Photovoltaic power generation and hydrogen energy coupling control method and device and storage medium

Abstract

The invention discloses a photovoltaic power generation and hydrogen energy coupling control method and device and a storage medium. The method comprises the following steps: establishing a photovoltaic power generation hydrogen production system in combination with dynamic array reconstruction, providing electric power required by photovoltaic dynamic reconstruction by utilizing a battery energy storage system, supplying power to an electrolytic bath in cooperation with photovoltaic output, and making up unbalanced power caused by battery energy storage and slow dynamic response of the electrolytic bath by utilizing a supercapacitor with quick response capability. The invention provides a power cooperative control method for a photovoltaic power generation hydrogen production system, and the hydrogen production efficiency of the system is improved by combining a dynamic array reconstruction technology. And the unbalanced power in the battery energy storage and the slow dynamic response of the electrolytic cell is made up by using the super capacitor with the quick response capability, so that the adaptability of the electrolytic cell and the battery energy storage to the photovoltaic power generation power fluctuation is improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic hydrogen production, and in particular to a control method, device and storage medium for coupling photovoltaic power generation and hydrogen energy. Background Art

[0002] Photovoltaic power generation systems use the photovoltaic effect of photovoltaic cells to directly convert solar radiation energy into electrical energy. They generally include photovoltaic arrays, inverters, transformers and other related auxiliary facilities. The current photovoltaic power generation system is greatly affected by the environment and weather. Many factors will affect the power generation efficiency of the photovoltaic system, such as dust on the surface of photovoltaic modules, partial shadows, module defects, etc. The efficiency of photovoltaic power generation will cause serious harm to power supply and production, so it is of great significance to study the power improvement efficiency of photovoltaic systems.

[0003] Through the technology of producing hydrogen by electrolysis of water, using photovoltaic power generation system to generate electricity and produce hydrogen, coupling electricity with hydrogen can achieve multi-energy complementarity of hydrogen and electricity. This can not only give play to the advantages of hydrogen energy storage and rapid power regulation, reduce the instability of high-proportion photovoltaic power generation system grid connection, increase the utilization hours of photovoltaic power generation system, but also make full use of abandoned wind and solar power, and improve the economic efficiency of photovoltaic power generation hydrogen production.

[0004] Connecting the photovoltaic power generation system and the hydrogen production unit through a microgrid can not only realize the consumption of the photovoltaic power generation system, but also promote the development of the hydrogen industry. In the process of hydrogen production by the photovoltaic power generation system, when the power generation is sufficient, how to absorb the output power of the photovoltaic power generation system; when the power generation is insufficient, how to use the output power of the photovoltaic power generation system, this is the problem faced by the photovoltaic power generation system hydrogen production system. Summary of the invention

[0005] The main technical problem solved by the present application is to provide a control method for coupling photovoltaic power generation with hydrogen energy to solve the above-mentioned problems.

[0006] In order to solve the above technical problems, a technical solution adopted in this application is to provide a control method for coupling photovoltaic power generation and hydrogen energy, including establishing a photovoltaic power generation and hydrogen production system in combination with dynamic array reconstruction, using a battery energy storage system to provide the electric power required for photovoltaic dynamic reconstruction, and at the same time cooperating with photovoltaic output to power the electrolyzer, and using a supercapacitor with fast response capability to compensate for the unbalanced power caused by battery energy storage and slow dynamic response of the electrolyzer.

[0007] The present application also provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method when executing the computer program.

[0008] The present application also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the described method when executed by a processor.

[0009] The beneficial effects of the present application are as follows: the present application proposes a power coordination control method for a photovoltaic power generation and hydrogen production system, and combines dynamic array reconstruction technology to improve the system's hydrogen production efficiency. And use supercapacitors with fast response capabilities to compensate for the unbalanced power in the slow dynamic response of battery energy storage and electrolyzers, thereby improving the adaptability of electrolyzers and battery energy storage to fluctuations in photovoltaic power generation. A first-order low-pass filtering algorithm is used to determine the actual output of the electrolyzer and battery energy storage at each moment, thereby determining the working power of the supercapacitor at each moment, achieving power coordination among the electrolyzer, battery energy storage, and supercapacitors, and improving the adaptability of the electrolyzer and battery energy storage to highly volatile photovoltaic output. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A photovoltaic power generation and hydrogen production system in combination with dynamic array reconstruction technology according to an embodiment of the present application;

[0011] Figure 2 is a schematic diagram of input and output of a control unit according to an embodiment of the present application;

[0012] Figure 3 is a schematic diagram of power allocation based on the FLF algorithm according to an embodiment of the present application;

[0013] Figure 4 is a circuit structure diagram of a first-order low-pass filter according to an embodiment of the present application;

[0014] Figure 5 This is a flow chart of a system power collaborative control strategy according to an embodiment of the present application;

[0015] Figure 6 This is a schematic diagram of a photovoltaic output curve in a typical scenario according to an embodiment of the present application;

[0016] Figure 7 is a schematic diagram of a real-time power control result in a typical scenario 1 according to an embodiment of the present application;

[0017] Figure 8 is a power coordination detail diagram in a typical scenario 1 according to an embodiment of the present application;

[0018] Fig. 9 is a schematic diagram of SOC values ​​of BESS#1 and BESS#2 in a typical scenario 1 according to an embodiment of the present application;

[0019] Fig.10 It is a schematic diagram of supercapacitor power in typical scenario 1 according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. The preferred embodiments of the present application are provided in the accompanying drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described in this specification. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0021] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present application. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0022] Figure 1-Figure 10 An embodiment of the control method for coupling photovoltaic power generation and hydrogen energy of the present application is shown, including establishing a photovoltaic power generation and hydrogen production system in combination with dynamic array reconstruction, using a battery energy storage system to provide the electric power required for photovoltaic dynamic reconstruction, and simultaneously cooperating with photovoltaic output to power the electrolyzer, and using a supercapacitor with fast response capability to compensate for the unbalanced power caused by battery energy storage and slow dynamic response of the electrolyzer.

[0023] The power coordination control method of the photovoltaic power generation hydrogen production system proposed in this application includes 5 operating modes. The operating mode of the system at the current moment is determined by the photovoltaic output at each moment and the state of charge (SOC) of the battery energy storage (BESS) at the previous moment, thereby determining the reference power of the electrolyzer and BESS at the current moment. Secondly, the actual output of the electrolyzer and BESS at each moment is determined by the first-order low-pass filtering (FLF) algorithm, thereby determining the working power of the supercapacitor (SC) at each moment, realizing the power coordination of the electrolyzer, BESS and SC, and improving the adaptability of the electrolyzer and BESS to high volatility photovoltaic output.

[0024] like Figure 1 The figure shows a photovoltaic power generation hydrogen production system combined with dynamic array reconstruction (DAR) technology, which includes a photovoltaic array, BESS, SC, electrolyzer and hydrogen storage tank. Through the coordinated power control of the electrolyzer, BESS and SC, the required electric power is provided for the photovoltaic DAR, and highly volatile photovoltaic power generation hydrogen production is achieved. The photovoltaic array, current injection (CI) device, electrolyzer, BESS and SC are all connected to the DC bus through a DC / DC converter. The system includes a control unit, and the input and output of the control unit are shown as follows Figure 2As shown in the figure, by collecting information from each device, the DAR algorithm and the power cooperative control algorithm are used to make optimization decisions, and real-time power control is performed on each device in the photovoltaic power generation hydrogen production system. Finally, when the amount of hydrogen stored in the hydrogen storage tank reaches a certain amount, the hydrogen will be sold to the hydrogen market.

[0025] The DAR technology in this system includes a TCT structure photovoltaic array, several DC / DC converters and CI devices. The control unit collects the electrical parameters of the photovoltaic array for optimization decision-making, calculates the optimal action plan of the electrical switch matrix, and then transmits the switch action signal to the electrical switch matrix, finally realizing the topological reconstruction of the photovoltaic array. At the same time, the system includes two battery energy storage systems, namely BESS#1 and BESS#2. BESS#1 has a small capacity and is used to provide electrical power to the CI device to realize photovoltaic DAR, thereby reducing the mismatch loss of the photovoltaic array. BESS#2 is designed as a large-capacity battery energy storage to cooperate with the electrolyzer to absorb the output of the photovoltaic system. In addition, photovoltaic output has the characteristics of high volatility and randomness, and the output power changes rapidly with changes in the environment. Although the response time of the proton exchange membrane (PEM) electrolyzer and BESS is fast (several seconds), they cannot fully adapt to the volatility of photovoltaic output, which leads to unbalanced DC bus power and reduced photovoltaic output utilization. The power response time of SC is within milliseconds, which can achieve fast response. Therefore, the system utilizes the fast-response SC device to compensate for the unbalanced power of the electrolyzer and BESS during the slow dynamic response process.

[0026] Mathematical model of each equipment unit

[0027] (1) Electrolyzer: The hydrogen production system produces hydrogen through the power-to-hydrogen (P2H) technology of electrolyzing water in the electrolyzer. Currently, PEM electrolyzers can be divided into two types: ordinary PEM electrolyzers and high-pressure PEM electrolyzers. The hydrogen produced by ordinary PEM electrolyzers (normal pressure electrolyzers) needs to be pressurized to the required pressure by an external hydrogen compressor before it can be stored in a hydrogen storage tank. High-pressure PEM electrolyzers can be pressurized inside the electrolyzer and directly output high-pressure hydrogen. For example, a 200bar-PEM electrolyzer has an output hydrogen pressure of 200bar, which can be directly stored in a hydrogen storage tank without the need for an external hydrogen compressor. In addition, high-pressure PEM electrolyzers are more efficient than ordinary PEM electrolyzers. Since the research focus of this application is the power coordinated control of photovoltaic power generation hydrogen production systems, in order to simplify the system model, this application selects a high-pressure PEM electrolyzer for modeling as follows:

[0028] H EL (t) = P P2H (t)E P2H η EL (1)

[0029]

[0030] Where: t is the time, P P2H and H EL is the electrical power required by the electrolyzer and the amount of hydrogen produced, E P2H is the conversion coefficient of P2H, η EL is the electrolyzer efficiency. P2H It is a binary variable, which represents the working status of the electrolytic cell. If it is in working status, its value is 1, otherwise it is 0. and are the maximum and minimum values ​​of the electrolytic cell input power respectively.

[0031] (2) BESS equipment: The SOC at each moment can be expressed by formula (3), and the upper and lower limits of SOC are expressed by formula (4). Formula (5) introduces the binary variable I Bat#k,ch and I Bat#k,disc To constrain the BESS from charging and discharging simultaneously. Formulas (6) and (7) represent the BESS charge and discharge rate constraints.

[0032]

[0033]

[0034] I Bat#k,ch (t)+I Bat#k,disc (t)≤1 (5)

[0035]

[0036]

[0037] Where: SOC Bat#k and C Bat#k is the charge state and battery capacity of BESS#k. Bat#k,ch and P Bat#k,disc are the charging and discharging powers respectively. η ch,#k and η disc,#k are the charge and discharge efficiencies, respectively. and They are the upper and lower limits of the battery energy storage SOC respectively. and is the maximum charge and discharge power.

[0038] (3) SC equipment: The mathematical model of SC equipment is similar to that of BESS and can be expressed as follows:

[0039]

[0040]

[0041] ISC,ch (t)+I SC,disc (t)≤1 (10)

[0042]

[0043]

[0044] Where: SOC SC and C SC is the charge state and capacity of SC. SC,ch and P SC,disc is the charge and discharge power of SC. ch,SC and η disc,SC is the charge and discharge efficiency. and It is the upper and lower limits of SOC. SC,ch and I SC,disc is a binary variable, indicating the SC charging and discharging status. and is the maximum charge and discharge power of SC.

[0045] Power collaborative control strategy based on FLF algorithm: Due to the high randomness and volatility of photovoltaic output, the sampling period of photovoltaic power selected in China is usually 1s. At the same time, due to the errors in the short-term prediction of photovoltaic output, it is rarely used in real-time regulation, and the sampling period of 1s also limits the application of intelligent optimization algorithms. Therefore, the power collaborative control strategy of the photovoltaic power generation and hydrogen production system designed in this application does not involve short-term prediction and intelligent optimization algorithms. This application designs 5 photovoltaic power generation and hydrogen production system operation modes to determine the reference power of the electrolyzer and BESS#2 at each moment, and uses the FLF algorithm to calculate the actual power of the electrolyzer, BESS#2 and SC at each moment. The power collaborative control strategy takes into account the working characteristics, response capabilities and factors affecting the degradation of the electrolyzer, BESS and SC, and combines photovoltaic DAR technology to improve the operating efficiency of the photovoltaic power generation and hydrogen production system.

[0046] The FLF algorithm model is as follows Figure 3 As shown in the figure, it is a power distribution control block diagram based on the FLF algorithm. The algorithm divides the input reference power into two parts: low-frequency power component and high-frequency power component. The low-frequency power component fluctuates slowly, and the response speed of BESS and electrolyzer can follow its fluctuation. This part of power is borne by BESS and electrolyzer. The high-frequency power component changes rapidly, requiring the energy storage medium to respond quickly, and it is allocated to SC to compensate for the unbalanced power in the slow dynamic response of BESS and electrolyzer.

[0047] The FLF algorithm is mainly improved from the principle of the FLF filter. The circuit structure of the FLF filter is as follows: Figure 4 As shown in the figure, Ui is the input signal, U o is the filtered output signal, R is the filter resistor, and C is the filter capacitor.

[0048] Based on the input-output relationship of the FLF filter circuit, its mathematical model can be expressed as follows:

[0049]

[0050] Where: τ is the filtering time constant, and τ = RC. In application, the output power of photovoltaic power generation is obtained by sampling, and the sampling period is T s , after discretizing the formula, we can get the following formula:

[0051]

[0052] Where: T s is the sampling period, P i is the input power signal, P o is the output power signal after filtering. This application redefines a filter coefficient α to simplify the FLF algorithm formula, and the value of α is as follows:

[0053]

[0054] Since the value range of τ is [0,∞), according to the formula, the value range of α is (0,1). At this time, the FLF algorithm formula can be expressed as follows:

[0055] P o (t) = αP i (t)+(1-α)P o (t-1)(16)

[0056] According to the formula, the actual output power of the electrolyzer and BESS#2 at time t is related to the input power signal (reference power) and the actual output power at time t-1, which can be expressed as follows:

[0057]

[0058]

[0059] Where: a and b are the filter coefficients of the electrolyzer and BESS#2. and are the reference powers of the electrolyzer and BESS#2, respectively, which are the input values ​​of the algorithm at the current moment.

[0060] Power coordination control strategy:

[0061] System operation constraints

[0062] (1) Power balance constraints

[0063] Before the PV system stops outputting power, the sum of the PV output power, the electrolyzer and the reference power of BESS#2 can be expressed as follows:

[0064]

[0065] Where: T0 is the moment when the photovoltaic array stops working. Since the dynamic response of the electrolyzer and BESS#2 is slow, the actual power at each moment cannot completely follow the reference power. Therefore, the system uses SC to compensate for the unbalanced power during the slow dynamic response of the electrolyzer and BESS#2. The power of SC at each moment can be expressed as follows:

[0066]

[0067] When SC participates in power coordination, the power balance formula in the photovoltaic power generation hydrogen production system can be expressed as follows:

[0068] P S0lar (t) = P P2H (t)+P Bat#2 (t)+P SC (t),t∈[1,T0] (21)

[0069]

[0070] P Bat#2 (t)=-P Bat#1 (t),t∈(T0,T](23)

[0071] Where: T0 is the time when the photovoltaic array stops working, P CI#h is the power required by the hth CI device. Bat#1 , P Bat#2 and P SC They are the powers of BESS#1, BESS#2 and SC respectively. Positive values ​​represent charging power, and negative values ​​represent releasing power, which can be expressed as follows:

[0072] P Bat#1 (t) = P Bat#1,ch (t)-P Bat#1,disc (t) (24)

[0073] P Bat#2 (t) = P Bat#2,ch (t)-P Bat#2,disc (t) (25)

[0074] P SC (t) = P SC,ch (t)-P SC,disc (t) (26)

[0075] (2) Equipment operation constraints

[0076] The equipment operation constraints include: electrolyzer operation constraints (Equation 27) and BESS operation constraints (Equation 28). In addition, at the beginning and end of the day, the SOC constraints in BESS#1 are expressed by equations (27) and (28), and the SOC at the beginning and end is the maximum SOC value of BESS#1 to ensure the power required for CI compensation on the next day. In addition, BESS#1 needs to have enough power before the next day to ensure the normal operation of DAR on the next day. At the same time, the power consumed by BESS#1 during the day is relatively random. In order to improve the robustness of system operation, the remaining power of BESS#2 at time T0 should be greater than the maximum power that BESS#1 may consume on that day. The SOC constraints of BESS#2 are expressed by equations (29) and (30). It is worth noting that the SOC value of BESS#2 at the end of the day is the initial value of the next day.

[0077]

[0078] SOC Bat#1 (T) = SOC Bat#1 (0) (28)

[0079]

[0080]

[0081] System operation mode

[0082] This application designs five system operation modes according to the working characteristics of the photovoltaic system, electrolyzer, BESS and SC. The specific operation modes are described as follows.

[0083] Mode 1: The photovoltaic output power is absorbed by BESS#2, and the electrolyzer is shut down. The above process can be expressed as follows:

[0084]

[0085] Mode 2: BESS#2 cooperates with photovoltaic output to power the electrolyzer. At the same time, in order to reduce the degradation of the electrolyzer due to input power fluctuations, the input power of the electrolyzer remains consistent with the previous moment. The above process can be expressed as follows:

[0086]

[0087] Mode 3: The photovoltaic output supplies power to the electrolyzer, and BESS#2 does not work. The above process can be expressed as follows:

[0088]

[0089] Mode 4: The electrolyzer operates at maximum power, and the remaining photovoltaic output is absorbed by BESS#2. The above process can be expressed as follows:

[0090]

[0091] Mode 5: After the PV system stops generating power, the electrolyzer stops, the SC does not work, and BESS#2 charges BESS#1. In order to reduce the BESS degradation caused by the fluctuation of SOC value, the charging power required by BESS#1 is evenly distributed to every moment after the PV system stops generating power. The above process can be expressed as follows:

[0092]

[0093] According to the different photovoltaic output, SOC value of BESS#2 and start / stop status of the electrolyzer, the system power coordinated control method flow is as follows: Figure 5 shown.

[0094] In the research of this application, the role of SC is to make up for the unbalanced power in the slow dynamic response process of the electrolyzer and BESS#2, so it is considered that the capacity of SC is sufficient to meet the system's demand for SC power. Before T0, it can be divided into three working conditions:

[0095] (1) The photovoltaic output is less than the minimum input power of the electrolyzer When the SOC value of BESS#2 is small The system works in operation mode 1, the electrolyzer is shut down, and the photovoltaic output is absorbed by BESS#2. When the SOC of BESS#2 is large The system works in operation mode 2, and the start and stop status of the electrolytic cell follows the previous moment.

[0096] (2) The photovoltaic output is greater than the minimum input power of the electrolyzer and less than the maximum input power of the electrolyzer When the SOC of BESS#2 is small, the system works in operation mode 3, the photovoltaic output is used to power the electrolyzer, and BESS#2 does not work. When the SOC of BESS#2 is large, if the photovoltaic output at the current moment is less than the working power of the electrolyzer at the previous moment, the system works in operation mode 2, and the working power of the electrolyzer follows the previous moment. If the photovoltaic output at the current moment is greater than the working power of the electrolyzer at the previous moment, the system works in operation mode 3, the photovoltaic output is used to power the electrolyzer, and BESS#2 does not work.

[0097] (3) The photovoltaic output is greater than the maximum input power of the electrolyzer The system works in operation mode 4, the electrolyzer works at the maximum input power, and the remaining photovoltaic output power is absorbed by BESS#2.

[0098] After T0, the photovoltaic power generation hydrogen production system works in operation mode 5. It is worth noting that The selection of the value is a trade-off between system efficiency and robustness. The larger the value, the better the system robustness; the smaller the value, the higher the system efficiency, but it may cause the electrolyzer to start and stop frequently, and it may also happen that the remaining power in BESS#2 cannot meet the power demand of BESS#1 after the photovoltaic power stops output. Therefore, this application selects Make sure BESS#1 is fully charged at the end of the day.

[0099] Example verification and analysis: This application simulates and verifies the proposed photovoltaic power generation hydrogen production system power cooperative control method on the Matlab platform, with a sampling time of 1s. The photovoltaic DAR model selected in this application includes a 10×8 photovoltaic array, 2 DC / DC converters and 2 CI devices. The average decision time per second of the power cooperative control algorithm is 3.66×10 -7 s.

[0100] Description of data and model parameters

[0101] In the photovoltaic power generation hydrogen production system, the equipment parameters of the electrolyzer, SC and BESS are shown in Table 1.

[0102] Table 1 Equipment parameters of electrolyzer, SC and BESS

[0103]

[0104]

[0105] This application selects three typical scenarios for research and analysis, such as Figure 6 (a), (b) and (c) show the photovoltaic output curves for sunny, cloudy and rainy weather, respectively, which can represent three typical photovoltaic power output situations.

[0106] This application selects the power response time of PEM electrolyzer and BESS as 5s and 3s

[152]

[153] . It is generally believed that the response ends after 3τ-5τ. According to the formula, the filter coefficients of the electrolyzer and BESS with a sampling time of 1s are 0.500 and 0.625, respectively, that is, a=0.500 and b=0.625.

[0107] There are two trigger mechanisms for the implementation of DAR technology for photovoltaic arrays, namely event trigger mechanism and time trigger mechanism. The event trigger mechanism can respond immediately to real-time changing environments once predefined conditions are met. For example, when the control unit detects and calculates that the maximum power output of the photovoltaic array after DAR operation can be increased by 10%, a reconstruction operation is performed. This trigger mechanism may cause frequent switch matrix operations when the environment changes rapidly. The time trigger mechanism responds to external changes periodically. For example, the control unit can make a decision every 5 minutes. This trigger mechanism cannot respond immediately to real-time changing environments, but the switch matrix operation will not be too frequent. This application selects DAR technology with a time trigger mechanism and makes a decision every 5 minutes. In addition, local shadow conditions occur randomly 3 times a day and last for 30 minutes. Calculated based on the device parameters selected in this application The value of is 0.32, that is In addition, the present application sets the SOC value of BESS#2 at the initial time to 0.32.

[0108] Analysis of Power Cooperative Control Results

[0109] Example 1 takes the photovoltaic output curve of typical scenario 1 as the research object, and the real-time power control results are as follows: Figure 7 As shown in (a), the operating mode of the system at each moment is as follows Figure 7 (b) The SOC values ​​of BESS#1 and BESS#2 are shown in Fig. 9 As shown, the SC power is Fig.10 shown.

[0110] When the PV system just starts working, the power output is low and is absorbed by BESS#2. As the PV output gradually increases, the electrolyzer starts to work. Then the PV output fluctuates. When there is sufficient power remaining in BESS#2, BESS#2 cooperates with the PV output to provide electrical power to the electrolyzer. When the PV output is greater than the maximum operating power of the electrolyzer, the electrolyzer operates at maximum power, and the remaining PV output is absorbed by BESS#2. In the second half of the day, the PV output gradually decreases to less than the maximum input power of the electrolyzer. At this time, a large amount of electrical power is stored in BESS#2. BESS#2 cooperates with the PV output to power the electrolyzer, allowing the electrolyzer to operate at the maximum input power until the SOC value of BESS#2 drops to. Subsequently, when the PV output is less than the minimum input power of the electrolyzer, the electrolyzer stops working and the PV output is absorbed by BESS#2. Finally, after the PV system stops outputting, BESS#2 charges BESS#1, and the SOC value of BESS#1 reaches the maximum at the end of the day.

[0111] Figure 8 The following are the details of the power coordination of the photovoltaic hydrogen production system, and three time periods are selected. Figure 8 As shown in (a), the PV output continued to rise and exceeded the minimum input power of the electrolyzer at 7:32:38. The system switched from operation mode 2 to operation mode 3, and the electrolyzer began to work. At this time, the reference power of the electrolyzer and BESS#2 changed, but their actual power could not keep up with the reference power, resulting in the remaining PV output being absorbed by the SC. Figure 8 As shown in (b), the PV output starts to decrease at 8:36:11, and the system switches from operation mode 3 to operation mode 2. The working power of the electrolyzer follows the previous moment. BESS#2 releases power to cooperate with the PV output to power the electrolyzer. At this time, SC releases power to compensate for the unbalanced power caused by BESS#2. Figure 8 As shown in (c), at 16:56:03, the remaining power in BESS#2 is not enough to satisfy the electrolyzer to work according to the previous moment. The system switches from operation mode 2 to operation mode 3. The reference power of the electrolyzer decreases, while the reference power of BESS#2 increases. At this time, SC releases power to compensate for the unbalanced power caused by the electrolyzer and BESS#2.

[0112] In the photovoltaic power generation hydrogen production system selected in this application, a fast-response SC device is used to compensate for the unbalanced power of the electrolyzer and BESS during the slow dynamic response process. The FLF algorithm is used to determine the actual output of the electrolyzer and battery energy storage at each moment, thereby determining the power of the SC at each moment, and realizing the power coordination of BESS, SC and electrolyzer, which improves the adaptability of the electrolyzer and battery energy storage to highly volatile photovoltaic output.

[0113] This application proposes a power collaborative control method for a photovoltaic power generation hydrogen production system, which combines DAR technology to improve the system's hydrogen production efficiency. The system includes two BESSs, BESS#1 provides the electric power required by DAR, and BESS#2 cooperates with the electrolyzer to consume photovoltaic power generation, and uses the SC with fast response capability to compensate for the unbalanced power in the slow dynamic response of BESS and electrolyzer, thereby improving the adaptability of the electrolyzer and BESS to photovoltaic power generation power fluctuations. Five system operation modes are proposed for the photovoltaic hydrogen production system combined with DAR technology. The system operation mode at the current moment is determined based on the photovoltaic output at each moment and the SOC of BESS#2 at the previous moment, thereby determining the reference power of the electrolyzer and BESS#2 at the current moment. Secondly, the actual output of the electrolyzer and BESS at each moment is determined by the FLF algorithm, thereby determining the working power of the SC at each moment, realizing the power coordination of the electrolyzer, BESS and SC, and improving the adaptability of the electrolyzer and BESS to high volatility photovoltaic output.

[0114] The above are merely embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structural transformations made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A control method for coupling photovoltaic power generation with hydrogen energy, characterized in that: This includes establishing a photovoltaic power generation and hydrogen production system in combination with dynamic array reconstruction, using a battery energy storage system to provide the electrical power required for photovoltaic dynamic reconstruction, while coordinating photovoltaic output to power the electrolyzer, and using supercapacitors with fast response capabilities to compensate for the unbalanced power caused by battery energy storage and the slow dynamic response of the electrolyzer.

2. The control method for coupling photovoltaic power generation and hydrogen energy according to claim 1, characterized in that: The photovoltaic power generation and hydrogen production system includes a photovoltaic array, battery energy storage, supercapacitors, electrolyzers and hydrogen storage tanks; through the coordinated power control of the electrolyzer, battery energy storage and supercapacitors, the required electric power is provided for the photovoltaic dynamic array reconstruction, and highly volatile photovoltaic power generation and hydrogen production are realized at the same time; the photovoltaic array, current injection device, electrolyzer, battery energy storage and supercapacitors are all connected to the DC bus through a DC / DC converter; the photovoltaic power generation and hydrogen production system includes a control unit, which uses a dynamic array reconstruction algorithm and a power coordinated control algorithm to make optimization decisions and perform real-time power control of each device in the photovoltaic power generation and hydrogen production system.

3. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 2, characterized in that: A high-pressure proton exchange membrane electrolyzer was selected for modeling as follows: H EL (t)=P P2H (t)E P2H η EL (1) Where: t is the time, P P2H and H EL is the electrical power required by the electrolyzer and the amount of hydrogen produced, E P2H is the conversion coefficient of electricity to hydrogen, η EL is the electrolytic cell efficiency; I P2H is a binary variable, which represents the working state of the electrolytic cell. If it is in working state, its value is 1, otherwise it is 0; and are the maximum and minimum values ​​of the electrolytic cell input power, respectively; (2) Battery energy storage device: The state of charge at each moment can be expressed by formula (3), and the upper and lower limits of the state of charge are expressed by formula (4). Formula (5) introduces the binary variable I Bat#k,ch and I Bat#k,disc To constrain the battery storage energy to be unable to charge and discharge simultaneously; Formulas (6) and (7) represent the battery energy storage charge and discharge rate constraints; I Bat#k,ch (t)+I Bat#k,disc (t)≤1 (5) Where: SOC Bat#k and C Bat#k is the charge state of the battery energy storage #k and the battery capacity; P Bat#k,ch and P Bat#k,disc are charging and discharging power respectively; η ch,#k and η disc,#k are the charging and discharging efficiencies, respectively; and They are the upper and lower limits of the battery energy storage charge state respectively; and is the maximum charge and discharge power; (3) Supercapacitor device: The mathematical model of supercapacitor device is similar to that of battery energy storage and can be expressed as follows: I SC,ch (t)+I SC,disc (t)≤1 (10) Where: SOC SC and C SC is the charge state and capacity of the supercapacitor; P SC,ch and P SC,disc is the charging and discharging power of the supercapacitor; η ch,SC and η disc,SC is the charge and discharge efficiency; and I is the upper and lower limits of the state of charge; SC,ch and I SC,disc is a binary variable, indicating the charging and discharging status of the supercapacitor; and is the maximum charge and discharge power of the supercapacitor.

4. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 3, characterized in that: Power allocation based on the first-order low-pass filter algorithm. The algorithm divides the input reference power into two parts: low-frequency power component and high-frequency power component. The low-frequency power component fluctuates slowly, and the response speed of the battery energy storage and the electrolyzer can follow its fluctuation. This part of the power is borne by the battery energy storage and the electrolyzer. The high-frequency power component changes rapidly, requiring the energy storage medium to respond quickly, and is allocated to the supercapacitor to compensate for the unbalanced power in the slow dynamic response of the battery energy storage and the electrolyzer. Based on the input-output relationship of the first-order low-pass filter circuit, its mathematical model can be expressed as follows: Where: U i is the input signal, U o is the filter output signal, R is the filter resistor, C is the filter capacitor; τ is the filter time constant, and τ=RC; the output power of photovoltaic power generation is obtained by sampling, and the sampling period is T s , after discretizing the formula, we can get the following formula: Where: T s is the sampling period, P i is the input power signal, P o is the output power signal after filtering; this application redefines a filter coefficient α to simplify the first-order low-pass filter algorithm formula, and the value of α is as follows: Since the value range of τ is [0,∞), according to the above formula, the value range of α can be obtained as (0,1]; at this time, the first-order low-pass filter algorithm formula can be expressed as follows: P o (t)=αP i (t)+(1-α)P o (t-1) (16) According to the formula, the actual output power of the electrolyzer and battery energy storage #2 at time t is related to the input power signal and the actual output power at time t-1, which can be expressed as follows: Where: a and b are the filter coefficients of the electrolyzer and battery energy storage #2; and are the reference powers of the electrolyzer and battery energy storage #2, respectively.

5. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 4, characterized in that: Before the PV system stops outputting power, the sum of the reference power of the PV output power electrolyzer and battery energy storage #2 can be expressed as follows: Where: T0 is the moment when the photovoltaic array stops working; due to the slow dynamic response of the electrolyzer and battery energy storage #2, the actual power at each moment cannot completely follow the reference power. The system uses supercapacitors to compensate for the unbalanced power in the slow dynamic response process of the electrolyzer and battery energy storage #2; the power of the supercapacitor at each moment can be expressed as follows: When supercapacitors participate in power coordination, the power balance formula in the photovoltaic power generation hydrogen production system can be expressed as follows: P Solar (t)=P P2H (t)+P Bat#2 (t)+P SC (t),t∈[1,T0] (21) P Bat#2 (t)=-P Bat#1 (t),t∈(T0,T] (23) Where: T0 is the time when the photovoltaic array stops working, P CI#h is the power required by the hth current injection device; P Bat#1 , P Bat#2 and P SC They are the power of battery energy storage #1, battery energy storage #2 and supercapacitor respectively. Positive values ​​represent charging power and negative values ​​represent releasing power, which can be expressed as follows: P Bat#1 (t)=P Bat#1,ch (t)-P Bat#1,disc (t) (24) P Bat#2 (t)=P Bat#2,ch (t)-P Bat#2,disc (t) (25) P SC (t)=P SC,ch (t)-P SC,disc (t) (26)。 6. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 5, characterized in that: The equipment operation constraints include: the electrolyzer operation constraint is Equation 27, and the battery energy storage operation constraint is Equation 28; the state of charge at the initial and end times is the maximum state of charge value of battery energy storage #1 to ensure the power required for current injection compensation on the second day; battery energy storage #1 needs to have enough power before the second day to ensure the normal operation of the dynamic array reconstruction on the second day, and the remaining power of battery energy storage #2 at time T0 should be greater than the maximum power that battery energy storage #1 may consume on the same day; the state of charge constraint of battery energy storage #2 is expressed by Equations 29 and 30; the state of charge value of battery energy storage #2 at the end time of the day is the initial value of the next day; SOC Bat#1 (T)=SOC Bat#1 (0) (28) 7. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 6, characterized in that: According to the working characteristics of photovoltaic system, electrolyzer, battery energy storage and supercapacitor, five system operation modes are designed. The specific operation modes are as follows: Mode 1: The photovoltaic output power is absorbed by battery energy storage #2, and the electrolyzer is shut down. The above process can be expressed as follows: Mode 2: Battery energy storage #2 cooperates with photovoltaic output to power the electrolyzer. At the same time, in order to reduce the degradation of the electrolyzer due to input power fluctuations, the input power of the electrolyzer remains consistent with the previous moment. The above process can be expressed as follows: Mode 3: The photovoltaic output supplies power to the electrolyzer, and the battery energy storage #2 does not work. The above process can be expressed as follows: Mode 4: The electrolyzer operates at maximum power, and the remaining photovoltaic output is absorbed by battery energy storage #2. The above process can be expressed as follows: Mode 5: After the photovoltaic system stops generating power, the electrolyzer stops working, the supercapacitor stops working, and battery energy storage #2 charges battery energy storage #1. The charging power required by battery energy storage #1 is evenly distributed to every moment after the photovoltaic system stops generating power. The above process can be expressed as follows:

8. The control method for coupling photovoltaic power generation with hydrogen energy according to claim 7, characterized in that: The role of the supercapacitor is to make up for the unbalanced power in the slow dynamic response process of the electrolyzer and battery energy storage #2. Considering that the capacity of the supercapacitor is sufficient to meet the system's demand for supercapacitor power; before time T0, it can be divided into three working conditions: (1) The photovoltaic output is less than the minimum input power of the electrolyzer When the state of charge of battery energy storage #2 is small The system works in operation mode 1, the electrolyzer is shut down, and the photovoltaic output is absorbed by battery energy storage #2; when the state of charge of battery energy storage #2 is large The system works in operation mode 2, and the start and stop status of the electrolyzer follows the previous moment; (2) The photovoltaic output is greater than the minimum input power of the electrolyzer and less than the maximum input power of the electrolyzer When the state of charge of battery energy storage #2 is small, the system works in operation mode 3, the photovoltaic output is used to power the electrolyzer, and battery energy storage #2 does not work; when the state of charge of battery energy storage #2 is large, if the photovoltaic output at the current moment is less than the working power of the electrolyzer at the previous moment, the system works in operation mode 2, and the working power of the electrolyzer follows the previous moment; if the photovoltaic output at the current moment is greater than the working power of the electrolyzer at the previous moment, the system works in operation mode 3, the photovoltaic output is used to power the electrolyzer, and battery energy storage #2 does not work; (3) The photovoltaic output is greater than the maximum input power of the electrolyzer The system operates in operation mode 4, the electrolyzer operates at maximum input power, and the remaining photovoltaic output power is absorbed by battery energy storage #2.

9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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