Patent Application
20240318336
This application claims the benefit of priority of Indian patent application 202321020421, filed 23th of Mar. 2023, the entire contents of which are incorporated herein by reference.
The present invention is directed to a method for controlling an electrolyzer arrangement, an electrolyzer arrangement for the same and a power plant having said electrolyzer arrangement.
In prior art several systems of renewable energy power plants combined with hydrogen production plants are known as well as several control schemes for controlling the input power and system operation control are also known.
One example is EP 3 957 773 A1, which discloses an energy composite hydrogen production system and a control method therefore. The energy composite hydrogen production system comprises: an energy power generation system, a power conversion system, an alkali liquid hydrogen production system, and a non-alkali liquid hydrogen production system. An output end of the power conversion system is connected to an input electrode of the alkali liquid hydrogen production system and an input electrode of the non-alkali liquid hydrogen production system, respectively, so that the power conversion system can, according to the quantity of energy outputted by the energy power generation system, choose to provide hydrogen production energy to the alkali liquid hydrogen production system or the non-alkali liquid hydrogen production system. Furthermore, the non-alkali liquid hydrogen production system can replace battery energy storage so as to implement energy reception in a weak energy region, thereby avoiding the waste of energy and improving the economic benefits of hydrogen production.
Further prior art is IN 8992/DELNP/2012 A which discloses a nested configuration of electrolysis units, independently operated, the power output values of which are descendant in such a manner that, for any unit of the system, the sum of the power output values of the smaller electrolysis units is always greater than or equal to the “dead band” (DB) of said units, allowing reduction of the dead band of said hydrogen production system to negligible levels, avoiding loss or discharge of the energy generated in said renewable power stations, preferably one or several wind farms formed by a group of wind turbines, connected to the power grid as a consequence of the implementation of a primary control service therein or, in general, of any other active power control service, thereby optimizing the total energy obtained.
Further prior art is EP 4 057 476 A2 which discloses a system for producing hydrogen from renewable energy and a control method thereof. The system includes a renewable-energy-based power generation system, a primary hydrogen production system, a secondary hydrogen production system, and a controller. An output end of the renewable-energy-based power generation system is connected to the primary hydrogen production system and the secondary hydrogen production system via an electrical conversion device. A capacity of the primary hydrogen production system is greater than or equal to a capacity of the secondary hydrogen production system. The controller is configured to monitor an output electrical performance parameter of the renewable-energy-based power generation system in real time, and control turn on and turn off of the primary hydrogen production system and the secondary hydrogen production system.
The prior art fails to address the system power management, operation and control strategy within the hybrid system configuration with variable power sources. Furthermore; the balance of plant system operation standby mode/part load operation/full load operation will have different operating and control strategies which the prior art fails to provide.
One object of the present invention is to provide a method for controlling an electrolyzer arrangement with two or more electrolyzers of same or different technologies. Another object of the invention is to provide flexible operation modes for maximum capacity or maximum efficiency using the hybrid electrolyzer arrangement.
This object will be solved by a method for controlling an electrolyzer arrangement having at least two electrolyzers for optimized plant operation. In particular the electrolyzer arrangement comprises of two or more electrolyzers of similar or different technologies. The method comprises the steps of obtaining electrical power provided by an electrical power source, obtaining required electrical power of power plant and determining available power for hydrogen production based on provided electrical power and required electrical power, wherein determining an upper and lower operating limit of a primary electrolyzer of the electrolyzer arrangement and controlling the primary and at least one secondary electrolyzer depending on the available electrical power and operating limit of the primary electrolyzer and secondary electrolyzer.
Advantageously, the electrolyzer arrangement can be for example a combination of alkaline electrolyzer (ALK) and alkaline electrolyzer with different sizes; polymer electrolyte membrane electrolyzer (PEM) and alkaline electrolyzer or alkaline electrolyzer and polymer electrolyte membrane electrolyzer and solid oxide electrolyzer (SOEC). These electrolyzers are sized to meet the hydrogen production requirement while maintaining low level of cost of hydrogen.
More advantageously, an electrical power source can be a wind power plant, solar power plant, hydro power plant or energy storage system or a combination thereof.
According to a preferred embodiment, the method further comprises the step of starting the primary electrolyzer if available electrical power is between upper and lower operating limit of the primary electrolyzer and the secondary electrolyzer is in standby mode.
Advantageously, in this case the secondary electrolyzer is in standby mode. In this mode, the secondary electrolyzer consume minimum power to keep the electrolyzer in warm state so that it can quickly start it's operation when the power is sufficient to initiate it's operation.
According to a preferred embodiment, the method further comprises the step of starting the at least one secondary electrolyzer if the available electrical power is less than the lower operating limit of the primary electrolyzer, wherein the primary electrolyzer is in standby mode.
Advantageously, in this case the primary electrolyzer is in standby mode. In this mode, the primary electrolyzer consume minimum power to keep the electrolyzer in warm state so that it can quickly start it's operation when the power is sufficient to initiate it's operation. Advantageously minimum available electrical power can be used for hydrogen production via the at least one secondary electrolyzer.
According to a preferred embodiment, the method further comprises the step of starting the at least one secondary electrolyzer and primary electrolyzer if the available electrical power is higher than the upper operating limit of the primary electrolyzer.
According to a preferred embodiment, the method further comprises the step of operating at least one secondary electrolyzer and primary electrolyzer, if the available electrical power is between maximal operation point of the upper operating limit of the electrolyzer arrangement and maximal operation point of the upper operating limit of the primary electrolyzer then the electrolyzer arrangement provides maximum hydrogen production efficiency.
According to a preferred embodiment, the method further comprises the step of operating at least one secondary electrolyzer and primary electrolyzer, if the available electrical power is at maximal operating point of the upper operating limit of the electrolyzer arrangement and is at maximal operation point of the upper operating limit of the primary electrolyzer then the electrolyzer arrangement provides maximum hydrogen production rate.
In particular, with this configuration the optimal load and most efficient point is reached. The at least one secondary electrolyzer provides additional capacity to the primary electrolyzer and primary electrolyzer operates at operating point lower than maximum operating point and is at maximum hydrogen production efficiency. Advantageously, overpower of primary electrolyzer can be used for hydrogen production via the at least one secondary electrolyzer. In this context, starting has no restrictive meaning in sense of the respective electrolyzer starts from a non-operating point. It is clear that during the operation the available power can change and the electrolyzers can switch from standby mode to operation mode and vice versa. Especially in case the available power reaches the upper operational limit of the primary electrolyzer the at least one secondary electrolyzer will switch from standby mode to operation mode for providing additional capacity while the primary electrolyzer stays in operation mode,
According to a preferred embodiment, the method further comprises that the primary electrolyzer is characterized by a slow response time, e.g. in minutes and or limited low operating point and is higher in capacity and the at least one secondary electrolyzer is characterized by a fast response time, e.g. in seconds or similar response time and not limited by low operating point and is small in capacity.
Advantageously, the primary electrolyzer is a slow responding type of electrolyzer and the at least one secondary electrolyzer is a fast responding type of electrolyzer. In a more preferred embodiment the electrolyzer arrangement comprises an alkaline electrolyzer sized up to multi megawatt scale as primary electrolyzer and at least one polymer electrolyte membrane electrolyzer sized in kilowatt scale as secondary electrolyzer.
According to a preferred embodiment, the method further comprises that the upper and lower operating limit of electrolyzers depending on the balance of plant power requirement of the electrolyzers.
A further aspect of the invention is directed to an electrolyzer arrangement for producing hydrogen.
The electrolyzer arrangement for producing hydrogen comprising at least two electrolyzers, wherein the electrolyzer arrangement comprise a primary electrolyzer and at least one secondary electrolyzer, connected to a controller configured to executing said method mentioned above.
Advantageously, the electrolyzer arrangement can be for example a combination of alkaline electrolyzer (ALK) and alkaline electrolyzer with different sizes; polymer electrolyte membrane electrolyzer (PEM) and alkaline electrolyzer or alkaline electrolyzer and polymer electrolyte membrane electrolyzer and solid oxide electrolyzer (SOEC). Size and count of the electrolyzers of the electrolyzer arrangement depends on the provided electrical power by the power source. The higher the provided available electrical power the higher can be the size and count of the electrolyzers of the electrolyzer arrangement.
A further aspect of the present invention is directed to a power plant for producing electrical power and hydrogen.
The power plant for producing electrical power and hydrogen comprising at least one wind turbine or at least one solar power plant or at least one hydro power plant or at least one energy storage device or combination thereof, characterized by said electrolyzer arrangement mentioned above.
Advantageously, the power plant comprises of common water treatment & power distribution unit which regulates the input power as well as water required for the electrolyzer arrangement. Further the balance of plant components for the electrolyzer arrangement comprises a gas separation, purification equipment, thermal management to handle the requirements of both primary as well as secondary electrolyzers.
A further aspect of the present invention is directed to a method for operating said power plant.
A further aspect of the present invention is directed to a computer program product.
The computer program product comprises instructions which, when the program is executed by a computer, cause the computer to carry out the steps of said method mentioned above.
Advantages of the present invention are:
The invention will now be explained in more detail with respect to exemplary embodiments with reference to the enclosed drawings, wherein:
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.
The power source 2 comprises a hybrid renewable power arrangement comprising of solar power plant 7, a wind power plant 8 and a hydro power plant 9. The solar power plant 7 comprises at least one solar panel and the wind power plant 8 comprises at least one wind turbine. In consequence the power source 2 provides electrical power from renewable power sources with natural fluctuations, natural daily pattern and seasonal variations. Such fluctuations and pattern can be handled by the electrolyzer arrangement 3 according to the present invention, which will be explained later. The electrolyzer arrangement 3 and remaining balance of plant components of the electrolyzer arrangement 3 receives electrical power from the power source 2. The electrolyzer arrangement 3 receives the electrical power through a power management circuit 10. Further the power source 2 can optionally comprising of an energy storage device (not shown in
Further the power plant 1 comprises a water supply device 11 for providing water for hydrogen production. This water can be provided by tanks, pipelines and/or natural water sources like river or sea. From the water supply device 11, water will be provided to a water purification device 12 for cleaning the water from particulates, salts and other contaminations. The purified water will be stored in a purified water storage device 13. The purified water will be transferred to the primary electrolyzer 5 and to the secondary electrolyzer 4 with the help of flow control arrangement (not shown) so that electrolyzer operation can be handled independently or together depending upon the need. Further a water re-circulation loop consists of polishing system to purify re-circulating water (not shown in
The controller 6 controls and manages the input power and provides regulated power to the primary electrolyzer 5 and secondary electrolyzer 4, which is indicated by dashed line. When the power source 2 provides low electrical power like between 5-30% of nominal load required for primary electrolyzer 5, the controller 6 configured so that the electrical power will be provided to the secondary electrolyzer 4 while the primary electrolyzer 5 is maintained in standby mode. In this mode, the primary electrolyzer 5 consume minimum power like between 1-5% of nominal electrical capacity, to keep it in warm state so that it can quickly start it's operation when the power is sufficient to initiate it's operation. If the electrical power is in a sufficient range then the primary electrolyzer 5 will be activated and the secondary electrolyzer 4 will be in standby mode. When more electrical power available is than from the primary electrolyzer 5 is required, both the primary electrolyzer 5 and the secondary electrolyzer 4 operate to produce maximum amount of hydrogen. In another scenario, when more power is available both the electrolyzer 4, 5 operates at highest efficiency point i.e. less than 100% capacity factor e.g. 80-90% capacity point and varies from one technology to another. In this case there is no need to curtail the extra electrical power from the power source 2. The additional electrical power can be diverted to energy storage device (not shown) while maintaining electrolyzer arrangement 3 operation at highest efficiency point. The secondary electrolyzer 4 is used in two scenarios; when input electrical power available is less than lower operating limit of the primary electrolyzer 5 and additional electrical power is available more than the primary electrolyzer 5 requirements beyond maximum efficiency point. The controller 6 maybe is implemented in a park controller of the power plant (if available).
In a not shown embodiment the power plant 1 can comprise more than one electrolyzer arrangement 3. These electrolyzer arrangements can be controlled by an individual controller or by a central controller.
In following the method for controlling an electrolyzer arrangement 3 will be explained with help of
Step S1 comprises obtaining available electrical power provided by the power source 2. This data will be provided to the controller 6. To obtain the electrical power several methods are possible, for example measuring output power from the power source 2, in particular from the solar power plant 7, wind power plant 8 and hydro power plant 9 via a measuring device not shown. Another example can be that the plant controller of the respective power plants 7, 8, 9 maybe determine the electrical power output and send the data to the controller 6. Or any other suitable method is possible. Available power check will be done continuously during the operation.
Step S2 comprises obtaining a required electrical power of the electrolyzer arrangement 3. The required electrical power for the primary electrolyzer 5 and secondary electrolyzers 4 determined by excluding the power required for the auxiliaries of the power plant 1. This covers all required power of the primary electrolyzer 5 and secondary electrolyzer 4 for standby mode and operation mode. Depending on this as well as the size and count of the respective electrolyzers have influence of the required power. It is also possible that the remaining electrical power consuming components of the power plant 1 will be considered for determining the required electrical power. In this case also the consumed power of water supply device 11, water purification device 12, purified water storage device 13, cooling system 14, 15, gas purification module 16, gas purification system 17 and hydrogen storage/consumer 18 can be considered.
Step S3 comprises determining available power for hydrogen production based on provided electrical power and required electrical power. The available power for hydrogen production is the result of the difference between provided electrical power of step S1 and required electrical power of step S2.
Step S4 comprises of determining power consumption from a pre-defined upper and lower operating limit of the primary electrolyzer 5 of the electrolyzer arrangement 3. In particular, the upper and lower operating limit of the primary electrolyzer 5 depends on the stack operating limits and the balance of plant operating limits of the primary electrolyzer 5.
Step S5 comprises controlling the primary electrolyzer 5 and the secondary electrolyzer 4 via the controller 6 depending on the available electrical power and determined operating limits of the primary electrolyzer 5. The individual primary electrolyzer 5 and secondary electrolyzer 4 will be switched from operation mode to standby mode and vice-versa depending on current available electrical power. Therefore the following configurations are possible:
In scenario 3 both the secondary electrolyzer 4 and primary electrolyzer 5 are in operation mode. This means that the upper operating limit of the secondary electrolyzer 4 and upper operating limit of the primary electrolyzer 5 cumulating to the upper operating limit of the electrolyzer arrangement 3 (see
If the available electrical power decreasing below the upper operating limit of the primary electrolyzer 5 then the secondary electrolyzer 4 switches from operation mode in standby mode. Also here in case that the available electrical power is between the upper and lower operating limit of the primary electrolyzer 5, it will stay in operation mode until the available electrical power falls below the lower operating limit of the primary electrolyzer 5. If the available electrical power falls below the lower operating limit of the primary electrolyzer 5 then the primary electrolyzer 5 switches from operation mode to standby mode. At the same time the secondary electrolyzer 4 switches from standby mode to operation mode.
This shows that over a wide bandwidth of available power the electrolyzer arrangement 3 can produce hydrogen with highest efficiency because of using all available electrical power and all electrolyzers working at optimal operation conditions. This optimal operation may help in reducing the production costs of hydrogen.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202321020421 | Mar 2023 | IN | national |
