Power frequency domain distribution control method and system of multi-mode off-grid hydrogen production system

Abstract

The invention belongs to the technical field of new energy hydrogen production, and particularly discloses a power frequency domain distribution control method and system of a multi-mode off-grid hydrogen production system. The method specifically comprises the steps that instantaneous power is obtained through direct-current bus voltage and current collected in real time, Fourier transform is carried out after discretization processing, frequency domain characteristics of the instantaneous power are obtained, and power distribution instructions of a low-frequency band and a high-frequency band are generated; adjusting and controlling the duty ratio of a DC / DC electrolytic cell power supply at the alkaline electrolytic cell side according to the low-frequency-band power instruction, adjusting and controlling the duty ratio of a DC / DC electrolytic cell power supply at the proton exchange membrane electrolytic cell side 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; according to the invention, the fluctuation power of different frequency bands can be consumed, the hydrogen production efficiency is improved, the service life of equipment is prolonged, and the performance and economical efficiency of a hydrogen production system are improved.

Description

Technical Field

[0001] The present 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 multi-mode off-grid hydrogen production system. Background Art

[0002] Traditional hydrogen production systems mostly use a single type of electrolyzer, such as alkaline electrolyzer ALK or proton exchange membrane electrolyzer PEM, which makes it difficult to take into account low-frequency high-power fluctuations (such as minute-level fluctuations of photovoltaic / wind power) and high-frequency low-power fluctuations (such as second-level fluctuations), resulting in low hydrogen production efficiency and large equipment losses.

[0003] Existing power allocation methods (such as rotation strategies based on operating time or fixed-ratio allocation) cannot match power frequency characteristics in real time, resulting in frequent electrolyzer starts and stops or long-term deviations from the optimal operating range, affecting system life. High-frequency power fluctuations can easily introduce harmonic pollution, and traditional LC filters are difficult to adapt to broadband fluctuations, affecting grid power quality. Summary of the Invention

[0004] In response to the defects of the existing technology, the purpose of this application is to provide a power frequency domain allocation control method and system for a multi-modal off-grid hydrogen production system, aiming to solve the problem that the existing single electrolyzer is difficult to take into account both low-frequency high-power fluctuations and high-frequency low-power fluctuations, resulting in low hydrogen production efficiency and large equipment losses.

[0005] To achieve the above objectives, in a first aspect, the present application provides a method for controlling power frequency domain allocation of a multi-mode off-grid hydrogen production system, comprising the following steps: Step 1: Obtain instantaneous power through real-time acquisition of DC bus voltage and current, discretize it, and perform Fourier transform to obtain the frequency domain characteristics of instantaneous power, generating power allocation instructions for low-frequency and high-frequency bands; Step 2: The duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side is adjusted and controlled according to the low-frequency power command, and the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side is adjusted and controlled according to the high-frequency power command, so as to dynamically match the power of the alkaline electrolyzer and the proton exchange membrane electrolyzer; Among them, the alkaline electrolyzer and the proton exchange membrane electrolyzer in the multi-modal off-grid hydrogen production system 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 fluctuating power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuating power; the low-frequency band frequency is 0.01Hz~1Hz, and the high-frequency band frequency is 1Hz~100Hz.

[0006] Further preferably, step one specifically includes the following steps: Step 1.1: Collect voltage and current from the DC bus 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 Fourier transform on the discrete power sequence to obtain the frequency domain complex sequence of power and calculate the amplitude spectrum of each frequency component; Step 1.4: Divide the power frequency into low-frequency band power and high-frequency band power, and combine the amplitude spectrum of each frequency band component to obtain the power allocation instructions for the low-frequency band and the high-frequency band.

[0007] Further preferably, in step S1.4, obtaining the power allocation instructions for the low frequency band and the high frequency band according to the amplitude spectrum of the components of each frequency band specifically includes the following steps: The low-frequency band energy and high-frequency band energy are calculated based on the amplitude spectrum of each frequency band component, and then the power distribution ratio of the alkaline electrolyzer and proton exchange membrane electrolyzer is obtained; Based on the power allocation ratio of alkaline electrolyzer and proton exchange membrane electrolyzer, a basic allocation of high-frequency energy ratio and low-frequency energy ratio is made; If a transient event is detected, a transient correction is performed on the high-frequency energy ratio, and then the maximum power of the high-frequency energy is limited according to temperature feedback to obtain power allocation instructions for the low-frequency and high-frequency bands.

[0008] Further preferably, step 2 specifically includes the following steps: Initialize the duty cycle of the corresponding DC / DC electrolyzer power supply according to the low-frequency target power and the high-frequency target power; According to the error between the low-frequency band actual power obtained based on the power allocation instruction and the low-frequency band target power, the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer is dynamically adjusted; and according to the error between the high-frequency band actual power obtained based on the power allocation instruction and the high-frequency band target power, the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer is dynamically adjusted.

[0009] Further preferably, the mutation point is detected and the transient high-frequency energy is quantified by calculating the time domain difference of the instantaneous power signal of the proton exchange membrane electrolyzer; If the energy of the transient high-frequency band is greater than the preset threshold, it is marked as a transient event; If a transient event is detected, the energy ratio of the high frequency band after transient correction is:

[0010] in, Allocate power share for proton exchange membrane electrolyzers; is the instantaneous power in; is the quantized transient high-frequency energy when a transient event is detected; γ is the proportional coefficient; The maximum power of high-frequency energy is:

[0011] in, is the real-time temperature of the proton exchange membrane electrolyzer; is the maximum allowable power of the proton exchange membrane electrolyzer; is the instantaneous power of the proton exchange membrane electrolyzer; It is the ideal operating temperature of the proton exchange membrane electrolyzer under normal working conditions.

[0012] The initial duty cycle value of the DC / DC electrolyzer power supply is: ; in, is the voltage value of the DC bus; is the total current of the DC bus; is the energy conversion efficiency; The duty cycle after dynamic adjustment is:

[0013] in, is the gain coefficient of the proportional controller; is the gain coefficient of the integral controller; k is the serial number of the current sampling moment; is the error between the actual power and the target power.

[0014] In a second aspect, the present application provides a power frequency domain allocation control system for a multi-modal off-grid hydrogen production system, comprising: Signal acquisition module, used to collect DC bus voltage and current in real time to obtain instantaneous power; The signal processing module is used to perform Fourier transform on the instantaneous power after discretization, obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for low-frequency bands and high-frequency bands; A 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; Among them, the alkaline electrolyzer and the proton exchange membrane electrolyzer in the multi-modal off-grid hydrogen production system 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 fluctuating power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuating power; the low-frequency band frequency is 0.01Hz~1Hz, and the high-frequency band frequency is 1Hz~100Hz.

[0015] Further preferably, the signal processing module includes: A data discrete unit is used to discretely sample the instantaneous power and obtain a discrete power sequence; A Fourier transform unit, used for performing Fourier transform on the discrete power sequence to obtain a frequency domain complex sequence of power; an amplitude calculation unit, for calculating the amplitude spectrum of each frequency component; The instruction generation unit is used to divide the power frequency into low-frequency band power and high-frequency band power, and obtain the power allocation instructions of the low-frequency band and the high-frequency band based on the amplitude spectrum of each frequency band component.

[0016] Further preferably, the instruction generating unit includes: The first calculation component is used to calculate the low-frequency band energy and the high-frequency band energy according to the amplitude spectrum of each frequency band component, and then obtain the power distribution ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer; The second calculation component is used to allocate power proportions based on the alkaline electrolyzer and the proton exchange membrane electrolyzer, and perform basic allocation of high-frequency energy proportions and low-frequency energy proportions; 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 to obtain power allocation instructions for the low frequency band and the high frequency band.

[0017] Further preferably, the control module includes: A duty cycle initialization unit, configured to initialize the duty cycle of the corresponding DC / DC electrolyzer power supply according to the low-frequency target power and the high-frequency target power; The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer according to the error between the low-frequency band actual power obtained based on the power allocation instruction and the low-frequency band target power; and dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer according to the error between the high-frequency band actual power obtained based on the power allocation instruction and the high-frequency band target power.

[0018] Further preferably, the high-frequency energy ratio after transient correction in the third calculation component is:

[0019] in, Allocate power share for proton exchange membrane electrolyzers; is the instantaneous power in; is the quantized transient high-frequency energy when a transient event is detected; γ is the proportional coefficient; The maximum power of high-frequency energy is:

[0020] in, is the real-time temperature of the proton exchange membrane electrolyzer; is the maximum allowable power of the proton exchange membrane electrolyzer; is the real-time power of the proton exchange membrane electrolyzer; It is the ideal operating temperature of the proton exchange membrane electrolyzer under normal working conditions.

[0021] Further preferably, the initial value of the duty cycle of the DC / DC electrolyzer power supply in the duty cycle initialization unit is: ; in, is the voltage value of the DC bus; is the total current of the DC bus; is the energy conversion efficiency; Further preferably, the duty cycle dynamically adjusted in the duty cycle updating unit is:

[0022] in, is the gain coefficient of the proportional controller; is the gain coefficient of the integral controller; k is the serial number of the current sampling moment; is the error between the actual power and the target power.

[0023] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies: The power frequency domain allocation control method for a multi-modal hydrogen production system proposed in this application, in the scenarios of photovoltaic hydrogen production and wind power hydrogen production, compared with the traditional single ALK hydrogen production or PEM hydrogen production method, uses alkaline electrolyzers and proton exchange membrane electrolyzers to absorb fluctuating power in different frequency bands, which not only improves the hydrogen production efficiency, but also extends the equipment life, thereby improving the performance and economy of the hydrogen production system.

[0024] The power frequency domain allocation control method for the multi-modal hydrogen production system proposed in this application enables both electrolyzers to operate in their optimal working ranges by reasonably allocating power, thereby improving hydrogen production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a topology diagram of an off-grid hydrogen production system with multi-modal electrolyzer power frequency domain allocation provided by an embodiment of the present application; Figure 2 This is a flowchart of FFT frequency domain decomposition and power allocation provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0027] The term "and / or" in this application describes an association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, or B exists alone. The symbol " / " in this application indicates that the associated objects are in an "or" relationship, for example, A / B means A or B.

[0028] The terms "first" and "second" and the like in the description and claims of this application are used to distinguish different objects rather than to describe a specific order of the objects.

[0029] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0030] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more.

[0031] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0032] The present application provides a method for controlling power frequency domain allocation of a multi-mode off-grid hydrogen production system, comprising the following steps: Step S1: Figure 1 As shown, wind power or photovoltaic power is fed into the DC bus via a converter, and the alkaline electrolyzer (ALK) and proton exchange membrane electrolyzer (PEM) are connected to the DC bus via independent DC-DC modules. The ALK is used to absorb low-frequency fluctuating power (0.01Hz to 1Hz), while the PEM responds to high-frequency fluctuating power (1Hz to 100Hz). The alkaline electrolyzer (ALK) and the proton exchange membrane electrolyzer (PEM) are connected in parallel. Step S2: FFT frequency domain decomposition and power allocation: Figure 2This is the FFT frequency domain decomposition and power allocation flow chart. The DC bus voltage and current information is low-pass filtered and then fed into the data processing unit. 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 is used to monitor input power fluctuations in real time. The Fast Fourier Transform spectrum analysis module is used to decompose the frequency domain characteristics of the input power in real time. The controller is used to dynamically adjust the power allocation ratio between ALK and PEM based on the frequency domain characteristics. The power frequency allocation control method for a multi-modal discrete hydrogen production system provided in this application specifically includes the following steps: Step S2.1: Signal acquisition: Real-time voltage acquisition from the DC bus terminal and current , calculate the instantaneous power ; Step S2.2: Discretization: Sampling frequency For continuous signals Perform discrete sampling to obtain discrete sequence ;in, Sampling interval; Step S2.3: Windowing: To reduce spectrum leakage, add a window (such as a Hamming window) to the discrete signal: ; in, N is the window length (e.g. 2048 points); Step S2.4: FFT calculation: Perform FFT on the windowed signal to obtain a frequency domain complex sequence :

[0033] Step S2.5: Calculate the amplitude spectrum of each frequency component ;

[0034] The actual frequency corresponding to the kth point on the frequency axis is: ; Step S3: frequency band division and energy calculation, specifically including the following steps: Step S3.1: Define the frequency band: Low frequency band: (e.g. 0.01 Hz ~ 1 Hz); high frequency band: (e.g. 1Hz~100Hz); among them, is the boundary value of the lowest frequency component, corresponding to the slowest power fluctuation; The frequency dividing point for dividing the low frequency band (ALK response) and the high frequency band (PEM response); is the boundary value of the highest frequency component, which is determined by the system control bandwidth limit; Step S3.2: Low frequency energy :

[0035] High frequency energy :

[0036] Step S3.3: Power allocation ratio: ALK allocated power ratio: ; PEM allocated power ratio: ; Step S4: Basic allocation: frequency band energy ratio based on FFT:

[0037] Step S5: transient correction: detecting the mutation point and quantifying the transient high-frequency energy by calculating the time domain difference (gradient) of the instantaneous power signal of the proton exchange membrane electrolyzer; The difference is calculated as: ; 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; More specifically, if Marked as transient event;

[0038] in, is the instantaneous power signal of the proton exchange membrane electrolyzer calculated for the nth time; W is the integration window length (e.g. 10ms); To quantify the transient high frequency energy when a transient event is detected; If a transient event is detected, temporarily increase the PEM power: ; Where γ is the proportional coefficient, such as 0.1; To quantify the transient high frequency energy when a transient event is detected; is the total instantaneous power; Step S6: Thermal balance constraint: Limit the maximum power of the PEM based on temperature feedback:

[0039] in, is the real-time temperature of the proton exchange membrane electrolyzer; =60℃, =80℃; is the maximum allowable power of the proton exchange membrane electrolyzer; It is the ideal operating temperature of the proton exchange membrane electrolyzer under normal working conditions; is the real-time power of the proton exchange membrane electrolyzer; Step S7: adjusting the duty cycle of the DC / DC module based on the allocation instruction to achieve dynamic power matching between ALK and PEM; Step S7.1: According to the target power , solve for the initial duty cycle: ; Among them, 0.1≤ ≤0.9 to avoid overload of the switch tube; is the voltage value of the DC bus; is the total current of the DC bus; is the energy conversion efficiency; Step S7.2: Using actual power With target power Error As input, dynamically adjust the duty cycle;

[0040] in, Determine by frequency domain analysis and set the integral limit, such as ; k is the sequence number of the current sampling moment; is the error between the actual power and the target power.

[0041] Example 1 Taking an off-grid hydrogen production station 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 in the electrolyzer, and data is transmitted to the main control unit via the CAN bus. A combined design of liquid cooling (ALK) and air cooling (PEM) is used, with an integrated temperature feedback control valve. The voltage and current information of the 1000V DC bus is filtered out of high-frequency noise by an LPF and then fed into an ARM Cortex-M7 control board for 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 high-frequency band (PEM). The steps are as follows: Signal acquisition: Real-time voltage acquisition from the DC bus terminal and current , calculate the instantaneous power ; Discretization processing: sampling frequency For continuous signals Perform discrete sampling to obtain discrete sequence ;in, =10ms sampling interval; Windowing: To reduce spectrum leakage, add a window (such as a Hamming window) to the discrete signal: ; in, N =2048 is the window length; FFT calculation: Perform FFT on the windowed signal to obtain a frequency domain complex sequence :

[0042] Calculate the amplitude spectrum of each frequency component ;

[0043] The actual frequency corresponding to the kth point on the frequency axis is: ; Frequency band division and energy calculation include the following steps: Define the low frequency band: ; High frequency band: ; Low frequency energy :

[0044] High frequency energy :

[0045] Power distribution ratio: ALK allocated power ratio: ; PEM allocated power ratio: ; Basic allocation: frequency band energy ratio based on FFT:

[0046] Transient Correction: If a transient event is detected ( ), temporarily increase the PEM power: ; Among them, γ=0.1 is the proportional coefficient; Thermal equilibrium constraint: Limits the maximum power of the PEM based on temperature feedback:

[0047] in, is the real-time temperature; =60℃, =80℃; Based on the distribution instructions, the duty cycle of the DC / DC module is adjusted to achieve dynamic power matching between ALK and PEM; according to the target power , solve for the initial duty cycle: ; Among them, 0.1≤ ≤0.9; With actual power With target power Error As input, dynamically adjust the duty cycle;

[0048] in, , Determine by frequency domain analysis and set integral limit, .

[0049] Example 2 The present application provides a power frequency domain distribution control system for a multi-mode off-grid hydrogen production system, comprising: Signal acquisition module, used to collect DC bus voltage and current in real time to obtain instantaneous power; The signal processing module is used to perform Fourier transform on the instantaneous power after discretization, obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for low-frequency bands and high-frequency bands; A 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; Among them, the alkaline electrolyzer and the proton exchange membrane electrolyzer in the multi-modal off-grid hydrogen production system 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 fluctuating power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuating power; the low-frequency band frequency is 0.01Hz~1Hz, and the high-frequency band frequency is 1Hz~100Hz.

[0050] Further preferably, the signal processing module includes: A data discrete unit is used to discretely sample the instantaneous power and obtain a discrete power sequence; A Fourier transform unit, used for performing Fourier transform on the discrete power sequence to obtain a frequency domain complex sequence of power; an amplitude calculation unit, for calculating the amplitude spectrum of each frequency component; The instruction generation unit is used to divide the power frequency into low-frequency band power and high-frequency band power, and obtain the power allocation instructions of the low-frequency band and the high-frequency band based on the amplitude spectrum of each frequency band component.

[0051] Further preferably, the instruction generating unit includes: The first calculation component is used to calculate the low-frequency band energy and the high-frequency band energy according to the amplitude spectrum of each frequency band component, and then obtain the power distribution ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer; The second calculation component is used to allocate power proportions based on the alkaline electrolyzer and the proton exchange membrane electrolyzer, and perform basic allocation of high-frequency energy proportions and low-frequency energy proportions; 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 to obtain power allocation instructions for the low frequency band and the high frequency band.

[0052] Further preferably, the control module includes: A duty cycle initialization unit, configured to initialize the duty cycle of the corresponding DC / DC electrolyzer power supply according to the low-frequency target power and the high-frequency target power; The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer according to the error between the low-frequency band actual power obtained based on the power allocation instruction and the low-frequency band target power; and dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer according to the error between the high-frequency band actual power obtained based on the power allocation instruction and the high-frequency band target power.

[0053] Further preferably, the high-frequency energy ratio after transient correction in the third calculation component is:

[0054] in, Allocate power share for proton exchange membrane electrolyzers; is the total instantaneous power; is the quantized transient high-frequency energy when a transient event is detected; γ is the proportional coefficient; The maximum power of high-frequency energy is:

[0055] in, is the real-time temperature of the proton exchange membrane electrolyzer; is the maximum allowable power of the proton exchange membrane electrolyzer; is the instantaneous power of the proton exchange membrane electrolyzer; It is the ideal operating temperature of the proton exchange membrane electrolyzer under normal working conditions.

[0056] Further preferably, the initial value of the duty cycle of the DC / DC electrolyzer power supply in the duty cycle initialization unit is: ; in, is the voltage value of the DC bus; is the total current of the DC bus; is the energy conversion efficiency; Further preferably, the duty cycle dynamically adjusted in the duty cycle updating unit is:

[0057] in, is the gain coefficient of the proportional controller; is the gain coefficient of the integral controller; k is the sequence number of the current sampling moment; is the error between the actual power and the target power.

[0058] In summary, the power frequency domain allocation control method for the multi-modal hydrogen production system proposed in this application, in the scenarios of photovoltaic hydrogen production and wind power hydrogen production, compared with the traditional single ALK hydrogen production or PEM hydrogen production method, can increase the hydrogen production efficiency from 75% to 88%; the dynamic response delay is shortened from 200ms to 50ms; and the equipment life ALK and PEM life are extended by 18% and 22% respectively. Experiments show that this method can effectively absorb fluctuating power and improve the performance and economy of the hydrogen production system.

[0059] This application rationally allocates power, allowing both electrolyzers to operate within their optimal operating ranges, improving hydrogen production efficiency. It also reduces the number of electrolyzer starts and stops, extending equipment life and reducing operating costs.

[0060] It should be understood that expressions such as "include" 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 "include" and / or "have" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0061] In addition, 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.

[0062] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. 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. Among them, "fixed connection" means that the two are connected to each other and the relative position relationship after the connection remains unchanged. "Rotational connection" means that the two are connected to each other and can rotate relative to each other after the connection. "Sliding connection" means that the two are connected to each other and can slide relative to each other after the connection. The directional terms mentioned in the embodiments of the present application, such as "top", "bottom", "inside", "outside", "left", "right", etc., are only reference to the directions of the accompanying drawings. Therefore, the directional terms used are for better and clearer explanation and understanding of the embodiments of the present application, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0063] In addition, in the embodiments of the present application, the mathematical concepts mentioned include symmetry, equality, parallelism, and perpendicularity. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense. A small amount of deviation is allowed, and it is possible to be approximately symmetric, approximately equal, approximately parallel, or approximately perpendicular. For example, A and B are parallel, which 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, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0064] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A power frequency domain allocation control method for a multi-mode off-grid hydrogen production system, characterized in that: The following steps are involved: Step 1: Obtain instantaneous power through 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: The duty cycle of the DC / DC electrolyzer power supply on the alkaline electrolyzer side is adjusted and controlled according to the low-frequency power command, and the duty cycle of the DC / DC electrolyzer power supply on the proton exchange membrane electrolyzer side is adjusted and controlled according to the high-frequency power command, so as to dynamically match the power of the alkaline electrolyzer and the proton exchange membrane electrolyzer; Among them, the alkaline electrolyzer and the proton exchange membrane electrolyzer in the multi-modal off-grid hydrogen production system 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 fluctuating power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuating power; the low-frequency band frequency is 0.01Hz~1Hz, and the high-frequency band frequency is 1Hz~100Hz.

2. The power frequency domain allocation control method according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 1.1: Collect voltage and current from the DC bus 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 Fourier transform on the discrete power sequence to obtain the frequency domain complex sequence of power and calculate the amplitude spectrum of each frequency component; Step 1.4: Divide the power frequency into low-frequency band power and high-frequency band power, and combine the amplitude spectrum of each frequency band component to obtain the power allocation instructions for the low-frequency band and the high-frequency band.

3. The power frequency domain allocation control method according to claim 2, characterized in that: In step S1.4, the power allocation instructions for the low frequency band and the high frequency band are obtained according to the amplitude spectrum of the components of each frequency band, which specifically includes the following steps: The low-frequency band energy and high-frequency band energy are calculated based on the amplitude spectrum of each frequency band component, and then the power distribution ratio of the alkaline electrolyzer and proton exchange membrane electrolyzer is obtained; Based on the power allocation ratio of alkaline electrolyzer and proton exchange membrane electrolyzer, a basic allocation of high-frequency energy ratio and low-frequency energy ratio is made; If a transient event is detected, a transient correction is performed on the high-frequency energy ratio, and then the maximum power of the high-frequency energy is limited according to 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 any one of claims 1 to 3, characterized in that: Step 2 specifically includes the following steps: Initialize the duty cycle of the corresponding DC / DC electrolyzer power supply according to the low-frequency target power and the high-frequency target power; According to the error between the low-frequency band actual power obtained based on the power allocation instruction and the low-frequency band target power, the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer is dynamically adjusted; and according to the error between the high-frequency band actual power obtained based on the power allocation instruction and the high-frequency band target power, the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer is dynamically adjusted.

5. 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, the mutation point is detected and the transient high-frequency energy is quantified; If the energy of the transient high-frequency band is greater than the preset threshold, it is marked as a transient event; If a transient event is detected, the energy ratio of the high frequency band after transient correction is: in, Allocate power share for proton exchange membrane electrolyzers; is the instantaneous power in; is the quantized transient high-frequency energy when a transient event is detected; γ is the proportional coefficient; The maximum power of high-frequency energy is: in, is the real-time temperature of the proton exchange membrane electrolyzer; is the maximum allowable power of the proton exchange membrane electrolyzer; is the instantaneous power of the proton exchange membrane electrolyzer; It is the ideal operating temperature of the proton exchange membrane electrolyzer under normal working conditions.

6. The power frequency domain allocation control method according to claim 4, characterized in that: The initial duty cycle of the DC / DC electrolyzer power supply is: ； in, is the voltage value of the DC bus; is the total current of the DC bus; is the energy conversion efficiency; The duty cycle after dynamic adjustment is: in, is the gain coefficient of the proportional controller; is the gain coefficient of the integral controller; k is the sequence number of the current sampling moment; is the error between the actual power and the target power.

7. A power frequency domain distribution control system for a multi-mode off-grid hydrogen production system, characterized in that: include: Signal acquisition module, used to collect DC bus voltage and current in real time to obtain instantaneous power; The signal processing module is used to perform Fourier transform on the instantaneous power after discretization, obtain the frequency domain characteristics of the instantaneous power, and generate power allocation instructions for low-frequency bands and high-frequency bands; A 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; Among them, the alkaline electrolyzer and the proton exchange membrane electrolyzer in the multi-modal off-grid hydrogen production system 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 fluctuating power, and the proton exchange membrane electrolyzer is used to respond to high-frequency fluctuating power; the low-frequency band frequency is 0.01Hz~1Hz, and the high-frequency band frequency is 1Hz~100Hz.

8. The power frequency domain allocation control system according to claim 7, characterized in that: The signal processing module includes: A data discrete unit is used to discretely sample the instantaneous power and obtain a discrete power sequence; A Fourier transform unit, used for performing Fourier transform on the discrete power sequence to obtain a frequency domain complex sequence of power; an amplitude calculation unit, for calculating the amplitude spectrum of each frequency component; The instruction generation unit is used to divide the power frequency into low-frequency band power and high-frequency band power, and obtain the power allocation instructions of the low-frequency band and the high-frequency band based on the amplitude spectrum of each frequency band component.

9. The power frequency domain allocation control system according to claim 8, characterized in that: Instruction generation unit, including: The first calculation component is used to calculate the low-frequency band energy and the high-frequency band energy according to the amplitude spectrum of each frequency band component, and then obtain the power distribution ratio of the alkaline electrolyzer and the proton exchange membrane electrolyzer; The second calculation component is used to allocate power proportions based on the alkaline electrolyzer and the proton exchange membrane electrolyzer, and perform basic allocation of high-frequency energy proportions and low-frequency energy proportions; 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 to obtain power allocation instructions for the low frequency band and the high frequency band.

10. The power frequency domain allocation control system according to any one of claims 7 to 9, characterized in that: The control module includes: A duty cycle initialization unit, configured to initialize the duty cycle of the corresponding DC / DC electrolyzer power supply according to the low-frequency target power and the high-frequency target power; The duty cycle update unit is used to dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the alkaline electrolyzer according to the error between the low-frequency band actual power obtained based on the power allocation instruction and the low-frequency band target power; and dynamically adjust the duty cycle of the DC / DC electrolyzer power supply of the proton exchange membrane electrolyzer according to the error between the high-frequency band actual power obtained based on the power allocation instruction and the high-frequency band target power.

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