A power frequency domain allocation control method and system of a multi-modal off-grid hydrogen production system

Abstract

The application belongs to the technical field of new energy hydrogen production, and specifically discloses a power frequency domain distribution control method and system of a multi-modal off-grid hydrogen production system. The method specifically comprises the following steps: obtaining instantaneous power through real-time acquisition of DC bus voltage and current, performing Fourier transform after discretization processing to obtain frequency domain characteristics of the instantaneous power, and generating power distribution instructions of low and high frequency bands; adjusting and controlling the duty cycle of the DC / DC electrolytic cell power supply on the side of the alkaline electrolytic cell according to the low-frequency band power instruction, and adjusting and controlling the duty cycle of the DC / DC electrolytic cell power supply on the side of the proton exchange membrane electrolytic cell according to the high-frequency band power instruction, and dynamically matching the power of the alkaline electrolytic cell and the proton exchange membrane electrolytic cell; through the application, different frequency band fluctuation power can be accommodated, not only the hydrogen production efficiency is improved, but also the equipment life is prolonged, and the performance and economy of the hydrogen production system are improved.

Description

Technical Field

[0001] This application belongs to the field of new energy hydrogen production technology, and more specifically, relates to a power frequency domain allocation control method and system for a multimodal off-grid hydrogen production system. Background Technology

[0002] Traditional hydrogen production systems often use a single type of electrolyzer, such as an alkaline electrolyzer (ALK) or a proton exchange membrane electrolyzer (PEM). These systems struggle to accommodate both low-frequency, high-power fluctuations (such as minute-level fluctuations in photovoltaic / wind power) and high-frequency, low-power fluctuations (such as second-level fluctuations), resulting in low hydrogen production efficiency and high equipment wear.

[0003] Existing power allocation methods (such as time-based rotation strategies or fixed-ratio allocation) cannot match power frequency domain characteristics in real time, leading to frequent start-ups and shutdowns of electrolyzers or long-term deviations from the optimal operating range, affecting system lifespan. Furthermore, high-frequency power fluctuations easily introduce harmonic pollution, making it difficult for traditional LC filters to adapt to wide-bandgap fluctuation scenarios, thus impacting power grid quality. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this application is to provide a power frequency domain allocation control method and system for a multimodal off-grid hydrogen production system, aiming to solve the problem that existing single electrolyzers cannot simultaneously handle low-frequency high-power fluctuations and high-frequency low-power fluctuations, resulting in low hydrogen production efficiency and high equipment wear.

[0005] To achieve the above objectives, in a first aspect, this application provides a power frequency domain allocation control method for a multimodal off-grid hydrogen production system, comprising the following steps:

[0006] Step 1: Obtain instantaneous power by real-time acquisition of DC bus voltage and current, discretize it and perform Fourier transform to obtain the frequency domain characteristics of instantaneous power, and generate power allocation instructions for low-frequency and high-frequency bands.

[0007] Step 2: Adjust the duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side according to the low-frequency power command, and adjust the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side according to the high-frequency power command to achieve dynamic power matching between the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0008] In the multimodal off-grid hydrogen production system, the alkaline electrolyzer and the proton exchange membrane electrolyzer are connected in parallel. The alkaline electrolyzer and the proton exchange membrane electrolyzer are connected to the DC bus through independent DC / DC electrolyzer power supplies. The alkaline electrolyzer is used to absorb low-frequency fluctuation power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuation power. The low-frequency range is 0.01Hz~1Hz, and the high-frequency range is 1Hz~100Hz.

[0009] More preferably, step one specifically includes the following steps:

[0010] Step 1.1: Collect voltage and current data from the DC bus terminal in real time and calculate instantaneous power;

[0011] Step 1.2: Discretely sample the instantaneous power to obtain a discrete power sequence;

[0012] Step 1.3: Perform a Fourier transform on the discrete power sequence to obtain the frequency domain complex sequence of the power, and calculate the amplitude spectrum of each frequency component;

[0013] Step 1.4: Divide the power frequency into low-frequency power and high-frequency power, and obtain the power allocation instructions for the low-frequency and high-frequency bands by combining the amplitude spectrum of each frequency band component.

[0014] More preferably, step S1.4, which obtains power allocation instructions for low-frequency and high-frequency bands based on the amplitude spectrum of each frequency band component, specifically includes the following steps:

[0015] The low-frequency energy and high-frequency energy are calculated based on the amplitude spectrum of each frequency band component, thereby obtaining the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0016] Based on the power allocation ratio of alkaline electrolyzers and proton exchange membrane electrolyzers, a basic allocation of the energy ratio in the high-frequency band and the energy ratio in the low-frequency band is carried out.

[0017] If a transient event is detected, the high-frequency energy ratio is transiently corrected, and the maximum power of the high-frequency energy is limited based on temperature feedback to obtain power allocation instructions for the low-frequency and high-frequency bands.

[0018] More preferably, step two specifically includes the following steps:

[0019] The duty cycle of the corresponding DC / DC electrolytic cell power supply is initialized based on the target power of the low-frequency band and the target power of the high-frequency band.

[0020] The duty cycle of the DC / DC power supply of the alkaline electrolyzer is dynamically adjusted based on the error between the actual power and the target power of the low-frequency band obtained from the power allocation command; and the duty cycle of the DC / DC power supply of the proton exchange membrane electrolyzer is dynamically adjusted based on the error between the actual power and the target power of the high-frequency band obtained from the power allocation command.

[0021] More preferably, the transient high-frequency energy is detected and quantified by calculating the time-domain difference of the instantaneous power signal of the proton exchange membrane electrolyzer;

[0022] If the transient high-frequency energy exceeds a preset threshold, it is marked as a transient event;

[0023] If a transient event is detected, the proportion of high-frequency energy after transient correction is:

[0024]

[0025] in, Allocate power percentages to the proton exchange membrane electrolyzer; The instantaneous power in the middle; This is used to quantize the transient high-frequency energy when a transient event is detected; γ is a proportionality coefficient.

[0026] The maximum power of high-frequency energy is:

[0027]

[0028] in, This refers to the real-time temperature of the proton exchange membrane electrolyzer. This refers to the maximum permissible power of a proton exchange membrane electrolyzer. The instantaneous power of the proton exchange membrane electrolyzer; This is the ideal operating temperature for a proton exchange membrane electrolyzer under normal operating conditions.

[0029] The initial duty cycle value of the DC / DC electrolytic cell power supply is:

[0030] ;

[0031] in, This is the voltage value of the DC bus; This represents the total current of the DC bus. Energy conversion efficiency;

[0032] The dynamically adjusted duty cycle is:

[0033]

[0034] in, This is the gain coefficient of the proportional controller; This is the gain coefficient of the integral controller; k This is the sequence number of the current sampling time; This represents the error between the actual power and the target power.

[0035] Secondly, this application provides a power frequency domain allocation control system for a multimodal off-grid hydrogen production system, comprising:

[0036] The signal acquisition module is used to acquire DC bus voltage and current in real time and obtain instantaneous power.

[0037] The signal processing module is used to discretize the instantaneous power and then perform a Fourier transform to obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for the low-frequency and high-frequency bands.

[0038] The control module is used to adjust the duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side according to the low-frequency power command, and to adjust the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side according to the high-frequency power command, so as to dynamically match the power of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0039] In the multimodal off-grid hydrogen production system, the alkaline electrolyzer and the proton exchange membrane electrolyzer are connected in parallel. The alkaline electrolyzer and the proton exchange membrane electrolyzer are connected to the DC bus through independent DC / DC electrolyzer power supplies. The alkaline electrolyzer is used to absorb low-frequency fluctuation power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuation power. The low-frequency range is 0.01Hz~1Hz, and the high-frequency range is 1Hz~100Hz.

[0040] More preferably, the signal processing module includes:

[0041] The data discrete unit is used to discretely sample the instantaneous power to obtain a discrete power sequence;

[0042] The Fourier transform unit is used to perform Fourier transform on discrete power sequences to obtain the frequency domain complex sequence of power.

[0043] Amplitude calculation unit, used to calculate the amplitude spectrum of each frequency component;

[0044] The instruction generation unit is used to divide the power frequency into low-frequency power and high-frequency power, and obtain the power allocation instructions for the low-frequency and high-frequency bands by combining the amplitude spectrum of each frequency band component.

[0045] More preferably, the instruction generation unit includes:

[0046] The first calculation component is used to calculate the low-frequency energy and high-frequency energy based on the amplitude spectrum of each frequency band component, and then obtain the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0047] The second calculation component is used to perform a basic allocation of the high-frequency energy ratio and the low-frequency energy ratio based on the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0048] The third computing component is used to perform transient correction on the high-frequency energy ratio if a transient event is detected, and then limit the maximum power of the high-frequency energy according to temperature feedback, and obtain the power allocation instructions for the low-frequency and high-frequency bands.

[0049] More preferably, the control module includes:

[0050] The duty cycle initialization unit is used to initialize the duty cycle of the corresponding DC / DC electrolytic cell power supply according to the target power of the low-frequency band and the target power of the high-frequency band.

[0051] The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer based on the error between the actual power and the target power of the low-frequency band obtained from the power allocation command; and to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer based on the error between the actual power and the target power of the high-frequency band obtained from the power allocation command.

[0052] More preferably, the proportion of high-frequency energy after transient correction in the third computing component is:

[0053]

[0054] in, Allocate power percentages to the proton exchange membrane electrolyzer; The instantaneous power in the middle; This is used to quantize the transient high-frequency energy when a transient event is detected; γ is a proportionality coefficient.

[0055] The maximum power of high-frequency energy is:

[0056]

[0057] in, This refers to the real-time temperature of the proton exchange membrane electrolyzer. This refers to the maximum permissible power of a proton exchange membrane electrolyzer. This represents the real-time power of the proton exchange membrane electrolyzer. This is the ideal operating temperature for a proton exchange membrane electrolyzer under normal operating conditions.

[0058] More preferably, the initial duty cycle value of the DC / DC electrolytic cell power supply in the duty cycle initialization unit is:

[0059] ;

[0060] in, This is the voltage value of the DC bus; This represents the total current of the DC bus. Energy conversion efficiency;

[0061] More preferably, the dynamically adjusted duty cycle in the duty cycle update unit is:

[0062]

[0063] in, This is the gain coefficient of the proportional controller; This is the gain coefficient of the integral controller; k This is the sequence number of the current sampling time; This represents the error between the actual power and the target power.

[0064] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art:

[0065] The power frequency domain allocation control method for the multimodal hydrogen production system proposed in this application, compared with the traditional single ALK or PEM hydrogen production methods in photovoltaic and wind power hydrogen production scenarios, can absorb power fluctuations in different frequency bands by using alkaline electrolyzers and proton exchange membrane electrolyzers. This not only improves hydrogen production efficiency but also extends equipment lifespan, thereby enhancing the performance and economy of the hydrogen production system.

[0066] The power frequency domain allocation control method for the multimodal hydrogen production system proposed in this application improves hydrogen production efficiency by rationally allocating power so that both types of electrolyzers can operate in their optimal operating range. Attached Figure Description

[0067] Figure 1 This is a topology diagram of an off-grid hydrogen production system with multimodal electrolyzer power frequency domain allocation provided in an embodiment of this application;

[0068] Figure 2 This is a flowchart of FFT frequency domain decomposition and power allocation provided in the embodiments of this application. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0070] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. In this application, the symbol " / " indicates that the related objects are in an "or" relationship, for example, A / B means A or B.

[0071] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, rather than to describe a specific order of objects.

[0072] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0073] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0074] The embodiments of this application are described below with reference to the accompanying drawings.

[0075] This application provides a power frequency domain allocation control method for a multimodal off-grid hydrogen production system, including the following steps:

[0076] Step S1: As Figure 1 As shown, wind power or photovoltaic power is fed into the DC bus via an inverter. The alkaline electrolyzer (ALK) and proton exchange membrane electrolyzer (PEM) are connected to the DC bus through independent DC-DC modules. The ALK is used to absorb low-frequency power fluctuations (0.01Hz~1Hz), and the PEM responds to high-frequency power fluctuations (1Hz~100Hz). The alkaline electrolyzer (ALK) and the proton exchange membrane electrolyzer (PEM) are connected in parallel.

[0077] Step S2: FFT frequency domain decomposition and power allocation: Figure 2 The flowchart illustrates the FFT frequency domain decomposition and power allocation process. DC bus voltage and current information is low-pass filtered and then sent to the data processing unit. The FFT (Fast Fourier Transform) is used to decompose the frequency domain characteristics of the input power in real time, generating power allocation instructions for the low-frequency band (ALK) and high-frequency band (PEM). The monitoring module monitors the fluctuations in input power in real time; the FFT spectrum analysis module decomposes the frequency domain characteristics of the input power in real time; and the controller dynamically adjusts the power allocation ratio of ALK and PEM based on the frequency domain characteristics.

[0078] The power frequency distribution control method for a multimodal discrete hydrogen production system provided in this application specifically includes the following steps:

[0079] Step S2.1: Signal Acquisition: Real-time acquisition of voltage from the DC bus terminal. and current Calculate instantaneous power ;

[0080] Step S2.2: Discretization processing: based on sampling frequency For continuous signals Discrete sampling is performed to obtain discrete order. ;in, Sampling interval;

[0081] Step S2.3: Windowing: To reduce spectral leakage, the discrete signal is windowed (e.g., a Hamming window).

[0082] ;

[0083] in, N The window length (e.g., 2048 points);

[0084] Step S2.4: FFT calculation: Perform FFT on the windowed signal to obtain a complex sequence in the frequency domain. :

[0085]

[0086] Step S2.5: Calculate the amplitude spectrum of each frequency component. ;

[0087]

[0088] The actual frequency corresponding to the k-th point on the frequency axis is: ;

[0089] Step S3: Frequency band allocation and energy calculation, specifically including the following steps:

[0090] Step S3.1: Define the frequency band:

[0091] Low frequency band: (e.g., 0.01 Hz ~ 1 Hz); High frequency band: (e.g., 1Hz~100Hz); where, This represents the boundary value for the lowest frequency component, corresponding to the slowest power fluctuation; The frequency boundary between the low-frequency band (ALK response) and the high-frequency band (PEM response); The boundary value for the highest frequency component is determined by the system control bandwidth limit;

[0092] Step S3.2: Low-frequency energy :

[0093]

[0094] High-frequency energy :

[0095]

[0096] Step S3.3: Power allocation ratio:

[0097] ALK power allocation percentage: ;

[0098] PEM power allocation percentage: ;

[0099] Step S4: Basic Allocation: Frequency Band Energy Ratio Based on FFT:

[0100]

[0101] Step S5: Transient correction: By calculating the time-domain difference (gradient) of the instantaneous power signal of the proton exchange membrane electrolyzer, abrupt change points are detected and transient high-frequency energy is quantified;

[0102] The difference is calculated as follows: ;

[0103] If the transient high-frequency energy is greater than a preset threshold θ (e.g., 10% of the rated power), it is marked as a transient event.

[0104] More specifically, if Mark as a transient event;

[0105]

[0106] in, The instantaneous power signal of the nth calculated proton exchange membrane electrolyzer; W The integration window length (e.g., 10ms); To quantize the transient high-frequency energy when detecting transient events;

[0107] If a transient event is detected, temporarily increase the PEM power: Where γ is a proportionality coefficient, such as 0.1; To quantize the transient high-frequency energy when detecting transient events; This represents the total instantaneous power;

[0108] Step S6: Thermal equilibrium constraint: Limit the maximum power of the PEM based on temperature feedback.

[0109]

[0110] in, This refers to the real-time temperature of the proton exchange membrane electrolyzer. =60℃, =80℃; This refers to the maximum permissible power of a proton exchange membrane electrolyzer. This is the ideal operating temperature for a proton exchange membrane electrolyzer under normal operating conditions. This represents the real-time power of the proton exchange membrane electrolyzer.

[0111] Step S7: Adjust the duty cycle of the DC / DC module based on the allocation command to achieve dynamic power matching between ALK and PEM;

[0112] Step S7.1: Based on the target power Solve for the initial duty cycle: Where, 0.1≤ ≤0.9, to avoid overloading the switching transistor; This is the voltage value of the DC bus; This represents the total current of the DC bus. Energy conversion efficiency;

[0113] Step S7.2: Using actual power With target power error The duty cycle is dynamically adjusted based on the input.

[0114]

[0115] in, The amplitude is determined by frequency domain analysis and an integral limit is set, such as... ; k This is the sequence number of the current sampling time; This represents the error between the actual power and the target power.

[0116] Example 1

[0117] Taking an off-grid hydrogen production station test as an example, the station is equipped with ALK (500 Nm³ / h) and PEM (200 Nm³ / h) modules, connected to the DC bus via a DC / DC converter. Voltage, current, and temperature sensors are deployed at key nodes of the electrolyzer, and the data is transmitted to the main control unit via a CAN bus. A combined liquid cooling (ALK) and air cooling (PEM) design is adopted, with an integrated temperature feedback regulating valve. The voltage and current information of the 1000V DC bus are filtered by an LPF to remove high-frequency noise and then sent to the ARM Cortex-M7 control board to achieve real-time spectrum analysis, with a sampling frequency of 100Hz and a resolution of 1Hz. The FFT decomposes the frequency domain characteristics of the input power in real time to generate power allocation instructions for the low-frequency band (ALK) and the high-frequency band (PEM). The steps are as follows:

[0118] Signal acquisition: Real-time voltage acquisition from the DC bus terminal. and current Calculate instantaneous power ;

[0119] Discretization processing: based on sampling frequency For continuous signals Discrete sampling is performed to obtain discrete order. ;in, =10ms sampling interval;

[0120] Windowing: To reduce spectral leakage, discrete signals are windowed (e.g., with a Hamming window).

[0121] ;

[0122] in, N =2048 is the window length;

[0123] FFT calculation: Perform an FFT on the windowed signal to obtain a complex sequence in the frequency domain. :

[0124]

[0125] Calculate the amplitude spectrum of each frequency component. ;

[0126]

[0127] The actual frequency corresponding to the k-th point on the frequency axis is: ;

[0128] Frequency band allocation and energy calculation specifically include the following steps:

[0129] Define low frequency band: High-frequency band: ;

[0130] Low-frequency energy :

[0131]

[0132] High-frequency energy :

[0133]

[0134] Power distribution ratio:

[0135] ALK power allocation percentage: ;

[0136] PEM power allocation percentage: ;

[0137] Basic Allocation: Frequency Band Energy Ratio Based on FFT:

[0138]

[0139] Transient correction: If a transient event is detected ( Temporarily increase PEM power: Where γ = 0.1, is the proportionality coefficient;

[0140] Thermal equilibrium constraint: Limiting the maximum power of the PEM based on temperature feedback.

[0141]

[0142] in, Real-time temperature; =60℃, =80℃;

[0143] The duty cycle of the DC / DC module is adjusted based on allocation commands to achieve dynamic power matching between ALK and PEM; according to the target power... Solve for the initial duty cycle: Where, 0.1≤ ≤0.9;

[0144] With actual power With target power error The duty cycle is dynamically adjusted based on the input.

[0145]

[0146] in, , The amplitude was determined using frequency domain analysis, and an integral limit was set. .

[0147] Example 2

[0148] This application provides a power frequency domain allocation control system for a multimodal off-grid hydrogen production system, including:

[0149] The signal acquisition module is used to acquire DC bus voltage and current in real time and obtain instantaneous power.

[0150] The signal processing module is used to discretize the instantaneous power and then perform a Fourier transform to obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for the low-frequency and high-frequency bands.

[0151] The control module is used to adjust the duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side according to the low-frequency power command, and to adjust the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side according to the high-frequency power command, so as to dynamically match the power of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0152] In the multimodal off-grid hydrogen production system, the alkaline electrolyzer and the proton exchange membrane electrolyzer are connected in parallel. The alkaline electrolyzer and the proton exchange membrane electrolyzer are connected to the DC bus through independent DC / DC electrolyzer power supplies. The alkaline electrolyzer is used to absorb low-frequency fluctuation power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuation power. The low-frequency range is 0.01Hz~1Hz, and the high-frequency range is 1Hz~100Hz.

[0153] More preferably, the signal processing module includes:

[0154] The data discrete unit is used to discretely sample the instantaneous power to obtain a discrete power sequence;

[0155] The Fourier transform unit is used to perform Fourier transform on discrete power sequences to obtain the frequency domain complex sequence of power.

[0156] Amplitude calculation unit, used to calculate the amplitude spectrum of each frequency component;

[0157] The instruction generation unit is used to divide the power frequency into low-frequency power and high-frequency power, and obtain the power allocation instructions for the low-frequency and high-frequency bands by combining the amplitude spectrum of each frequency band component.

[0158] More preferably, the instruction generation unit includes:

[0159] The first calculation component is used to calculate the low-frequency energy and high-frequency energy based on the amplitude spectrum of each frequency band component, and then obtain the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0160] The second calculation component is used to perform a basic allocation of the high-frequency energy ratio and the low-frequency energy ratio based on the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer.

[0161] The third computing component is used to perform transient correction on the high-frequency energy ratio if a transient event is detected, and then limit the maximum power of the high-frequency energy according to temperature feedback, and obtain the power allocation instructions for the low-frequency and high-frequency bands.

[0162] More preferably, the control module includes:

[0163] The duty cycle initialization unit is used to initialize the duty cycle of the corresponding DC / DC electrolytic cell power supply according to the target power of the low-frequency band and the target power of the high-frequency band.

[0164] The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer based on the error between the actual power and the target power of the low-frequency band obtained from the power allocation command; and to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer based on the error between the actual power and the target power of the high-frequency band obtained from the power allocation command.

[0165] More preferably, the proportion of high-frequency energy after transient correction in the third computing component is:

[0166]

[0167] in, Allocate power percentages to the proton exchange membrane electrolyzer; This represents the total instantaneous power; This is used to quantize the transient high-frequency energy when a transient event is detected; γ is a proportionality coefficient.

[0168] The maximum power of high-frequency energy is:

[0169]

[0170] in, This refers to the real-time temperature of the proton exchange membrane electrolyzer. This refers to the maximum permissible power of a proton exchange membrane electrolyzer. The instantaneous power of the proton exchange membrane electrolyzer; This is the ideal operating temperature for a proton exchange membrane electrolyzer under normal operating conditions.

[0171] More preferably, the initial duty cycle value of the DC / DC electrolytic cell power supply in the duty cycle initialization unit is:

[0172] ;

[0173] in, This is the voltage value of the DC bus; This represents the total current of the DC bus. Energy conversion efficiency;

[0174] More preferably, the dynamically adjusted duty cycle in the duty cycle update unit is:

[0175]

[0176] in, This is the gain coefficient of the proportional controller; This is the gain coefficient of the integral controller; k This is the sequence number of the current sampling time; This represents the error between the actual power and the target power.

[0177] In summary, the power frequency domain allocation control method for multimodal hydrogen production systems proposed in this application, compared with traditional single ALK or PEM hydrogen production methods, increases hydrogen production efficiency from 75% to 88% in photovoltaic and wind power hydrogen production scenarios; reduces dynamic response delay from 200ms to 50ms; and extends equipment life by 18% and 22% for ALK and PEM respectively. Experiments show that this method can effectively absorb fluctuating power and improve the performance and economy of hydrogen production systems.

[0178] This application improves hydrogen production efficiency by rationally allocating power, enabling both types of electrolyzers to operate within their optimal operating range. Simultaneously, this application reduces the number of start-ups and shutdowns of the electrolyzers, extending equipment lifespan and lowering operating costs.

[0179] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0180] Furthermore, in this application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0181] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. "Fixed connection" refers to a connection where the relative positional relationship remains unchanged after connection. "Rotary connection" refers to a connection where the components can rotate relative to each other after connection. "Sliding connection" refers to a connection where the components can slide relative to each other after connection. The directional terms mentioned in the embodiments of this application, such as "top," "bottom," "inner," "outer," "left," and "right," are only for reference to the directions in the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of this application, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0182] Furthermore, the mathematical concepts mentioned in the embodiments of this application, such as symmetry, equality, parallelism, and perpendicularity, are limitations specific to the current technological level, rather than absolute and strict mathematical definitions. Slight deviations are permissible; approximations of symmetry, equality, parallelism, and perpendicularity are all acceptable. For example, "A and B are parallel" means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. "A and B are perpendicular" means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0183] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A power frequency domain allocation control method for a multimodal off-grid hydrogen production system, characterized in that, Includes the following steps: Step 1: Obtain instantaneous power by real-time acquisition of DC bus voltage and current, discretize and perform Fourier transform to obtain the frequency domain characteristics of instantaneous power, and generate power allocation instructions for low-frequency and high-frequency bands. Step 2: Adjust the duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side according to the low-frequency power command, and adjust the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side according to the high-frequency power command to achieve dynamic power matching between the alkaline electrolyzer and the proton exchange membrane electrolyzer. Step two specifically includes the following steps: The duty cycle of the corresponding DC / DC electrolytic cell power supply is initialized based on the target power of the low-frequency band and the target power of the high-frequency band. Based on the error between the actual power in the low-frequency band and the target power in the low-frequency band obtained from the power allocation command, the duty cycle of the DC / DC power supply of the alkaline electrolyzer is dynamically adjusted; and based on the error between the actual power in the high-frequency band and the target power in the high-frequency band obtained from the power allocation command, the duty cycle of the DC / DC power supply of the proton exchange membrane electrolyzer is dynamically adjusted. In the multimodal off-grid hydrogen production system, the alkaline electrolyzer and the proton exchange membrane electrolyzer are connected in parallel. The alkaline electrolyzer and the proton exchange membrane electrolyzer are connected to the DC bus through independent DC / DC electrolyzer power supplies. The alkaline electrolyzer is used to absorb low-frequency fluctuation power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuation power. The low-frequency range is 0.01Hz~1Hz, and the high-frequency range is 1Hz~100Hz.

2. The power frequency domain allocation control method according to claim 1, characterized in that, Step one specifically includes the following steps: Step 1.1: Collect voltage and current data from the DC bus terminal in real time and calculate instantaneous power; Step 1.2: Discretely sample the instantaneous power to obtain a discrete power sequence; Step 1.3: Perform a Fourier transform on the discrete power sequence to obtain the frequency domain complex sequence of the power, and calculate the amplitude spectrum of each frequency component; Step 1.4: Divide the power frequency into low-frequency power and high-frequency power, and obtain the power allocation instructions for the low-frequency and high-frequency bands by combining the amplitude spectrum of each frequency band component.

3. The power frequency domain allocation control method according to claim 2, characterized in that, Step S1.4 involves obtaining power allocation instructions for the low-frequency and high-frequency bands based on the amplitude spectrum of each frequency band component. This specifically includes the following steps: The low-frequency energy and high-frequency energy are calculated based on the amplitude spectrum of each frequency band component, thereby obtaining the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer. Based on the power allocation ratio of alkaline electrolyzers and proton exchange membrane electrolyzers, a basic allocation of the energy ratio in the high-frequency band and the energy ratio in the low-frequency band is carried out. If a transient event is detected, the high-frequency energy ratio is transiently corrected, and the maximum power of the high-frequency energy is limited based on temperature feedback to obtain power allocation instructions for the low-frequency and high-frequency bands.

4. The power frequency domain allocation control method according to claim 3, characterized in that, By calculating the time-domain difference of the instantaneous power signal of the proton exchange membrane electrolyzer, abrupt change points are detected and transient high-frequency energy is quantified. If the transient high-frequency energy exceeds a preset threshold, it is marked as a transient event; If a transient event is detected, the proportion of high-frequency energy after transient correction is: in, Allocate power percentages to the proton exchange membrane electrolyzer; The instantaneous power in the middle; This is used to quantize the transient high-frequency energy when a transient event is detected; γ is a proportionality coefficient. The maximum power of high-frequency energy is: in, This refers to the real-time temperature of the proton exchange membrane electrolyzer. This refers to the maximum permissible power of a proton exchange membrane electrolyzer. The instantaneous power of the proton exchange membrane electrolyzer; This is the ideal operating temperature for a proton exchange membrane electrolyzer under normal operating conditions.

5. The power frequency domain allocation control method according to claim 1, characterized in that, The initial duty cycle value of the DC / DC electrolytic cell power supply is: ； in, This is the voltage value of the DC bus; This represents the total current of the DC bus. Energy conversion efficiency; The dynamically adjusted duty cycle is: in, This is the gain coefficient of the proportional controller; This is the gain coefficient of the integral controller; k This is the sequence number of the current sampling time; This represents the error between the actual power and the target power.

6. A power frequency domain distribution control system for a multimodal off-grid hydrogen production system, characterized in that, include: The signal acquisition module is used to acquire DC bus voltage and current in real time and obtain instantaneous power. The signal processing module is used to discretize the instantaneous power and then perform a Fourier transform to obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for the low-frequency and high-frequency bands. The control module is used to adjust the duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side according to the low-frequency power command, and to adjust the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side according to the high-frequency power command, so as to dynamically match the power of the alkaline electrolyzer and the proton exchange membrane electrolyzer. The control module includes: The duty cycle initialization unit is used to initialize the duty cycle of the corresponding DC / DC electrolytic cell power supply according to the target power of the low-frequency band and the target power of the high-frequency band. The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer based on the error between the actual power of the low-frequency band and the target power of the low-frequency band obtained based on the power allocation command; and to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer based on the error between the actual power of the high-frequency band and the target power of the high-frequency band obtained based on the power allocation command. In the multimodal off-grid hydrogen production system, the alkaline electrolyzer and the proton exchange membrane electrolyzer are connected in parallel. The alkaline electrolyzer and the proton exchange membrane electrolyzer are connected to the DC bus through independent DC / DC electrolyzer power supplies. The alkaline electrolyzer is used to absorb low-frequency fluctuation power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuation power. The low-frequency range is 0.01Hz~1Hz, and the high-frequency range is 1Hz~100Hz.

7. The power frequency domain allocation control system according to claim 6, characterized in that, The signal processing module includes: The data discrete unit is used to discretely sample the instantaneous power to obtain a discrete power sequence; The Fourier transform unit is used to perform Fourier transform on discrete power sequences to obtain the frequency domain complex sequence of power. Amplitude calculation unit, used to calculate the amplitude spectrum of each frequency component; The instruction generation unit is used to divide the power frequency into low-frequency power and high-frequency power, and obtain the power allocation instructions for the low-frequency and high-frequency bands by combining the amplitude spectrum of each frequency band component.

8. The power frequency domain allocation control system according to claim 7, characterized in that, Instruction generation unit, including: The first calculation component is used to calculate the low-frequency energy and high-frequency energy based on the amplitude spectrum of each frequency band component, and then obtain the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer. The second calculation component is used to perform a basic allocation of the high-frequency energy ratio and the low-frequency energy ratio based on the power allocation ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer. The third computing component is used to perform transient correction on the high-frequency energy ratio if a transient event is detected, and then limit the maximum power of the high-frequency energy according to temperature feedback, and obtain the power allocation instructions for the low-frequency and high-frequency bands.

Images