Photovoltaic, photo-thermal and hydrogen fuel cell collaborative peak and frequency regulation system and control method

Abstract

The invention discloses a photovoltaic, photo-thermal and hydrogen fuel cell collaborative peak regulation and frequency modulation system and a control method, the collaborative peak regulation and frequency modulation system comprises a photovoltaic subsystem, a photo-thermal subsystem, a hydrogen fuel cell subsystem and a central controller, and each subsystem cooperatively works through an energy flow and a signal flow. The hydrogen fuel cell subsystem serves as energy type energy storage to stabilize long-time electric power fluctuation and achieve power grid peak load shifting, the photo-thermal subsystem serves as power type energy storage to stabilize short-time electric power fluctuation and achieve power grid frequency modulation, and the control method adopts a hierarchical control framework and comprises an upper layer, namely an optimized dispatching layer, and a middle layer, namely a cooperative control layer. According to the system, a light-heat-hydrogen fuel cell multi-energy-flow coupling framework is constructed, a layered optimization control strategy is combined, energy is utilized in a gradient mode, light-heat waste heat is used for water electrolysis hydrogen production, the comprehensive energy efficiency of the system is improved, rapid response and accurate adjustment of the frequency of an electric power system are achieved, and the absorption capacity of renewable energy sources is improved.

Description

Technical Field

[0001] The present invention relates to the field of new energy power generation technology, and in particular to a photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system and control method. Background Art

[0002] As the global energy structure transforms towards a low-carbon and clean one, the proportion of renewable energy represented by photovoltaic power generation in the power system is rapidly increasing. However, photovoltaic power generation is affected by factors such as light intensity, weather conditions, and the alternation of day and night, and has significant intermittent, volatile and unpredictable characteristics, making it difficult to match its output with the grid load demand in real time. In traditional power systems, peak-shaving and frequency regulation tasks mainly rely on the rapid start and stop or output adjustment of thermal power units. However, thermal power peak regulation has problems such as slow response speed, high carbon emissions, and frequent start and stop that depletes equipment life. It is difficult to meet the grid flexibility needs under the access of a high proportion of renewable energy.

[0003] To address these challenges, energy storage technology has become a key means of smoothing out fluctuations in renewable energy and enhancing grid flexibility. While current mainstream energy storage technologies, such as electrochemical energy storage and pumped hydro storage, can achieve power regulation from seconds to hours, they suffer from limitations such as limited capacity, high costs, short cycle life, and strong geographical dependence, making it difficult to simultaneously meet the dual demands of large-scale, long-term peak regulation and high-frequency frequency regulation. Against this backdrop, multi-energy complementary and synergistic systems have become a research hotspot. These systems integrate multiple energy sources with energy storage technologies to achieve complementary advantages and synergistic optimization.

[0004] Solar thermal power generation technology, with its built-in heat storage system, can generate electricity continuously for several to dozens of hours in the absence of sunlight, providing a natural peak-shaving capability. However, its high initial investment and relatively low thermal-to-electricity conversion efficiency make it uneconomical in a single operating mode. Hydrogen fuel cell technology, using hydrogen as a carrier, offers advantages such as high energy density, rapid response, and zero carbon emissions, making it suitable for long-term energy storage and rapid frequency regulation. However, the synergistic efficiency and economic efficiency of the hydrogen energy industry chain (hydrogen production, storage, and use) still need to be improved. While existing technologies have explored combined photovoltaic-solar thermal power generation systems or hydrogen energy storage systems, most solutions only achieve single-dimensional optimization (such as solar thermal peak shaving or hydrogen energy storage), lacking in-depth exploration of the dynamic coupling between photovoltaics, solar thermal energy, and hydrogen fuel cells. Furthermore, no coordinated control method has been developed for all-time periods, covering frequency regulation from seconds to daily peak shaving. Summary of the Invention

[0005] In order to overcome the above problems, the present invention proposes a photovoltaic, solar thermal, and hydrogen fuel cell collaborative peak-shaving and frequency regulation system and control method. By constructing a solar-thermal-hydrogen fuel cell multi-energy flow coupling architecture and combining a hierarchical optimization control strategy, it utilizes photovoltaic daytime output, solar thermal heat storage system nighttime peak-shaving, and hydrogen fuel cell second-level frequency regulation to cover the grid regulation needs from minute to daily levels; at the same time, it utilizes energy in a cascade manner, and uses solar thermal waste heat for water electrolysis to produce hydrogen, thereby improving the overall energy efficiency of the system, achieving rapid response and precise regulation of the power system frequency as a whole, and improving the renewable energy absorption capacity.

[0006] The technical solution adopted in the present invention is:

[0007] The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency regulation system includes a photovoltaic subsystem, a solar thermal subsystem, a hydrogen fuel cell subsystem, and a central controller. Each subsystem works in coordination through energy flow and signal flow. The hydrogen fuel cell subsystem acts as an energy-type energy storage to smooth out long-term power fluctuations and achieve peak shaving and valley filling in the power grid. The solar thermal subsystem acts as a power-type energy storage to smooth out short-term power fluctuations and achieve power grid frequency regulation.

[0008] The photovoltaic subsystem includes a photovoltaic array, a photovoltaic inverter, and a DC / DC converter. The photovoltaic array converts solar energy into direct current (DC), the photovoltaic inverter converts DC into AC for grid connection, and the DC / DC converter supplies power to the electrolyzer.

[0009] The solar thermal subsystem includes a tower collector, a molten salt heat storage tank, a steam generator, a steam turbine generator set, and a heat exchanger. The tower collector collects solar heat and stores it in the molten salt heat storage tank. The molten salt heat storage tank drives the steam turbine generator set to generate electricity through the steam generator. The waste heat of the molten salt heat storage tank is used to assist hydrogen production through the heat exchanger.

[0010] The hydrogen fuel cell subsystem includes an electrolyzer, a hydrogen storage tank, a hydrogen fuel cell, and an inverter. The electrolyzer uses the electricity from the photovoltaic subsystem to produce hydrogen, the hydrogen storage tank stores hydrogen, the hydrogen fuel cell converts hydrogen into electrical energy, and the inverter converts the direct current generated by the hydrogen fuel cell into alternating current for grid connection.

[0011] The central controller communicates with each subsystem, receives grid load, electricity price signals and subsystem status, including photovoltaic output, heat storage tank temperature, and hydrogen storage tank pressure, and issues control instructions to coordinate operations.

[0012] As a further description of the present invention, in a photovoltaic subsystem,

[0013] The photovoltaic array uses high-efficiency monocrystalline silicon components and is arranged according to the optimal inclination and spacing of the local latitude.

[0014] The photovoltaic inverter supports maximum power point tracking function.

[0015] The DC / DC converter adopts a bidirectional Buck-Boost converter with an input voltage range of DC 300V-800V. The output voltage can be accurately adjusted to the operating voltage of the electrolyzer, providing a stable DC power supply for the electrolyzer.

[0016] As a further description of the present invention, in the photothermal subsystem,

[0017] The tower collector adopts a heliostat field and a central absorber structure. The number of heliostats is configured according to the installed capacity. The reflectivity is ≥95%, and the molten salt temperature at the absorber outlet can reach 565°C.

[0018] The molten salt heat storage tank adopts a double tank structure, and the volume of a single tank is , filled with sodium nitrate-potassium nitrate mixed molten salt, with a melting point of 220°C, a heat storage efficiency of ≥92%, and supports continuous heat release at full load for 10 hours;

[0019] The steam turbine generator set is driven by high-temperature and high-pressure steam generated by a steam generator, and the power generation efficiency is greater than or equal to 40%;

[0020] The heat exchanger uses a plate heat exchanger to transfer the waste heat from the molten salt heat storage tank to the electrolyzer circulating water system, improving the hydrogen production efficiency by 15%-20%.

[0021] As a further description of the present invention, in a hydrogen fuel cell subsystem,

[0022] The electrolyzer is a proton exchange membrane electrolyzer with a rated power of 500kW, a hydrogen production rate greater than or equal to 0.12Nm³ / kWh, a working pressure of 30bar, and supports rapid start and stop;

[0023] The hydrogen storage tank adopts a 35MPa high-pressure gaseous hydrogen storage tank with a total volume of 2000m³ and a hydrogen storage capacity of approximately 2800kg, equipped with a pressure sensor and a safety valve;

[0024] The hydrogen fuel cell uses a 200kW proton exchange membrane fuel cell stack with a response time of less than 1s and a power generation efficiency of ≥55%, and is equipped with an air compressor and a hydrogen circulation pump;

[0025] The inverter adopts a bidirectional inverter, supports four-quadrant operation, and can complete active or reactive power regulation within 10ms to meet the frequency regulation requirements of the power grid.

[0026] As a further description of the present invention, the central controller adopts Siemens S7-1500 PLC controller.

[0027] A control method for a photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system adopts a hierarchical control architecture, including an upper layer, a middle layer, and a lower layer.

[0028] The upper layer, namely the optimization scheduling layer, uses model predictive control and genetic algorithms to formulate a global optimization scheduling strategy based on grid load forecasts, electricity price signals and subsystem status, with the goal of minimizing frequency deviation, maximizing economic benefits and minimizing equipment losses;

[0029] The middle layer, namely the collaborative control layer, converts the optimized scheduling strategy into specific instructions and coordinates the operation of subsystems through PID controllers, fuzzy controllers and rule engines;

[0030] The lower layer, the execution layer, executes device control instructions to adjust photovoltaic output, heat storage tank charging and discharging rates, electrolyzer start and stop, and fuel cell power.

[0031] The control method comprises the following steps:

[0032] S01: Data acquisition, real-time acquisition of grid frequency, load, electricity price and subsystem status;

[0033] S02: Forecasting and Optimization: Using the LSTM model to predict load, the optimal scheduling solution is solved through multi-objective functions and constraints. The multi-objective functions include minimizing frequency deviation, maximizing economic benefits, and minimizing equipment losses. The constraints include photovoltaic output limits, thermal storage tank temperature range, and hydrogen storage tank pressure limits.

[0034] S03: The command is issued to control the photovoltaic to perform maximum power tracking or power limiting operation, and adjust the valve opening of the molten salt heat storage tank, the voltage of the electrolyzer, the steam inlet of the turbine and the gas flow of the fuel cell;

[0035] S04: State feedback and closed-loop control, real-time monitoring of status and dynamic adjustment of instructions, triggering rapid frequency modulation of the hydrogen fuel cell when the frequency deviation exceeds ±0.05Hz.

[0036] As a further description of the present invention, the preset hydrogen storage tank pressure threshold in the rule engine is: below 25 bar, the electrolyzer is started, and above 34 bar, the electrolyzer is stopped;

[0037] The electricity price threshold is less than 0.3 yuan / kWh during the off-peak period to start hydrogen production and trigger corresponding actions.

[0038] As a further description of the present invention, the optimization scheduling strategy of the collaborative control layer also includes a day mode, a night or rainy day mode, and an emergency frequency modulation scenario mode.

[0039] In the daytime mode, the photovoltaic subsystem provides power first, and the remaining power is used to provide power to the electrolyzer for hydrogen production through the DC / DC converter. The molten salt heat storage tank of the solar thermal subsystem stores the excess heat energy of the tower collector.

[0040] In the nighttime or rainy day mode, the molten salt heat storage tank of the solar thermal subsystem releases heat through the steam generator to drive the steam turbine generator set to generate electricity, maintain base load power supply, and smooth out short-term power fluctuations. The hydrogen fuel cell subsystem responds to frequency deviations;

[0041] In the emergency frequency regulation scenario mode, the steam turbine generator set of the solar thermal subsystem quickly adjusts its output, the hydrogen fuel cell of the hydrogen fuel subsystem operates in a short-term overload state, and non-critical loads are suspended.

[0042] As a further description of the present invention, the objective function of minimizing the frequency deviation is Expressed as:

[0043] ,

[0044] in: represents the actual frequency of the power grid at time t, Indicates the rated frequency of the power grid, Indicates the length of the optimization cycle;

[0045] The objective function of maximizing economic benefits Expressed as:

[0046] ,

[0047] in: represents the amount of electricity sold by the system to the grid at time t, represents the electricity price at time t, represents the amount of electricity purchased by the system from the grid at time t, represents the electricity purchase price at time t, represents the system operating cost at time t, including equipment maintenance and depreciation costs;

[0048] The objective function of minimizing equipment loss is Expressed as:

[0049] ,

[0050] in: represents the equipment depreciation cost at time t, Represents the equipment maintenance cost at time t.

[0051] As a further description of the present invention, the optimization algorithm in the S02 prediction and optimization is optimized by MPC combined with genetic algorithm.

[0052] Beneficial effects of the present invention:

[0053] The present invention provides a photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency regulation system and control method. The coordinated peak-shaving and frequency regulation system includes a photovoltaic subsystem, a solar thermal subsystem, a hydrogen fuel cell subsystem, and a central controller to construct a solar-thermal-hydrogen fuel cell multi-energy flow coupling architecture. The control method adopts a hierarchical control architecture, including an optimization scheduling layer, a collaborative control layer, and an execution layer. Through a hierarchical optimization control strategy, the system utilizes photovoltaic daytime output, solar thermal heat storage system nighttime peak shaving, and hydrogen fuel cell second-level frequency regulation to cover grid regulation needs from minute to daily levels. At the same time, the system utilizes energy in a tiered manner, using solar thermal waste heat for water electrolysis to produce hydrogen, thereby improving the overall energy efficiency of the system, and achieving rapid response and precise regulation of the power system frequency as a whole, improving the renewable energy absorption capacity, and achieving stable operation and efficient utilization of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a schematic diagram of the structure of the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak and frequency regulation system proposed in the present invention;

[0055] Figure 2 This is a block diagram of the control method for the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system proposed in the present invention.

[0056] Description of Reference Numerals

[0057] 1- Photovoltaic subsystem, 11- Photovoltaic array, 12- Photovoltaic inverter, 13- DC / DC converter,

[0058] 2- Solar thermal subsystem, 21- Tower collector, 22- Molten salt heat storage tank, 23- Steam generator, 24- Steam turbine generator set, 25- Heat exchanger,

[0059] 3-Hydrogen fuel cell subsystem, 31-Electrolyzer, 32-Hydrogen storage tank, 33-Hydrogen fuel cell, 34-Inverter,

[0060] 4-Central controller. DETAILED DESCRIPTION

[0061] The specific implementation of the present invention is described below with reference to the accompanying drawings and embodiments:

[0062] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose that can be achieved by the present invention.

[0063] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0064] like Figures 1-2 As shown, it shows a specific embodiment of the present invention:

[0065] Example 1

[0066] The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system includes a photovoltaic subsystem 1, a solar thermal subsystem 2, a hydrogen fuel cell subsystem 3, and a central controller 4. Each subsystem works in coordination through energy flow and signal flow. The hydrogen fuel cell subsystem 3 acts as an energy-type energy storage to smooth out long-term power fluctuations and realize peak shaving and valley filling of the power grid. The solar thermal subsystem 2 acts as a power-type energy storage to smooth out short-term power fluctuations and realize power grid frequency regulation.

[0067] In this embodiment, Figure 1 As shown, the coordinated peak-shaving and frequency-regulating system has built a multi-energy flow coupling architecture of solar-thermal-hydrogen fuel cells, which utilizes the daytime output of photovoltaics, the nighttime peak-shaving of the solar-thermal heat storage system, and the second-level frequency regulation of hydrogen fuel cells to cover the grid regulation needs from minute to daily levels, and realizes the rapid response and precise regulation of the power system frequency as a whole, improves the renewable energy absorption capacity, and realizes the stable operation and efficient utilization of the power system.

[0068] The photovoltaic subsystem 1 includes a photovoltaic array 11, a photovoltaic inverter 12, and a DC / DC converter 13. The photovoltaic array 11 converts solar energy into direct current (DC), the photovoltaic inverter 12 converts DC into AC for grid connection, and the DC / DC converter 13 supplies power to the electrolyzer 31.

[0069] The solar thermal subsystem 2 includes a tower collector 21, a molten salt heat storage tank 22, a steam generator 23, a steam turbine generator set 24, and a heat exchanger 25. The tower collector 21 collects solar heat and stores it in the molten salt heat storage tank 22. The molten salt heat storage tank 22 drives the steam turbine generator set 24 to generate electricity through the steam generator 23. The waste heat of the molten salt heat storage tank 22 is used to assist hydrogen production through the heat exchanger 25.

[0070] The hydrogen fuel cell subsystem 3 includes an electrolyzer 31, a hydrogen storage tank 32, a hydrogen fuel cell 33, and an inverter 34. The electrolyzer 31 uses the electricity of the photovoltaic subsystem 1 to produce hydrogen, the hydrogen storage tank 32 stores hydrogen, the hydrogen fuel cell 33 converts hydrogen into electricity, and the inverter 34 converts the direct current generated by the hydrogen fuel cell 33 into alternating current for grid connection.

[0071] The central controller 4 communicates with each subsystem, receives grid load, electricity price signals and subsystem status, including photovoltaic output, heat storage tank temperature, and hydrogen storage tank pressure, and issues control instructions to coordinate operations.

[0072] In this embodiment, Figure 1 As shown, the photovoltaic array 11 in the photovoltaic subsystem 1 is connected to the grid through the photovoltaic inverter 12, and the electrolyzer 31 is powered by the DC / DC converter 13. The hydrogen produced by the electrolyzer 31 is stored in the hydrogen storage tank 32. The tower collector 21 in the solar thermal subsystem 2 stores heat energy in the molten salt heat storage tank 22. The molten salt heat storage tank 22 drives the steam turbine generator set 24 to generate electricity through the steam generator 23. The waste heat of the molten salt heat storage tank 22 is used to assist in hydrogen production through the heat exchanger 25. In the hydrogen fuel cell subsystem 3, the hydrogen in the hydrogen storage tank 32 is supplied to the hydrogen fuel cell 33, and the generated electricity is connected to the grid through the inverter 34. The central controller 4 is connected to each subsystem It receives grid load demand, electricity price signals and subsystem status, namely photovoltaic output, molten salt heat storage tank 22 temperature, and hydrogen storage tank 32 pressure, and issues control instructions, including maximum power tracking control instructions to the photovoltaic array 11, electrolyzer start and stop instructions to the electrolyzer 31, heat storage tank charge and discharge instructions to the molten salt heat storage tank 21, turbine output adjustment instructions to the steam turbine generator set 24, and fuel cell power instructions to the hydrogen fuel cell 33. Through the above connection structure, the system realizes the coordinated work of photovoltaic, solar thermal and hydrogen fuel cells, effectively regulates the grid load, provides stable power supply, and at the same time utilizes energy in a cascade manner to improve the overall energy efficiency of the system.

[0073] Example 2

[0074] Based on the above embodiment 1, the hardware components of the coordinated peak-shaving and frequency-modulating system are as follows:

[0075] Specifically, in the photovoltaic subsystem 1,

[0076] The photovoltaic array 11 uses high-efficiency monocrystalline silicon components and is arranged according to the optimal inclination and spacing of the local latitude.

[0077] The photovoltaic inverter 12 supports the maximum power point tracking function.

[0078] The DC / DC converter 13 adopts a bidirectional Buck-Boost converter with an input voltage range of DC 300V-800V. The output voltage can be accurately adjusted to the working voltage of the electrolytic cell 31, providing a stable DC power supply for the electrolytic cell 31.

[0079] In this embodiment, the photovoltaic array 11 uses a single crystal PERC component with a conversion efficiency of ≥22%. The optimal tilt angle at the local latitude is, for example, 30° north latitude. The optimal tilt angle is The spacing is the minimum distance to ensure no obstruction on the winter solstice, thereby maximizing the efficiency of solar energy reception. The photovoltaic inverter 12 uses a three-phase smart inverter with maximum power point tracking (MPPT) function, supports dynamic response to grid frequency deviation within 0.2s, and can adjust the operating point in real time to maintain the maximum power output of the photovoltaic array. The conversion efficiency is ≥98.5%. The output voltage of the DC / DC converter 13 can be accurately adjusted to the operating voltage of the electrolytic cell 31, that is, DC 200V, with an efficiency of ≥96%, providing a stable DC power supply for the electrolytic cell 31.

[0080] Specifically, in the photothermal subsystem 2,

[0081] The tower collector 21 adopts a heliostat field and a central absorber structure. The number of heliostats is configured according to the installed capacity. For example, a 100MW system is configured with 5,000 10m² heliostats with a reflectivity of ≥95%. The molten salt temperature at the absorber outlet reaches 565°C.

[0082] The molten salt heat storage tank 22 adopts a double tank structure, namely a high temperature tank and a low temperature tank, and the volume of a single tank is , filled with sodium nitrate-potassium nitrate mixed molten salt, with a melting point of 220°C, a heat storage efficiency of ≥92%, and supports continuous heat release at full load for 10 hours;

[0083] The steam turbine generator set 24 is driven by high-temperature and high-pressure steam generated by the steam generator 23. The parameters of the superheated steam in this embodiment are: 17 MPa, 540°C, driving a 100MW condensing steam turbine generator set 24 with a power generation efficiency greater than or equal to 40%;

[0084] The heat exchanger 25 adopts a plate heat exchanger to transfer the waste heat of the molten salt heat storage tank 22 to the circulating water system of the electrolyzer 31 with a temperature of ≥290°C after heat release, thereby improving the hydrogen production efficiency by 15%-20%.

[0085] Specifically, in the hydrogen fuel cell subsystem 3,

[0086] The electrolyzer 31 is a proton exchange membrane electrolyzer with a rated power of 500 kW, a hydrogen production rate greater than or equal to 0.12 Nm³ / kWh, a working pressure of 30 bar, and supports rapid start and stop, with a start-up time of less than 5 minutes;

[0087] The hydrogen storage tank 32 is a 35MPa high-pressure gaseous hydrogen storage tank with a total volume of 2000m³ and a hydrogen storage capacity of approximately 2800kg. It is equipped with a pressure sensor and a safety valve. The accuracy of the pressure sensor is ±0.5%FS.

[0088] The hydrogen fuel cell 33 uses a 200kW proton exchange membrane fuel cell stack with a response time of less than 1s and a power generation efficiency of ≥55%, and is equipped with an air compressor and a hydrogen circulation pump;

[0089] The inverter 34 is a bidirectional inverter that supports four-quadrant operation and can complete active or reactive power regulation within 10ms to meet the frequency regulation requirements of the power grid.

[0090] Specifically, the central controller 4 adopts a Siemens S7-1500 PLC controller, equipped with 16-channel analog input / output modules and 32-channel digital modules, and communicates with each subsystem through the OPC UA protocol. The communication delay is less than 100ms. It has a built-in real-time database to store data such as frequency, load, and equipment status, and supports historical data tracing and trend analysis.

[0091] Example 3

[0092] A control method for a photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system, wherein the control method adopts a hierarchical control architecture, including an upper layer, a middle layer, and a lower layer.

[0093] The upper layer, namely the optimization scheduling layer, uses model predictive control and genetic algorithms to formulate a global optimization scheduling strategy based on grid load forecasts, electricity price signals and subsystem status, with the goal of minimizing frequency deviation, maximizing economic benefits and minimizing equipment losses;

[0094] The middle layer, namely the collaborative control layer, converts the optimized scheduling strategy into specific instructions and coordinates the operation of subsystems through PID controllers, fuzzy controllers and rule engines;

[0095] The lower layer, the execution layer, executes device control instructions to adjust photovoltaic output, heat storage tank charging and discharging rates, electrolyzer start and stop, and fuel cell power.

[0096] The control method comprises the following steps:

[0097] S01: Data acquisition, real-time acquisition of grid frequency, load, electricity price and subsystem status;

[0098] S02: Prediction and optimization: Use the LSTM model to predict load and solve the optimal scheduling plan through multi-objective functions and constraints. The multi-objective functions include minimizing frequency deviation, maximizing economic benefits, and minimizing equipment losses. The constraints include photovoltaic output limit, molten salt heat storage tank 22 temperature range, and hydrogen storage tank 32 pressure limit.

[0099] S03: Instructions are issued to control the photovoltaic system to perform maximum power tracking or power limiting operation, adjust the valve opening of the molten salt heat storage tank 22, the voltage of the electrolyzer 31, the steam inlet of the steam turbine generator set 24, and the gas flow of the hydrogen fuel cell 33;

[0100] S04: State feedback and closed-loop control, real-time monitoring of the state and dynamic adjustment of instructions, triggering rapid frequency modulation of the hydrogen fuel cell 33 when the frequency deviation exceeds ±0.05Hz.

[0101] Specifically, the pressure threshold of the hydrogen storage tank 32 is preset in the rule engine as follows: if it is lower than 25 bar, the electrolyzer 31 is started, and if it is higher than 34 bar, the electrolyzer 31 is stopped;

[0102] The electricity price threshold is less than 0.3 yuan / kWh during the off-peak period to start hydrogen production and trigger corresponding actions.

[0103] Specifically, the objective function of minimizing the frequency deviation is Expressed as:

[0104] ,

[0105] in: represents the actual frequency of the power grid at time t, Indicates the rated frequency of the power grid, Indicates the length of the optimization cycle;

[0106] The objective function of maximizing economic benefits Expressed as:

[0107] ,

[0108] in: represents the amount of electricity sold by the system to the grid at time t, represents the electricity price at time t, represents the amount of electricity purchased by the system from the grid at time t, represents the electricity purchase price at time t, represents the system operating cost at time t, including equipment maintenance and depreciation costs;

[0109] The objective function of minimizing equipment loss is Expressed as:

[0110] ,

[0111] in: represents the equipment depreciation cost at time t, Represents the equipment maintenance cost at time t.

[0112] Specifically, the optimization algorithm in the S02 prediction and optimization is optimized by MPC combined with genetic algorithm.

[0113] In this embodiment, the implementation process of the control method is as follows: the upper layer is based on the LSTM neural network model, inputs historical load data such as a resolution of 15 minutes, and weather forecasts such as light intensity and temperature, and predicts the grid load in the next hour with an error of ≤3%. MPC combined with genetic algorithm is used as the optimization algorithm, with 15 minutes as the optimization cycle. The weight of minimizing the sum of squared frequency deviations in the objective function is 0.5, the weight of maximizing the peak-valley electricity price arbitrage income is 0.3, and the weight of minimizing the equipment loss cost is 0.2. Finally, the output instruction generates a photovoltaic output curve, a molten salt heat storage tank 22 charging and discharging power curve, an electrolyzer 31 start-stop period curve, a hydrogen fuel cell 33 standby power curve, etc.

[0114] The middle-layer PID controller adjusts the molten salt flow rate of the heat storage tank, such as controlling the temperature deviation ≤±5℃ and the fuel cell output power response speed ≤2s. The fuzzy controller handles the sudden drop in photovoltaic output, such as cloud cover, and quickly adjusts the turbine output through fuzzy rules such as input light mutation rate and frequency deviation and output solar thermal power compensation. The rule engine presets the hydrogen storage tank 32 pressure threshold, such as starting the electrolyzer when it is lower than 25bar and stopping when it is higher than 34bar. The electricity price threshold, such as starting hydrogen production when it is less than 0.3 yuan / kWh during the off-peak period, triggers the corresponding action.

[0115] The photovoltaic inverter 12 in the photovoltaic control subsystem 1 of the lower layer executes MPPT or power limiting instructions, and realizes output control by adjusting the reference voltage with an accuracy of ±2% of the rated power. The electric valve in the heat storage control adjusts the molten salt flow rate with an opening of 0-100% and an adjustment accuracy of ±1%, realizing dynamic matching of charging and discharging heat power. In the hydrogen production / power generation control, the electrolyzer starts and stops according to the instructions, and the DC / DC converter 13 adjusts the current to the rated value with an error of ±1A. The hydrogen fuel cell 33 realizes rapid power tracking by adjusting the air / hydrogen flow rate, and the adjustment rate is ≥10% of the rated power / s.

[0116] In the closed-loop control process, data is collected from grid signals: frequency is collected in real time via the PMU phasor measurement unit with an accuracy of ±0.001 Hz, load with a resolution of 1 second, and electricity price signals are updated in real time. Subsystem status: PV inverter 12 transmits real-time output and temperature. The temperature of the molten salt heat storage tank 22 is collected via a platinum resistance sensor with an accuracy of ±0.5°C. The pressure of the hydrogen storage tank 32 is monitored via a pressure transmitter with an accuracy of ±0.25%FS.

[0117] During status feedback and adjustment, the central controller 4 receives feedback data every 500ms. If the frequency deviation exceeds ±0.05Hz, the hydrogen fuel cell rapid frequency modulation is immediately triggered, with a response time of less than 1s; if the heat storage tank temperature is lower than the set lower limit, the collector absorption power is automatically increased.

[0118] Example 4

[0119] Specifically, the optimization scheduling strategy of the collaborative control layer also includes day mode, night or rainy day mode, and emergency frequency modulation scene mode.

[0120] In the daytime mode, the photovoltaic subsystem 1 provides power first, and the remaining power, such as the peak power output at noon, is provided to the electrolyzer 31 through the DC / DC converter 13 to produce hydrogen. The molten salt heat storage tank 22 of the solar thermal subsystem 2 stores the excess heat energy of the tower collector 21.

[0121] In the nighttime or rainy day mode, the solar thermal subsystem 2 realizes peak regulation through solar thermal power generation. The molten salt heat storage tank 22 releases heat through the steam generator 23 to drive the steam turbine generator set 24 to generate electricity, maintain basic load power supply, and the output fluctuation is ≤5% of the rated power. Short-term power fluctuations are smoothed and frequency modulation is achieved through the hydrogen fuel cell subsystem. The hydrogen fuel cell subsystem 3 responds to frequency deviations. When the grid frequency fluctuation exceeds ±0.1Hz, the hydrogen fuel cell adjusts the output within 1s. The duration of a single frequency modulation is ≤30min to avoid excessive consumption of stored hydrogen.

[0122] In the emergency frequency regulation scenario mode, the steam turbine generator set 24 of the solar thermal subsystem 2 quickly adjusts its output, the hydrogen fuel cell 33 of the hydrogen fuel subsystem 3 is temporarily overloaded, and non-critical loads are suspended. When the system frequency drops sharply, such as when the drop value is greater than 0.2 Hz, the central controller immediately triggers the following actions: the steam turbine generator set of the solar thermal subsystem starts a rapid load increase and decrease mode, with a rate greater than or equal to 5% of the rated power / min; the hydrogen fuel cell outputs at maximum power, with a short-term overload of 120% of the rated power, and the duration is ≤10 minutes; non-critical loads, such as the electrolyzer, are suspended to give priority to ensuring grid stability.

[0123] In this embodiment, energy efficiency and economic optimization can also be achieved. In the waste heat recovery, the waste heat of the solar thermal subsystem, accounting for about 10% of the total heat storage, is used to heat the electrolyte of the electrolyzer, so that the energy consumption of hydrogen production is reduced from 4.5kWh / Nm³ to 3.8kWh / Nm³, saving about 5 million kWh of electricity annually; in the peak-valley arbitrage, the electricity price signal is guided to start the electrolyzer to produce hydrogen during the valley period of 23:00-7:00 with an electricity price of 0.3 yuan / kWh, and the fuel cell is used to generate electricity and connect to the grid during the peak period of 10:00-15:00 with an electricity price of 0.8 yuan / kWh. The annual income is expected to increase by more than 20%.

[0124] The preferred embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

[0125] Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the present invention is not limited to the specific embodiments, and the scope of the present invention is defined by the appended claims.

Claims

1. Photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak and frequency regulation system, characterized by: The invention comprises a photovoltaic subsystem (1), a solar thermal subsystem (2), a hydrogen fuel cell subsystem (3) and a central controller (4), wherein each subsystem works in coordination through energy flow and signal flow, wherein the hydrogen fuel cell subsystem (3) acts as an energy-type energy storage to smooth out long-term power fluctuations and realize peak shaving and valley filling of the power grid, and the solar thermal subsystem (2) acts as a power-type energy storage to smooth out short-term power fluctuations and realize power grid frequency modulation; The photovoltaic subsystem (1) includes a photovoltaic array (11), a photovoltaic inverter (12), and a DC / DC converter (13). The photovoltaic array (11) converts solar energy into direct current (DC), the photovoltaic inverter (12) converts DC into alternating current (AC) for grid connection, and the DC / DC converter (13) supplies power to the electrolyzer (31). The solar thermal subsystem (2) includes a tower collector (21), a molten salt heat storage tank (22), a steam generator (23), a steam turbine generator set (24), and a heat exchanger (25). The tower collector (21) collects solar heat and stores it in the molten salt heat storage tank (22). The molten salt heat storage tank (22) drives the steam turbine generator set (24) to generate electricity through the steam generator (23). The waste heat of the molten salt heat storage tank (22) is used to assist in hydrogen production through the heat exchanger (25). The hydrogen fuel cell subsystem (3) includes an electrolyzer (31), a hydrogen storage tank (32), a hydrogen fuel cell (33), and an inverter (34). The electrolyzer (31) uses the electrical energy of the photovoltaic subsystem (1) to produce hydrogen. The hydrogen storage tank (32) stores hydrogen. The hydrogen fuel cell (33) converts hydrogen into electrical energy. The inverter (34) converts the direct current generated by the hydrogen fuel cell (33) into alternating current for grid connection. The central controller (4) communicates with each subsystem, receives grid load, electricity price signals and subsystem status, wherein the subsystem status includes photovoltaic output, heat storage tank temperature and hydrogen storage tank pressure, and the central controller (4) issues control instructions to coordinate operation.

2. The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system according to claim 1 is characterized in that: In the photovoltaic subsystem (1), The photovoltaic array (11) uses high-efficiency single-crystal silicon components and is arranged according to the optimal inclination angle and spacing of the local latitude. The photovoltaic inverter (12) supports a maximum power point tracking function. The DC / DC converter (13) adopts a bidirectional Buck-Boost converter with an input voltage range of DC 300V-800V. The output voltage can be accurately adjusted to the working voltage of the electrolytic cell (31), providing a stable DC power supply for the electrolytic cell (31).

3. The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-modulating system according to claim 1 is characterized in that: In the photothermal subsystem (2), The tower collector (21) adopts a heliostat field and a central heat absorber structure, the number of heliostats is configured according to the installed capacity, the reflectivity is ≥95%, and the molten salt temperature at the heat absorber outlet reaches 565°C; The molten salt heat storage tank (22) adopts a double tank structure, and the volume of a single tank is , filled with sodium nitrate-potassium nitrate mixed molten salt, with a melting point of 220°C, a heat storage efficiency of ≥92%, and supports continuous heat release at full load for 10 hours; The steam turbine generator set (24) is driven by high-temperature and high-pressure steam generated by the steam generator (23), and the power generation efficiency is greater than or equal to 40%; The heat exchanger (25) adopts a plate heat exchanger to transfer the waste heat of the molten salt heat storage tank (22) to the circulating water system of the electrolyzer (31), thereby improving the hydrogen production efficiency by 15%-20%.

4. The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system according to claim 1 is characterized in that: In the hydrogen fuel cell subsystem (3), The electrolyzer (31) is a proton exchange membrane electrolyzer with a rated power of 500 kW, a hydrogen production rate greater than or equal to 0.12 Nm³ / kWh, a working pressure of 30 bar, and supports rapid start and stop; The hydrogen storage tank (32) adopts a 35MPa high-pressure gaseous hydrogen storage tank with a total volume of 2000m³ and a hydrogen storage capacity of approximately 2800kg, and is equipped with a pressure sensor and a safety valve; The hydrogen fuel cell (33) uses a 200kW proton exchange membrane fuel cell stack with a response time of less than 1s and a power generation efficiency of ≥55%, and is equipped with an air compressor and a hydrogen circulation pump; The inverter (34) adopts a bidirectional inverter, supports four-quadrant operation, and can complete active or reactive power regulation within 10ms to meet the frequency regulation requirements of the power grid.

5. The photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system according to claim 1 is characterized in that: The central controller (4) adopts Siemens S7-1500 PLC controller.

6. A control method for a photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-modulating system, applied to the system according to any one of claims 1 to 5, characterized in that: The control method adopts a hierarchical control architecture, including upper, middle and lower layers. The upper layer, namely the optimization scheduling layer, uses model predictive control and genetic algorithms to formulate a global optimization scheduling strategy based on grid load forecasts, electricity price signals and subsystem status, with the goal of minimizing frequency deviation, maximizing economic benefits and minimizing equipment losses; The middle layer, namely the collaborative control layer, converts the optimized scheduling strategy into specific instructions and coordinates the operation of subsystems through PID controllers, fuzzy controllers and rule engines; The lower layer, i.e., the execution layer, executes device control instructions to adjust photovoltaic output, heat storage tank charging and discharging rates, electrolyzer start and stop, and fuel cell power; The control method comprises the following steps: S01: Data acquisition, real-time acquisition of grid frequency, load, electricity price and subsystem status; S02: prediction and optimization, using the LSTM model to predict the load, solving the optimal scheduling scheme through multi-objective functions and constraints, the multi-objective functions include minimizing frequency deviation, maximizing economic benefits, and minimizing equipment losses, and the constraints include photovoltaic output limit, molten salt heat storage tank (22) temperature range, and hydrogen storage tank (32) pressure limit; S03: The command is issued to control the photovoltaic system to perform maximum power tracking or power limiting operation, and to adjust the valve opening of the molten salt heat storage tank (22), the voltage of the electrolyzer (31), the steam inlet of the steam turbine generator set (24), and the gas flow of the hydrogen fuel cell (33); S04: State feedback and closed-loop control, real-time monitoring of the state and dynamic adjustment of the instructions, triggering the rapid frequency modulation of the hydrogen fuel cell (33) when the frequency deviation exceeds ±0.05Hz.

7. The control method of the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak and frequency regulation system according to claim 6, characterized in that: The rule engine presets the hydrogen storage tank (32) pressure threshold as follows: if the pressure is lower than 25 bar, the electrolyzer (31) is started; if the pressure is higher than 34 bar, the electrolyzer (31) is stopped; The electricity price threshold is less than 0.3 yuan / kWh during the off-peak period to start hydrogen production and trigger corresponding actions.

8. The control method of the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system according to claim 6, characterized in that: The optimization scheduling strategy of the collaborative control layer also includes day mode, night or rainy day mode, and emergency frequency modulation scenario mode. In the daytime mode, the photovoltaic subsystem (1) is given priority in power supply, and the remaining power is provided to the electrolyzer (31) for hydrogen production via the DC / DC converter (13), and the molten salt heat storage tank (22) of the solar thermal subsystem (2) stores the excess heat energy of the tower collector (21); The molten salt heat storage tank (22) of the solar thermal subsystem (2) releases heat through the steam generator (23) to drive the steam turbine generator set (24) to generate electricity, maintain the base load power supply, and smooth out short-term power fluctuations. The hydrogen fuel cell subsystem (3) responds to frequency deviations; In the emergency frequency modulation scenario mode, the steam turbine generator set (24) of the solar thermal subsystem (2) quickly adjusts its output, the hydrogen fuel cell (33) of the hydrogen fuel subsystem (3) operates in a short-term overload mode, and non-critical loads are suspended.

9. The control method of the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak and frequency regulation system according to claim 6, characterized in that: The objective function of minimizing the frequency deviation is Expressed as: ， in: represents the actual frequency of the power grid at time t, Indicates the rated frequency of the power grid, Indicates the length of the optimization cycle; The objective function of maximizing economic benefits Expressed as: ， in: represents the amount of electricity sold by the system to the grid at time t, represents the electricity price at time t, represents the amount of electricity purchased by the system from the grid at time t, represents the electricity purchase price at time t, represents the system operating cost at time t, including equipment maintenance and depreciation costs; The objective function of minimizing equipment loss is Expressed as: ， in: represents the equipment depreciation cost at time t, Represents the equipment maintenance cost at time t.

10. The control method of the photovoltaic, solar thermal, and hydrogen fuel cell coordinated peak-shaving and frequency-regulating system according to claim 6, characterized in that: The optimization algorithm in the S02 prediction and optimization is optimized by MPC combined with genetic algorithm.

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