A wind power off-grid hydrogen production system and its control method

Abstract

The present application relates to a wind power off-grid hydrogen production system and a control method thereof, wherein the system includes a wind turbine, a black start power supply, an energy storage converter, a machine-side converter, a grid-side converter, a DC bus capacitor, a first transformer, a second transformer, a third transformer, an AC-DC converter, a DC-DC converter, an electrolyzer, a first switch, a second switch, a third switch and a fourth switch; the system includes a black start mode, a normal operation mode and an emergency operation mode; in the black start mode, the system is started from a closed state to an operating state by the black start power supply; in the normal operation mode, the system power balance is maintained by adjusting the electrolysis power; in the emergency operation mode, the system power balance is maintained by adjusting the output power of the wind turbine; the system of the present application can fully explore the flexible adjustment capability of the electrolyzer load, and does not require additional energy storage devices other than the black start power supply, and can realize wind power off-grid hydrogen production without energy storage.

Description

Technical Field

[0001] The present application relates to the field of wind power hydrogen production, and in particular to a wind power off-grid hydrogen production system and a control method thereof. Background Art

[0002] Wind power hydrogen production is a technology that converts wind energy into electricity through wind turbines, and then converts this electricity into hydrogen through electrolysis equipment. Wind power hydrogen production technologies are categorized into grid-connected and off-grid wind power hydrogen production. Grid-connected wind power hydrogen production involves connecting wind turbines to the grid, converting wind energy into electricity, and then transmitting it through the grid to electrolysis equipment for hydrogen production. Off-grid wind power hydrogen production involves converting wind energy into electricity and then directly supplying it to electrolysis equipment for hydrogen production, bypassing the grid. Off-grid wind power hydrogen production is independent of the grid, offering greater flexibility and independence, reducing energy losses and costs during grid transmission. However, off-grid wind power hydrogen production technology is currently immature, and the volatility and intermittency of wind power can easily lead to system instability. Some studies have proposed using energy storage to form a grid or converting wind turbines into grid-connected wind turbines, but both approaches are costly, technically challenging, and require complex control methods. Summary of the Invention

[0003] In view of this, the present application proposes a wind power off-grid hydrogen production system and its control method, control device, electronic equipment and storage medium, which can fully tap the flexible adjustment capability of the electrolyzer load, do not rely on energy storage devices to balance the volatility and intermittency of wind power, and do not require additional energy storage devices other than black start power supplies, thereby realizing wind power off-grid hydrogen production without energy storage.

[0004] According to one aspect of the present application, a wind power off-grid hydrogen production system is provided, comprising a wind turbine, a black start power supply, an energy storage converter, a machine-side converter, a grid-side converter, a DC bus capacitor, a first transformer, a second transformer, a third transformer, an AC-DC converter, a DC-DC converter, an electrolyzer, a first switch, a second switch, a third switch and a fourth switch; the stator of the wind turbine is connected to the low-voltage side of the second transformer through the fourth switch; the rotor of the wind turbine is connected to the AC side of the machine-side converter; the DC bus capacitor is connected in parallel to the machine-side converter. between the DC side of the grid-side converter and the DC side of the grid-side converter; the AC side of the grid-side converter is connected to the low-voltage side of the second transformer through the first switch; the black start power supply is connected to the DC side of the energy storage converter; the AC side of the energy storage converter is connected to the low-voltage side of the first transformer; the high-voltage side of the first transformer is connected to the low-voltage side of the second transformer; the high-voltage side of the second transformer is connected to the high-voltage side of the third transformer; the low-voltage side of the third transformer is connected to the AC side of the AC-DC converter through the second switch; the DC side of the AC-DC converter The first side is connected to the first DC side of the DC-DC converter; the second DC side of the DC-DC converter is connected to the electrolyzer via the third switch; the operating modes of the system include a black start mode, a normal operating mode, and an emergency operating mode; in the black start mode, the system is started from a closed state to an operating state by the black start power supply; wherein, when the system is in the operating state, the wind turbine is used to convert wind energy into electrical energy; the electrical energy generated by the wind turbine is used to provide the electrolyzer with electrolytic hydrogen production and to charge the black start power supply; in the normal operating mode, the maximum output power of the wind turbine is not greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply; the system power balance is maintained by adjusting the electrolysis power of the electrolyzer; wherein, the system power balance means that the output power of the wind turbine is equal to the electrolysis power of the electrolyzer; in the emergency operating mode, the maximum output power of the wind turbine is greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply; the system power balance is maintained by adjusting the output power of the wind turbine.

[0005] In one possible implementation, when the system is in a shutdown state, the first switch, the second switch, the third switch, and the fourth switch are all disconnected. In the black start mode, the process of starting the system from the shutdown state to the operating state using the black start power supply includes: starting the energy storage converter and making the energy storage converter operate in an inverter mode to convert the direct current output by the black start power supply into alternating current; the inverter mode refers to an operating mode for converting direct current into alternating current; closing the first switch, starting the grid-side converter and making the grid-side converter operate in a rectifier mode; the rectifier mode refers to an operating mode for converting alternating current into direct current; when the voltage across the DC bus capacitor stabilizes, starting the generator-side converter to control the stator voltage of the wind turbine to meet a grid-connection condition; the grid-connection condition is that the stator voltage is equal to the voltage on the low-voltage side of the second transformer; when the stator voltage meets the grid-connection condition, closing the second switch and the third switch in sequence to start the electrolyzer; closing the fourth switch, and switching the operating mode of the energy storage converter to the rectifier mode.

[0006] In a possible implementation, in the normal operating mode, the wind turbine performs maximum power point tracking (MPPT) to achieve the maximum output power.

[0007] In one possible implementation, the process of maintaining the system power balance by adjusting the electrolysis power of the electrolyzer includes: determining the first output power of the wind turbine for MPPT at a first wind speed and the initial electrolyzer PU characteristic curve; the electrolyzer PU characteristic curve is used to represent the change of the electrolysis power of the electrolyzer with the system AC voltage; the system AC voltage represents the voltage on the high-voltage side of the second transformer; determining the first system stable AC voltage based on the first output power and the initial electrolyzer PU characteristic curve; the first system stable AC voltage is the system AC voltage corresponding to the first output power in the initial electrolyzer PU characteristic curve; when the wind speed changes from the first wind speed to the second wind speed, determining the second output power of the wind turbine for MPPT at the second wind speed; adjusting the initial electrolyzer PU characteristic curve by changing the duty cycle of the DC-DC converter so that in the adjusted electrolyzer PU characteristic curve, the system AC voltage corresponding to the second output power is the first system stable AC voltage.

[0008] In a possible implementation, in the emergency operation mode, the wind turbine does not perform MPPT, and the electrolyzer operates at the maximum electrolysis power.

[0009] According to another aspect of the present application, a control method for a wind power off-grid hydrogen production system is provided, which is applied to the above-mentioned wind power off-grid hydrogen production system; the method comprises: when the system is in a normal operation mode or an emergency operation mode, based on the proportional integral (PI) control algorithm, a rotor voltage reference value is obtained according to the d-axis component reference value of the rotor current of the wind generator in the dq coordinate system, the q-axis component reference value of the rotor current, the actual value of the d-axis component of the rotor current, and the actual value of the q-axis component of the rotor current; a first control signal is generated according to the rotor voltage reference value; the first control signal is used to control the on and off of the switching element inside the machine-side converter so that the rotor voltage of the wind generator is equal to the rotor voltage reference value; based on the PI control algorithm, a grid-side voltage reference value is obtained according to the d-axis component reference value of the grid-side current in the dq coordinate system, the q-axis component reference value of the grid-side current, the actual value of the d-axis component of the grid-side current, and the actual value of the q-axis component of the grid-side current; the grid-side current represents the current on the AC side of the grid-side converter; the grid-side voltage represents the voltage on the AC side of the grid-side converter; generating a second control signal based on the grid-side voltage reference value; the second control signal is used to control the on and off of the internal switching element of the grid-side converter to make the grid-side voltage equal to the grid-side voltage reference value; when the system is in normal operation mode, obtaining a first DC-DC duty cycle based on the reference value of the input voltage of the DC-DC converter and the actual value of the input voltage of the DC-DC converter based on a PI control algorithm; generating a third control signal based on the first DC-DC duty cycle; the third control signal is used to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle; when the system is in emergency operation mode, obtaining a second DC-DC duty cycle based on the reference value of the electrolysis voltage of the electrolytic cell and the actual value of the electrolysis voltage based on a PI control algorithm; generating a fourth control signal based on the second DC-DC duty cycle; the fourth control signal is used to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

[0010] In a possible implementation, the reference value of the d-axis component of the rotor current is obtained based on the PI control algorithm according to the reference value of the active power of the wind turbine and the actual value of the active power; wherein, when the system is in normal operation mode, the reference value of the active power is obtained based on the MPPT algorithm according to the rotor speed of the wind turbine; when the system is in emergency operation mode, the reference value of the active power is obtained based on the system AC voltage; the system AC voltage represents the voltage on the high-voltage side of the second transformer; the reference value of the q-axis component of the rotor current is obtained based on the reference value of the reactive power of the wind turbine and the actual value of the active power. The actual value of the reactive power is obtained based on the PI control algorithm; the reference value of the d-axis component of the grid-side current is obtained based on the PI control algorithm according to the reference value of the DC bus voltage and the actual value of the DC bus voltage; the DC bus voltage represents the voltage across the DC bus capacitor; the reference value of the electrolysis voltage is obtained based on the PI control algorithm according to the reference value of the electrolysis power of the electrolytic cell and the actual value of the electrolysis power; the reference value of the electrolysis power is the maximum electrolysis power; the reference value of the reactive power, the reference value of the q-axis component of the grid-side current and the reference value of the input voltage of the DC-DC converter are obtained by artificial setting.

[0011] In a possible implementation, obtaining a rotor voltage reference value based on a proportional-integral (PI) control algorithm according to a d-axis component reference value of the rotor current of the wind turbine in a dq coordinate system, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current includes calculating a d-axis component reference value and a q-axis component reference value of the rotor voltage of the wind turbine according to the following formula based on the d-axis component reference value of the rotor current, the q-axis component reference value of the rotor current, the actual value of the d-axis component of the rotor current, and the actual value of the q-axis component of the rotor current: in, represents a reference value of a q-axis component of the rotor voltage; represents a reference value of the d-axis component of the rotor voltage; represents a reference value of the q-axis component of the rotor current; represents the d-axis component reference value of the rotor current; i rq represents the actual value of the q-axis component of the rotor current; i rd represents the actual value of the d-axis component of the rotor current; K irP Indicates proportional control gain; K irI Indicates the integral adjustment gain; 1 / s indicates the integral link; ω sl Indicates slip frequency; L m Represents the excitation inductance; L s Represents leakage inductance; ims represents the excitation current; σ represents the magnetic permeability; L r represents the self-inductance of the rotor winding; and obtaining the rotor voltage reference value according to the d-axis component reference value of the rotor voltage and the q-axis component reference value of the rotor voltage.

[0012] In a possible implementation, obtaining the grid-side voltage reference value based on a PI control algorithm according to the d-axis component reference value of the grid-side current, the q-axis component reference value of the grid-side current, the actual value of the d-axis component of the grid-side current, and the actual value of the q-axis component of the grid-side current in the dq coordinate system includes: calculating the d-axis component reference value of the grid-side voltage and the q-axis component reference value of the grid-side voltage according to the following formula: in, represents a reference value of the q-axis component of the grid-side voltage; represents the reference value of the d-axis component of the grid-side voltage; represents a reference value of the q-axis component of the grid-side current; represents the reference value of the d-axis component of the grid-side current; i cq represents the actual value of the q-axis component of the grid-side current; i cd represents the actual value of the d-axis component of the grid-side current; K icP Indicates proportional control gain; K icI represents the integral adjustment gain; 1 / s represents the integral link; ω represents the angular frequency of the grid voltage, and the grid voltage represents the voltage on the low-voltage side of the second transformer; u gq represents the q-axis component of the grid voltage; L represents the filter inductance value; the grid-side voltage reference value is obtained according to the d-axis component reference value of the grid-side voltage and the q-axis component reference value of the grid-side voltage.

[0013] According to another aspect of the present application, a control device for an off-grid wind power hydrogen production system is provided, for controlling the above-mentioned off-grid wind power hydrogen production system; the device comprises: a rotor voltage reference value determination module for determining, when the system is in a normal operation mode or an emergency operation mode, a rotor voltage reference value based on a PI control algorithm according to a d-axis component reference value of a rotor current of the wind turbine generator, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current in a dq coordinate system; and a first control module for generating a first control signal based on the rotor voltage reference value; The first control signal is used to control the conduction and disconnection of the internal switching element of the machine-side converter so that the rotor voltage of the wind turbine is equal to the rotor voltage reference value; the grid-side voltage reference value determination module is used to obtain the grid-side voltage reference value based on the PI control algorithm according to the d-axis component reference value of the grid-side current in the dq coordinate system, the q-axis component reference value of the grid-side current, the actual value of the d-axis component of the grid-side current, and the actual value of the q-axis component of the grid-side current when the system is in normal operation mode or emergency operation mode; the grid-side current represents the current on the AC side of the grid-side converter; the grid-side voltage represents the grid a first DC-DC duty cycle determination module for determining a first DC-DC duty cycle based on a reference value of an input voltage of the DC-DC converter and an actual value of an input voltage of the DC-DC converter when the system is in a normal operating mode; a third control module for determining a first DC-DC duty cycle based on a PI control algorithm and a reference value of an input voltage of the DC-DC converter and an actual value of an input voltage of the DC-DC converter when the system is in a normal operating mode; and a third control module for determining a first DC-DC duty cycle based on a PI control algorithm and a reference value of an input voltage of the DC-DC converter and an actual value of an input voltage of the DC-DC converter. a first control module for determining an electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage, and generating a third control signal; the third control signal is used to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle; a second DC-DC duty cycle determination module is used to obtain a second DC-DC duty cycle based on a PI control algorithm according to a reference value of the electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage when the system is in an emergency operation mode; a fourth control module is used to generate a fourth control signal according to the second DC-DC duty cycle; the fourth control signal is used to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

[0014] According to another aspect of the present application, an electronic device is provided, comprising: a processor; and a memory for storing instructions executable by the processor; wherein the processor is configured to implement the above-mentioned control method of the wind power off-grid hydrogen production system when executing the instructions stored in the memory.

[0015] According to another aspect of the present application, a non-volatile computer-readable storage medium is provided, on which computer program instructions are stored, wherein the computer program instructions, when executed by a processor, implement the control method of the above-mentioned wind power off-grid hydrogen production system.

[0016] According to another aspect of the present application, a computer program product is provided, comprising a computer-readable code, or a non-volatile computer-readable storage medium carrying the computer-readable code. When the computer-readable code runs in a processor of an electronic device, the processor in the electronic device executes the above-mentioned control method for the off-grid wind power hydrogen production system.

[0017] The wind power off-grid hydrogen production system of the present application starts the system from a closed state to an operating state through a black start power supply in a black start mode; when the system is in an operating state and the maximum output power of the wind turbine does not exceed the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply, the system operates in a normal operating mode, in which the system power balance is maintained by adjusting the electrolysis power; when the system is in an operating state and the maximum output power of the wind turbine exceeds the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply, the system enters an emergency operating mode, in which the system power balance is maintained by adjusting the output power of the wind turbine; the wind power off-grid hydrogen production system of the present application can fully explore the flexible adjustment capability of the electrolyzer load, maintain system stability by adjusting the power of the electrolyzer or wind turbine in different operating modes, does not rely on energy storage devices to balance the volatility and intermittency of wind power, and does not require additional energy storage devices other than the black start power supply, thereby realizing wind power off-grid hydrogen production without energy storage.

[0018] Other features and aspects of the present application will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the application and, together with the description, serve to explain the principles of the application.

[0020] Figure 1 A structural schematic diagram of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown.

[0021] Figure 2 A schematic diagram illustrating a normal operating mode of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown.

[0022] Figure 3 A schematic diagram illustrating an emergency operation mode of an off-grid wind power hydrogen production system according to an embodiment of the present application is shown.

[0023] Figure 4A flow chart illustrating a method for controlling an off-grid wind power hydrogen production system according to an embodiment of the present application is shown.

[0024] Figure 5 A control block diagram of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown.

[0025] Figure 6 A schematic diagram showing simulation results of controlling a wind power off-grid hydrogen production system according to a control method according to an embodiment of the present application is shown.

[0026] Figure 7 A structural schematic diagram of a control device of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown.

[0027] Figure 8 A block diagram of an electronic device 1900 according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0028] Various exemplary embodiments, features, and aspects of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0029] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0030] In addition, numerous specific details are provided in the detailed description below to better illustrate the present application. Those skilled in the art will appreciate that the present application can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0031] Figure 1 A schematic structural diagram of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown in FIG. Figure 1 As shown, the system may include a wind turbine side and a hydrogen production side. The wind turbine side includes a wind turbine generator, a black start power supply, an energy storage converter, a machine-side converter, a grid-side converter, a DC bus capacitor (i.e. Figure 1 C in DC ), the first transformer, the second transformer, the first switch (ie Figure 1 QF1 in) and the fourth switch (i.e. Figure 1 The hydrogen production side includes a third transformer, an alternating current (AC)-direct current (DC) converter, a DC-DC converter, an electrolyzer, a second switch (i.e. Figure 1 QF2 in) and the third switch (i.e. Figure 1 QF3 in ).

[0032] Among them, the stator of the wind turbine is connected to the low-voltage side of the second transformer through QF4; the rotor of the wind turbine is connected to the AC side of the machine-side converter; the DC bus capacitor is connected in parallel between the DC side of the machine-side converter and the DC side of the grid-side converter; the AC side of the grid-side converter is connected to the low-voltage side of the second transformer through QF1; the black start power supply is connected to the DC side of the energy storage converter; the AC side of the energy storage converter is connected to the low-voltage side of the first transformer; the high-voltage side of the first transformer is connected to the low-voltage side of the second transformer; the high-voltage side of the second transformer is connected to the high-voltage side of the third transformer; the low-voltage side of the third transformer is connected to the AC side of the AC-DC converter through QF2; the DC side of the AC-DC converter is connected to the first DC side of the DC-DC converter; the second DC side of the DC-DC converter is connected to the electrolyzer through QF3.

[0033] For example, the wind turbine generator may be a doubly fed induction generator (DFIG), which, in addition to the generator body, also includes blades, a gearbox, a nacelle, and other structures. The wind turbine generator is hereinafter referred to as a wind turbine.

[0034] The generator-side converter, the grid-side converter, and the DC bus capacitor may form a back-to-back converter. For example, the capacity of the back-to-back converter may be approximately 30% of the wind turbine capacity.

[0035] Exemplarily, the second transformer may be a box-type transformer, and the third transformer may be a rectifier phase-shifting transformer.

[0036] Exemplarily, the AC-DC converter may be a 24-pulse uncontrolled rectifier, and the DC-DC converter may be a multiple interleaved parallel Buck converter.

[0037] As an example, the first transformer can be a 400V / 1140V transformer, the second transformer can be a 1140V / 35kV box-type transformer, and the third transformer can be a 35kV / 660V rectifier phase-shifting transformer. The stator of the DFIG is connected to the low-voltage side of the 1140V / 35kV box-type transformer, and the rotor of the DFIG is connected to the low-voltage side of the 1140V / 35kV box-type transformer via a back-to-back converter. The small-capacity black start power supply is connected to the low-voltage side of the 1140V / 35kV box-type transformer via an energy storage converter and a 400V / 1140V transformer. The 400V / 1140V transformer can be placed inside the wind turbine nacelle. After the above-mentioned wind turbine-side equipment is boosted by the 1140V / 35kV box-type transformer, the power is transmitted to the hydrogen production side via a 35kV transmission line. The 35kV / 660V rectifier-phase-shifting transformer on the hydrogen production side reduces the 35kV voltage to 660V. The low-voltage windings of the 35kV / 660V rectifier-phase-shifting transformer undergo phase shifting, with a phase difference of 7.5°, enabling multi-pulse rectification. The AC-DC converter and DC-DC converter can be considered electrolysis power sources. The AC-DC converter converts alternating current (AC) to direct current (DC), while the DC-DC converter converts DC to adjust the electrolysis voltage, current, and power of the electrolyzer, thereby changing the electrolysis cell's load characteristics.

[0038] It should be noted that Figure 1 This is a topological diagram of the wind power off-grid hydrogen production system of this application. Those skilled in the art should understand that Figure 1 The topological diagram of a single wind turbine and a single electrolyzer connected via an AC transmission line can be expanded to a wind farm (including multiple wind turbines) and an electric hydrogen production plant (including multiple electrolyzers) connected via an AC transmission line (for example, a 220kV or 35kV transmission line), forming an off-grid wind power hydrogen production system in an engineering sense.

[0039] The wind power off-grid hydrogen production system of the present application may include three operating modes, namely black start mode, normal operation mode and emergency operation mode. In black start mode, the system is started from the off state to the operating state by the black start power supply. Among them, when the system is in the operating state, the wind turbine is used to convert wind energy into electrical energy; the electrical energy generated by the wind turbine is used to provide electrolysis to the electrolyzer for hydrogen production, and to charge the black start power supply. At this time, the black start power supply is equivalent to an energy storage device. The electrical energy stored in the black start power supply can be used to supply factory electricity (i.e., the normal working electricity of the wind power plant) when the wind turbine is shut down, and to provide AC voltage during the wind turbine startup process to enable the wind turbine to start smoothly. In normal operation mode, the system is in operation, and the maximum output power of the wind turbine is not greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply. In emergency operation mode, the system is in operation, and the maximum output power of the wind turbine is greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply.

[0040] The black start of the off-grid wind power hydrogen production system in the embodiment of the present application refers to the process of independently starting the system to normal operation using only the black start power supply without relying on the main power grid. Table 1 shows the switch operation and converter operation in the black start mode.

[0041] Table 1

[0042]

[0043]

[0044] When the system is in the shutdown state, QF1, QF2, QF3, and QF4 are all disconnected. In black start mode, the process of starting the system from the shutdown state to the operating state using the black start power supply can include: first, turning on the energy storage converter and setting it to operate in inverter mode to convert the DC power output by the black start power supply into AC power. Inverter mode refers to the operating mode that converts DC power into AC power. In this case, the energy storage converter can be considered a DC / AC inverter, and the first transformer can be considered a step-up transformer. The DC voltage output by the black start power supply is converted to AC voltage by the DC / AC inverter, and then stepped up by the step-up transformer before being output to the low-voltage side of the second transformer, thereby actively providing stable AC voltage amplitude and frequency. QF1 is then closed, and the grid-side converter is subsequently turned on and set to operate in rectification mode to maintain a stable DC bus voltage (i.e., the voltage across the DC bus capacitors). Rectification mode refers to the operating mode that converts AC power into DC power. Once the DC bus voltage stabilizes, the generator-side converter is turned on. It adjusts the excitation voltage and current to control the wind turbine's stator voltage to meet grid-connection requirements. This grid-connection requirement requires that the stator voltage be equal to the voltage on the low-voltage side of the second transformer (i.e., the phase, amplitude, and frequency of the stator voltage and the voltage on the low-voltage side of the second transformer are equal). The black-start power supply, energy storage converter, first transformer, second transformer, third transformer, AC-DC converter, DC-DC converter, and electrolyzer can be considered to form a microgrid. Only when the stator voltage meets the grid-connection requirements can the wind turbine be smoothly integrated into this microgrid. Controlling the stator voltage to meet the grid-connection requirements through the generator-side converter is called pre-synchronization control. When the stator voltage meets the grid-connection requirements, QF2 and QF3 are closed sequentially to start the electrolysis power supply and electrolyzer. Finally, QF4 is closed, the wind turbine is connected to the microgrid, and power is supplied to the hydrogen production side. The system is successfully started and put into operation. The working mode of the energy storage converter is switched to rectification mode. The power generated by the wind turbine is used to charge the black start power supply, replenishing the energy consumption during the black start process and the power supply for the plant, so as to prepare for the next black start and continuously supply power to the plant when the wind turbine is shut down.

[0045] After the system is successfully started, it switches to normal operating mode. The normal operating mode of the wind power off-grid hydrogen production system in the embodiment of the present application means that the maximum power generated by the wind turbine (i.e., the maximum output power of the wind turbine) does not exceed the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply.

[0046] In normal operation, wind turbines can be configured to perform Maximum Power Point Tracking (MPPT) to maximize wind energy capture, reduce wind curtailment, and achieve maximum output power. MPPT technology is a control technique that maximizes wind turbine power output. The output power of a wind turbine during MPPT varies with wind speed. Its core goal is to optimize the turbine's operation under varying wind speeds to ensure maximum power output under all circumstances. Furthermore, in the case of multiple wind turbines, one wind turbine (the master) actively establishes the system frequency, while the remaining wind turbines (the slaves) sample and follow the master's frequency to implement Space Vector Control (SVC). SVC technology can treat AC motors as DC motors, independently controlling both speed and magnetic field components. In normal operation, system power balance can be maintained solely by adjusting the electrolytic cell's electrolysis power, thereby maintaining system voltage stability. System power balance means that the power generated by the wind turbine can be absorbed by the electrolytic cell, i.e., the wind turbine's output power = the electrolytic cell's electrolysis power. Since the black start power supply has a small capacity, it can be fully charged soon after the black start process. However, system power balance takes a long time to consider. In the process of maintaining system power balance, the charging power of the black start power supply is not considered.

[0047] In one possible implementation, the process of maintaining system power balance by adjusting the electrolysis power of the electrolytic cell may include:

[0048] Determine a first output power of the wind turbine for MPPT at a first wind speed and an initial electrolytic cell PU characteristic curve; the electrolytic cell PU characteristic curve is used to represent the change of the electrolytic power of the electrolytic cell with the system AC voltage; the system AC voltage is the voltage on the high-voltage side of the second transformer (i.e., the voltage on the high-voltage side of the third transformer);

[0049] Determine a first system stable AC voltage according to the first output power and the initial electrolytic cell PU characteristic curve; the first system stable AC voltage is the system AC voltage corresponding to the first output power in the initial electrolytic cell PU characteristic curve;

[0050] When the wind speed changes from the first wind speed to the second wind speed, determining a second output power of the wind turbine performing MPPT at the second wind speed;

[0051] By changing the duty cycle of the DC-DC converter, the initial electrolytic cell PU characteristic curve is adjusted so that in the adjusted electrolytic cell PU characteristic curve, the system AC voltage corresponding to the second output power is the first system stable AC voltage.

[0052] Figure 2 A schematic diagram showing a normal operating mode of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown. Figure 2 Middle black dotted line The black dotted line represents the PU characteristic curve of the fan when the wind speed is v1 (i.e. the first wind speed). The PU characteristic curve of the fan is used to represent the output power of the fan as the system AC voltage u changes. ac changes from Figure 2 It can be seen that the output power of the fan during MPPT is related to the wind speed, and the output power does not change with the system AC voltage. Figure 2 middle It indicates the power (i.e. the first output power) generated by the wind turbine during MPPT when the wind speed is v1. It indicates the power generated by the wind turbine during MPPT when the wind speed is v2 (i.e. the second output power). Figure 2 Medium purple curve The purple curve represents the initial PU characteristic curve of the electrolytic cell (i.e., the PU characteristic curve of the electrolytic cell when the DC-DC converter duty cycle is not changed). The PU characteristic curve of the electrolytic cell after adjustment (i.e. the PU characteristic curve of the electrolytic cell after changing the duty cycle of the DC-DC converter) is used to indicate the electrolytic power of the electrolytic cell as the system AC voltage u ac The system AC voltage corresponding to the intersection of the fan PU characteristic curve and the electrolyzer PU characteristic curve can be called the system stable AC voltage.

[0053] like Figure 2 As shown, when the wind speed is v1, the fan PU characteristic curve PU characteristic curve of electrolyzer Intersect at ①, and the corresponding system stable AC voltage is (i.e. the stable AC voltage of the first system). When the wind speed increases to v2, the PU characteristic curve of the fan moves up along the y-axis, and the output power of the fan increases to At this time, the fan PU characteristic curve PU characteristic curve of electrolyzer Intersect at point ②, and the corresponding system stable AC voltage is from Figure 2 As you can see, That is, when the wind speed increases, the system stable AC voltage will also increase. In order to maintain the system stable AC voltage constant or keep the change of the system stable AC voltage within a small range, the electrolytic cell PU characteristic curve can be adjusted so that the system AC voltage corresponding to the intersection of the fan PU characteristic curve and the adjusted electrolytic cell PU characteristic curve remains or in nearby.

[0054] The DC / DC converter on the hydrogen production side can sample the system DC voltage (i.e., the voltage on the first DC side of the DC-DC converter, i.e., the voltage on the DC side of the AC-DC converter). The system DC voltage can reflect the level of the system AC voltage, and further reflect the source-load power balance (i.e., the balance between the total power emitted by the power source and the total power consumed by the load) and the system voltage stability level. When the wind speed increases, the output power of the fan increases, the system AC voltage will increase, and the system DC voltage will also increase accordingly. When an upward trend in the system DC voltage is detected, the PU characteristic curve of the electrolyzer can be adjusted by changing the duty cycle of the DC-DC converter. The duty cycle of the DC-DC converter indicates the proportion of the conduction time of the internal switching element of the DC-DC converter to the entire switching cycle. Changing the duty cycle of the DC-DC converter can change the output voltage of the DC-DC converter, thereby changing the load characteristics of the electrolyzer (i.e., the PU characteristic curve of the electrolyzer can be adjusted), so that the PU characteristic curve of the fan And the PU characteristic curve of the electrolytic cell after adjustment Intersect at point ③, and the corresponding system stable AC voltage drops back to After adjusting the electrolyzer's PU characteristic curve, the electrolysis power changes under the same stable system AC voltage. This is equivalent to maintaining system power balance by adjusting the electrolysis power when the fan output power changes with wind speed. In this way, the electrolysis power of the electrolyzer is actively adjusted according to the sampled system DC voltage, so that the electrolysis power actively follows the fan output power, maintaining system power balance and further maintaining system voltage stability.

[0055] The emergency operation mode of the wind power off-grid hydrogen production system in the embodiment of the present application means that the maximum power generated by the wind turbine exceeds the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply. At this time, the electrolyzer's ability to regulate the system power balance reaches its limit, and the system power balance and system voltage stability cannot be maintained by relying solely on the electrolyzer.

[0056] When the maximum output power of the fan exceeds the sum of the maximum electrolysis power and the maximum charging power, the system switches from normal operation mode to emergency operation mode. In emergency operation mode, the fan no longer performs MPPT, and the electrolyzer can maintain the rated current under the regulation of the DC-DC converter, thereby operating at the rated power (i.e., the maximum electrolysis power). The rated power of the electrolyzer can be set in advance by those skilled in the art, and the operation of the electrolyzer at the rated power is also called full power operation. In emergency operation mode, the system power balance can be maintained by adjusting the output power of the fan, thereby maintaining system voltage stability.

[0057] Figure 3 The schematic diagram of the emergency operation mode of the off-grid wind power hydrogen production system according to an embodiment of the present application is shown. The black dotted line in Figure 3 (i.e., the black dotted line ①) represents the fan PU characteristic curve when the wind speed is v3 and the purple curve P elz It represents the electrolytic cell PU characteristic curve. It can be seen that when the system AC voltage u ac After reaching a certain value, the electrolytic cell reaches the maximum electrolysis power It indicates the maximum power generated by the wind turbine when performing MPPT at wind speed v3. Greater than the sum of the maximum electrolysis power and the maximum charging power, the fan PU characteristic curve and electrolytic cell PU characteristic curve P elz There is no intersection, and the system is unstable. At this time, you can switch the fan control mode so that the fan no longer performs MPPT and the fan output power tracks Figure 3 The red drooping solid line shows the active reduction of output power, which is consistent with the electrolyzer PU characteristic curve P elz Generate an intersection point to stabilize the system. Figure 3 The red drooping solid line in the figure can be called the PU droop curve, and controlling the output power of the fan to follow the changes in the PU droop curve can be called PU droop control. The system AC voltage corresponding to the intersection of the PU droop curve and the electrolyzer PU characteristic curve is the system stable AC voltage. At the same time, the electrolyzer operates at full power under the regulation of the DC-DC converter. By limiting the output power of the fan in the emergency operation mode, the system power balance can be maintained, thereby maintaining the system voltage stability. It should be noted that the slope of the PU droop curve should be appropriate. If the slope is too small (such as Figure 3 PU droop curve in ), PU droop curve and electrolytic cell PU characteristic curve P elz Intersect at point ②, the corresponding system stable AC voltage Exceeds the upper limit of the system AC voltage When the slope is appropriate (such as Figure 3PU droop curve in ), PU droop curve and electrolytic cell PU characteristic curve P elz Intersecting at point ③, the corresponding system stable AC voltage Does not exceed the upper limit of the system AC voltage It can be preset by those skilled in the art. and The relationship can be

[0058] The wind power off-grid hydrogen production system of the present application also includes a special operating mode. In the normal operating mode, the electrolysis power of the electrolyzer follows the output power of the wind turbine to maintain the system power balance. However, when the rising speed of the wind turbine output power is too fast, and the rising speed of the electrolysis power of the electrolyzer cannot keep up with the rising rate of the wind turbine output power, the electrolysis power will be subject to the climbing constraint and cannot reach the upper limit. At this time, it is impossible to maintain the system power balance by adjusting the electrolysis power alone, and the system switches from the normal operating mode to the special operating mode. In the special operating mode, it is necessary to adjust the wind turbine output power and the electrolysis power of the electrolyzer at the same time to maintain the system power balance.

[0059] The wind power off-grid hydrogen production system of the embodiment of the present application starts the system from the off state to the running state through the black start power supply in the black start mode; when the system is in the running state and the maximum output power of the wind turbine does not exceed the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply, the system operates in the normal operation mode, in which the system power balance is maintained by adjusting the electrolysis power; when the system is in the running state and the maximum output power of the wind turbine exceeds the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply, the system enters the emergency operation mode, in which the system power balance is maintained by adjusting the output power of the wind turbine. The wind power off-grid hydrogen production system of the embodiment of the present application can fully explore the flexible adjustment capability of the electrolyzer load, maintain system stability by adjusting the power of the electrolyzer or the wind turbine in different operating modes, does not rely on energy storage devices to balance the volatility and intermittency of wind power, and does not require additional energy storage devices other than the black start power supply, thereby realizing wind power off-grid hydrogen production without energy storage.

[0060] The present application also proposes a control method for a wind power off-grid hydrogen production system. The control method for a wind power off-grid hydrogen production system of the present application provides a control method for the converters on the wind turbine side and the hydrogen production side during the operation process after the system is successfully started.

[0061] Figure 4 A flow chart showing a control method for a wind power off-grid hydrogen production system according to an embodiment of the present application is shown. The method can be applied to a wind power off-grid hydrogen production system according to an embodiment of the present application, such as Figure 4As shown, the method may include:

[0062] S401. When the system is in normal operation mode or emergency operation mode, a rotor voltage reference value is obtained based on a proportional-integral (PI) control algorithm according to a d-axis component reference value of the rotor current of the wind turbine, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current in a dq coordinate system.

[0063] S402. Generate a first control signal according to the rotor voltage reference value; the first control signal is used to control the on and off of the internal switching element of the machine-side converter to make the rotor voltage of the wind turbine equal to the rotor voltage reference value.

[0064] S403. Obtain a grid-side voltage reference value based on a PI control algorithm according to a reference value of the d-axis component of the grid-side current in the dq coordinate system, a reference value of the q-axis component of the grid-side current, an actual value of the d-axis component of the grid-side current, and an actual value of the q-axis component of the grid-side current; the grid-side current represents the current on the AC side of the grid-side converter; and the grid-side voltage represents the voltage on the AC side of the grid-side converter.

[0065] S404. Generate a second control signal according to the grid-side voltage reference value; the second control signal is used to control the on and off of the internal switching element of the grid-side converter to make the grid-side voltage equal to the grid-side voltage reference value.

[0066] S405: When the system is in a normal operating mode, obtain a first DC-DC duty cycle based on a PI control algorithm according to a reference value of an input voltage of the DC-DC converter and an actual value of the input voltage of the DC-DC converter;

[0067] S406 . Generate a third control signal according to the first DC-DC duty cycle; the third control signal is used to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle.

[0068] S407: When the system is in the emergency operation mode, a second DC-DC duty cycle is obtained based on a PI control algorithm according to a reference value of the electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage.

[0069] S408 . Generate a fourth control signal according to the second DC-DC duty cycle; the fourth control signal is used to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

[0070] Figure 5 A control block diagram of a wind power off-grid hydrogen production system according to an embodiment of the present application is shown. Figure 5The structure outside the wind power off-grid hydrogen production system can be called the control system of the wind power off-grid hydrogen production system. Figure 5 As shown, the control system of the off-grid wind power hydrogen production system may include a reactive power controller, an active power controller, a first current controller, a second current controller, a first voltage controller, a second voltage controller, and a third voltage controller. All of the above controllers in the control system are proportional integral (PI) controllers. The PI controller combines proportional control and integral control to achieve precise regulation of the error (i.e., the difference between the reference value and the actual value). The control modes of the control system may include a normal control mode and an emergency control mode.

[0071] When the wind power off-grid hydrogen production system is in normal operation mode, the control system is in normal control mode. The control block diagram for controlling the wind turbine side in normal control mode is as follows: Figure 5 The yellow part of the wind turbine side is shown in the figure. The control of the wind turbine side can be divided into two parts: generator-side converter control and grid-side converter control.

[0072] In normal control mode, the generator-side converter controls reactive power between the generator and the AC microgrid (i.e., the microgrid consisting of the second transformer, third transformer, AC-DC converter, DC-DC converter, and electrolyzer) and performs MPPT. The generator-side converter is controlled using dual closed-loop PI control. The outer power loop compares the wind turbine power reference with the actual wind turbine power value calculated through sampling. The PI controller generates the inner current loop rotor current reference. This rotor current reference is compared with the actual rotor current value calculated through sampling, and the PI controller generates the rotor voltage reference. The specific implementation process is as follows.

[0073] The power of a wind turbine is divided into active power and reactive power. Active power refers to the useful power generated by the wind turbine, that is, the power converted into electrical energy output. Reactive power is the power generated by the wind turbine during the power generation process for the conversion of electric and magnetic fields in the circuit. Reactive power will not be converted into electrical energy output. For active power, the maximum output power reference value of the wind turbine (i.e., active power reference value) can be obtained by collecting the rotor speed Ω of the wind turbine in real time and calculating it based on the MPPT algorithm. ); The actual output power P of the wind turbine can be calculated by real-time sampling of the grid voltage (i.e., the voltage on the low-voltage side of the second transformer) and the grid current (i.e., the current on the low-voltage side of the second transformer). g (ie, the actual value of active power). For reactive power, the reference value of reactive power It can be set by those skilled in the art according to actual needs, for example, it can be set to 0; the actual value of reactive power Q e It can be obtained through measurement. The method of measuring reactive power can refer to the existing technology. and P g Input into the active power controller, the active power controller calculates the reference value of the rotor current d-axis component of the wind turbine in the two-phase rotating coordinate system (dq coordinate system) based on the PI control algorithm Will and Q e Input into the reactive controller, which calculates the q-axis component reference value of the wind turbine rotor current in the dq coordinate system based on the PI control algorithm. and The specific calculation process of can refer to the relevant technology. And the actual value i of the d-axis component of the rotor current of the fan obtained by real-time sampling rd and the actual value of the q-axis component of the rotor current i rq The voltage is input to the first current controller, which calculates the rotor voltage reference value of the wind turbine based on the PI control algorithm. The calculation formula is as follows:

[0074]

[0075] in, Indicates the reference value of the q-axis component of the wind turbine rotor voltage, Indicates the reference value of the d-axis component of the fan rotor voltage, K irP represents the proportional gain of the first current controller, K irI represents the integral adjustment gain of the first current controller, s represents the complex frequency variable, 1 / s represents the integral link in the control system, ω sl Indicates the slip frequency (i.e. the frequency difference between the fan's rotor rotation speed and the stator magnetic field rotation speed), L m Indicates the excitation inductance (i.e. the mutual inductance between the magnetic field generated by the fan's excitation winding and the stator winding), L s Represents leakage inductance (i.e., the inductance generated by partial magnetic flux leaking to the outside of the wind turbine winding due to factors such as incomplete insulation or winding design), i ms represents the excitation current (i.e. the current passing through the fan excitation winding to generate the magnetic field), σ represents the magnetic permeability coefficient, L r Indicates the self-inductance of the rotor winding (i.e. the induction effect of the magnetic field generated by the current change in the fan rotor winding on the same winding itself). and The rotor voltage reference value of the wind turbine in the dq coordinate system can be obtained by synthesis.

[0076] Formulas (1) and (2) can be called rotor voltage control equations. and Afterwards, you can and Generate the first control signal. The process of generating the first control signal is as follows: first, perform dq-αβ coordinate system transformation, and transform the dq coordinate system into and Converted to the two-phase stationary coordinate system (αβ coordinate system) and Since the dq coordinate system is a rotating coordinate system and the αβ coordinate system is a stationary coordinate system, an angle θ is required to convert the dq coordinate system to the αβ coordinate system. sl As a benchmark, θ sl It can be obtained based on the stator voltage orientation. and The first control signal is generated through space vector pulse width modulation (SVPWM). The generator-side converter contains multiple switching elements. The first control signal generated by SVPWM is a pulse width modulation (PWM) signal that controls the ratio of the on-time and off-time of the switching elements within the generator-side converter to the entire switching cycle, thereby ensuring that the wind turbine rotor voltage reaches a reference value.

[0077] In normal control mode, the grid-side converter's primary function is to maintain a constant DC bus voltage. The grid-side converter is controlled using a dual closed-loop PI control system. The outer voltage loop compares the DC bus voltage reference with the actual DC bus voltage value sampled in real time. The PI controller generates the inner current loop's grid-side current reference. This grid-side current reference is then compared with the actual grid-side current value sampled in real time, and the PI controller generates the grid-side voltage reference. The grid-side current represents the current on the AC side of the grid-side converter, and the grid-side voltage represents the voltage on the AC side of the grid-side converter. The specific implementation process is as follows.

[0078] Actual value of DC bus voltage u dc2 The DC bus voltage reference value is obtained through real-time sampling. It can be set by those skilled in the art according to actual needs. As an example, if the AC bus voltage (i.e., the voltage on the AC side of the machine-side converter) is required to be 690V, the AC bus voltage needs to be controlled by stabilizing the DC bus voltage. The link between the AC bus voltage and the DC bus voltage is an AC-DC converter (i.e., the machine-side converter). If the voltage transformation ratio of the AC-DC converter is 1.41, the DC bus voltage reference value needs to be set to 690V*1.41 so that the AC bus voltage can be stabilized at 690V. dc2 and Input to the first voltage controller, the first voltage controller calculates the grid-side current d-axis component reference value in the dq coordinate system based on the PI control algorithm Reference value of the q-axis component of the grid-side current It can be set by skilled technicians according to actual needs. Since the q-axis component of the grid-side current can reflect the reactive power, it is generally hoped that the reactive power is 0. Can be set to 0. And the actual value i of the grid-side current d-axis component obtained by real-time sampling cd and the actual value of the grid-side current q-axis component i cq The voltage is input to the second current controller, which calculates the grid-side voltage reference value based on the PI control algorithm. The calculation formula is as follows:

[0079]

[0080] in, Indicates the reference value of the q-axis component of the grid-side voltage, Indicates the reference value of the d-axis component of the grid-side voltage, K icP represents the proportional gain of the second current controller, K icI represents the integral adjustment gain of the second current controller, 1 / s represents the integral link in the control system, ω represents the grid voltage angular frequency, L represents the filter inductance value, u gq Represents the q-axis component of the grid voltage. and The grid-side voltage reference value in the dq coordinate system can be obtained by synthesis.

[0081] Formulas (3) and (4) can be called grid-side voltage control equations. and Afterwards, you can and Generate the second control signal. The process of generating the second control signal is as follows: first, perform dq-αβ coordinate system transformation, and transform the dq coordinate system into and Converted to αβ coordinate system respectively and Reference angle θ for dq-αβ coordinate system transformation s The reference angle can be obtained by real-time acquisition of the grid voltage and locking the phase of the grid voltage through a phase-locked loop (PLL). This method of determining the reference angle is called grid voltage orientation. and The second control signal is generated through SVPWM. The grid-side converter contains multiple switching elements. The second control signal generated by SVPWM is a PWM signal that controls the ratio of the on-time and off-time of the switching elements within the grid-side converter to the entire switching cycle, thereby ensuring that the grid-side voltage reaches the reference value.

[0082] It should be noted that the voltage and current values ​​actually collected in the wind power off-grid hydrogen production system (e.g. Figure 5 The grid voltage in Grid current Grid-side voltage Grid-side current rotor current ) is the value in the three-phase stationary coordinate system (abc coordinate system). In order to facilitate control, abc-dq coordinate system transformation is required. Converted to dq coordinate system respectively Then proceed with subsequent calculations. and The actual output power P of the fan can be calculated g ;Will Decomposition can be performed to obtain the actual value u of the q-axis component of the grid voltage gq ;Will Decomposition can be used to obtain the actual value of the rotor current d-axis component i rd and the actual value of the q-axis component of the rotor current i rq ;Will Decomposition can be used to obtain the actual value of the grid-side current d-axis component i cd and the actual value of the grid-side current q-axis component i cq .

[0083] The control block diagram for controlling the hydrogen production side in normal control mode is as follows Figure 5 The yellow portion of the hydrogen production side is shown in Figure 2. In normal control mode, the control objective on the hydrogen production side is to maintain a constant DC-DC converter input voltage, thereby maintaining system voltage stability within a narrow range under varying wind turbine power inputs. In normal control mode, the DC-DC converter is controlled using PI control. The actual DC-DC converter input voltage and the input voltage reference value are combined via the PI controller to generate a first DC-DC duty cycle. Based on this first DC-DC duty cycle, a third control signal is generated. The specific implementation process is as follows.

[0084] from Figure 5 As can be seen in the figure, a capacitor C is connected in parallel between the AC-DC converter and the DC-DC converter on the hydrogen production side. By sampling the voltage across C, the actual input voltage value u of the DC-DC converter can be obtained. dc1 . DC-DC converter input voltage reference value It can be set by those skilled in the art according to actual needs. dc1 and The second voltage controller calculates the first DC-DC duty cycle d based on the PI control algorithm. dc1 .ddc1 The specific calculation process of d can refer to the relevant technology. dc1 It cannot be directly recognized by the DC-DC converter, and needs to be PWM-ed to obtain a PWM signal (i.e., the third control signal) that can be recognized by the DC-DC converter. The PWM signal can control the ratio of the on-time and off-time of the internal switching element of the DC-DC converter to the entire switching cycle, so that the duty cycle of the DC-DC converter is consistent with the d dc1 equal, so that u dc1 and equal.

[0085] When the wind power off-grid hydrogen production system is in emergency operation mode, the control system is in emergency control mode. The control block diagram for controlling the wind turbine side in emergency control mode is as follows: Figure 5 The blue part of the wind turbine side is shown. In the emergency control mode, the control method of the grid-side converter is the same as that in the normal control mode; in the control method of the generator-side converter, only the method of obtaining the active power reference value has changed, and the subsequent control method remains unchanged. In the emergency control mode, the active power reference value According to the PU droop curve, the real-time acquisition system AC voltage u ac , in the PU droop curve u ac The corresponding fan output power is

[0086] The control block diagram for controlling the hydrogen production side in emergency control mode is as follows Figure 5 As shown in the blue part of the hydrogen production side. In the emergency control mode, the DC-DC converter on the hydrogen production side needs to control the electrolysis power of the electrolyzer to maintain at the rated value (i.e., the maximum electrolysis power) so that the electrolyzer operates at full power. The electrolysis power is the output power of the DC-DC converter. Therefore, in the emergency control mode, the control target of the hydrogen production side becomes to control the output power of the DC-DC converter to maintain the maximum electrolysis power. In the emergency control mode, the control of the DC-DC converter is a dual closed-loop PI control. The power outer loop can compare the actual value of the electrolysis power with the electrolysis power reference value, and generate an electrolysis voltage reference value through the PI controller; the voltage inner loop can compare the actual value of the electrolysis voltage with the electrolysis voltage reference value, and generate a second DC-DC duty cycle through the PI controller; and a fourth control signal is generated according to the second DC-DC duty cycle. The specific implementation process is as follows.

[0087] The output voltage of the DC-DC converter (i.e. electrolysis voltage) U ELZ and output current (i.e. electrolysis current) I ELZ Perform real-time sampling, according to U ELZ and I ELZ Calculate the actual value of electrolysis power P ELZElectrolysis power reference value That is, the electrolytic power rating, It can be preset by those skilled in the art. ELZ and Input into the power controller, which calculates the electrolysis voltage reference value based on the PI control algorithm Will U ELZ and The third voltage controller calculates the second DC-DC duty cycle d based on the PI control algorithm. dc2 . and d dc2 The specific calculation process of can refer to the relevant technology. The second DC-DC duty cycle is PWM-processed to obtain a PWM signal (i.e., the fourth control signal) that can be recognized by the DC-DC converter. The PWM signal can control the ratio of the on-time and off-time of the internal switching element of the DC-DC converter to the entire switching cycle, so that the duty cycle of the DC-DC converter is consistent with d dc2 equal, so that P ELZ and The electrolyzer maintains full power operation.

[0088] The control system of the off-grid wind power hydrogen production system also includes a special control mode. When the off-grid wind power hydrogen production system is in special operating mode, the control system operates in special control mode. In this special control mode, the control methods for the wind turbine-side converter and the grid-side converter are the same as those in emergency control mode. The control method for the DC-DC converter on the hydrogen production side is the same as that in normal control mode, and will not be repeated here.

[0089] The control method of the wind power off-grid hydrogen production system in the embodiment of the present application can fully explore the flexible adjustment capability of the electrolyzer load. On the basis of basically no modification to the original grid-following wind turbine, through a simple and mature control algorithm, the electrolyzer and wind turbine are respectively responsible for the voltage and frequency support functions, without relying on energy storage devices to balance the volatility and intermittency of wind power. According to the intrinsic characteristics of the electrolysis power of the electrolyzer and the voltage coupling of the microgrid, wind power off-grid hydrogen production without energy storage is realized.

[0090] Figure 6 A schematic diagram showing simulation results of controlling a wind power off-grid hydrogen production system according to a control method according to an embodiment of the present application is shown. Figure 6 The simulation results of wind power off-grid hydrogen production simulation using Simulink simulation tool based on the control strategy proposed in this application are shown, including the simulation results of electrolyzer filter power, wind turbine inverter output power, electrolyzer filter voltage, grid voltage, and DC bus a phase voltage effective value. Figure 6As shown in the figure, the wind turbine performs MPPT, and the output power of the wind turbine inverter changes according to the wind speed. The control strategy on the hydrogen production side can ensure that the electrolysis power of the electrolyzer automatically follows the change of the wind turbine output power, thereby achieving system power balance and keeping the voltage amplitude and frequency of the microgrid stable.

[0091] Based on the same inventive concept of the above control method embodiment, the present application also proposes a control device for a wind power off-grid hydrogen production system, which is used to control the wind power off-grid hydrogen production system of the embodiment of the present application.

[0092] Figure 7 A schematic diagram of the structure of a control device for a wind power off-grid hydrogen production system according to an embodiment of the present application is shown. Figure 7As shown, the device may include: a rotor voltage reference value determination module 701, which is used to obtain a rotor voltage reference value based on a PI control algorithm according to a d-axis component reference value of the rotor current of the wind turbine generator in a dq coordinate system, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current when the system is in a normal operation mode or an emergency operation mode; a first control module 702, which is used to generate a first control signal according to the rotor voltage reference value; the first control signal is used to control the conduction and disconnection of the internal switching element of the machine-side converter to Make the rotor voltage of the wind turbine equal to the rotor voltage reference value; the grid-side voltage reference value determination module 703 is used to obtain the grid-side voltage reference value based on the PI control algorithm according to the d-axis component reference value of the grid-side current in the dq coordinate system, the q-axis component reference value of the grid-side current, the actual value of the d-axis component of the grid-side current, and the actual value of the q-axis component of the grid-side current when the system is in normal operation mode or emergency operation mode; the grid-side current represents the current on the AC side of the grid-side converter; the grid-side voltage represents the voltage on the AC side of the grid-side converter; the second control module 704 is used The first DC-DC duty cycle determination module 705 is configured to generate a second control signal according to the grid-side voltage reference value; the second control signal is configured to control the on / off of the internal switching element of the grid-side converter to make the grid-side voltage equal to the grid-side voltage reference value; the first DC-DC duty cycle determination module 705 is configured to obtain a first DC-DC duty cycle based on the PI control algorithm according to the reference value of the input voltage of the DC-DC converter and the actual value of the input voltage of the DC-DC converter when the system is in normal operation mode; the third control module 706 is configured to generate a third control signal according to the first DC-DC duty cycle. signal; the third control signal is used to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle; a second DC-DC duty cycle determination module 707 is used to obtain a second DC-DC duty cycle based on a PI control algorithm according to a reference value of the electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage when the system is in emergency operation mode; a fourth control module 708 is used to generate a fourth control signal according to the second DC-DC duty cycle; the fourth control signal is used to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

[0093] In a possible implementation, the reference value of the d-axis component of the rotor current is obtained based on the PI control algorithm according to the reference value of the active power of the wind turbine and the actual value of the active power; wherein, when the system is in normal operation mode, the reference value of the active power is obtained based on the MPPT algorithm according to the rotor speed of the wind turbine; when the system is in emergency operation mode, the reference value of the active power is obtained based on the system AC voltage; the system AC voltage represents the voltage on the high-voltage side of the second transformer; the reference value of the q-axis component of the rotor current is obtained based on the reference value of the reactive power of the wind turbine and the actual value of the active power. The actual value of the reactive power is obtained based on the PI control algorithm; the reference value of the d-axis component of the grid-side current is obtained based on the PI control algorithm according to the reference value of the DC bus voltage and the actual value of the DC bus voltage; the DC bus voltage represents the voltage across the DC bus capacitor; the reference value of the electrolysis voltage is obtained based on the PI control algorithm according to the reference value of the electrolysis power of the electrolytic cell and the actual value of the electrolysis power; the reference value of the electrolysis power is the maximum electrolysis power; the reference value of the reactive power, the reference value of the q-axis component of the grid-side current and the reference value of the input voltage of the DC-DC converter are obtained by artificial setting.

[0094] In a possible implementation, the rotor voltage reference value determination module 701 is further configured to calculate a d-axis component reference value and a q-axis component reference value of the rotor voltage of the wind turbine generator according to the d-axis component reference value of the rotor current, the q-axis component reference value of the rotor current, the actual value of the d-axis component of the rotor current, and the actual value of the q-axis component of the rotor current using the following formula: in, represents a reference value of the q-axis component of the rotor voltage; represents a reference value of the d-axis component of the rotor voltage; represents a reference value of the q-axis component of the rotor current; represents the d-axis component reference value of the rotor current; i rq represents the actual value of the q-axis component of the rotor current; i rd represents the actual value of the d-axis component of the rotor current; K irP Indicates proportional control gain; K irI Indicates the integral adjustment gain; 1 / s indicates the integral link; ω sl Indicates slip frequency; L m Represents the excitation inductance; L s Represents leakage inductance; i ms represents the excitation current; σ represents the magnetic permeability; L rrepresents the self-inductance of the rotor winding; and obtaining the rotor voltage reference value according to the d-axis component reference value of the rotor voltage and the q-axis component reference value of the rotor voltage.

[0095] In one possible implementation, the grid-side voltage reference value determination module 703 is further configured to calculate the grid-side voltage d-axis component reference value and the grid-side voltage q-axis component reference value according to the grid-side current d-axis component reference value, the grid-side current d-axis component actual value, and the grid-side current q-axis component actual value by using the following formula: in, represents a reference value of the q-axis component of the grid-side voltage; represents the reference value of the d-axis component of the grid-side voltage; represents a reference value of the q-axis component of the grid-side current; represents the reference value of the d-axis component of the grid-side current; i cq represents the actual value of the q-axis component of the grid-side current; i cd represents the actual value of the d-axis component of the grid-side current; K icP Indicates proportional control gain; K icI represents the integral adjustment gain; 1 / s represents the integral link; ω represents the angular frequency of the grid voltage, and the grid voltage represents the voltage on the low-voltage side of the second transformer; u gq represents the q-axis component of the grid voltage; L represents the filter inductance value; the grid-side voltage reference value is obtained according to the d-axis component reference value of the grid-side voltage and the q-axis component reference value of the grid-side voltage.

[0096] The control device of the wind power off-grid hydrogen production system in the embodiment of the present application can fully explore the flexible adjustment capability of the electrolyzer load. Through a simple and mature control algorithm, the electrolyzer and the wind turbine are respectively responsible for the voltage and frequency support functions. According to the intrinsic characteristics of the electrolysis power of the electrolyzer and the voltage coupling of the microgrid, wind power off-grid hydrogen production without energy storage is realized.

[0097] In some embodiments, the functions or modules included in the device provided in the embodiments of the present application can be used to execute the method described in the above method embodiments. The specific implementation can refer to the description of the above method embodiments. For the sake of brevity, it will not be repeated here.

[0098] The present application also provides a computer-readable storage medium having computer program instructions stored thereon. When the computer program instructions are executed by a processor, the computer-readable storage medium implements the control method for the wind power off-grid hydrogen production system. The computer-readable storage medium can be volatile or non-volatile.

[0099] An embodiment of the present application further proposes an electronic device, comprising: a processor; a memory for storing instructions executable by the processor; wherein the processor is configured to implement the above-mentioned control method of the off-grid wind power hydrogen production system when executing the instructions stored in the memory.

[0100] An embodiment of the present application also provides a computer program product, including computer-readable code, or a non-volatile computer-readable storage medium carrying computer-readable code. When the computer-readable code runs in a processor of an electronic device, the processor in the electronic device executes the above-mentioned control method of the wind power off-grid hydrogen production system.

[0101] Figure 8 FIG1 shows a block diagram of an electronic device 1900 according to an embodiment of the present application. For example, the electronic device 1900 can be provided as a server or a terminal device. Figure 8 Electronic device 1900 includes a processing component 1922, which further includes one or more processors, and memory resources represented by memory 1932 for storing instructions executable by processing component 1922, such as application programs. The application programs stored in memory 1932 may include one or more modules, each corresponding to a set of instructions. Furthermore, processing component 1922 is configured to execute the instructions to implement the aforementioned control method for the off-grid wind power hydrogen production system.

[0102] The electronic device 1900 may further include a power supply component 1926 configured to perform power management of the electronic device 1900, a wired or wireless network interface 1950 configured to connect the electronic device 1900 to a network, and an input / output interface 1958 (I / O interface). The electronic device 1900 may operate based on an operating system stored in the memory 1932, such as Windows Server 2003. TM , Mac OS X TM , Unix TM ,Linux TM , FreeBSD TM or similar.

[0103] In an exemplary embodiment, a non-volatile computer-readable storage medium is also provided, such as a memory 1932 including computer program instructions. The above computer program instructions can be executed by the processing component 1922 of the electronic device 1900 to complete the control method of the above wind power off-grid hydrogen production system.

[0104] The present application may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present application.

[0105] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0106] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0107] The computer program instructions for performing the operation of the present application can be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data or source code or object code written in any combination of one or more programming languages, wherein the programming language includes object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions can be executed completely on the user's computer, partially on the user's computer, executed as an independent software package, partially on the user's computer and partially on a remote computer, or executed completely on a remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer by any type of network including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (such as by using an Internet service provider to connect to the Internet). In certain embodiments, by utilizing the state information of computer-readable program instructions to personalize electronic circuits, such as programmable logic circuits, field programmable gate arrays (FPGAs) or programmable logic arrays (PLAs), the electronic circuits can execute computer-readable program instructions, thereby realizing various aspects of the present application.

[0108] Various aspects of the present application are described herein with reference to flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer-readable program instructions.

[0109] These computer-readable program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, thereby producing a machine, so that when these instructions are executed by the processor of the computer or other programmable data processing device, a device is generated that implements the functions / actions specified in one or more blocks in the flowchart and / or block diagram. These computer-readable program instructions can also be stored in a computer-readable storage medium, where these instructions cause the computer, programmable data processing device, and / or other device to operate in a specific manner. Thus, the computer-readable medium storing the instructions comprises an article of manufacture that includes instructions for implementing various aspects of the functions / actions specified in one or more blocks in the flowchart and / or block diagram.

[0110] Computer-readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device, so that a series of operational steps are performed on the computer, other programmable data processing apparatus, or other device to produce a computer-implemented process, thereby causing the instructions executed on the computer, other programmable data processing apparatus, or other device to implement the functions / actions specified in one or more blocks in the flowchart and / or block diagram.

[0111] The flow charts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the system, method and computer program product according to multiple embodiments of the present application. In this regard, each box in the flow chart or block diagram can represent a part of a module, program segment or instruction, and the part of the module, program segment or instruction includes one or more executable instructions for realizing the logical function of the specification. In some alternative implementations, the functions marked in the box can also occur in a sequence different from that marked in the accompanying drawings. For example, two continuous boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flow chart, and the combination of the boxes in the block diagram and / or flow chart can be implemented by a special hardware-based system that performs the function or action of the specification, or can be implemented by a combination of special hardware and computer instructions.

[0112] While various embodiments of the present application have been described above, the above descriptions are illustrative, non-exhaustive, and not intended to be limiting of the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A wind power off-grid hydrogen production system, characterized in that: It includes a wind turbine, a black start power supply, an energy storage converter, a machine-side converter, a grid-side converter, a DC bus capacitor, a first transformer, a second transformer, a third transformer, an AC-DC converter, a DC-DC converter, an electrolyzer, a first switch, a second switch, a third switch, and a fourth switch; The stator of the wind turbine is connected to the low-voltage side of the second transformer through the fourth switch; the rotor of the wind turbine is connected to the AC side of the machine-side converter; the DC bus capacitor is connected in parallel between the DC side of the machine-side converter and the DC side of the grid-side converter; the AC side of the grid-side converter is connected to the low-voltage side of the second transformer through the first switch; the black start power supply is connected to the DC side of the energy storage converter; the AC side of the energy storage converter is connected to the low-voltage side of the first transformer; the high-voltage side of the first transformer is connected to the low-voltage side of the second transformer; the high-voltage side of the second transformer is connected to the high-voltage side of the third transformer; the low-voltage side of the third transformer is connected to the AC side of the AC-DC converter through the second switch; the DC side of the AC-DC converter is connected to the first DC side of the DC-DC converter; the second DC side of the DC-DC converter is connected to the electrolyzer through the third switch; The operating modes of the system include black start mode, normal operation mode and emergency operation mode; In the black start mode, the system is started from a shutdown state to an operating state by the black start power supply; wherein, when the system is in the operating state, the wind turbine is used to convert wind energy into electrical energy; the electrical energy generated by the wind turbine is used to provide the electrolyzer with electrolytic hydrogen production and to charge the black start power supply; In the normal operating mode, the maximum output power of the wind turbine is no greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply; the system power balance is maintained by adjusting the electrolysis power of the electrolyzer; wherein the system power balance indicates that the output power of the wind turbine is equal to the electrolysis power of the electrolyzer; In the emergency operation mode, the maximum output power of the wind generator is greater than the sum of the maximum electrolysis power of the electrolyzer and the maximum charging power of the black start power supply; the system power balance is maintained by adjusting the output power of the wind generator.

2. The system according to claim 1, wherein: When the system is in the off state, the first switch, the second switch, the third switch and the fourth switch are all disconnected; In the black start mode, the process of starting the system from the shutdown state to the running state by using the black start power supply includes: Turning on the energy storage converter and making the energy storage converter operate in an inverter mode to convert the direct current output by the black start power supply into alternating current; the inverter mode represents an operating mode for converting direct current into alternating current; Closing the first switch, turning on the grid-side converter and making the grid-side converter operate in a rectification mode; the rectification mode is an operating mode for converting alternating current into direct current; When the voltage across the DC bus capacitor is stable, turning on the machine-side converter to control the stator voltage of the wind turbine generator to meet a grid-connected condition; the grid-connected condition is that the stator voltage is equal to the voltage on the low-voltage side of the second transformer; When the stator voltage meets the grid connection condition, closing the second switch and the third switch in sequence to start the electrolyzer; The fourth switch is closed, and the operating mode of the energy storage converter is switched to the rectification mode.

3. The system according to claim 1, wherein: In the normal operating mode, the wind turbine performs maximum power point tracking (MPPT) to achieve the maximum output power.

4. The system according to claim 3, characterized in that The process of maintaining the power balance of the system by adjusting the electrolysis power of the electrolytic cell includes: Determining a first output power of the wind turbine performing MPPT at a first wind speed and an initial electrolytic cell PU characteristic curve; the electrolytic cell PU characteristic curve is used to represent a change in the electrolytic power of the electrolytic cell with a system AC voltage; the system AC voltage represents a voltage on the high-voltage side of the second transformer; Determining a first system stable AC voltage according to the first output power and the initial electrolytic cell PU characteristic curve; the first system stable AC voltage is the system AC voltage corresponding to the first output power in the initial electrolytic cell PU characteristic curve; When the wind speed changes from the first wind speed to a second wind speed, determining a second output power of the wind turbine performing MPPT at the second wind speed; The initial electrolytic cell PU characteristic curve is adjusted by changing the duty cycle of the DC-DC converter, so that in the adjusted electrolytic cell PU characteristic curve, the system AC voltage corresponding to the second output power is the first system stable AC voltage.

5. The system according to claim 3, wherein: In the emergency operation mode, the wind turbine does not perform MPPT, and the electrolyzer operates at the maximum electrolysis power.

6. A control method for a wind power off-grid hydrogen production system, characterized in that: Applicable to the wind power off-grid hydrogen production system according to any one of claims 1 to 5; the method comprises: When the system is in normal operation mode or emergency operation mode, Obtaining a rotor voltage reference value based on a proportional-integral (PI) control algorithm according to a d-axis component reference value of the rotor current of the wind turbine in a dq coordinate system, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current; generating a first control signal according to the rotor voltage reference value; the first control signal is used to control the on and off of the switch element inside the machine-side converter so that the rotor voltage of the wind turbine is equal to the rotor voltage reference value; Obtaining a grid-side voltage reference value based on a PI control algorithm according to a d-axis component reference value of the grid-side current in a dq coordinate system, a q-axis component reference value of the grid-side current, an actual value of the d-axis component of the grid-side current, and an actual value of the q-axis component of the grid-side current; the grid-side current represents the current on the AC side of the grid-side converter; and the grid-side voltage represents the voltage on the AC side of the grid-side converter; generating a second control signal according to the grid-side voltage reference value; the second control signal is used to control the conduction and disconnection of the internal switching element of the grid-side converter so that the grid-side voltage is equal to the grid-side voltage reference value; When the system is in normal operating mode, Obtaining a first DC-DC duty cycle based on a PI control algorithm according to a reference value of an input voltage of the DC-DC converter and an actual value of the input voltage of the DC-DC converter; generating a third control signal according to the first DC-DC duty cycle; wherein the third control signal is used to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle; When the system is in emergency operation mode, Obtaining a second DC-DC duty cycle based on a PI control algorithm according to a reference value of the electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage; A fourth control signal is generated according to the second DC-DC duty cycle; the fourth control signal is used to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

7. The method according to claim 6, characterized in that The reference value of the d-axis component of the rotor current is obtained based on a PI control algorithm according to a reference value of the active power of the wind turbine and an actual value of the active power; wherein, when the system is in a normal operation mode, the reference value of the active power is obtained based on an MPPT algorithm according to the rotor speed of the wind turbine; when the system is in an emergency operation mode, the reference value of the active power is obtained based on the system AC voltage; the system AC voltage represents the voltage on the high voltage side of the second transformer; The q-axis component reference value of the rotor current is obtained based on a PI control algorithm according to a reference value of the reactive power of the wind turbine and an actual value of the reactive power; The reference value of the d-axis component of the grid-side current is obtained based on a PI control algorithm according to a reference value of the DC bus voltage and an actual value of the DC bus voltage; the DC bus voltage represents the voltage across the DC bus capacitor; The reference value of the electrolysis voltage is obtained based on a PI control algorithm according to a reference value of the electrolysis power of the electrolytic cell and an actual value of the electrolysis power; the reference value of the electrolysis power is the maximum electrolysis power; The reference value of the reactive power, the reference value of the q-axis component of the grid-side current, and the reference value of the input voltage of the DC-DC converter are obtained by artificial setting.

8. The method according to claim 6 or 7, characterized in that The method of obtaining a rotor voltage reference value based on a proportional-integral (PI) control algorithm according to a d-axis component reference value of the rotor current of the wind turbine in a dq coordinate system, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current comprises: According to the d-axis component reference value of the rotor current, the q-axis component reference value of the rotor current, the actual value of the d-axis component of the rotor current, and the actual value of the q-axis component of the rotor current, a d-axis component reference value of the rotor voltage of the wind turbine and a q-axis component reference value of the rotor voltage are calculated by the following formula: in, represents a reference value of the q-axis component of the rotor voltage; represents a reference value of the d-axis component of the rotor voltage; represents a reference value of the q-axis component of the rotor current; represents the d-axis component reference value of the rotor current; i rq represents the actual value of the q-axis component of the rotor current; i rd represents the actual value of the d-axis component of the rotor current; K irP Indicates proportional control gain; K irI Indicates the integral adjustment gain; 1 / s indicates the integral link; ω sl Indicates slip frequency; L m Represents the excitation inductance; L s Represents leakage inductance; i ms represents the excitation current; σ represents the magnetic permeability; L r Indicates the rotor winding self-inductance; The rotor voltage reference value is obtained according to the d-axis component reference value of the rotor voltage and the q-axis component reference value of the rotor voltage.

9. The method according to claim 6 or 7, characterized in that Obtaining a grid-side voltage reference value based on a PI control algorithm according to a d-axis component reference value of the grid-side current in a dq coordinate system, a q-axis component reference value of the grid-side current, an actual value of the d-axis component of the grid-side current, and an actual value of the q-axis component of the grid-side current, includes: According to the d-axis component reference value of the grid-side current, the q-axis component reference value of the grid-side current, the actual value of the d-axis component of the grid-side current, and the actual value of the q-axis component of the grid-side current, the d-axis component reference value of the grid-side voltage and the q-axis component reference value of the grid-side voltage are calculated by the following formula: in, represents a reference value of the q-axis component of the grid-side voltage; represents a reference value of the d-axis component of the grid-side voltage; represents a reference value of the q-axis component of the grid-side current; represents the reference value of the d-axis component of the grid-side current; i cq represents the actual value of the q-axis component of the grid-side current; i cd represents the actual value of the d-axis component of the grid-side current; K icP Indicates proportional control gain; K icI represents the integral adjustment gain; 1 / s represents the integral link; ω represents the angular frequency of the grid voltage, and the grid voltage represents the voltage on the low-voltage side of the second transformer; u gq represents the q-axis component of the grid voltage; L represents the filter inductance value; The grid-side voltage reference value is obtained according to the d-axis component reference value of the grid-side voltage and the q-axis component reference value of the grid-side voltage.

10. A control device for a wind power off-grid hydrogen production system, characterized in that: Used to control the wind power off-grid hydrogen production system according to any one of claims 1 to 5; the device comprises: a rotor voltage reference value determination module, configured to obtain a rotor voltage reference value based on a PI control algorithm according to a d-axis component reference value of the rotor current of the wind turbine generator, a q-axis component reference value of the rotor current, an actual value of the d-axis component of the rotor current, and an actual value of the q-axis component of the rotor current in a dq coordinate system when the system is in a normal operation mode or an emergency operation mode; a first control module, configured to generate a first control signal according to the rotor voltage reference value; the first control signal being configured to control the on and off of a switching element within the generator-side converter so that the rotor voltage of the wind turbine is equal to the rotor voltage reference value; a grid-side voltage reference value determination module, configured to, when the system is in a normal operating mode or an emergency operating mode, obtain a grid-side voltage reference value based on a PI control algorithm according to a d-axis component reference value of the grid-side current in a dq coordinate system, a q-axis component reference value of the grid-side current, an actual value of the d-axis component of the grid-side current, and an actual value of the q-axis component of the grid-side current; the grid-side current represents the current on the AC side of the grid-side converter; and the grid-side voltage represents the voltage on the AC side of the grid-side converter; a second control module, configured to generate a second control signal according to the grid-side voltage reference value; the second control signal being configured to control the on / off switching of a switching element within the grid-side converter so that the grid-side voltage is equal to the grid-side voltage reference value; a first DC-DC duty cycle determination module, configured to obtain a first DC-DC duty cycle based on a PI control algorithm according to a reference value of an input voltage of the DC-DC converter and an actual value of the input voltage of the DC-DC converter when the system is in a normal operating mode; a third control module, configured to generate a third control signal according to the first DC-DC duty cycle; the third control signal being configured to control the duty cycle of the DC-DC converter to be equal to the first DC-DC duty cycle; a second DC-DC duty cycle determination module, configured to obtain a second DC-DC duty cycle based on a PI control algorithm according to a reference value of an electrolysis voltage of the electrolytic cell and an actual value of the electrolysis voltage when the system is in an emergency operation mode; A fourth control module is configured to generate a fourth control signal according to the second DC-DC duty cycle; the fourth control signal is configured to control the duty cycle of the DC-DC converter to be equal to the second DC-DC duty cycle.

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