BATTERY POWER PLANT WITH A COOLING SYSTEM

Description

[0001] The invention relates to a battery power plant with a cooling system, wherein the battery power plant comprises a plurality of separate battery energy storage devices which are electrically interconnected to absorb or release electrical energy. The invention relates to a battery power plant with battery energy storage devices which are designed as redox flow batteries.

[0002] Such battery power plants with a multitude of separate battery energy storage units, also referred to as battery modules, are known from the prior art. For example, WO 2014 / 170373 A2 discloses a battery power plant with several parallel-connected battery strings, each battery string comprising several DC battery modules connected in series.

[0003] Furthermore, it is known from the prior art that individual redox flow battery modules can have a cooling system. Such a battery module includes one or more heat exchangers with which the electrolyte of the battery module can be cooled. The heat exchanger can be located at various points within the battery module, for example, in or on the electrolyte tanks, in the cells of the battery module, or on the pipe system through which the electrolyte is circulated. Reference is made to WO 2019 / 126381 A1, US 9,774,044 B2, and WO 2019 / 139566 A1. CN 203134898U also discloses a redox flow battery power plant in which the battery modules are connected in parallel and the batteries are cooled by a cooling system. The cooling system consists of a circuit and is connected to each battery.The electrolyte is cooled by means of heat exchangers, and the flow of the coolant is regulated by valves connected to a control unit with temperature sensors in the electrolyte. The heat exchangers are integrated into the electrolyte circuit and thus monitor the electrolyte temperature.

[0004] The object of the invention is to provide a battery power plant with redox flow type battery energy storage devices and with a cooling system which is suitable to improve the efficiency of the battery power plant.

[0005] The problem is solved according to the invention by an embodiment according to the independent claim. The problem is further solved by an operating method according to the independent method claim. Further advantageous embodiments of the present invention are found in the dependent claims.

[0006] The invention will be explained below with the aid of figures. The figures show, in detail: Fig.1 Redox flow battery module Fig.2 Battery power plant according to the invention Fig.3 Electrical structure of a battery power plant

[0007] Figure 1Figure 1 on the left shows a schematic representation of a redox flow battery module. The battery module is labeled 1. It comprises a cell array, labeled 2, and a reservoir, labeled 3. The cell array 2 is an arrangement of multiple redox flow cells, which can be arranged in any configuration. For example, it could be a single cell stack (i.e., several redox flow cells connected in series), several stacks connected in series, several stacks connected in parallel, or a combination of series and parallel connections of several stacks. The reservoir 3 serves to store the electrolyte and supply the cell array 2 with electrolyte. With few exceptions, the reservoir 3 comprises at least two tanks, a pipe system for connecting the tanks to the cell array 2, and pumps for circulating the electrolyte.. Figure 1 The figure shows two separate pumps. The electrolyte could just as easily be pumped using a double-head pump, i.e., two pumps driven by a common motor. The tank assembly 3 is designed to supply all cells of the cell arrangement 2 with electrolyte. Thus, when the pumps are circulating the electrolyte, all cells of the cell arrangement 2 are supplied with it.

[0008] The battery module 1 includes at least one temperature sensor, which is arranged so that it can detect an electrolyte temperature. Figure 1 Two such sensors are shown, one of which is labelled 4. The temperature sensors 4 are, in the embodiment according to Figure 1 They are arranged in the tank assembly 3. However, they could just as well be arranged at any other suitable location in the battery module 1 where they can detect an electrolyte temperature.

[0009] The battery module 1 further comprises at least one heat exchanger, which is arranged and designed such that it can exchange heat with an electrolyte of the battery module 1, i.e., that it can extract heat from an electrolyte or supply heat to an electrolyte. Figure 1 Two such heat exchangers are shown, one of which is labelled 5. The heat exchangers 5 are in the embodiment according to Figure 1 They are arranged in the tank assembly 3. However, they could just as well be arranged at any other suitable location in the battery module 1 where they can effect heat exchange with the electrolyte. For a heat exchanger 5 to function, it must be supplied with a cooling fluid from outside the battery module 1. Suitable supply lines must be provided for this purpose. Figure 1The supply lines are designed such that the two heat exchangers 5 shown are connected in series, i.e., the cooling fluid first flows through one and then the other heat exchanger 5. The heat exchangers 5 could just as easily be connected in parallel or each supplied with cooling fluid separately.

[0010] In vanadium-based redox flow battery modules, the two electrolytes (positive and negative electrolyte) exhibit different thermal behavior. Therefore, when connecting the heat exchangers in series, the flow direction of the cooling fluid would be chosen so that the cooling fluid first flows through the heat exchanger in contact with the positive electrolyte, and only then through the heat exchanger in contact with the negative electrolyte.

[0011] In the supply lines for the heat exchangers 5 with cooling fluid, at least one valve is arranged with which the flow of cooling fluid through the respective heat exchanger 5 can be controlled. Figure 1 Two such valves are shown, one of which is labelled 6. To ensure the functionality of the in Figure 1 In the illustrated embodiment, one of the two valves 6 would suffice. If two valves 6 are provided, this facilitates the installation or replacement of a battery module 1 in a battery power plant according to the invention, since the battery module in question can be completely decoupled from the cooling circuit. Figure 1 The valves 6 are shown outside of battery module 1. They could just as easily be part of battery module 1, i.e., located within the dashed frame.

[0012] On the right side of Figure 1A symbolic representation of battery module 1 is shown. The depicted "internal components" of battery module 1 are reduced to at least one temperature sensor 4 and at least one heat exchanger 5.

[0013] Figure 2 Figure 1 shows a battery power plant according to the invention. The battery power plant comprises a plurality of separate battery modules 1, wherein the battery modules 1 are arranged in several parallel-connected battery strings, and wherein each battery string comprises several battery modules 1 which are connected in series. Figure 2 Two such battery strings are shown, each marked by a dashed frame. One of the battery strings is labeled 7.

[0014] The battery power plant according to the invention comprises a cooling system for supplying the heat exchangers 5 of the battery modules 1 with cooling fluid. The cooling system comprises a supply and a return line. All battery modules 1 of the battery power plant are connected to the supply and return lines, i.e., the cooling circuit of the cooling system forms a parallel connection of all battery modules 1 of the battery power plant. At least one valve 6 is provided for each battery module 1, with which the flow of cooling fluid through the heat exchanger(s) 5 of the respective battery module 1 can be controlled.

[0015] To minimize the overall pipe length of the cooling system, it is advantageous to design the cooling system so that the heat exchangers of several battery modules form a so-called cooling line. A cooling line comprises two parallel pipes, with each battery module 1 belonging to the cooling line being connected to these two pipes. It is convenient, for example, for all battery modules belonging to a battery string to form a single cooling line. Unlike the electrical connection of the battery modules in a battery string, the associated heat exchangers 5 of the battery modules in a cooling line are connected in parallel. A cooling line can also connect the battery modules of more than one battery string. Figure 2The diagram shows two battery strings as an example, where the battery modules of each string are connected by an associated cooling line. The two parallel lines of the cooling lines each terminate in a cooling line which is... Figure 2 The cooling loop is located on the right and will be referred to below as the main cooling loop. The cooling loops and the main cooling loop form a cooling circuit.

[0016] The cooling system further includes at least one circulation pump with which the cooling fluid can be circulated in the cooling circuit. If the cooling system includes only one circulation pump, then this is expediently arranged in the main cooling line. Figure 2 The circulation pump shown is labeled 10. The cooling system thus comprises a supply and a return line, with the heat exchangers of the individual battery modules each being connected to the supply and return lines, as shown in Figure 2 depicted.

[0017] The cooling system also includes at least one cooling device, designated 9, which is connected to the supply and return lines of the cooling circuit. The cooling device 9 is designed to influence the temperature difference between the supply and return lines. Such a cooling device 9 can, for example, include a heat exchanger and a fan, wherein the heat exchanger is designed as a liquid / gas heat exchanger. The fan directs cool outside air past the heat exchanger, thus cooling the cooling fluid flowing through the heat exchanger.

[0018] The cooling system includes at least one three-way valve. Figure 2A total of three three-way valves are shown, one of which is labeled 8. One of the three-way valves 8 is arranged to control the flow rate of the cooling fluid flowing through the cooling unit 9. This three-way valve 8 thus allows the temperature difference between the supply and return lines in the main cooling circuit, and therefore the cooling capacity of the cooling system, to be influenced. If the flow rate flowing through the cooling unit 9 is increased, the temperature difference between the supply and return lines in the main cooling circuit also increases. If more than one cooling unit 9 is provided, a corresponding three-way valve 8 must be provided for each cooling unit 9. Optionally, a three-way valve 8 can also be provided for each cooling circuit, each arranged to control the flow rate of the cooling fluid flowing through that respective cooling circuit.which flows through the two parallel pipes of the cooling circuit. These additional three-way valves 8 allow the temperature difference between the supply and return lines of the cooling circuit in question to be controlled. Figure 2 Each cooling circuit depicted contains a three-way valve 8. Optionally, an additional pump may be arranged in each cooling circuit to ensure sufficient circulation of the cooling fluid in the respective cooling circuit regardless of the position of the associated three-way valve.

[0019] In addition to the temperature sensors 4 in the individual battery modules 1, the cooling system includes further temperature sensors outside the battery modules 1. These are located in Figure 2The two sensor symbols, one of which is labeled 12, represent the following: At least two sensors 12 are used to measure the temperature in the supply and return lines of the cooling circuit. Additional sensors 12 can optionally measure the temperature in the supply and return lines of the individual cooling loops. Furthermore, temperature sensors 12 can optionally be arranged at different locations within the battery power plant to measure the temperature at those locations.

[0020] The cooling system also includes a control unit, which is located in Figure 2The control unit 11, designated as 11, processes the measured values ​​acquired by sensors 4 and 12. Control unit 11 regulates the positions of valves 6 and 8 to improve the efficiency of the battery power plant. This efficiency could refer, for example, to energy efficiency with regard to the waste heat from the cooling system. However, it could also refer to the electrical efficiency of the battery power plant, as will become clear in the explanations below.

[0021] The control system can also advantageously incorporate further factors in the described control process. Such additional factors include, for example, the weather or a weather forecast, or the historical and predicted load profile of the battery power plant.

[0022] The control unit naturally also incorporates the thermal behavior of the battery modules into its control process. Generally, a redox flow battery module becomes electrically more efficient when it gets warmer, as this reduces its internal electrical resistance. However, the temperature of a battery module must not get too high, as exceeding a critical temperature triggers destructive processes that must be avoided at all costs. Therefore, the control unit's operation must generally be designed to keep the battery modules as warm as possible without thermally damaging them.

[0023] In vanadium-based redox flow battery modules, charging occurs via an endothermic reaction and discharging via an exothermic reaction. This means that without external heat input or removal, such a battery cools down during charging and heats up during discharging.

[0024] The control unit 11 can be centrally located. However, the control unit 11 can also comprise decentrally arranged sub-control units. For example, each battery module 1 can include a sub-control unit that processes the measured values ​​acquired by the temperature sensors 4 located in the respective battery module and controls the valves 6 belonging to that battery module. The sub-control units can operate at least partially autonomously. The connection between any sub-control units, sensors 4 and 12, and valves 6 and 8 with the control unit 11 can also be wireless.

[0025] The inventors have recognized that the battery power plant according to the invention can improve the energy efficiency of the power plant compared to a conventional battery power plant. This improvement in energy efficiency is achieved by reducing the waste heat generated by the battery power plant. The inventors have recognized that when operating a battery power plant with redox flow battery modules, situations repeatedly arise in which one or more battery modules do not need to be cooled or even need to be heated in order to reach their optimal operating range as quickly as possible, i.e., to reduce internal resistance and thereby increase electrical efficiency.

[0026] Battery modules in standby mode or being charged do not require cooling, as they cool themselves down naturally in these states. Battery modules newly integrated into the power plant or those that have undergone maintenance also require heat to reach their optimal operating temperature. Conversely, battery modules being discharged produce heat and therefore require cooling. This finding can be used in a battery power plant according to the invention to reduce the waste heat generated by the power plant. The operating method of such a battery power plant comprises at least one operating state in which the valves 6 and the three-way valve 8 are controlled such that at least one battery module absorbs heat from the cooling fluid circulating in the cooling circuit, which was transferred to the cooling fluid by another battery module.In other words, the battery modules that absorb heat act as coolers for the battery modules that release heat.

[0027] This can be achieved in several ways. For the sake of simplicity, let's assume that a first battery module B1 requires no cooling and that the electrolyte temperature in B1 is T1. Furthermore, let's assume that a second battery module B2 requires cooling and that the electrolyte temperature in B2 is T2. Then T1 < T2. To achieve the desired heat flow from B2 to B1, the three-way valve belonging to the cooling system can be controlled so that the supply temperature TV is such that T1 < TV < T2. If the cooling system is now (temporarily) switched off from the cooling circuit, the desired heat flow from B2 to B1 will inevitably occur.Another possibility is that for a certain period only B2 is connected to the cooling circuit while B1 is disconnected – then B2 transfers heat to the coolant fluid, and subsequently only B1 is connected to the cooling circuit while B2 is disconnected – then B1 absorbs heat from the coolant fluid. The valves 6 associated with the battery modules are used to connect to and disconnect from the cooling circuit. In this second possibility as well, the cooling device is disconnected from the cooling circuit for the duration of the desired heat flow (by means of the associated three-way valve 8).

[0028] The general case with many battery modules that do not require cooling and with many battery modules that do require cooling can be described as follows: the three-way valve 8 of the cooling unit is controlled such that the flow temperature TV is close to the average electrolyte temperature of the battery modules. Additionally, the valves 6 of the battery modules are controlled so that the corresponding battery modules are periodically switched in and out of the cooling circuit, the length of the half-periods depending on the cooling or heating requirements of the respective modules.

[0029] The optional three-way valves 8 for individual cooling circuits provide further degrees of freedom for the operation of a battery power plant according to the invention, since the supply temperatures of the individual cooling circuits can be individually adjusted with their aid. Furthermore, the individual cooling circuits can be completely switched into or out of the cooling circuit using these valves. This is advantageous when one or more cooling circuits as a whole have a different cooling requirement than other cooling circuits. This can be the case, for example, when the battery modules of one or more cooling circuits are arranged in locations within the power plant where a different ambient temperature prevails. This is the case, for example, when battery modules are stacked on top of each other in the power plant.The battery modules located at the top are exposed to higher air temperatures because the upper air layers are warmed by the waste heat from the battery modules below. It is therefore advantageous to group the battery modules of the different vertical levels into separate cooling loops. Using the three-way valves associated with these cooling loops, the supply temperature can be adjusted so that the supply temperature for cooling loops located higher up is lower than the supply temperature for those located lower down.

[0030] The inventors recognized that further advantageous operating modes for a battery power plant according to the invention could be identified, considering that such a battery power plant frequently has to operate under partial load. Partial load operation can be implemented in various ways. For almost all possible implementation methods, operating modes can be identified in which the efficiency of such a battery power plant can be increased according to the invention. To describe these operating modes, the electrical structure of such a battery power plant is explained in more detail below.

[0031] Figure 3This shows a highly simplified representation of the electrical structure of a battery power plant. On the left, the battery strings are indicated by a line-connected arrangement of battery modules. Each battery string is enclosed by a dashed rectangle. Each battery module can be connected to or removed from the battery string using a pair of switches. Each battery string is connected to a DC-DC converter. One of the DC-DC converters is labeled 13. Several battery strings are connected to each other via a DC bus, thus forming a battery string group. The DC-DC converters are located between the corresponding DC bus and the battery strings. Each battery string group is connected to the AC bus of the battery power plant via a DC-AC converter. One of the DC-AC converters is labeled 15. Figure 3Three battery strings form a battery string group. The number of battery strings per battery string group can be arbitrary and depends solely on the capacity of the DC-AC converters used and the nominal power of the battery strings. The AC busbar is connected to a transmission network via a transformer.

[0032] The right side of Figure 3 Figure 1 shows the control structure belonging to the battery power plant. Each battery string has its own control unit, one of which is designated 14. Each battery string group, in turn, has its own control unit, one of which is designated 16. The central control unit belonging to the battery power plant is designated 17. The subordinate control units 14 and 16 can be implemented separately or integrated into the control unit belonging to the central control unit. The same applies to the control unit 11 belonging to the cooling system.

[0033] There are several ways to implement partial load operation of the battery power plant: A: All battery modules are operated at partial load. B: In several battery strings, one or more battery modules are switched off from the respective battery strings and go into standby mode. C: One or more battery strings are operated at partial load or go into standby mode. D: One or more battery string groups are operated at partial load or go into standby mode.

[0034] Part-load operating mode A offers the advantage of maintaining a homogeneous state within the battery storage system, as all battery modules are operated uniformly, thus largely preventing uneven charge levels. However, precisely because of this homogeneity, this operating mode offers few or no opportunities for increasing the efficiency of the battery storage system.

[0035] In partial load operating modes BD, the battery modules will at least temporarily have an uneven state of charge, as some modules will charge or discharge less quickly or not at all compared to the others. However, this imbalance can be minimized or even avoided in the long term by periodically rotating the affected battery modules. Partial load operating modes BD also offer several advantages in terms of increasing the efficiency of the battery storage system. For example, in operating modes C and D, the associated DC-DC converters or DC-AC inverters can be put into standby mode, thus saving energy. Furthermore, as described above, the battery modules in standby mode can absorb heat and thus act as coolers for the other battery modules.This is advantageous when the relevant partial-load operating mode is a discharge process, since heat is produced during discharge and therefore cooling is required. It is clear that in such operating modes, the control unit 11 of the cooling system uses the information about the current electrical state (standby, discharge, charge) of the battery modules to control the valves 6 and the three-way valves 8.

[0036] The described positive effect can be further enhanced in partial-load operating modes C and D during discharge if the relevant battery strings or battery string groups are not put into standby mode but are switched to charging. This means that while a large portion of the battery modules are discharging, the remaining modules are being charged. The power output of the battery power plant then results from the power difference between the two battery module groups. Since charging a redox flow battery is endothermic, the cooling effect of the battery modules switched to charging mode is correspondingly greater compared to standby mode. Whether this results in an efficiency increase compared to operating modes that use standby depends on many factors and must therefore be considered on a case-by-case basis. Sometimes it will be more advantageous to temporarily activate the cooling device 9 if the cooling capacity of the battery modules in standby mode is no longer sufficient.

[0037] For a battery power plant to be configured to automatically execute the processes described above, it includes a computer system. The term "computer system" refers to all devices suitable for automating the described process steps, including, in particular, specially developed integrated circuits (ICs) or microcontrollers, as well as application-specific integrated circuits (ASICs). The control unit 11 or the controllers 14, 16 themselves can comprise a suitable computer system. Alternatively, the computer system can also be a separate device or part of a separate device. The present application also relates to a computer program comprising instructions that cause the battery power plant to execute the processes described above. Furthermore, the present application relates to a computer-readable medium on which such a computer program is stored.

[0038] Finally, it should be mentioned that large battery power plants can also comprise several buildings, with multiple parallel-connected battery strings arranged in each building. A separate cooling system can be provided for each building, or a single cooling system can be used for all buildings. In the first case, each building would be considered a battery power plant within the meaning of the present invention. In the second case, the entirety of the buildings would be considered a battery power plant within the meaning of the present invention. Reference symbol list

[0039] 1 Battery module 2 Cell array 3 Tank system 4 Temperature sensor 5 Heat exchanger 6 Valve 7 Battery string 8 Three-way valve 9 Cooling system 10 Circulating pump 11 Cooling system control unit 12 Temperature sensor 13 DC-DC converter 14 Battery string control unit 15 DC-AC inverter 16 Battery string group control unit 17 Battery power plant central control unit

Claims

1. Battery power plant comprising a plurality of battery modules (1) of the redox-flow type, wherein the battery modules (1) are arranged in a plurality of battery strings (7) connected in parallel, and wherein a battery string (7) respectively comprises a plurality of battery modules (1) which are connected in series, and wherein each battery module (1) comprises a tank device (3) for storing electrolyte, at least one temperature sensor (4) and at least one heat exchanger (5), wherein the temperature sensor (4) is arranged such that it is able to detect an electrolyte temperature, and wherein the heat exchanger (5) is arranged and formed such that it can exchange heat with an electrolyte, and wherein the battery power plant comprises a cooling system for supplying the heat exchangers (5) of the battery modules (1) with a cooling fluid, and wherein the cooling system comprises a cooling circuit with a feed flow and a return flow, at least one cooling device (9) and at least one circulating pump (10) for circulating the cooling fluid in the cooling circuit, and wherein the cooling device (9) is configured such that it can influence a temperature difference between feed flow and return flow, and wherein the cooling system comprises at least two further temperature sensors (12) for detecting the temperature of feed flow and return flow, characterized in that all battery modules (1) are connected to the feed flow and return flow of the cooling circuit such that the cooling circuit forms a parallel connection of all battery modules (1), and wherein the cooling system comprises at least one three-way valve (8) which is arranged to control a volume flow of the cooling fluid flowing through the cooling device (9), and wherein the cooling system comprises for each battery module (1) at least one valve (6) which is arranged to be able to control a volume flow of the cooling fluid flowing through the heat exchanger (5) of the associated battery module (1), and wherein the cooling system comprises a control device (11) adapted to be able to process the measurement values detected by the temperature sensors (4, 12) and to control the positions of the valves (6) and of the three-way valve (8) so as to improve an efficiency of the battery power plant.

2. Battery power plant according to claim 1, wherein a plurality of battery modules (1) form a cooling line, wherein the cooling line comprises two conduits extending in parallel, and wherein each battery module associated to the cooling line is connected to the two conduits in such a way that they form a parallel connection, and wherein a three-way valve (8) is provided for the cooling line and configured such that it is able to control a volume flow of the cooling fluid flowing through the cooling line in question, and wherein the control device (11) is configured in such a way that it is able to control the position of the three-way valve (8) associated to the cooling line.

3. Method for operating a battery power plant, wherein the battery power plant comprises a plurality of battery modules (1) of the redox-flow type, and wherein the battery modules (1) are arranged in a plurality of battery strings (7) connected in parallel, and wherein a battery string (7) respectively comprises a plurality of battery modules (1) which are connected in series, and wherein each battery module (1) comprises a tank device (3) for storing electrolyte, at least one temperature sensor (4) and at least one heat exchanger (5), wherein the temperature sensor (4) is arranged such that it is able to detect an electrolyte temperature, and the heat exchanger (5) is arranged and configured such that it can exchange heat with an electrolyte, and wherein the battery power plant comprises a cooling system for supplying the heat exchangers (5) of the battery modules (1) with a cooling fluid, and wherein the cooling system comprises a cooling circuit with a feed flow and a return flow, at least one cooling device (9) and at least one circulating pump (10) for circulating the cooling fluid in the cooling circuit, and wherein the cooling device (9) is configured such that it can influence a temperature difference between feed flow and return flow, and wherein the cooling system comprises at least two further temperature sensors (12) for detecting the temperature of the feed flow and the return flow, and wherein all battery modules (1) are connected to the feed flow and the return flow of the cooling circuit such that the cooling circuit forms a parallel connection of all battery modules, and wherein the cooling system comprises at least one three-way valve (8) which is arranged such that it is able to control a volume flow of the cooling fluid flowing through the cooling device (9), and wherein the cooling system comprises for each battery module (1) at least one valve (6) which is arranged to be able to control a volume flow of the cooling fluid flowing through the heat exchanger (5) of the associated battery module (1), and wherein the cooling system comprises a control device (11) which is configured to be able to process the measurement values detected by the temperature sensors (4, 12) and to control the positions of the valves (6) and of the three-way valve (8), and wherein the method comprises at least one operating state in which the valves (6) and the three-way valve (8) are controlled such that at least one battery module (1) absorbs heat from the cooling fluid circulating in the cooling circuit, which has been dissipated by another battery module (1) to the cooling fluid.

4. Method according to claim 3, wherein a plurality of battery modules (1) form a cooling line, wherein the cooling line comprises two conduits extending in parallel, and wherein each battery module associated to the cooling line is connected to the two conduits in such a way that they form a parallel circuit, and wherein a three-way valve (8) is provided for the cooling line and configured such that it is able to control a volume flow of the cooling fluid flowing through the cooling line in question, and wherein the control device (11) is configured such that it is able to control the position of the three-way valve (8) associated to the cooling line.

5. Method according to claim 3 or 4, wherein the battery power plant is operated in the at least one operating state in partial load, and the at least one battery module (1), which absorbs heat through the cooling fluid circulating in the cooling circuit, is in standby.

6. Method according to claim 3 or 4, wherein the battery power plant is operated in the at least one operating state in partial load, and the at least one battery module (1), which absorbs heat from the cooling fluid circulating in the cooling circuit, is charged.

7. Battery power plant according to claim 1 or 2, which is configured to automatically carry out the method according to any one of claims 3 to 6.

8. Computer program comprising instructions that cause the battery power plant of the preceding claim to carry out the method according to any one of claims 3 to 6.

9. Computer-readable medium, on which the computer program according to the preceding claim is stored.