A micro-grid simulation system and control method based on optical hydrogen electric coupling

Abstract

The present application relates to the technical field of micro-grid, and particularly relates to a micro-grid simulation system based on light-hydrogen electric coupling and a control method. The simulation system comprises a photovoltaic module, a battery module, an electrolytic cell module, a fuel cell module and a power grid / load module. The photovoltaic module comprises a photovoltaic assembly, a first DC / DC circuit and a first grid-connected circuit which are electrically connected in sequence. The battery module and the electrolytic cell module are connected in parallel at the output end of the first DC / DC circuit. The fuel cell module is connected in parallel at the output end of the first grid-connected circuit. The output end of the first grid-connected circuit is connected with the power grid / load module. Through the above arrangement, the comprehensive micro-grid joint control simulation of photovoltaic power generation-fuel cell power generation-hydrogen production power consumption-load power consumption can be effectively realized.

Description

Technical Field

[0001] This invention relates to the field of microgrid technology, and in particular to a microgrid simulation system and control method based on photohydrogen-electric coupling. Background Technology

[0002] With the increasing development of microgrid technology, the construction architecture and composition of energy storage systems in microgrids are becoming more diversified.

[0003] Energy storage systems are classified into short-term energy storage and long-term energy storage based on their storage duration. Short-term energy storage can quickly respond to energy demand in a short period of time and is suitable for scenarios such as grid frequency regulation and peak shaving and valley filling of power load. Long-term energy storage can meet more continuous and longer-term energy demand and can store excess capacity in the process of new energy power generation, and then release it to increase revenue when energy demand is at its peak.

[0004] However, most existing microgrid simulation systems focus on operating under a single type of power generation and a single control strategy, lacking a comprehensive microgrid simulation system implementation method that integrates photovoltaic power generation, fuel cell power generation, hydrogen production and electricity consumption, and load electricity consumption. Furthermore, they do not consider the start-up delay of hydrogen energy storage devices under grid connection and off-grid conditions, thus affecting the accurate control of system-level power. Summary of the Invention

[0005] To address at least one deficiency in the existing microgrid simulation systems, this invention provides a microgrid simulation system based on photo-hydrogen-electric coupling, comprising: a photovoltaic module, a battery module, an electrolyzer module, a fuel cell module, and a grid / load module;

[0006] The photovoltaic module includes a photovoltaic module, a first DC / DC circuit, and a first grid-connected circuit connected in sequence; the battery module and the electrolytic cell module are respectively connected in parallel to the output terminal of the first DC / DC circuit; the fuel cell module is connected in parallel to the output terminal of the first grid-connected circuit; the output terminal of the first grid-connected circuit is connected to the grid / load module.

[0007] In one embodiment, the first grid-connected circuit includes a first grid-connected inverter, which employs a PQ AC / DC axis decoupling control strategy; the photovoltaic module further includes a photovoltaic control strategy input unit, which includes an MPPT controller, which tracks the maximum output power of the photovoltaic module using the perturbation-observation method.

[0008] In one embodiment, the photovoltaic module is modeled as follows:

[0009]

[0010] In the formula, P pv For the rated output power of the photovoltaic module, S(t) and SST These represent the light intensity at time t and the standard light intensity, respectively; η loss (t) represents the power loss at time t due to temperature rise, η dc The efficiency of the first grid-connected inverter.

[0011] In one embodiment, the battery module includes a battery pack, a second DC / DC circuit, and a battery control strategy input unit; the battery pack is connected to the output terminal of the first DC / DC circuit through the second DC / DC circuit; the battery control strategy input unit is connected to the second DC / DC circuit to modulate the output duty cycle of the second DC / DC circuit according to the voltage loop PI control strategy, so that the output terminal of the first DC / DC circuit remains stable.

[0012] In one embodiment, the battery pack is modeled as follows:

[0013]

[0014] In the formula, S SOC N represents the percentage of battery remaining at time t; s With N p These represent the number of batteries connected in series and in parallel in the battery pack, respectively; Q n i is the rated capacity of the battery when fully charged; i(τ) is the battery current.

[0015] In one embodiment, the fuel cell module includes a fuel cell, a boost converter circuit, and a second grid-connected circuit connected in sequence. The second grid-connected circuit includes a second grid-connected inverter. It also includes a fuel cell control strategy input unit. The fuel cell control strategy input unit includes a power loop and a current loop connected together. The current loop is connected to the second grid-connected inverter. The power loop corrects the output power of the fuel cell, and the corrected output power P of the fuel cell at time t+1 is... fc (t+1) is represented as:

[0016]

[0017] In the formula, W pv，i P is the dynamic adjustment coefficient of the photovoltaic power signal at time i. pv，i (ti) represents the photovoltaic power at time ti; W el，i P is the dynamic adjustment coefficient of the electrolytic cell power signal at time i. el，i (ti) represents the electrolytic cell power at time ti; W l，i P is the dynamic adjustment coefficient of the load signal at time i. l，i (ti) represents the load power at time ti; W o Let P be the system self-loss coefficient at time i. o(t) represents the self-loss power at time i.

[0018] In one embodiment, the fuel cell model is as follows:

[0019] U fc =E Ner -U act -U ohm -U con

[0020]

[0021] In the formula, U fc E is the output voltage of the fuel cell. Ner U is the thermodynamic electromotive force; act To activate overvoltage, U ohm For ohmic overvoltage, U con E0 is the concentration overvoltage; R is the open-circuit voltage; T is the universal gas constant; F is the absolute temperature; and F is the Faraday constant. These are the pressures of hydrogen and oxygen, respectively. This is the water vapor partial pressure constant for fuel cells;

[0022] in, Represented as:

[0023]

[0024]

[0025]

[0026] In the formula, K r Fuel utilization coefficient, Valve molar constants for hydrogen and oxygen, respectively, τ h τ o The response time constants for hydrogen and oxygen are R, respectively. HO The oxygen-to-hydrogen consumption ratio; K represents the hydrogen production rate. f Fuel utilization rate; I is the fuel cell current; The hydrogen production rate is constant. In one embodiment, the electrolyzer module includes an electrolyzer, a third DC / DC circuit, and an electrolyzer control strategy input unit; the electrolyzer is connected to the output terminal of the first DC / DC circuit via the third DC / DC circuit; the electrolyzer control strategy input unit is connected to the third DC / DC circuit to control the electrolyzer to produce hydrogen based on the power difference between the rated output power of the photovoltaic module and the required power of the grid / load module.

[0027] The electrolytic cell model is as follows:

[0028]

[0029]

[0030] In the formula, n el η represents the hydrogen production rate of the electrolyzer. F For Faraday efficiency, n c Let i be the number of electrolytic cells connected in series. el U is the current in the electrolytic cell, F is the Faraday constant; c U is the terminal voltage of the electrolytic cell. r For reversible voltage, A F denoted as the area parameter of the electrolytic cell, r as the ohmic resistance parameter of the electrolyte, I as the DC current of electrolysis, s as the electrode overvoltage coefficient, and t as the electrode overvoltage coefficient.

[0031] In one embodiment, the grid / load module includes an off-grid control unit and a load control unit; one end of the off-grid control unit is connected to a first grid-connected circuit and a second grid-connected circuit, and the other end is connected to the load control unit; the off-grid control unit is used to control the system to generate hydrogen from curtailed solar power in off-grid mode and to generate electricity jointly by the photovoltaic module and the fuel cell module in grid-connected mode.

[0032] The present invention also provides a microgrid control method based on photohydrogen-electric coupling, which adopts the microgrid simulation system based on photohydrogen-electric coupling as described in any of the above embodiments.

[0033] Based on the above, compared with the prior art, the microgrid simulation system based on photohydrogen-electric coupling provided by the present invention can effectively realize the integrated microgrid joint control simulation of photovoltaic power generation, fuel cell power generation, hydrogen production and electricity consumption, and load electricity consumption. Moreover, the photovoltaic module and the fuel cell module are decoupled from each other and can be controlled independently, and unified grid connection is achieved in the grid / load module.

[0034] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other beneficial effects of the invention can be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Unless otherwise specified, the positional relationships shown in the drawings in the following description are based on the direction in which the components are drawn in the figure.

[0036] Figure 1 The structural block diagram of a microgrid simulation system based on photohydrogen-electric coupling provided in an embodiment of the present invention;

[0037] Figure 2 A structural block diagram of a microgrid simulation system based on photohydrogen-electric coupling provided for another embodiment of the present invention;

[0038] Figure 3 This is the circuit schematic of a photovoltaic module;

[0039] Figure 4 This is the circuit schematic of the battery module;

[0040] Figure 5 This is the circuit schematic of a fuel cell module;

[0041] Figure 6 This is the circuit schematic diagram of the electrolytic cell module;

[0042] Figure 7 This is a graph showing the current, voltage, and power of a fuel cell in one embodiment;

[0043] Figure 8 This is a VI curve diagram under the grid-connected model in one embodiment;

[0044] Figure 9 This is a PQ curve diagram under a grid-connected model in one embodiment;

[0045] Figure 10 This is a VI curve diagram under the grid-connected model in one embodiment;

[0046] Figure 11 This is a PQ curve diagram under a grid-connected model in one embodiment. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0049] Existing microgrid simulation systems primarily focus on single-type power generation and have limited load types. They lack a comprehensive control simulation system that addresses the integration of photovoltaic power generation, fuel cell power generation, hydrogen production, and load power consumption. Furthermore, there are no well-developed solutions for microgrid simulation systems, mathematical models, and control strategies related to photovoltaic-hydrogen-electricity coupling. Therefore, this invention provides a microgrid simulation system based on photovoltaic-hydrogen-electricity coupling for application in computer equipment.

[0050] Please see Figure 1 The microgrid simulation system based on photohydrogen-electric coupling includes at least: a photovoltaic module, a battery module, an electrolyzer module, a fuel cell module, and a grid / load module.

[0051] The photovoltaic module includes a photovoltaic module, a first DC / DC circuit, and a first grid-connected circuit connected in sequence; the battery module and the electrolyzer module are respectively connected in parallel to the output terminal of the first DC / DC circuit; the fuel cell module is connected in parallel to the output terminal of the first grid-connected circuit; the output terminal of the first grid-connected circuit is connected to the grid / load module. In specific implementations, for example... Figure 1 As shown, the first DC / DC circuit, the battery module, and the electrolytic cell module are connected to the DC bus on the DC side to achieve DC grid connection on the DC bus side. Then, they are connected to the fuel cell module on the AC bus through the first grid connection circuit to achieve AC grid connection on the power generation side. The grid side / load side of the AC bus is connected to the grid / load module.

[0052] In a preferred embodiment, please refer to Figure 3 The first grid-connected circuit includes a first grid-connected inverter, which is used to connect the power generated by the photovoltaic modules to the grid. The first grid-connected inverter adopts a PQ AC-DC decoupling control strategy, that is, the DC axis controls the active power and the AC axis controls the reactive power; the DC axis aims to control the DC bus Udc to a preset value, and this is achieved through voltage loop PI regulation.

[0053] The photovoltaic module also includes a photovoltaic control strategy input unit, which includes an MPPT (Maximum Power Point Tracking) controller. This means the photovoltaic module's control strategy employs maximum power point tracking to ensure maximum utilization of photovoltaic power generation. The MPPT controller tracks the maximum output power of the photovoltaic module using a perturbation-observation method. Specifically, the actual control loop uses perturbation-observation, where the perturbation change is the port voltage of the photovoltaic cell, thereby tracking its maximum output power.

[0054] Photovoltaic modules convert solar energy into electrical energy through the photovoltaic effect. Since the output power of a photovoltaic array is strongly correlated with solar radiation intensity and ambient temperature, in this embodiment, the photovoltaic module may include a photovoltaic array, a radiation intensity setting component, and a temperature intensity setting component. By setting certain values ​​for the radiation intensity and temperature intensity using the radiation intensity setting component and the temperature intensity setting component, the rated output power of the photovoltaic array under any solar radiation intensity and ambient temperature can be obtained. Therefore, the model of the photovoltaic module is as follows:

[0055]

[0056] In the formula, p pv For the rated output power of the photovoltaic module, S(t) and S ST These represent the light intensity at time t and the standard light intensity, respectively; η loss (t) represents the power loss at time t due to temperature rise, η dc The efficiency of the first grid-connected inverter.

[0057] In a preferred embodiment, please refer to Figure 2 , Figure 4 The battery module includes a battery pack, a second DC / DC circuit, and a battery control strategy input unit. The battery pack is connected to the output of the first DC / DC circuit through the second DC / DC circuit. The battery control strategy input unit is connected to the second DC / DC circuit to modulate the output duty cycle of the second DC / DC circuit according to the voltage loop PI control strategy, so that the output of the first DC / DC circuit remains stable.

[0058] In practical implementation, the battery pack can use lithium batteries, lead-acid batteries, or other types of energy storage batteries to play a crucial role in rapid voltage stabilization on the DC side, ensuring stable operation of the DC bus under the set voltage. Changes in the external environment can affect the load and the power demand of the electrolyzer module, causing differences in output power between the fuel cell module and the photovoltaic module, resulting in DC bus voltage fluctuations. To stabilize the DC bus voltage, the battery needs to absorb excess power or output the difference in power. This embodiment utilizes a voltage loop PI control through the cooperation of the battery control strategy input unit and the second DC / DC circuit. When the battery terminal voltage is higher than its internal potential, it charges; conversely, it discharges. Furthermore, the duty cycle of the second DC / DC circuit is modulated based on the difference between the DC bus reference voltage and the actual voltage, effectively simulating actual operating conditions such as voltage drops caused by DC bus fluctuations, thus maintaining a stable DC bus voltage.

[0059] Furthermore, the model of the battery pack is as follows:

[0060]

[0061] In the formula, S SOC N represents the percentage of battery remaining at time t; s With N p These represent the number of batteries connected in series and in parallel in the battery pack, respectively; Q n i is the rated capacity of the battery when fully charged; i(τ) is the battery current.

[0062] In a preferred embodiment, please refer to Figure 2 , Figure 5 The fuel cell module includes a fuel cell, a boost converter circuit, and a second grid-connected circuit connected in sequence. The second grid-connected circuit includes a second grid-connected inverter. The fuel cell can be a proton exchange membrane fuel cell. The second grid-connected circuit is connected in parallel to the output of the first grid-connected circuit. In this embodiment, the photovoltaic module and the fuel cell module are decoupled from each other, each consisting of its own first and second grid-connected inverters. They can be controlled independently or connected to the grid together, effectively realizing microgrid simulation on / off-grid mode control based on photovoltaic-hydrogen-electric coupling.

[0063] Because existing simulation systems do not consider the start-up delay of hydrogen storage devices in grid-connected and off-grid scenarios, accurate power control is impossible. To address this issue, in this embodiment, the fuel cell module further includes a fuel cell control strategy input unit; this unit includes a connected power loop and a current loop, with the current loop connected to the second grid-connected inverter. Since there is a certain start-up time for the fuel cell and electrolyzer, the power control signal at the current moment needs to be corrected and optimized to amplify the effective control signals from previous moments and suppress fluctuations in the current control signal due to the high complexity of the system. Specifically, the actual power value needs to consider the weighted signal from N moments ago to reduce power signal jitter errors within each system and improve the accuracy of the control signal. Therefore, the power loop corrects the output power of the fuel cell; the corrected output power P of the fuel cell at time t+1 is... fc (t+1) is represented as:

[0064]

[0065] In the formula, W pv，i P is the dynamic adjustment coefficient of the photovoltaic power signal at time i. pv，i (ti) represents the photovoltaic power at time ti; W el，i P is the dynamic adjustment coefficient of the electrolytic cell power signal at time i. el，i (ti) represents the electrolytic cell power at time ti; W l，i P is the dynamic adjustment coefficient of the load signal at time i. l，i (ti) represents the load power at time ti; W o Let P be the system self-loss coefficient at time i. o (t) represents the self-loss power at time i.

[0066] The dynamically weighted optimized power control described above can effectively achieve overall system operation management and realize unified power scheduling at the upper level. It also effectively improves the accuracy of control signals, achieving source-load power balance in microgrid on-grid and off-grid modes.

[0067] Preferably, the model of the fuel cell is as follows:

[0068] U fc =E Ner -U act -U ohm -U con

[0069]

[0070] In the formula, U fc E is the output voltage of the fuel cell. Ner U is the thermodynamic electromotive force;act To activate overvoltage, U ohm For ohmic overvoltage, U con E0 is the concentration overvoltage; R is the open-circuit voltage; T is the universal gas constant; F is the absolute temperature; and F is the Faraday constant. The pressures of hydrogen and oxygen, respectively. This is the water vapor partial pressure constant for fuel cells.

[0071] The degradation factor was incorporated into the output voltage equation and Nernst equation of the above fuel cell model, effectively taking into account the degradation of the fuel cell equipment and the actual service life of the equipment, thus more realistically reflecting the actual working conditions and further improving the accuracy of the simulation results.

[0072] in, Represented as:

[0073]

[0074]

[0075]

[0076] In the formula, K r Fuel efficiency coefficient Valve molar constants for hydrogen and oxygen, respectively, σ h τ o The response time constants for hydrogen and oxygen are R, respectively. HO The oxygen-to-hydrogen consumption ratio; K represents the hydrogen production rate. f I represents fuel utilization rate; I represents fuel cell current. The hydrogen generation rate is constant. In this embodiment, the hydrogen generation rate is... It consists of two parts, one of which is a constant. The other part is proportional to the output current of the fuel cell.

[0077] Based on the above equations, a circuit model of a proton exchange membrane fuel cell based on a voltage source can be built in Simulink.

[0078] In a preferred embodiment, please refer to Figure 2 , Figure 6 The electrolyzer module includes an electrolyzer, a third DC / DC circuit, and an electrolyzer control strategy input unit. The electrolyzer is connected to the output terminal of the first DC / DC circuit via the third DC / DC circuit. The electrolyzer control strategy input unit is connected to the third DC / DC circuit to control the electrolyzer to produce hydrogen based on the power difference between the rated output power of the photovoltaic module and the power required by the grid / load module.

[0079] In practice, the electrolyzer can be an alkaline electrolyzer or a proton exchange membrane electrolyzer; and the specific hydrogen storage method can be a hydrogen storage tank or a high-pressure hydrogen storage tank, etc.

[0080] Preferably, since the electrolyzer electrolyzes water into hydrogen and oxygen, the hydrogen production rate is directly proportional to the current in the electrolysis circuit, and the electrolyzer has a nonlinear internal resistance, the electrolyzer model can be:

[0081]

[0082]

[0083] In the formula, n el η is the hydrogen production rate of the electrolyzer. F For Faraday efficiency, n c Let i be the number of electrolytic cells connected in series. el U is the current in the electrolytic cell, F is the Faraday constant; c U is the terminal voltage of the electrolytic cell. r For reversible voltage, A F U is the area parameter of the electrolytic cell, r is the ohmic resistance parameter of the electrolyte, I is the DC current of the electrolytic cell, s is the electrode overvoltage coefficient, and t is the electrode overvoltage coefficient. Among these, parameter U... r A F Depending on the temperature and type of electrolyzer, the specific parameters can be obtained through statistical processing of experimental data. Based on this, and combined with the external characteristic curves of the electrolyzer's output (UI), a current-source-based electrolyzer model can be built in Simulink.

[0084] Because existing common fuel cell and electrolyzer modeling considers multidimensional factors, including complex physical processes such as electrochemical reactions of reactant gases, gas flow, and heat exchange, and because the various subsystems are strongly coupled, the complexity of the model increases with the number of observations, thus affecting simulation judgment. Therefore, this study simplifies the fuel cell and electrolyzer models based on semi-empirical models without affecting the model results, enabling more efficient integration with the simulation system. Furthermore, in the specific modeling process, the fuel cell and electrolyzer are modeled as circuit mathematical models based on voltage and current sources, requiring only attention to the external voltage and current characteristics of hydrogen energy storage, without needing to consider internal mechanism changes, thereby further simplifying the model and reducing the difficulty of co-simulating microgrid systems based on photo-hydrogen-electric coupling.

[0085] In a preferred embodiment, the grid / load module includes an off-grid / parallel control unit and a load control unit. One end of the off-grid / parallel control unit is connected to a first grid-connected circuit and a second grid-connected circuit, respectively, and the other end is connected to the load control unit. The off-grid / parallel control unit is used to control the system's hydrogen production from curtailed solar power in off-grid mode and the combined power generation of the photovoltaic module and fuel cell module in grid-connected mode, thereby achieving source-load power balance and system stability in both on-grid and off-grid modes of the microgrid. The load control unit can adjust or set the power of the load in the grid / load module according to the actual load power.

[0086] Based on the above, in the actual power dispatching process, the microgrid simulation system based on photohydrogen-electric coupling provided by the embodiments of the present invention takes into account the grid connection stability of power generation on the generation side (photovoltaic module, fuel cell module), DC bus voltage stability and synchronous control of dual power generation systems, and also effectively considers the real-time performance and accuracy of power dispatching on the load side and the grid side.

[0087] Furthermore, under the control commands of the upper-level system, based on the circuit characteristics of the generation and load sides, the photovoltaic module employs maximum power point output control and disturbance observation method control to find the operating point with the maximum output power and continuously supply power to the load. The battery module is used to stabilize the DC bus voltage (750V). When there is a power difference between the generation and load sides, it can easily cause fluctuations in the DC bus voltage. PI control is performed based on the difference between the bus voltage and the measured value. The fuel cell module outputs power according to the upper-level control power, based on the optimization formula P... fc (t+1) Output control of the fuel cell is implemented to replenish energy to the load side. The electrolyzer, as a hydrogen production device, converts electrical energy into chemical energy for use in the fuel cell when the photovoltaic module's power output exceeds the output, thus producing hydrogen.

[0088] To further illustrate the reliability of the microgrid simulation system based on photo-hydrogen-electric coupling provided by this invention, this embodiment constructs a microgrid energy simulation system based on photo-hydrogen-electric coupling provided by this invention. This simulation system can achieve power balance, stable output, and high dynamic response under both grid-connected and off-grid conditions. Based on this simulation system, firstly, a fuel cell load response test is conducted under a stepped output power command. The fuel cell power command is set from 20% P... rated Up to 100% P rated Then, the simulated current, voltage, and power output curves of the fuel cell can be obtained, as shown in the figure. Figure 7 As shown, where P rated This is expressed as the rated power of the fuel cell.

[0089] Next, the relevant parameters of the simulation system were assigned values, specifically setting the maximum output power of the photovoltaic module to 100kW and the illuminance under steady-state conditions to 1000W / m².2 The temperature is kept constant at 30℃. The energy storage battery has a capacity of 62.5kWh and an initial SOC of 49.998. The electrolyzer module establishes a current source model based on the UI characteristics of the electrolyzer output terminal, with a maximum energy consumption of up to 200kW.

[0090] In grid-connected mode, the fuel cell is connected at t=1.5s, the 50kW load is connected at t=2.0s, and the electrolyzer is connected at t=2.5s. Irradiance gradually increases from 0s to 0.5s, with the photovoltaic output power reaching its maximum at t=0.5s. Based on the above settings, the following can be obtained: Figure 8 , Figure 9 The output results shown are in the grid-connected mode, where, Figure 8 This is a VI curve diagram under grid-connected mode; Figure 9 This is the PQ curve diagram under grid-connected mode; based on Figure 8 As shown in the VI curve, the three-phase current of the photovoltaic module's first grid-connected circuit reaches the maximum steady-state output current from 0s to 0.5s. When AC and DC loads are connected sequentially at t=2.0s and t=2.5s, the system exhibits good dynamic response performance, reaching a stable state within a short time. Furthermore, according to... Figure 9 As can be seen from the PQ curve, the photovoltaic, fuel cell, and load all reach the power command issued by the upper-level dispatch system under steady-state conditions, and the remaining energy is fed back to the grid.

[0091] In off-grid mode, the irradiance gradually increases from 0s to 0.5s, with the photovoltaic output power reaching its maximum at t=0.5s. From t=1.5s to 2.5s, the DC bus voltage continues to rise because the generated power exceeds the load power. At t=2.5s, due to the connection of the electrolytic cell, there is a short-term voltage drop on the DC side of the grid, but it recovers quickly and returns to normal. Specifically, the following can be obtained... Figure 10 , Figure 11 The output results shown are in the off-network mode, where, Figure 10 This is a VI curve diagram in off-grid mode; Figure 11 This is the PQ curve in off-grid mode. According to... Figure 10 The VI curve shows that the photovoltaic grid-connected three-phase current of the first grid-connected circuit of the photovoltaic module reaches the maximum steady-state output current of the photovoltaic module from 0s to 0.5s, and according to... Figure 11 The PQ curves show that when AC and DC loads are connected sequentially at t=2.0s and t=2.5s, the system exhibits good dynamic response performance and reaches a stable state within a short time. Based on experiments involving dynamic load additions and power generation modules under grid-connected and off-grid conditions, the system ultimately responds quickly to upper-level power dispatch commands, achieving stable output.

[0092] This invention also provides a microgrid control method based on photo-hydrogen-electric coupling, employing a microgrid simulation system based on photo-hydrogen-electric coupling as described in any of the above embodiments. Its specific functions, effects, and methods can be referred to the above method embodiments, and will not be repeated here.

[0093] In summary, compared with the prior art, the microgrid simulation system and control method based on photohydrogen-electric coupling provided by the present invention have at least the following advantages:

[0094] I. It accurately and effectively provides a novel simulation system for integrated microgrids based on optical-hydrogen-electric coupling;

[0095] Second, by setting the battery module, the actual operating conditions such as voltage drop caused by fluctuations at the DC bus end are effectively considered, ensuring stable operation of the DC bus end under the set voltage.

[0096] Third, based on the semi-empirical model, the models of fuel cells and electrolyzers are effectively simplified without affecting the model results, and can be more efficiently integrated with the simulation system; in addition, degradation factors are added to the modeling to more realistically reflect the actual working conditions.

[0097] Fourth, based on the power optimization formula of fuel cells, this invention amplifies the effective control signal in the preceding time step by using a dynamic weighted optimization power control method, and suppresses the fluctuation of the current control signal caused by the high complexity of the system, resulting in higher control accuracy.

[0098] Fifth, on the one hand, it effectively balances the grid connection stability of power generation on the power generation side (photovoltaic module and fuel cell module), DC bus voltage stability and synchronous control of dual power generation systems. On the other hand, it effectively considers the real-time performance and accuracy of power dispatching on the load side and the grid side, while also taking into account the start-up delay factor of actual hydrogen energy storage equipment.

[0099] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0100] Although this document frequently uses terms such as photovoltaic module, battery module, electrolyzer module, fuel cell module, and grid / load module, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present), in the specification, claims, and accompanying drawings of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A microgrid simulation system based on photo-hydrogen-electric coupling, characterized in that, include: Photovoltaic modules, battery modules, electrolytic cell modules, fuel cell modules, grid / load modules; The photovoltaic module includes a photovoltaic module, a first DC / DC circuit, and a first grid-connected circuit connected in sequence; the battery module and the electrolytic cell module are respectively connected in parallel to the output terminal of the first DC / DC circuit; the fuel cell module is connected in parallel to the output terminal of the first grid-connected circuit; the output terminal of the first grid-connected circuit is connected to the grid / load module. The fuel cell module includes a fuel cell, a boost converter circuit, and a second grid-connected circuit connected in sequence. The second grid-connected circuit includes a second grid-connected inverter. It also includes a fuel cell control strategy input unit. The fuel cell control strategy input unit includes a connected power loop and a current loop. The current loop is connected to the second grid-connected inverter. The power loop corrects the output power of the fuel cell. The output power corrected by the fuel cell at any time Represented as: In the formula, For the first Dynamic adjustment coefficient of photovoltaic power signal at any time. for Photovoltaic power at any given time; For the first Dynamic adjustment coefficient of electrolytic cell power signal at all times. for The power of the electrolytic cell at any given time; For the first Dynamic adjustment coefficient of load signal at all times. for Load power at any given moment; The system's self-loss coefficient, Let be the self-dissipated power at time t; The grid / load module includes an off-grid control unit and a load control unit; one end of the off-grid control unit is connected to the first grid-connected circuit and the second grid-connected circuit respectively, and the other end is connected to the load control unit. The off-grid control unit is used to control the system to generate hydrogen from curtailed solar power in off-grid mode and to generate electricity jointly by the photovoltaic module and the fuel cell module in grid-connected mode.

2. The microgrid simulation system based on photohydrogen-electric coupling according to claim 1, characterized in that: The first grid-connected circuit includes a first grid-connected inverter, which adopts a PQ AC / DC axis decoupling control strategy; the photovoltaic module also includes a photovoltaic control strategy input unit, which includes an MPPT controller, and the MPPT controller tracks the maximum output power of the photovoltaic module according to the perturbation and observation method.

3. The microgrid simulation system based on photohydrogen-electric coupling according to claim 1, characterized in that: The model of the photovoltaic module is as follows: In the formula, The rated output power of the photovoltaic module. and They are respectively Real-time light intensity and standard light intensity; for Power loss during constant temperature rise. The efficiency of the first grid-connected inverter.

4. The microgrid simulation system based on photohydrogen-electric coupling according to claim 1, characterized in that: The battery module includes a battery pack, a second DC / DC circuit, and a battery control strategy input unit. The battery pack is connected to the output of the first DC / DC circuit through the second DC / DC circuit. The battery control strategy input unit is connected to the second DC / DC circuit to modulate the output duty cycle of the second DC / DC circuit according to the voltage loop PI control strategy, so that the output of the first DC / DC circuit remains stable.

5. The microgrid simulation system based on photohydrogen-electric coupling according to claim 4, characterized in that, The model of the battery pack is as follows: In the formula, The percentage of battery remaining at time t; and These represent the number of batteries connected in series and in parallel in the battery pack, respectively. The rated capacity of the battery when fully charged; This represents the battery current.

6. The microgrid simulation system based on photohydrogen-electric coupling according to claim 1, characterized in that, The model of the fuel cell is as follows: In the formula, This refers to the output voltage of the fuel cell. It is the thermodynamic electromotive force; To activate overvoltage, For ohmic overvoltage, This is concentration overvoltage; Open circuit voltage, For general gas constants, Absolute temperature It is Faraday's constant. , These are the pressures of hydrogen and oxygen, respectively. This is the water vapor partial pressure constant for fuel cells; in, , Represented as: In the formula, Fuel efficiency coefficient , The valve molar constants for hydrogen and oxygen, respectively. , These are the response time constants for hydrogen and oxygen, respectively. The oxygen-to-hydrogen consumption ratio; The hydrogen production rate; For fuel utilization rate; This refers to the fuel cell current. The constant hydrogen production rate.

7. The microgrid simulation system based on photohydrogen-electric coupling according to claim 1, characterized in that: The electrolyzer module includes an electrolyzer, a third DC / DC circuit, and an electrolyzer control strategy input unit; the electrolyzer is connected to the output terminal of the first DC / DC circuit through the third DC / DC circuit; the electrolyzer control strategy input unit is connected to the third DC / DC circuit to control the electrolyzer to produce hydrogen based on the power difference between the rated output power of the photovoltaic module and the power required by the grid / load module. The electrolytic cell model is as follows: In the formula, The hydrogen production rate of the electrolyzer. For Faraday efficiency, The number of electrolytic cells connected in series. This refers to the current in the electrolytic cell. It is Faraday's constant; This is the terminal voltage of the electrolytic cell. It is a reversible voltage. For the electrolytic cell area parameters, These are the ohmic resistance parameters of the electrolyte. This is the DC current of the electrolytic cell. The overvoltage coefficient of the first electrode. This represents the overvoltage coefficient of the second electrode.

8. A microgrid control method based on photo-hydrogen-electric coupling, characterized in that: The microgrid simulation system based on photohydrogen-electric coupling as described in any one of claims 1-7 is adopted.

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