Power distribution method and system for frequency modulation participated by multiple electrolytic cells facing network construction requirements

Abstract

The invention belongs to the technical field of power electronics, and discloses a power distribution method and system for frequency modulation participated by multiple electrolytic cells facing a network construction demand, and the method comprises the steps: collecting the frequency data of a power grid side, and calculating the real-time frequency deviation of the power grid side; calculating a virtual droop coefficient according to the upper and lower limits of the frequency deviation allowed by the power grid side and the operating power of the electrolytic cell, and calculating based on the virtual droop coefficient and the real-time frequency deviation of the power grid side to obtain the power variation of the electrolytic cell; according to the power variation of the electrolytic cell and the voltage and current data of each single electrolytic cell, obtaining a power distribution relationship among the single electrolytic cells, and constructing a nonlinear constraint optimization problem according to the power distribution relationship; establishing a target function and a constraint condition; and solving a nonlinear constraint optimization problem to obtain a power distribution method. According to the method, the power distribution problem of the multi-PEM electrolytic cell participating in system frequency modulation is studied, and the dual targets of primary frequency modulation and maximum hydrogen production are achieved by taking the maximum hydrogen production and the stability of a power grid system as targets.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a power distribution method and system for frequency modulation with multiple electrolyzers oriented to network construction needs. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] With the global energy crisis and environmental degradation, renewable energy, particularly photovoltaic and wind power, has been rapidly developed. However, the large-scale integration of renewable energy into the grid can reduce the system's frequency response capabilities, thereby impacting the safe and stable operation of microgrids. Traditional frequency regulation methods (such as energy storage systems and diesel generators) are limited by response speed, cost, and carbon emissions, making them incapable of meeting the dynamic regulation requirements of scenarios with a high proportion of renewable energy access. Furthermore, with the rapid development of green hydrogen, proton exchange membrane (PEM) electrolyzers, unconstrained by the SOC requirement for energy storage and capable of providing sustainable frequency response, offer a new approach to microgrid frequency regulation. By adjusting the input power of electrolyzer clusters in real time, they can both absorb the fluctuating output of renewable energy and provide rapid frequency regulation assistance.

[0004] However, the coordinated participation of multiple electrolyzers in frequency regulation still faces key technical bottlenecks. On the one hand, the start-stop characteristics, efficiency curves, and dynamic responses of electrolyzers vary significantly, making it difficult for traditional power allocation strategies to balance equipment efficiency and frequency regulation accuracy. On the other hand, there is a contradiction between the strong inertia demand for frequency support in grid-type microgrids and the discrete nature of electrolyzer power regulation. Existing research has mostly focused on the frequency regulation potential of a single electrolyzer, lacking a multi-electrolyzer collaborative optimization model and dynamic power allocation mechanism. Therefore, it is urgent to construct a multi-timescale electrolyzer cluster frequency regulation power allocation optimization framework. By dynamically coordinating the electrolyzer operating status and power allocation ratio, it is possible to achieve multi-objective optimization of frequency regulation economy, equipment life, and system stability, providing theoretical support for the flexible resource aggregation of new power systems. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a power distribution method and system for multiple electrolyzers participating in frequency modulation oriented to grid construction needs, studies the power distribution problem of multiple PEM electrolyzers participating in system frequency modulation, and takes maximum hydrogen production and grid system stability as the goals, achieving the dual goals of primary frequency modulation and maximum hydrogen production.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a power distribution method for multiple electrolyzers participating in frequency modulation oriented to network construction needs, comprising the following steps: Collect grid-side frequency data in real time and calculate the real-time frequency deviation of the grid side; The virtual droop coefficient is calculated based on the upper and lower limits of the frequency deviation allowed on the grid side and the operating power of the electrolyzer. The power change of the electrolyzer is obtained based on the virtual droop coefficient and the real-time frequency deviation on the grid side. According to the power variation of the electrolytic cell and the voltage and current data of each single electrolytic cell, the power distribution relationship between each single electrolytic cell is obtained, and a nonlinear constrained optimization problem is constructed based on this power distribution relationship; With the goal of maximizing hydrogen production and maintaining grid system stability, an objective function is established and constraints are set; Solve the nonlinear constrained optimization problem and obtain the power allocation method.

[0007] As an optional implementation, the SQP algorithm is used to solve the nonlinear constrained optimization problem by constructing a quadratic programming subproblem to approximate the original problem.

[0008] As an optional implementation method, when power absorption and maximum hydrogen production cannot be met at the same time, that is, the optimal solution cannot be obtained under the target constraints, power absorption is given the highest priority, and priority is given to ensuring that power is fully utilized without affecting the overall stable operation of the power grid system.

[0009] As an optional implementation, when a single electrolytic cell fails, the failed single electrolytic cell is bypassed for maintenance, and the power of the electrolytic cell is redistributed among the remaining electrolytic cells.

[0010] As an optional implementation, the objective function is:

[0011] in, n H2 , n H2,i are the total hydrogen production of the electrolyzer and the hydrogen production of each single electrolyzer, t is the electrolysis time, η F is the Faraday electrolysis efficiency.

[0012] As an optional implementation manner, the target constraints include power allocation coefficient, frequency modulation range of the electrolyzer, and energy conversion efficiency.

[0013] In a second aspect, the present invention provides a power distribution system for multiple electrolyzers participating in frequency modulation for network construction needs, comprising: The PV power generation grid-connected module uses the MPPT control strategy to adjust the photovoltaic operation to the maximum power point, delivering power to the PEM electrolyzer and microgrid system; The energy storage module is connected to the DC bus through a DC / DC converter and maintains the bus voltage at the grid-connected voltage through voltage and current dual closed-loop control; The PEM electrolyzer module is connected to the DC bus through a DC / DC converter and uses a power-current dual-loop control based on PI control to maintain stable operation of the electrolyzer. The data acquisition module collects the operating parameters of the PV power generation grid-connected module, energy storage module, PEM electrolyzer module and the grid side, and uploads the operating parameters to the microgrid energy management system for frequency regulation and power distribution optimization.

[0014] In a third aspect, the present invention provides an electronic device comprising a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0015] In a fourth aspect, the present invention provides a computer-readable storage medium for storing computer instructions, wherein when the computer instructions are executed by a processor, the method described in the first aspect is performed.

[0016] In a fifth aspect, the present invention provides a computer program product, comprising a computer program, which implements the method described in the first aspect when executed by a processor.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present disclosure proposes a power distribution method and system for frequency modulation with multiple electrolyzers for network construction needs, studies the power distribution problem of multiple PEM electrolyzers participating in system frequency modulation, and designs a corresponding power distribution strategy based on the photovoltaic hydrogen storage grid-connected system to distribute the power variation of the PEM electrolyzers to achieve the dual goals of primary frequency modulation and maximum hydrogen production. When power absorption and maximum hydrogen production cannot be met at the same time, that is, the optimal solution cannot be obtained under the target constraints, power absorption is placed at the highest priority to ensure that the power is fully utilized without affecting the overall stable operation of the power grid system. In addition, an electrolyzer fault bypass and emergency control method is designed. When an electrolyzer fails, the faulty electrolyzer is promptly bypassed and repaired, and the power of the electrolytic stack is redistributed to ensure the overall stable operation of the system.

[0018] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0020] Figure 1 This is a schematic diagram of the configuration structure of the power distribution system with multiple electrolyzers participating in frequency modulation for network construction needs of the present invention; Figure 2 This is a framework diagram of the power distribution method for multiple electrolyzers participating in frequency modulation oriented to network construction needs of the present invention; Figure 3 A flow chart of the optimal power allocation solution method of the present invention; Figure 4 This is a flow chart of the fault bypass judgment and power redistribution of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0025] Example 1 like Figure 2 As shown, this embodiment provides a power distribution method for multiple electrolyzers participating in frequency modulation oriented to network construction needs, including the following steps: Collect grid-side frequency data in real time and calculate the real-time frequency deviation of the grid side; The virtual droop coefficient is calculated based on the upper and lower limits of the frequency deviation allowed on the grid side and the operating power of the electrolyzer. The power change of the electrolyzer is obtained based on the virtual droop coefficient and the real-time frequency deviation on the grid side. According to the power variation of the electrolytic cell and the voltage and current data of each single electrolytic cell, the power distribution relationship between each single electrolytic cell is obtained, and a nonlinear constrained optimization problem is constructed based on this power distribution relationship; With the goal of maximizing hydrogen production and maintaining grid system stability, an objective function is established and constraints are set; Solve the nonlinear constrained optimization problem and obtain the power allocation method.

[0026] This paper proposes a power allocation strategy based on MATLAB / fmincon for network construction needs, studies the power allocation problem of multiple PEM electrolyzers participating in system frequency modulation, and takes maximum hydrogen production as the goal to achieve the dual goals of primary frequency modulation and maximum hydrogen production.

[0027] Based on the solar energy storage hydrogen production grid-connected system, the present invention designs a corresponding power allocation strategy to change the power variation ΔP of the PEM electrolyzer to e For allocation, the power allocation strategy is as follows Figure 2 shown.

[0028] (1-1) Virtual droop coefficient design: The PEM electrolyzer participates in the system's primary frequency modulation based on the grid-side frequency deviation by simulating the renewable energy droop control strategy. The power change of the PEM electrolyzer in this way is:

[0029] in, K D is the droop control coefficient, Δ f is the frequency deviation value.

[0030] Virtual droop coefficient K D Solved by the following formula:

[0031] in, P e,max and P e,min The sum of the maximum and minimum power adjustments provided to the electrolyzer, Δ f min and Δ f max They are the upper and lower limits of the frequency deviation allowed on the grid side.

[0032] In actual engineering applications, the maximum operating power of a PEM electrolyzer is generally 110%-120% of its rated power, while the minimum operating power is generally 10%-20% of the rated power. In this article, the power range for PEM electrolyzer frequency modulation is assumed to be 20%-120% of the rated power. To ensure normal grid-side operation, the allowable frequency deviation is set to ±0.2Hz.

[0033] (1-2) Calculation of rated power of PEM electrolyzer: The rated power of a PEM electrolyzer is generally obtained from the rated current density and the corresponding rated voltage of the electrolyzer. The rated current density varies depending on the manufacturer and is generally 1-3A / cm2. In the simulation of this invention, the rated current density of the electrolyzer is set to 2A / cm2. The rated voltage is obtained from the VI curve. The rated power of the electrolyzer is calculated as follows:

[0034] in, V e,rated is the rated voltage, i e,rated is the rated current density, A is the electrode area.

[0035] (2-1) Solve the power distribution relationship of the electrolytic cell: According to the power allocation strategy in step (1), the power allocation relationship between the electrolytic cells is:

[0036] in, k i is the power distribution coefficient of the i-th electrolytic cell, U e,i and I e,i are the voltage and current of the i-th electrolytic cell respectively.

[0037] Step (2-2) Optimization target establishment: The maximization objective is hydrogen production, and the relationship is:

[0038] in, n H2 , n H2,i are the total hydrogen production of the electrolyzer and the hydrogen production of each electrolyzer, t is the electrolysis time, η F is the Faraday electrolysis efficiency (the actual hydrogen production needs to be multiplied by the Faraday electrolysis efficiency, which is usually 95%-99%).

[0039] Steps (2-3) Establishment of target constraints: The target constraints are the power distribution coefficient, the frequency modulation range of the electrolyzer, and the energy conversion efficiency, and the relationship is as follows:

[0040] in, η eLVH is the lower heating value of hydrogen, which is 3.54 kWh / Nm. Under actual operating conditions, the energy conversion efficiency of PEM electrolyzers ranges from 60% to 80%.

[0041] Steps (2-4) Optimal solution: Under the above known conditions, optimization objectives and constraints, the optimal solution process based on MATLAB / fmincon is as follows Figure 3 To prevent system instability caused by excessively small disturbances, the deadband of the PEM electrolyzer frequency response is set to -0.01 to 0.01 Hz. The SQP algorithm solves nonlinear constrained optimization problems by constructing quadratic programming subproblems to approximate the original problem. When the SQP algorithm cannot find an optimal solution, the degradation strategy (priority allocation) may not guarantee a global optimum, but it can still find a feasible solution.

[0042] Electrolyzer fault bypass and emergency control method: When an electrolytic cell fails, it is necessary to promptly bypass the faulty electrolytic cell for repair and redistribute the power of the electrolytic stack to avoid affecting the overall stable operation of the system. The fault bypass judgment and power redistribution flow chart is as follows: Figure 4 The specific steps are as follows: (3-1) Real-time monitoring of the operating voltage of the PEM electrolyzer.

[0043] First, monitor the working voltage of the electrolyzer. The working voltage range of a single PEM electrolyzer is 1.6~2.2V. When the working voltage is greater than 2.2V, the electrolyzer is operating at high voltage, which may cause membrane dissolution and catalyst deactivation. In severe cases, it may cause thermal runaway. However, short-term high voltage will not cause serious accidents. Therefore, when the working voltage exceeds 2.2V for more than 1 minute, the electrolyzer is determined to be faulty, the bypass switch is triggered, and the faulty electrolyzer branch is bypassed for maintenance. However, when the electrolyzer voltage is in a low voltage state, that is, less than 1.6V, hydrogen and oxygen in the electrolyzer will mix, and when reaching a certain concentration (4%~75% H2), it will cause an explosion. Therefore, when it is monitored that the electrolyzer is in a low-voltage working state, the electrolyzer should be immediately determined to be faulty, the faulty electrolyzer branch should be bypassed, and maintenance should be carried out.

[0044] (3-2) Power redistribution after electrolyzer fault bypass.

[0045] When a single electrolyzer fails and bypasses, the power of the electrolyzer stack needs to be redistributed to ensure that the overall stable operation of the system is not affected. At this time, the number of electrolyzer units connected to the DC bus becomes n-1, and the process obtained in step (2) above is re-solved. When power consumption and maximum hydrogen production cannot be met simultaneously, that is, the optimal solution cannot be obtained under the target constraints, power consumption is given the highest priority. First, ensure that the power is fully utilized without affecting the overall stable operation of the system, and find a feasible solution.

[0046] Example 2 This embodiment provides a power distribution system for multiple electrolyzers participating in frequency modulation, which is tailored to network construction needs and includes: The PV power generation grid-connected module uses the MPPT control strategy to adjust the photovoltaic operation to the maximum power point, delivering power to the PEM electrolyzer and microgrid system; The energy storage module is connected to the DC bus through a DC / DC converter and maintains the bus voltage at the grid-connected voltage through voltage and current dual closed-loop control; The PEM electrolyzer module is connected to the DC bus through a DC / DC converter and uses a power-current dual-loop control based on PI control to maintain stable operation of the electrolyzer. The data acquisition module collects the operating parameters of the PV power generation grid-connected module, energy storage module, PEM electrolyzer module and the grid side, and uploads the operating parameters to the microgrid energy management system for frequency regulation and power distribution optimization.

[0047] The overall system topology and control block diagram of the present invention are as follows: Figure 1 The circuit topology of the photovoltaic-storage-hydrogen production coupling system consists of a PV power generation grid-connected module, a PEM electrolyzer module, an energy storage module, a DC bus, and a grid-side load.

[0048] The PV power generation system utilizes a perturbation-observation MPPT control strategy to maintain maximum power point (MPPT) operation, delivering power to the PEM electrolyzer and microgrid. The energy storage module is connected to the DC bus via a DC / DC converter, maintaining the bus voltage at the grid-connected voltage of 800V through dual closed-loop voltage and current control. The majority of the PV power is used for grid connection, with the grid-connected inverter utilizing a droop control + PI dual closed-loop control strategy. A small portion of the power is used for system frequency regulation. When frequency regulation is not required, it is used for hydrogen electrolysis to avoid wasted solar power. The PEM electrolyzer module is connected to the DC bus via a DC / DC converter, utilizing a dual power and current control strategy based on PI control to maintain stable electrolyzer operation.

[0049] It should be noted that the above modules correspond to the steps described in Example 1, and the examples and application scenarios implemented by the above modules and the corresponding steps are the same, but are not limited to the contents disclosed in the above Example 1. It should be noted that the above modules, as part of the system, can be executed in a computer system such as a set of computer-executable instructions.

[0050] In further embodiments, there is also provided: An electronic device includes a memory and a processor, and computer instructions stored in the memory and executed by the processor, wherein when the computer instructions are executed by the processor, the method described in Example 1 is performed. For the sake of brevity, no further details are given here.

[0051] It should be understood that in this embodiment, the processor may be a central processing unit (CPU), or may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), off-the-shelf field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0052] The memory may include a read-only memory and a random access memory, and provides instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0053] A computer-readable storage medium is used to store computer instructions, and when the computer instructions are executed by a processor, the method described in Example 1 is performed.

[0054] The method in Example 1 can be directly implemented as a hardware processor, or can be implemented using a combination of hardware and software modules in the processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, it will not be described in detail here.

[0055] A computer program product includes a computer program, which implements the method described in embodiment 1 when executed by a processor.

[0056] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions contained in program modules, which are executed in a device on a real or virtual processor of a target to perform the process / method described above. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided between program modules as needed. The machine-executable instructions for the program modules can be executed in local or distributed devices. In distributed devices, program modules can be located in local and remote storage media.

[0057] The computer program code for implementing the method of the present invention can be written in one or more programming languages. These computer program codes can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that when the program code is executed by the computer or other programmable data processing device, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on a computer, partially on a computer, as an independent software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0058] In the context of the present invention, computer program code or related data can be carried by any appropriate carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals include electrical, optical, radio, acoustic, or other forms of propagated signals, such as carrier waves, infrared signals, and the like.

[0059] Those skilled in the art will appreciate that the units and algorithm steps of the various examples described in conjunction with this embodiment can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0060] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A power distribution method for multiple electrolyzers participating in frequency modulation for network construction needs, characterized by: The following steps are involved: Collect grid-side frequency data in real time and calculate the real-time frequency deviation of the grid side; The virtual droop coefficient is calculated based on the upper and lower limits of the frequency deviation allowed on the grid side and the operating power of the electrolyzer. The power change of the electrolyzer is obtained based on the virtual droop coefficient and the real-time frequency deviation on the grid side. According to the power variation of the electrolytic cell and the voltage and current data of each single electrolytic cell, the power distribution relationship between each single electrolytic cell is obtained, and a nonlinear constrained optimization problem is constructed based on this power distribution relationship; With the goal of maximizing hydrogen production and maintaining grid system stability, an objective function is established and constraints are set; Solve the nonlinear constrained optimization problem and obtain the power allocation method.

2. The power distribution method for multiple electrolyzers participating in frequency modulation oriented to network construction requirements as claimed in claim 1, characterized in that: The SQP algorithm is used to solve nonlinear constrained optimization problems by constructing quadratic programming subproblems to approximate the original problem.

3. The power distribution method for multiple electrolyzers participating in frequency modulation according to claim 1, characterized in that: When power absorption and maximum hydrogen production cannot be met at the same time, that is, the optimal solution cannot be obtained under the target constraints, power absorption is given the highest priority, and priority is given to ensuring that power is fully utilized without affecting the overall stable operation of the power grid system.

4. The power distribution method for multiple electrolyzers participating in frequency modulation according to claim 1, characterized in that: When a single electrolyzer fails, the failed single electrolyzer is bypassed for maintenance, and the power of the electrolyzer is redistributed among the remaining electrolyzers.

5. The power distribution method for multiple electrolyzers participating in frequency modulation according to claim 1, characterized in that: The objective function is: in, n H2 , n H2,i are the total hydrogen production of the electrolyzer and the hydrogen production of each single electrolyzer, t is the electrolysis time, η F is the Faraday electrolysis efficiency.

6. The power distribution method for multiple electrolyzers participating in frequency modulation according to claim 1, characterized in that: The target constraints include power allocation coefficient, frequency modulation range of electrolyzer and energy conversion efficiency.

7. A power distribution system with multiple electrolyzers participating in frequency modulation for network construction needs, characterized by: include: The PV power generation grid-connected module uses the MPPT control strategy to adjust the photovoltaic operation to the maximum power point, delivering power to the PEM electrolyzer and microgrid system; The energy storage module is connected to the DC bus through a DC / DC converter and maintains the bus voltage at the grid-connected voltage through voltage and current dual closed-loop control; The PEM electrolyzer module is connected to the DC bus through a DC / DC converter and uses a power-current dual-loop control based on PI control to maintain stable operation of the electrolyzer; The data acquisition module collects the operating parameters of the PV power generation grid-connected module, energy storage module, PEM electrolyzer module and the grid side, and uploads the operating parameters to the microgrid energy management system for frequency regulation and power distribution optimization.

8. An electronic device, characterized in that: The invention comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor, wherein when the computer instructions are executed by the processor, the method according to any one of claims 1 to 6 is completed.

9. A computer-readable storage medium, characterized in that Used to store computer instructions, which, when executed by a processor, complete the method according to any one of claims 1 to 6.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when executed by a processor.

Images