Load control of high-power wind turbines and synergistic method for hydrogen production by electrolysis of water

Abstract

The application discloses a high-power wind turbine load control and a hydrogen production method by electrolysis of water, which comprises the following steps: a wind turbine electrolysis cell off-grid micro-grid system is established, and wind turbine generators and DC / DC converters in the system are controlled; a, the error between the aerodynamic power of the wind turbine generator and the current optimal power is sampled, then the feedforward coefficient is superimposed on the output electric power of the wind turbine generator, and the speed of MPPT tracking is accelerated; the PI controller takes the optimal rotating speed output by the MPPT and the rotating speed measurement value of the wind turbine generator as inputs, and the PI controller controls the electromagnetic torque output by the wind turbine generator; b, the DC / DC converter is controlled by using a double closed loop PI control. The application fully considers the dynamic power change requirement of the electrolysis cell and the output electric power change characteristics of the wind turbine generator, designs a constant bandwidth MPPT control strategy below the rated wind speed of the wind turbine generator, and realizes the on-demand power output of the wind turbine generator.

Description

Technical Field

[0001] This invention relates to the fields of power grid technology, distributed generation technology, and water electrolysis hydrogen production technology, and particularly to a wind turbine load control and a method for coordinating water electrolysis hydrogen production. Background Technology

[0002] Among the relatively mature new energy power generation technologies, wind power has received widespread attention due to its abundant reserves and zero pollutant emissions. However, wind power is greatly affected by the environment, resulting in poor power quality, high randomness, and low prediction accuracy. When the wind speed in the external environment changes randomly, the output power of the wind turbine also fluctuates. This randomness and volatility pose a huge challenge to power quality and stability.

[0003] Hydrogen energy storage, due to its abundant reserves, clean and environmentally friendly characteristics, high energy density, controllable safety, and wide application, can meet various forms of electricity demand. Furthermore, hydrogen energy can be stored on a large or small scale without significant loss, making hydrogen production and storage the ideal solution to problems such as poor power quality and strong voltage fluctuations in wind power systems. With the rapid development of electrolysis hydrogen production and fuel cell technologies, and breakthroughs in key technologies and components, wind-powered hydrogen production technology offers a new approach to improving wind energy utilization.

[0004] Currently, countries worldwide are actively researching key technologies for wind power-to-hydrogen systems. For wind turbines, the timescale of high-frequency power changes is on the order of milliseconds / seconds; however, for alkaline electrolyzers, the dynamic response timescale is on the order of 10 minutes. When the rate of change of input and output power exceeds this dynamic time, the electrode coating may peel off, affecting its lifespan. Furthermore, although high-frequency power from wind turbines can be mitigated through external energy storage, the charging and discharging cycle limitations of energy storage systems mean that absorbing high-frequency power through storage will affect the lifespan of the energy storage system, increase the frequency of replacement, and significantly increase system costs. Therefore, it is necessary to optimize the design of the wind turbine control system so that the unit does not respond to high-frequency wind speed changes, thus ensuring that the output power does not include high-frequency power caused by tracking rapidly changing wind speeds, in order to better meet the energy needs of the electrolyzer. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a high-power wind turbine load control and a method for coordinated water electrolysis hydrogen production, so as to solve technical problems such as bus voltage fluctuation control, system energy flow control, and coordinated control of alkaline electrolyzers and wind turbines in off-grid microgrid systems with wind turbine electrolyzers containing water electrolysis hydrogen production loads.

[0006] The present invention provides a method for load control of high-power wind turbines and its synergistic application in hydrogen production via water electrolysis, comprising the following steps:

[0007] Step 1: Establish an off-grid microgrid system for the wind turbine electrolyzer. The off-grid microgrid system for the wind turbine electrolyzer includes a DC bus, wind turbine generators, a water electrolysis hydrogen production electrolyzer, and a DC / DC converter. The DC bus is connected to the water electrolysis hydrogen production electrolyzer through the DC / DC converter, and the power output terminal of the wind turbine generator is connected to the DC bus.

[0008] Step 2: Control the wind turbine generators and DC / DC converters in the off-grid microgrid system of the wind turbine electrolyzer using the following method:

[0009] a. The error between the aerodynamic power of the sampled wind turbine and the current optimal power is then added to the output electrical power of the wind turbine using a feedforward coefficient to accelerate MPPT tracking. The PI controller uses the optimal speed output by MPPT and the measured speed of the wind turbine as inputs, and outputs electromagnetic torque to the wind turbine. The electromagnetic torque is calculated using the following control equation:

[0010]

[0011] In the formula, T e The electromagnetic torque of the wind turbine generator; ω opt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine generator; k p and k i For PI parameters; the relationship for implementing the power feedback MPPT strategy is:

[0012]

[0013] In the formula, ω opt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine, Pe is the output power of the wind turbine, and P is the power output of the wind turbine. r k represents the aerodynamic power of the wind turbine. f Forward coefficients, k opt For optimal power coefficient;

[0014] b. A dual-loop PI control DC / DC converter is adopted, with an outer loop being a voltage loop and an inner loop being a current loop. The outer loop PI controller takes the nominal value and the measured value of the DC bus voltage as inputs, while the inner loop PI controller outputs a drive signal to the switching transistors of the DC / DC converter. Limiting is applied at the outer loop output to ensure that the current input reference of the water electrolysis hydrogen production electrolyzer is at most the rated current value. The drive signal d output by the inner loop PI controller to the switching transistors of the DC / DC converter is calculated using the following control equation:

[0015]

[0016] In the formula, V ref This is the nominal value of the DC bus voltage; Vbus This is the measured value of the DC bus voltage; i ref and i ael These are the inner loop current reference and the hydrogen production current of the electrolyzer, respectively, where I aelmin For the minimum hydrogen production current, when i ref Selecting this value indicates that the alkaline electrolyzer is operating at its lowest hydrogen production power; the drive signal d is the duty cycle of the DC / DC converter switch; k ip and k ii These are the inner loop PI parameters, k vp and k vi These are the outer loop PI parameters.

[0017] Furthermore, the aforementioned method for coordinating high-power wind turbine load control and hydrogen production via water electrolysis also includes adjusting the feedforward coefficient k. f To ensure a constant bandwidth in the off-grid microgrid system for wind turbine electrolyzers, the feedforward coefficient k... f The adjustment method is as follows:

[0018]

[0019] In the formula, k f Here, J is the feedforward coefficient, J is the moment of inertia of the wind turbine, and k is the feedforward coefficient. opt For the optimal power coefficient, ω Q ω is the rotational speed of the wind turbine in steady state. cn This is the required control system bandwidth.

[0020] Furthermore, the water electrolysis for hydrogen production is an alkaline electrolyzer.

[0021] The beneficial effects of this invention are:

[0022] This invention discloses a high-power wind turbine load control method and its application in coordinating water electrolysis for hydrogen production. It enables control of system bus voltage fluctuations using the water electrolysis unit. The invention fully considers the dynamic power variation requirements of the electrolyzer and the output power variation characteristics of the wind turbine, designing a constant bandwidth MPPT control strategy below the wind turbine's rated wind speed, achieving on-demand power output from the wind turbine. Simultaneously, it smooths the wind turbine's output power, achieving dynamic power coordination between the wind turbine and the water electrolysis hydrogen production system, thereby improving the electrolyzer's operating efficiency and lifespan. Attached Figure Description

[0023] Figure 1This is a topology diagram of an off-grid microgrid system with a wind turbine electrolyzer for hydrogen production via water electrolysis. The distributed power sources serving as the system's source-side input include wind turbines, which convert wind energy into electrical energy and connect it to the AC bus as a current source. The water electrolyzer for hydrogen production is the main load of the system and is connected to the bus via a front-end DC / DC converter. The power required by the electrolyzer is controlled so that the wind turbine output power does not include the high-frequency power caused by tracking rapidly changing wind speeds, thus meeting the energy needs of the electrolyzer. Simultaneously, the bus voltage and frequency in the system are kept stable, achieving coordinated system control.

[0024] Figure 2 This is a schematic diagram of the constant bandwidth MPPT control and coordinated control principle for wind turbine generators.

[0025] Figure 3 This is a topology diagram of the DC / DC converter and controller on the electrolytic cell side.

[0026] Figure 4 The figure shows the simulation results of the system under sinusoidal wind speed. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the embodiments.

[0028] The high-power wind turbine load control and its synergistic method for hydrogen production via water electrolysis in this embodiment includes the following steps:

[0029] Step 1: Establish an off-grid microgrid system for the wind turbine electrolyzer. This system includes a DC bus, wind turbine generators, a water electrolysis hydrogen production electrolyzer, and a DC / DC converter. The DC bus is connected to the water electrolysis hydrogen production electrolyzer via the DC / DC converter, and the power output terminal of the wind turbine generators is connected to the DC bus. In this embodiment, the water electrolysis hydrogen production electrolyzer is an alkaline electrolyzer; however, other types of electrolyzers can also be used.

[0030] Step 2: Control the wind turbine generators and DC / DC converters in the off-grid microgrid system of the wind turbine electrolyzer using the following method:

[0031] a. The error between the aerodynamic power of the sampled wind turbine and the current optimal power is then added to the output electrical power of the wind turbine using a feedforward coefficient to accelerate MPPT tracking. The PI controller uses the optimal speed output by MPPT and the measured speed of the wind turbine as inputs, and outputs electromagnetic torque to the wind turbine. The electromagnetic torque is calculated using the following control equation:

[0032]

[0033] In the formula, T e The electromagnetic torque of the wind turbine generator; ωopt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine generator; k p and k i The PI parameters are obtained through trial and error in this embodiment. The relationship for implementing the power feedback MPPT strategy is as follows:

[0034]

[0035] In the formula, ω opt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine, Pe is the output power of the wind turbine, and P is the power output of the wind turbine. r k represents the aerodynamic power of the wind turbine. f Forward coefficients, k opt This represents the optimal power factor.

[0036] b. A dual-loop PI control DC / DC converter is adopted, with an outer loop being a voltage loop and an inner loop being a current loop. The outer loop PI controller takes the nominal value and the measured value of the DC bus voltage as inputs, while the inner loop PI controller outputs a drive signal to the switching transistors of the DC / DC converter. Limiting is applied at the outer loop output to ensure that the current input reference of the water electrolysis hydrogen production electrolyzer is at most the rated current value. The drive signal d output by the inner loop PI controller to the switching transistors of the DC / DC converter is calculated using the following control equation:

[0037]

[0038] In the formula, V ref This is the nominal value of the DC bus voltage; V bus This is the measured value of the DC bus voltage; i ref and i ael These are the inner loop current reference and the hydrogen production current of the electrolyzer, respectively, where I aelmin For the minimum hydrogen production current, when i ref Selecting this value indicates that the alkaline electrolyzer is operating at its lowest hydrogen production power; the drive signal d is the duty cycle of the DC / DC converter switch; k ip and k ii These are the inner loop PI parameters, k vp and k vi These are the outer loop PI parameters, which are obtained by trial and error in this embodiment.

[0039] As an improvement to the above embodiments, the high-power wind turbine load control and the coordinated method for water electrolysis hydrogen production also includes adjusting the feedforward coefficient k. f To ensure a constant bandwidth in the off-grid microgrid system for the wind turbine electrolyzer, the wind turbine's response speed to wind speed is designed on demand based on the wind turbine's characteristics and the electrolyzer's dynamic response requirements. The feedforward coefficient k... fThe adjustment method is as follows:

[0040]

[0041] In the formula, k f Here, J is the feedforward coefficient, J is the moment of inertia of the wind turbine, and k is the feedforward coefficient. opt For the optimal power coefficient, ω Q ω is the rotational speed of the wind turbine in steady state. cn This is the required control system bandwidth.

[0042] The effectiveness of the high-power wind turbine load control and its synergistic application in hydrogen production via water electrolysis in this embodiment is verified by simulation.

[0043] Figure 4 The simulation results are presented under sinusoidal wind speed. In this embodiment, the rated power of the wind turbine is 10kW, and the rated power of the alkaline electrolyzer is set to be less than 10kW. State-average equation modeling is used, and the simulation time is set to 100s. Under a sinusoidal wind input with an average wind speed of 8m / s and a frequency of 0.5Hz, the control system bandwidth is set to 1.2rad / s. Coordinated control and constant bandwidth MPPT control are simulated and analyzed. Ignoring the start-up process, it can be seen that the aerodynamic power varies sinusoidally from 1340W to 9000W with the sinusoidal wind, which cannot meet the energy demand of the electrolyzer. After coordinated control, the output power of the wind turbine varies sinusoidally from 3650W to 6230W, excluding the high-frequency power caused by tracking rapidly changing wind speeds. The operating power of the electrolyzer also varies approximately between 3650W and 6230W. The system input meets the power requirements of the electrolyzer, and the system operates smoothly with stable bus voltage and frequency, achieving coordinated system control.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for load control of a high-power wind turbine and its synergistic application in hydrogen production via water electrolysis, characterized in that, Includes the following steps: Step 1: Establish an off-grid microgrid system for the wind turbine electrolyzer. The off-grid microgrid system for the wind turbine electrolyzer includes a DC bus, wind turbine generators, a water electrolysis hydrogen production electrolyzer, and a DC / DC converter. The DC bus is connected to the water electrolysis hydrogen production electrolyzer through the DC / DC converter, and the power output terminal of the wind turbine generator is connected to the DC bus. Step 2: Control the wind turbine generators and DC / DC converters in the off-grid microgrid system of the wind turbine electrolyzer using the following method: a. The error between the aerodynamic power of the sampled wind turbine and the current optimal power is then added to the output electrical power of the wind turbine using a feedforward coefficient to accelerate MPPT tracking. The PI controller uses the optimal speed output by MPPT and the measured speed of the wind turbine as inputs, and outputs electromagnetic torque to the wind turbine. The electromagnetic torque is calculated using the following control equation: In the formula, T e The electromagnetic torque of the wind turbine generator; ω opt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine generator; k p and k i For PI parameters; the relationship for implementing the power feedback MPPT strategy is: In the formula, ω opt The optimal speed for MPPT output is given by ω, where ω is the measured speed of the wind turbine, Pe is the output power of the wind turbine, and P is the power output of the wind turbine. r k represents the aerodynamic power of the wind turbine. f Forward coefficients, k opt For optimal power coefficient; b. A dual-loop PI control DC / DC converter is adopted, with an outer loop being a voltage loop and an inner loop being a current loop. The outer loop PI controller takes the nominal value and the measured value of the DC bus voltage as inputs, while the inner loop PI controller outputs a drive signal to the switching transistors of the DC / DC converter. Limiting is applied at the outer loop output to ensure that the current input reference of the water electrolysis hydrogen production electrolyzer is at most the rated current value. The drive signal d output by the inner loop PI controller to the switching transistors of the DC / DC converter is calculated using the following control equation: Select according to the situation In the formula, V ref This is the nominal value of the DC bus voltage; V bus This is the measured value of the DC bus voltage; i ref and i ael These are the inner loop current reference and the hydrogen production current of the electrolyzer, respectively, where I aelmin For the minimum hydrogen production current, when i ref Selecting this value indicates that the alkaline electrolyzer is operating at its lowest hydrogen production power; the drive signal d is the duty cycle of the DC / DC converter switch; k ip and k ii These are the inner loop PI parameters, k vp and k vi These are the outer loop PI parameters.

2. The method for load control of high-power wind turbines and its synergistic application in water electrolysis for hydrogen production according to claim 1, characterized in that: This also includes adjusting the feedforward coefficient k f To ensure a constant bandwidth in the off-grid microgrid system for wind turbine electrolyzers, the feedforward coefficient k... f The adjustment method is as follows: In the formula, k f Here, J is the feedforward coefficient, J is the moment of inertia of the wind turbine, and k is the feedforward coefficient. opt For the optimal power coefficient, ω Q ω is the rotational speed of the wind turbine in steady state. cn This is the required control system bandwidth.

3. The method for load control of a high-power wind turbine and its synergistic application in water electrolysis for hydrogen production according to claim 1 or 2, characterized in that: The electrolytic cell for hydrogen production via water electrolysis is an alkaline electrolytic cell.

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