-up of an unequipped storage unit in a black-start mode on the generator side are shown. Figure 7 Simulation results of offshore AC bus voltage when the storage unit drives the unstorage wind turbine in black start mode on the turbine side; Figure 8 Simulation results of AC bus voltage on stator side of storage unit when storage unit drives non-storage unit to start in black start mode on the generator side; Figure 9 Simulation results of the AC bus voltage on the stator side of the unequipped unit when the equipped storage unit drives the unequipped storage unit to start in the black start mode on the generator side; Figure 10 Simulation results of DC bus voltage of back-to-back converter for unconnected storage units when the storage unit drives the unconnected storage unit to start in black start mode on the generator side; Figure 11 Simulation results of active power of wind turbines when the turbine-storage unit drives the start-up of the non-storage unit in black start mode on the turbine side; Figure 12 The simulation results of the reactive power of the wind turbines when the turbine-mounted storage unit drives the start-up of the un-stored storage unit in black-start mode on the turbine side are shown in the figure. Figures 7-12It can be seen that at t=0.5s, switch S1 closes, the RSC of the DFIG-1 storage unit is activated, and the stator voltage rises linearly from 0 to 0.8pu. At t=1s, switches S2 and S3 close, connecting the stator side of DFIG-1 to the AC side of the grid-side converter, which maintains the stability of the bus capacitor voltage. At t=1.05s, switches S4 and S5 close, the RSC of DFIG-1 engages the active-voltage control loop, and the active power reference value rises from 0 to 0.8pu. At this time, the offshore AC voltage amplitude increases to 0.97pu. At 2s, switches S6 and S7 close, and the DC bus capacitor of the un-storage DFIG-2 begins pre-charging to the steady-state value of 0.75pu. At 2.5s, the GSC of DFIG-2 is activated, further controlling the DC bus voltage to 1pu. At 4s, switch S8 closes, activating the RSC of DFIG-2, and its stator voltage linearly rises from 0 to 0.8pu, during which pre-synchronization control is performed. At 6s, switch S9 closes, engaging the active-voltage control loop of DFIG-2's RSC, and the active power reference value rises from 0 to 0.4pu. At 8s, the active power reference value of DFIG-2 continues to rise to 0.8pu, and at 10s, the active power of DFIG-1 and DFIG-2 rises to 1.0pu, completing the black start on the machine side and entering a stable operating state. Simulation results show that the voltage and power fluctuations are small during the machine-side black start process, reactive power is evenly distributed, and the entire start-up process is relatively smooth.

[0124] Figures 13-16 The simulation results of a grid-connected storage unit driving the startup of an unconnected storage unit in a grid-side black-start mode are shown. Figure 13 Simulation results of offshore AC bus voltage when the storage unit drives the start-up of the non-storage unit in grid-side black start mode; Figure 14 Simulation results of the AC bus voltage on the stator side of the unconnected storage unit when the storage unit drives the unconnected storage unit to start in the grid-side black start mode; Figure 15 Simulation results of DC bus voltage of back-to-back converters of unconnected storage units when the storage unit drives the start-up of the unconnected storage unit in grid-side black start mode. Figure 16 The simulation results of the active and reactive power of the wind turbines when the turbines with integrated storage units drive the startup of unintegrated storage units in grid-side black-start mode are shown in the figure. Figures 13-16It can be seen that at t=0.5s, switches S3 and S4 are closed, DFIG-1's GSC is activated and operates in grid-type mode, and the PCC AC bus voltage rises linearly from 0 to 0.8pu. At 2s, switches S6 and S7 are closed, and the DFIG-2 DC bus capacitor begins pre-charging to a steady-state value of 0.75pu. At 2.5s, DFIG-2's GSC is activated, further controlling the DC bus voltage to 1pu. At 4s, S8 is closed, DFIG-2's RSC is activated, and its stator voltage rises linearly from 0 to 0.8pu; this process involves pre-synchronization control. At 6s, switch S9 is closed, and DFIG-2's RSC engages the reactive power-frequency control loop. At 6.5s, S4 is disconnected. At this time, DFIG-2 has successfully established the AC bus voltage, and the active power reference value has risen from 0 to 0.6 pu. At 8s, the active power reference value of DFIG-2 continues to rise to 0.8 pu, and at 10s, the active power of DFIG-2 rises to 1.0 pu. The system's grid-side black start is complete, and it enters a stable operating state. The simulation results show that the voltage and power fluctuations during the grid-side black start process are small, and the entire start-up process is relatively smooth.

[0125] In summary, the innovation of this invention lies in configuring an energy storage system on the DC bus of some wind turbines, enabling them to achieve dual-path black-start capability on both the turbine side and the grid side. In the turbine side path, the energy storage system provides excitation to the rotor side via the DC bus, controlling the stator voltage to rise linearly and establish an AC voltage, thereby driving wind turbines without energy storage to successfully complete excitation and grid connection. In the grid side path, the energy storage system directly establishes the AC bus voltage through the grid-side converter, providing startup conditions for wind turbines without energy storage. The two paths can be switched according to the energy storage capacity and wind speed conditions, ensuring reliable startup of the system under different operating conditions.

[0126] Based on the above method, this invention enables black start of wind farms without relying on additional diesel engines, large-capacity centralized energy storage, or auxiliary converters, reducing system cost and complexity. Simultaneously, the dual-path mechanism enhances the flexibility and adaptability of the black start process, achieving smooth grid connection and stable operation. Therefore, this invention provides a practical technical solution for autonomous black start of offshore wind farms via a DRU-HVDC system, and offers new insights for the application and promotion of grid-connected wind turbines.

[0127] Corresponding to the aforementioned embodiments of the distributed energy storage-assisted doubly-fed wind farm black start method, the present invention also provides an embodiment of the distributed energy storage-assisted doubly-fed wind farm black start system.

[0128] This invention also provides a distributed energy storage-assisted black start system for doubly-fed induction generator (DFIG) wind farms. A distributed energy storage system is connected to the DC bus of the grid-side converter of some DFIG wind turbine units. The system includes:

[0129] The control module is used to control the modular multilevel converter (MMC) to control the DC-side voltage of the DRU converter to the rated value;

[0130] The data acquisition module is used to collect data on the energy storage capacity of the turbine units with energy storage, the current wind speed, and the operating status of the turbine units without energy storage during the black start of the wind farm.

[0131] The mode selection execution module is used to select either "generator-side start-up mode" or "grid-side start-up mode" based on the energy storage capacity of the power storage unit and the current wind speed.

[0132] 1) When the energy storage capacity of the distributed energy storage unit meets the black start energy requirements of the distributed energy storage unit and the current wind speed of the unit is between the cut-in wind speed and the cut-out wind speed, the unit-side start-up mode is executed. The unit-side start-up mode is to establish the DC bus voltage on the grid side through the distributed energy storage system and provide excitation to the rotor side, so as to realize the stator voltage building and grid-connected output of the distributed energy storage unit.

[0133] 2) When the current wind speed of the distributed energy storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the undistributed energy storage unit meets the start-up condition, the grid-side start-up mode is executed. The grid-side start-up mode is to establish the offshore AC bus voltage through the distributed energy storage system and the grid-side converter to provide black start energy for the undistributed energy storage unit.

[0134] 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side.

[0135] 4) When the energy storage capacity of the wind turbine is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started unit will charge its energy storage system as the energy source for subsequent start-up.

[0136] With the above structure, the system can achieve autonomous black start of offshore doubly fed wind farms via DRU-HVDC transmission system without the need for external diesel engines, large-capacity centralized energy storage or additional auxiliary converters, and has the advantages of low cost, strong adaptability and high start-up efficiency.

[0137] Regarding the system in the above embodiments, the specific ways in which each module performs operations have been described in detail in the embodiments related to the method, and will not be elaborated here.

[0138] For the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to in the description of the method embodiments. The system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0139] Accordingly, this application also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; and when the one or more programs are executed by the one or more processors, causing the one or more processors to implement the quasi-cascadeless model predictive control method for PWM rectifiers as described above.

[0140] Accordingly, this application also provides a computer-readable storage medium storing computer instructions that, when executed by a processor, implement the quasi-cascadeless model predictive control method for PWM rectifiers as described above.

[0141] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0142] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A distributed energy storage assisted black start method for doubly-fed wind farms, characterized in that, The method involves connecting a distributed energy storage system to the DC bus of the grid-side converter of some doubly-fed wind turbine units. The modular multilevel converter (MMC) controls the DC-side voltage of the DRU converter to its rated value. During the black start of a wind farm, the energy storage capacity of the energy storage units with storage capacity, the current wind speed, and the operating status of the units without storage capacity are collected. Based on the energy storage capacity of the aforementioned power storage unit and the current wind speed, select either "unit-side start-up mode" or "grid-side start-up mode": 1) When the energy storage capacity of the distributed energy storage unit meets the black start energy requirement of the distributed energy storage unit and the current wind speed of the unit is between the cut-in wind speed and the cut-out wind speed, the unit-side start mode is executed. The unit-side start mode is to establish the DC bus voltage on the grid side through the distributed energy storage system and provide excitation to the rotor side, so as to realize the stator voltage building and grid-connected output of the distributed energy storage unit. 2) When the current wind speed of the distributed energy storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the undistributed energy storage unit meets the start-up condition, the grid-side start-up mode is executed. The grid-side start-up mode is to establish the offshore AC bus voltage through the distributed energy storage system and the grid-side converter to provide black start energy for the undistributed energy storage unit. 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side. 4) When the energy storage capacity of the distributed storage unit is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started unit will charge its energy storage system as the energy source for subsequent start-up.

2. The method of claim 1, wherein, The machine-side startup modes include: A1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units; A2: After the DC bus voltage stabilizes, the rotor-side converter of the power distribution unit is controlled by a grid-type control. The AC bus voltage amplitude is adjusted according to the active power-voltage amplitude characteristic, and the AC system frequency is adjusted according to the reactive power-frequency characteristic. Alternatively, when using virtual synchronous control with closed-loop air gap flux linkage, the air gap flux linkage amplitude is adjusted according to the active power to stabilize the AC voltage. A3: After the stator terminal of the energy storage unit successfully establishes AC voltage, the grid-side converter selects the conventional vector control mode and achieves DC bus voltage stability through the cascade control of the DC bus voltage outer loop and the current inner loop. That is, the function of maintaining DC bus voltage stability is transferred from the DC side energy storage to the grid-side converter control. At this time, the energy storage equipment is disconnected, and the energy storage unit has been successfully started and is transmitting power. A4: After the storage unit is successfully started, the non-storage unit is controlled to establish its DC bus voltage by absorbing the active power output of the started unit, thereby completing rotor excitation, no-load start-up and grid-connected power generation.

3. The method of claim 1, wherein, The network-side startup mode includes: B1: Control the distributed energy storage system to establish the DC bus voltage between the grid-side converters of the distributed energy storage units; B2: After the DC bus voltage stabilizes, the distributed energy storage system is controlled to establish the offshore AC bus voltage through the grid-side converter of the energy storage unit. The grid-side converter selects the grid-type control mode. B3: The offshore AC bus voltage directly constructed through the distributed energy storage system provides black start energy for the un-storage-equipped generator units and completes their startup.

4. The method according to claim 2 or 3, characterized in that, The grid-side converter of the power generation unit is also equipped with a dual-mode control switch, which is used to select the conventional vector control mode in the generator-side startup mode and the grid-type control mode in the grid-side startup mode.

5. The method according to claim 1 or 2, characterized in that, Before grid connection, non-storage-equipped generator units need to perform pre-synchronization control of stator voltage and common coupling point voltage, including phase pre-synchronization and amplitude pre-synchronization, in order to reduce grid connection current surges.

6. A distributed energy storage-assisted doubly-fed wind farm black start system, characterized in that, A distributed energy storage system is connected to the DC bus of the grid-side converter of some doubly-fed wind turbine units. This system includes: The control module is used to control the modular multilevel converter (MMC) to control the DC-side voltage of the DRU converter to the rated value; The data acquisition module is used to collect data on the energy storage capacity of the turbine units with energy storage, the current wind speed, and the operating status of the turbine units without energy storage during the black start of the wind farm. The mode selection execution module is used to select either "generator-side start-up mode" or "grid-side start-up mode" based on the energy storage capacity of the power storage unit and the current wind speed. 1) When the energy storage capacity of the distributed energy storage unit meets the black start energy requirement of the distributed energy storage unit and the current wind speed of the unit is between the cut-in wind speed and the cut-out wind speed, the unit-side start mode is executed. The unit-side start mode is to establish the DC bus voltage on the grid side through the distributed energy storage system and provide excitation to the rotor side, so as to realize the stator voltage building and grid-connected output of the distributed energy storage unit. 2) When the current wind speed of the distributed energy storage unit does not meet the unit cut-in wind speed condition, but the current wind speed of the undistributed energy storage unit meets the start-up condition, the grid-side start-up mode is executed. The grid-side start-up mode is to establish the offshore AC bus voltage through the distributed energy storage system and the grid-side converter to provide black start energy for the undistributed energy storage unit. 3) When the energy storage capacity of the distribution and storage unit is insufficient but the wind speed meets the start-up conditions, the already started unit will provide energy to start the unit on the generator side. 4) When the energy storage capacity of the distributed storage unit is insufficient and the wind speed does not meet the standard, its start-up will be delayed, and the already started unit will charge its energy storage system as the energy source for subsequent start-up.

7. An electronic device, characterized in that, include: One or more processors; Memory, used to store one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in any one of claims 1-5.

8. A computer-readable storage medium storing computer instructions thereon, characterized in that, When executed by the processor, this instruction implements the steps of the method as described in any one of claims 1-5.

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