Method for controlling a system for producing green hydrogen
By prioritizing photovoltaic installations and strategically operating wind turbines based on weather and topography, the method addresses the variability in energy yield from solar and wind sources, ensuring a stable power supply to electrolysis processes while reducing wear and maintenance costs.
Patent Information
- Application Number
- DE102024103045
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-02-02
- Publication Date
- 2025-08-07
AI Technical Summary
The variability in energy yield from solar and wind sources due to weather conditions poses challenges for maintaining a consistent power supply to electrolysis processes, leading to potential damage and safety risks, and the high investment and maintenance costs of hybrid power plants with both systems.
A method for controlling a hybrid power plant using photovoltaic and wind energy systems, where photovoltaic installations have priority, and wind turbines are selectively operated based on weather forecasts and topography to maintain a stable power supply for electrolysis, minimizing wear and optimizing energy distribution.
This approach ensures a consistent power supply to electrolysis processes, reduces mechanical wear on wind turbines, and lowers maintenance costs by strategically using wind and solar energy based on weather predictions and topographical conditions.
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Abstract
Description
[0001] The invention relates to a method for controlling a system for producing green hydrogen.
[0002] When using renewable energy sources such as solar and wind power, there is always the problem that the energy yield depends on the current position of the sun and local weather conditions such as cloud cover, wind speed, etc. By combining photovoltaic systems (photovoltaic systems) and wind turbines (wind turbines) to create hybrid power plants, this dependency can be reduced, and the systems can be constructed at locations where fewer weather-related losses are expected. This allows even processes where short-term fluctuations in the electrical power fed into the grid to be based on renewable energy supplies. One such vulnerable process is electrolysis for the production of green hydrogen gas.Short-term power outages can disrupt the process and damage the electrolyzer or lead to hydrogen mixing. In the worst case, if safety precautions are not followed, this can lead to an explosion risk if the hydrogen concentration at the electrolyzer's anode is too high and mixes with oxygen. The electrolyzer can be shut down into hot standby mode in less than two minutes in a controlled process, e.g., before nightfall.
[0003] Powering such an electrolyzer with hybrid power generation systems that simultaneously incorporate photovoltaic and wind turbines reduces the risk of a short-term drop in power output. This requires installing wind turbines with sufficient power to largely compensate for energy losses caused by temporary cloud shading of the photovoltaic systems. If even a complete failure of the photovoltaic system must be considered, the same power must be installed in the form of wind turbines. Conversely, the power of the installed photovoltaic systems must be sufficient to essentially power the electrolysis process alone in calm conditions. Providing full capacity with both wind turbines and photovoltaic systems results in high investment costs.
[0004] In order to produce green hydrogen economically, a widely distributed installation of several photovoltaic systems and wind turbines is necessary in a favorable geographical location where there is no public AC grid with additional power plants to bridge short-term demand periods and no electrical energy consumers to cushion production peaks.
[0005] The aim of the present invention is to provide a method for controlling a hybrid power plant using renewable energies, in which the economical use of the two energy sources is controlled in a targeted manner in order to ensure a constant power supply for the electrolysis plants.
[0006] This object is achieved by a method for controlling a system for producing green hydrogen having the features of claim 1.
[0007] A prerequisite for implementing the method according to the invention is the use of a hybrid energy generation plant in which the two different energy sources, namely photovoltaic systems and wind turbines, are present in sufficient numbers and are widely distributed, so that they can be selected by zone and / or combined into groups. All photovoltaic systems and wind turbines are interconnected by power lines to form a local power grid.
[0008] The method according to the invention is based on the following assumptions: - In all cases where the power sources are controlled in the hybrid power plant, daylight hours are taken into account so that the photovoltaic systems can generate electricity. - In all cases, wind speeds are assumed to be above a switch-on wind speed for the wind turbine so that electricity can be generated from wind energy. - The installed capacity (IC) of the electrolyzer and all other additional consumers in the middle and downstream areas of the local electricity grid is smaller than the sum of the capacity of wind and photovoltaic systems, so that during the times of nominal wind speed and full production of the photovoltaic systems, either the photovoltaic systems and / or the wind turbines would have to be throttled. - The production of PV systems in different nodes does not affect the other nodes nearby at all, while wind turbines create a wake on their downwind side, so that a wind turbine generator located in the lee of another operating wind turbine generator operates less efficiently, even if a minimum distance of e.g. 10, preferably 5 rotor diameters is maintained between them. - The wear and tear of wind turbines depend, among other things, on the operating hours. A wind turbine generator that is throttled back or idled exhibits less wear than one in continuous operation. The aging and wear of photovoltaic systems are less dependent on the degree of utilization. - Wind turbines can be easily throttled or shut down by adjusting the rotor blades, whereas photovoltaic systems cannot be throttled down as easily. When exposed to the sun and not generating electricity, the panels become even hotter. Single-axis tracking could contribute to reducing electricity generation. The photovoltaic system can be intentionally turned out of the sun when no electricity generation is desired, and the heating of the photovoltaic system is intended to reduce this.
[0009] Taking the above considerations into account, if the feed-in power is too high, photovoltaic systems should be used as a priority and wind turbines should be throttled first.
[0010] In the method according to the invention, an energy requirement value (EBW) is established which defines the necessary electrical input power for the electrolysis process. In particular, this energy requirement value is not kept static over the entire operating time, but is adjusted continuously or at regular intervals of 10 seconds to 1 minute, e.g. depending on the position of the sun, since, as already mentioned, long-term fluctuations in the input power for the electrolysis process are still possible, whereas short-term fluctuations disrupt the electrolysis process or cause damage to the electrolysis system. For example, two hours before sunrise, the energy requirement value EBW can be continuously reduced while the electrolyzer is shut down. The energy requirement value (EBW) is always smaller than the installed capacity (IC), so that reserve units are available to bridge short-term power drops.
[0011] The weather conditions in the vicinity of the power generation units, i.e., the photovoltaic and wind turbines, are continuously monitored. Based on the forecast data obtained from weather observations, an expected energy yield (EEW) is calculated for each type of power source for a forecast period that begins, with a limited probability, several days in advance and is continuously optimized to seconds with a very high probability. The calculation of the energy yield (EEW) begins several days in advance and is initially based only on weather and wind forecasts. The energy yield is then continuously adjusted with increasing accuracy through more accurate forecasts and on-site measurements (including those using all-sky cameras).
[0012] In addition, the difference between the energy yield value EEW and the energy demand value EBW is determined.
[0013] In terms of both investment costs and maintenance costs relative to the installed nominal power, photovoltaic systems are significantly cheaper than wind turbines. As long as the EBW of the electrolysis process can be covered by solar energy alone, all photovoltaic systems will be operated at full capacity and all wind turbines will be kept in standby mode to reduce mechanical wear and extend their service life.
[0014] Conversely, wind turbines are only deployed when the energy yield (EEW) of the photovoltaic systems is significantly lower than the energy demand (EBW) or even drops to zero. A significant shortage of electrical energy, which must be compensated for by active measures in the control process, occurs when: - it is expected that the energy yield value EEW will fall below the EBW for at least 1 minute and - the difference between EBW and energy yield value EEW is greater than 1%; this usually corresponds to about half the nominal power of a wind turbine.
[0015] If it is expected that the energy yield value EEW of the photovoltaic systems will soon be reduced and their output is no longer sufficient to fully cover the energy demand value EBW, additional wind turbines are used to generate additional electricity, but throttled to minimum load so that only the difference between the energy demand value and the EEG of the photovoltaic systems is provided by wind turbines.
[0016] If, based on weather observations, it is expected that the energy yield (EEW) of only individual photovoltaic systems will be reduced by passing clouds, it is possible to precisely calculate which of the photovoltaic systems within the energy generation facility are likely to be shaded at a given time based on the known wind direction and wind speed on the one hand, and the equally known topography of the photovoltaic systems on the other. Accordingly, several wind turbines are started up in good time before the shading occurs, which can compensate for the expected lower energy yield. By controlling the blade position of the wind turbines in operation, the generated electrical power can be finely adjusted to the changing energy demand over time.
[0017] A special feature of the invention is that it doesn't simply utilize all the wind turbines present in the hybrid power plant, but rather selects individual wind turbines from the entire installed fleet for generator operation. This reduces the mechanical wear and tear of the wind turbines as a whole.
[0018] In addition, the selected wind turbines will be operated in a roving cluster. This means that all wind turbines at the site will be grouped into temporary clusters extending perpendicular to the expected wind direction. These groups are not fixed but are constantly reorganized depending on weather observation data. Only those wind turbines that maintain a sufficient distance of at least five times the rotor diameter from each other in the direction of the wind will be used in generator mode.
[0019] For example, if 16 wind turbines are arranged in a nearly regular arrangement of four rows and four columns, and the wind direction is perpendicular to one side of this arrangement, it is possible to use only the first and third or only the second and fourth rows for energy generation, or to switch from operation with the first and third rows to operation with the second and fourth rows. This reduces the mutual influence of the wind turbines and increases the service life of the wind turbine, as only half of the wind turbines are used at one time. The arrangement in linear rows and columns is only an example. In a real large-scale hybrid power plant extending over an area of at least 500 km 2 or even more than 10,000 km 2The positions of the wind turbines are determined individually according to the geographical conditions. However, such arrangements can be divided into rows and columns, even if they do not extend linearly in the geometric sense.
[0020] According to one aspect of the method according to the invention, a computer-aided service life log is maintained so that, under similar wind conditions, the same wind turbines are not always deployed, but rather, for example, those with the fewest operating hours are selected for operation. In the example described above, it could be provided that, during a few operating days – assuming a constant wind direction – rows 1 and 3 are prioritized first, followed by rows 2 and 4.
[0021] As an alternative to preferentially shutting down the wind turbine with the highest fatigue load in order to increase its service life, those wind turbines that are already highly stressed can be selected and are to be replaced next.
[0022] The lifetime log can record various parameters such as total operating hours, idle hours, and hours in generator mode. It is also possible to use digital twins of the wind turbine to calculate the fatigue of specific parts such as shafts, couplings, etc. based on the recorded wind data.
[0023] If a wind field passes through the area of the hybrid power plant within a short period of time, it is possible to plan ahead to operate the rows of wind turbines like a traveling wave. This means that all wind turbines located in the direction of the wind field are switched from idle to power-generating operation when the switch-on wind speed is reached, but before the main wind field arrives. The blade control then assigns the highest load to the first row, then to the second row, while the load on the first row is already being reduced again, then to the third row, and so on.
[0024] If the wind direction changes, the existing wind turbines are re-clustered, i.e. combined into other groups that are aligned perpendicular to the wind direction.
[0025] Since the direction of cloud movement generally corresponds to the wind direction at a height relevant for wind turbines, it is always possible, when photovoltaic systems and wind turbines are installed next to each other, to form multiple clusters of wind turbines in a shape that corresponds to the shape of the moving cloud fields. The clusters of wind turbines are then operated sequentially in the expected direction of cloud movement, so that in a first cluster, the wind turbines are already in generator mode before the photovoltaic systems are shaded. The next clusters of wind turbines, viewed in the direction of wind and cloud movement, are then switched on one after the other before the neighboring photovoltaic systems are shaded, and the wind turbine clusters are switched off again as soon as the shading of the photovoltaic systems has ended.
[0026] The invention will be explained in more detail below with reference to the exemplary embodiment shown in the drawings. The figures show: Fig. 1 a first example of the topography of a green hydrogen production system; Fig. 2 a second example of the topography of a green hydrogen production system; Fig. 3 an exemplary power generation node in plan view; Fig. 4 an exemplary energy utilization node in plan view; Fig. 5 Functional diagram of a system for producing green hydrogen according to a first embodiment; Fig. 6 Functional diagram of a system for producing green hydrogen according to a second embodiment; Fig. 7 to 15 show a schematic representation of the topography of a node of a hybrid power plant with wind and moving clouds; and Fig. 16 to 18 a flow diagram of a method for controlling a system for producing green hydrogen.
[0027] Fig. Figure 1 shows a first example of a system 100 for producing green hydrogen, which is distributed across a coastal region 1 of a country. In this example, the maximum extent in the north-south direction is approximately 50 km and in the east-west direction approximately 250 km. The system 100 comprises a total of 24 upstream power generation nodes 10.1, ..., 10.24 and a downstream power utilization node 30 located on a sea 2 or lake. The lines between the power generation nodes 10.1, ..., 10.24 indicate the area boundaries of each node. The points within the boundaries each represent a wind turbine 11, which is electrically connected to the adjacent power generation node in the area.
[0028] The energy generation nodes 10.1, ..., 10.24 and the energy utilization node 30 are interconnected by a network of intermediate connecting lines 20, which includes at least one hydrogen pipeline. At the same time, the route of the intermediate connecting line 20 can be used to construct a parallel roadway, particularly in previously undeveloped parts of the coastal region 1.
[0029] A main section of an intermediate connecting line 20 extends from the northeasternmost power generation node 10.1, ..., 10.24 to the power consumption node 30. The connection of the individual power generation nodes 10.1, ..., 10.24 to the intermediate connecting line 20 can be made in different ways: - The easternmost power generation nodes 10.1, 10.2, 10.3, 10.4 are directly connected to a main line of the intermediate connector 20. - Some power generation nodes, such as the westernmost power generation nodes 10.21, 10.22, 10.23, and 10.24, are connected in a group of four by a north-south branch interconnector 29.1. At an intersection point, the branch interconnector is connected to the main line. In addition, another group of four nodes is connected by a north-south branch interconnector 29.2. - A Y-shaped branch connection line is provided at the power generation nodes 10.9, ..., 10.12. The power generation nodes 10.9, 10.10 are connected to the power generation node 10.11, from which the branch connection line runs to the power generation node 10.12. The connection is established at the intersection of the branch connection line 29.4 with the main line of the intermediate connecting line 20.
[0030] Fig. Figure 2 shows a second, smaller, and simplified example of a power generation plant 100', also constructed in the coastal region 1 of the country near the sea 2. It consists of ten power generation nodes 10.1', ..., 10.10'. Each power generation node 10.1', ..., 10.10' is assigned an area of approximately 20 km x 20 km. A plurality of wind turbines 11, each represented by a dot, are arranged in the area of the nodes 10.1', ..., 10.10' and electrically connected to the associated node. In this example, each power generation node 10.1', ..., 10.10' is connected via its own stub line to a main line of an intermediate connector line 20', which extends from east to west to a power utilization node 30 at the sea 2.
[0031] Fig. Figure 3 shows an example of a single power generation node 10 in plan view. This is designed so that several central units are arranged within an arrangement of four rectangular arrays of photovoltaic systems 12. The central units include an electrolyzer 13, a flow battery module 16, and a central station 19, which houses, among other things, controls and accommodations for the personnel. The photovoltaic systems 12 are electrically connected to each other and to the central units. The wind turbines 11 belonging to the power generation node 10 are also electrically connected to it; the electrical connecting lines from the wind turbines 11 to the central units are in Fig. shown in dashed lines.
[0032] The central units are located along an intermediate connector line 20, which includes a hydrogen pipeline 22 (dashed line), a fresh water pipeline 21 (dashed line), and a high-voltage line 23 (solid line). A roadway 24, shown as a double line, is located along the intermediate connector line 20.
[0033] Fig. Figure 4 shows an example of a downstream energy utilization node 30 in a top view. It is a complex of facilities constructed near the sea 2. The energy utilization node 30 comprises a harbor 31, a seawater desalination plant 32, and an ammonia plant 33. In addition, further facilities are located in a central station 35. The energy utilization node 30 is connected to the network of interconnecting pipelines 20 and parallel roads 24. The hydrogen generated in the energy generation node 10 is pumped through the hydrogen pipeline 22 to the ammonia plant 33. The liquid ammonia produced there is loaded onto ships in the harbor 31. The seawater desalination plant 32 extracts seawater from the sea 2 via a siphoning pipeline 36.The fresh water obtained therefrom is supplied to the ammonia plant 33 as cooling water and is pumped upstream via the fresh water line 22 within the intermediate connecting line 20 to supply the electrolysis plants in the nodes 10.
[0034] Without reference to a possible topography, Fig. 5 is a functional diagram of a simple form of the power generation plant 100' as shown in Fig. 2. On the left side, two functionally identical power generation nodes 10' are shown, each comprising the following: - a large number of wind turbines 11; - a variety of photovoltaic systems 12; - an electrolyzer 13; and - a local electricity distribution network 14, - via which the wind turbines 11, the photovoltaic systems 12 and the electrolyzer 13 are connected within the node.
[0035] For example, each node 10 is configured so that the connected wind turbines 11 and photovoltaic systems 12 generate 1 GW of power at peak, with most of the power being used in the electrolysis process. In an exemplary configuration, the total renewable energy generation is divided into similar nodes 10, each with 1 GW. Each node 10 consists of the following elements: - 500 MW wind - 500 MW solar - 650 MW water electrolysis in conjunction with the photovoltaic systems 12.
[0036] The power-generating nodes 10' are each connected to an intermediate connector line 20', which includes a hydrogen line 22'. The hydrogen produced from the electrolyzer 13 of node 10 is transported downstream via this line. It can be used: - for the production of hot briquetted iron (HBI) from iron ore 40 in an HBI plant 34, - for the production of ammonia in an ammonia plant 33, which can be liquefied and easily transported by ship via a port 31. - For storage in tanks 37 or for direct liquefaction and transport by ship.
[0037] The energy utilization node 30 is also assigned to the seawater desalination plant 32, through which fresh water is pumped upstream through the fresh water pipe 21 to the node 10.
[0038] Hydrogen-consuming units can be installed along the intermediate connector line 20 or centralized in the downstream node 30. For example, hydrogen- or ammonia-powered engines can be used to operate a seawater desalination plant 32 operating on the reverse osmosis principle.
[0039] In the Fig. In the embodiment of a simple green hydrogen generation system 100' shown in Figure 5, the interconnector line 20' does not contain a high-voltage electrical line. Thus, the energy generated at the nodes 10' is conducted only in the form of locally generated hydrogen through the hydrogen line 22'. The only electrical connections in this green hydrogen generation system are established via the local power distribution grid 14 within each node 10.
[0040] Fig. Figure 6 is a functional diagram of a more complex green hydrogen production system 100 with a higher level of equipment. On the left side, two functionally identical power generation nodes 10 are shown, each comprising: - several wind turbines 11; - several arrays of photovoltaic systems 12; - an electrolyzer 13; - a local electricity distribution network 14 connected via a transformer 15 to a high-voltage line 23 as part of the wide area network provided by the interconnector line 20; - a flow battery module 16 for long-term buffering of the devices connected to the internal power distribution network 14; - a lithium-ion battery 17 for short-term buffering and / or stabilization of the power distribution network 14 on site; - a rotor inertia storage device 18 for stabilizing the frequency of the local power distribution network 14.
[0041] With such a configuration, the operation of the power-generating node 10 can be extended to periods of low wind speed and low solar energy, making it more resilient. Reserve capacities of electrical energy and hydrogen gas are stored in the node and can be used for the continuous operation of all control systems, the substation, the compressors, and the cooling systems for the electrolyzer and the compressors. Finally, the stored energy can also be used to keep the electrolysis process running at a low level.
[0042] A rotor inertia storage system 18 ensures the stability of the on-site power distribution network 14 during short interruptions in power generation of approximately 1 to 3 minutes.
[0043] The energy generation nodes 10 are each connected to the intermediate connector line 20, which comprises the fresh water line 21, the hydrogen line 22 and a high-voltage electrical line 23. Via the hydrogen line 22, the hydrogen obtained from the electrolysis unit 13 of the node is supplied to the energy utilization node 30, where it can be used in the same way as previously described with reference to Fig. 5 described.
[0044] Any surplus electrical energy that cannot be processed on-site in the electrolyzer 13 of the power-generating node 10 can be fed into the high-voltage electrical grid for consumption at any downstream energy-consuming node 30. However, on-site hydrogen production and control of the green hydrogen production system 10 via the hydrogen gas supply continue to take priority over the generation of electrical power distributed via long-distance transmission lines.
[0045] Fig. Figure 7 is a schematic representation of the topography of a node 300 of a hybrid power plant comprising sixteen wind turbines 301...316 arranged in four columns 321...324 and four rows 331...334. Many photovoltaic systems are grouped and arranged in a node 320.
[0046] The illustrations in Fig. 7 and the following illustrations in the Fig. Figures 8 to 11 are only schematic and not to scale. Rather, the distance between adjacent rows 331...334 and between adjacent columns 321...324 of wind turbines 301...316 is at least 5 times the rotor diameter, preferably at least 10 times. In some applications, even a minimum distance of 3 times the rotor diameter is sufficient.
[0047] A wind field 350 moving from north to south across the area of node 300 is symbolized by three block arrows. The active wind turbines 301...304, 309...312 in rows 331, 333 are in generator mode. They are symbolized by the dashed circle around the propeller blades, while the wind turbines in rows 322, 324 without such a circle symbol are in idle mode. With the moving wind field 350, a field of clouds 340 moves over node 300 and toward the node center 320 with the photovoltaic systems.
[0048] In a following state of the same node 300, which is in Fig. As shown in Figure 8, clouds 340 are now located above the photovoltaic systems in node center 320, resulting in significant solar power losses there. These losses can be compensated for by switching the wind turbines in rows 331 and 333 to generator mode in a timely manner.
[0049] Fig. Figure 9 shows the situation with the wind field 350 moving away from node 300, which also drives the clouds 340 away from the node center 320 with the photovoltaic systems.
[0050] While in the state of node 300 in the Fig. 7 and Fig. 8 The wind turbines in rows 331, 333 were in generator mode, but the generator mode now transitions in a wave-like manner to rows 332, 334, while rows 331, 333 return to idle mode. In this way, the wind energy in wind field 350, which extends beyond node 300, is optimally utilized because, on the one hand, the wind turbines generate electricity where the wind speed is highest, and, on the other hand, rows 331...334 maintain sufficiently large distances from each other so that mutual influence due to wake effects is significantly reduced or completely avoided.
[0051] Fig. Figure 10 shows a state of node 300 after the wind direction 350 has changed and a field of clouds 340 is drifting from west to east over the node. The wind turbines 301...316 of node 300 have been regrouped so that the wind turbines in columns 321, 323 are initially in generator mode and are switched to idle mode after columns 322, 324 have been activated.
[0052] Another situation is in Fig. 11 to illustrate the flexibility of the control method. In this node 300', photovoltaic systems are installed at a total of four nodes 320.1, 320.2, 320.3, and 320.4. Given the northerly wind direction 350 and the L-shape of the cloud field 340 determined from weather observations, it is to be expected that the photovoltaic systems in the two western node centers 320.1 and 320.3 will both suffer a power loss when clouds 340 cover them. However, in the two eastern node centers 320.2 and 320.4, only one after the other will suffer a power loss, since the cloud field 340 is not as large there in the direction of travel.
[0053] In the example, the cluster of wind turbines located in Fig. 11, which are marked by the dashed circle and are to be switched to generator mode to compensate for shaded photovoltaic systems, are selected such that the cloud shape is reflected in the arrangement of the selected wind turbine. This cluster arrangement has the advantageous side effect that the wind turbines selected for generator mode are arranged near the photovoltaic systems in the node centers 320.1, 320.2, 320.3, 320.4, thereby minimizing the length of the electrical energy transmission lines between the selected wind turbines and the node centers and consequently minimizing the transmission losses.
[0054] After explaining the general concept of the control method according to the invention using the Fig. The schemes shown in Figures 7 to 11 illustrate the procedure using the Fig. 12 to 15, each of which shows a western area that is part of the system 100 for producing green hydrogen from Fig. 1 is.
[0055] In the Fig. Under the weather conditions shown in Figure 12, the entire western area is cloud-free. The wind direction of the approaching wind field 350 is north. All photovoltaic systems 12 at all nodes 10.17...10.24 are to operate without lead. The northernmost nodes, 10.17 and 10.21, can be used primarily to supply downstream facilities, as their wind turbines generate more electricity due to their location in the wind direction. The wind turbines at the subsequent nodes 10.18 and 10.22 will be shut down first, thus reducing the wake. Nodes 10.19 and 10.23 can also utilize wind generation, and the wind turbines at nodes 10.20 and 10.24 will also be throttled back.
[0056] A control strategy can be used to determine where and to what extent individual wind turbines can be throttled or switched off, thus optimizing overall production.
[0057] As in Fig. As can be seen in Figure 13, wind field 350 is moving a large cloud field 340, which is influencing the photovoltaic systems at the upwind nodes 10.17 and 10.21. Power generation by wind turbines will be maximized at these nodes to compensate for the losses in the photovoltaic systems' energy yield. Other nodes 10.18, 10.19, 10.20, 10.22, 10.23, and 10.24 will continue to operate with maximum photovoltaic power and reduced wind energy generation. These nodes will have lower wind energy production because the upwind nodes 10.17 and 10.21 will cause more wake effects.
[0058] In the Fig. In the situation shown in Figure 14, clouds 340 have passed the upwind nodes 10.17 and 10.21 and now cover nodes 10.18 and 10.22. At nodes 10.18 and 10.22, below the clouds, wind energy production is maximized to compensate for the losses of the photovoltaic systems. At nodes 10.17 and 10.21, the photovoltaic systems are ramped up again after clouds 340 have passed. Wind energy production at nodes 10.17 and 10.21 can be throttled back, resulting in a smaller wake effect, allowing the downstream nodes 10.18 and 10.22 to increase wind energy production. All other nodes 10.19, 10.20, 10.23, 10.24, which are downwind of nodes 10.18, 10.22, will have lower wind production, as nodes 10.18, 10.22 will generate more wake effects.
[0059] In the Fig. In the state shown in Figure 15, clouds 340 have already passed over most of the site and now only cover the photovoltaic systems at nodes 10.20 and 10.24. At the cloud-covered nodes 10.20 and 10.24, wind energy production is maximized to compensate for the loss of the photovoltaic systems. At all other nodes located upwind of nodes 10.20 and 10.24, the photovoltaic systems are ramped up after clouds 340 have passed. At all nodes, wind energy production is low, allowing nodes 10.20 and 10.24 to increase wind energy production.
[0060] An example of the implementation of the method according to the invention is described with reference to the flow charts in the Fig. described.
[0061] In a starting phase that is in the upper half of Fig. As shown in Figure 16, a starting parameter is required on which the subsequent steps are based. The amount of electrical energy required for the constant operation of the electrolyzer or a set of several electrolyzers is defined as the energy demand value (EBW). In principle, this value is constant for the electrolyzer(s) installed in the monitored power plant or its monitored area. However, it can vary, for example, due to changes in the ambient temperature. The starting parameter can be set by input via the user interface or using historical data, provided the hardware schema has remained unchanged.
[0062] After the start of the procedure, the weather conditions in the monitored area of the power plant and its surroundings are continuously monitored, at least in a windward area of the wind turbine sites.
[0063] Based on the weather conditions obtained from weather monitoring and / or forecasting, the expected energy yield (EEW) is calculated for each type of power generation unit within the area controlled and monitored by the method. The energy yield (EEW) is the forecast value for the expected electrical energy generated.
[0064] A comparison between the energy demand value EBW on the one hand and the total energy yield values EEW of all photovoltaic systems on the other hand shows whether the yield of solar energy in the system will be sufficient or not: - If sufficient solar energy yield is expected, all photovoltaic systems will be operated at full capacity, while the wind turbines will remain idle; running wind turbines will be stopped so that they are no longer part of the energy supply system during the calculated forecast period. - If the solar energy yield is zero (e.g. at night) or very low compared to the expected energy yield of the wind turbines, the energy supply of the electrolyzer(s) is based exclusively on the wind turbines. - In the third alternative, neither the expected energy yield of the photovoltaic systems nor the expected energy yield of the wind turbines is sufficient to operate the electrolyzer(s) alone.
[0065] The last alternative is more complex, but will occur more frequently in reality than the other cases. According to the invention, the use of photovoltaic systems generally takes priority over the use of wind turbines, so that if additional wind turbines are required to support the supply of electrical energy to the electrolyzer, their number is kept to a minimum and / or the running wind turbines are throttled to a minimum load.
[0066] To ensure the most effective use of wind turbines in terms of maintenance costs and the service life of the turbines, a wind turbine cluster is formed according to certain criteria.
[0067] To find the best wind turbine cluster for operation in the next operating period, a cost-benefit ratio is calculated for at least two different cluster models, using digital twins of each wind turbine so that the optimization takes into account the individual characteristics of each wind turbine.
[0068] In the Fig. In the example shown in Figure 17, four cluster models are defined and compared: - According to an initial potential cluster model, from the multitude of wind turbines installed in the power plant, those that are arranged in rows perpendicular to the wind direction are selected. - According to a second cluster model, wind turbines are selected from a node area that has a similar size and shape to the moving cloud field detected during the previous monitoring. - In another cluster model, those wind turbines are selected that have the fewest operating hours since their installation. - In another cluster model, those wind turbines are selected that have the fewest remaining operating hours before the end of their service life or before the end of the maintenance interval.
[0069] As a result of the calculation, the cluster model with the best cost-benefit ratio is selected and the corresponding wind turbine in the field is set to generator operation.
[0070] The following considerations are made for building cluster models that can be compared with each other and then used for operation if they are suitable: - Wind conditions such as wind speed, wake, turbulence, wind shear, etc. at each wind turbine site. - Temperature and solar radiation can affect the ambient temperature at the wind turbine's location. A wind turbine shaded by a cloud may operate more efficiently in a hot climate, and vice versa in a cold climate where the combination of wind and solar power cannot be chosen frequently. Wind turbines exposed to the sun and at very high temperatures, or wind turbines away from the sun and at very low temperatures, may require throttling or shutdown. - Operating time of each wind turbine: How many operating hours does the wind turbine have? This could lead to the conclusion to equalize the operating hours per wind turbine or to use some wind turbines more heavily to replace them sooner than newer wind turbines. - When is the next scheduled maintenance due? Depending on the service personnel's schedule and the availability of spare parts, the appointment may be extended or expedited. - What is the current maintenance status of each wind turbine, and what impact might the next operating period have on them? Is there a component that requires limited operation of the wind turbine due to damage or wear? - Are there any known problems with a particular wind turbine such that not all installed wind turbines are available in a particular area? - In densely populated areas, further considerations might include the turbine's location in relation to noise receptors / shadows or other environmental constraints. Can environmental disturbances be avoided if certain wind turbines remain shut down? - How far is the wind turbine from the load, i.e., the distance from the electrolyzer to the node to which the wind turbines are connected? The shorter the distances, the lower the electrical losses. - Consideration of the balance of plant (BOP): When forming a wind turbine cluster, it is important to know whether maintenance or repair work is planned for a specific part of the wind farm. For example, if an overhead line to a specific wind turbine requires maintenance, that wind turbine should not be included in a cluster, or at least not given priority.
[0071] Based on these considerations and input data, the electricity costs for each wind turbine can be calculated using a digital model. The result of this calculation will create a ranking of the wind turbines with the lowest electricity costs under current conditions.
[0072] A control device then selects those wind turbines with the lowest electricity generation costs until the required capacity defined by the energy demand value EBW is reached.
[0073] If wind and / or solar conditions fluctuate greatly or are highly intermittent, excess energy can be stored in a battery energy storage system (BESS), or vice versa. Any missing energy can be quickly discharged from a BESS at any time. The BESS thus balances the fluctuations in the expected energy yield (EEW) and the energy demand (EBW) by using a battery instead of constantly switching the wind turbine on and off.
[0074] Alternatively, wind turbines can remain in operation but be operated in a throttled mode, e.g. by intentionally increasing the pitch angle.
[0075] In the Fig. In the example of the control method shown in Figure 17, a simple form is used, since many cluster models are compared at once and one of them is selected to be put into operation.
[0076] An alternative method used in Fig. As shown in Figure 18, the definition and selection of the cluster model is more complex: First, a subset of wind turbines is selected in the area affected by shading or other weather influences, and in a second step, some wind turbines are selected from this subset according to other criteria mentioned above, such as service life or wear, etc. This multi-stage approach is preferably applied in large plants where the number of available wind turbines is greater than the number of required wind turbines.
[0077] While in the Fig. 17, four cluster models are defined and compared in parallel, an alternative subroutine is provided, which is Fig. 18 of the procedure, an initial set of criteria is used to calculate a cost-benefit ratio. This initial set of criteria is weather-dependent. The result is a large subset of wind turbines suitable for clustering to generate additional power.
[0078] In a second step, another set of criteria is used to make the final selection of those wind turbines to be commissioned from the first subset. The second group of criteria relates to service life, maintenance intervals, or wear and tear.
[0079] The Fig. The two-stage approach shown in Figure 18 is advantageous for large power plants with a large number of available wind turbines. With this approach, the cluster formed is based on both weather-related and lifetime considerations. Reference symbol: 1 coastal region 2 Sea 100 systems for producing green hydrogen 10; 10.1, ..., 10.24; 10' nodes 11 wind turbines 12 photovoltaic systems 13 Electrolyzer 14 electrical power distribution network 15 Transformer 16 Battery module 17 lithium-ion battery 18 rotor inertia storage 19 Main Station 20 connecting line 21 Fresh water pipe 22 Hydrogen pipeline 23 electrical high-voltage lines 24 lane 29.1, 29.2, 29.4 Secondary connection line 30 power consumption nodes 31 Port 32 water desalination plant 33 Ammonia treatment plant 34 HBI system 35 substation 36 spur lines 37 tanks 40 iron ores 300; 300' knots 301...304; 313...316 Wind turbines 320; 320.1, 320.2, 320.3, 320.4 Junction 321...324 columns 331...334 lines 340 clouds 350 wind fields
Claims
[1] Method for controlling a system (100; 300) for producing green hydrogen, comprising: a plurality of photovoltaic (PV) systems (12) arranged in geographically distributed node centers (300) of a power grid, and a plurality of wind turbines (WEA) (11) as power generation units arranged at geographically distributed locations surrounding the grid nodes, wherein: the plurality of photovoltaic systems (12) and the plurality of wind turbines (11) are used as power generation units for generating electrical energy and at least one electrolyzer (13) is used for generating green hydrogen, wherein the installed power (IC) of the electrolyzer (13) and all other energy-consuming devices in the power plant is less than the power of the sum of the maximum power (MC) of the photovoltaic systems (12) and the plurality of wind turbines (11) together, the method comprising at least the following steps: (a) definition of an energy demand value (EBW) of the electrical power required for the continuous operation of the electrolyser (13) and other consumers, where EBW < IC; (b) continuous monitoring of weather conditions in the vicinity of the power generation units and upwind of the photovoltaic installations (12); c) Separate calculation of an expected energy yield (EEW) for each type of power generation unit based on the weather conditions obtained from monitoring; (d) allocating an individual workload for both the photovoltaic systems (12) and the wind turbines (11), selected according to the following prioritisation scheme: i. if the expected energy yield value EEW(PV) of the photovoltaic systems (12) alone is sufficient to meet the energy demand value EBW, all photovoltaic systems (12) are operated at full load and all wind turbines (11) are operated at idle or switched off; ii. If the expected energy yield EEW(PV) of the photovoltaic systems (12) is zero or below the threshold, but the expected energy yield EEW(WTG) of the wind turbines (11) is high, only the wind turbines (11) are used; iii. if moving clouds (340) are detected and, due to the partial shading of some photovoltaic systems, it is expected that the expected energy yield value EEW(PV) of the photovoltaic systems is not sufficient to meet the energy demand value EBW alone, the wind turbines (11) are used in addition to the photovoltaic systems, but are cut to a minimum load so that only the difference between the energy demand value EBW and the expected energy yield value EEW(PV) of the photovoltaic systems (12) is provided by the wind turbines (11) in generator mode, wherein the wind turbines (11) intended for generator mode are selected from the set of wind turbines (11) to form a cluster. [2] The method according to claim 1, wherein - based on the weather conditions obtained from the monitoring, a fatigue and wear indicator (EVI) is calculated for each individual wind turbine and - the individual workload of each wind turbine is set so that the fatigue and wear indicators (EVI) for all wind turbines in the renewable energy hybrid power plant remain below a threshold value. [3] Method according to claim 1 or 2, wherein the wind turbines (11) are grouped together to form a cluster in at least one row running transversely to the current wind direction (350). [4] Method according to claim 1 or 2, wherein the wind turbines (11) are selected such that the cluster corresponds in size and shape to the moving cloud field (340). [5] A method according to any one of claims 1 to 4, wherein in cases (ii) and (iii) wind turbines located upwind are selected to be operated with higher priority or to be assigned a higher individual workload than wind turbines located downwind. [6] Method according to one of claims 1 to 5, wherein in cases (ii) and (iii) wind turbines which are closer to the electrolyzer (13) are selected to operate in generator mode with higher priority or to be assigned a higher individual workload than wind turbines which are further away. [7] A method according to any one of claims 1 to 6, wherein in case (iii) individual wind turbines from a group of neighbouring wind turbines are selected to operate with higher priority or to be assigned a higher individual workload such that the distance between the selected operational wind turbines is at least 5 rotor diameters.