A method and a control arrangement for controlling a renewable power plant

Abstract

A method (200) and a control arrangement (150) for controlling a renewable power plant (100) comprising one or more renewable electric power generating units (103) and one or more power-to-gas units (120), the renewable power plant (100) being connected to a gas transmission network (126) is presented. The method (200) comprises: obtaining (210) one or more parameters of the gas transmission network (126), the one or more parameters of the gas transmission network (126) being generated based on a predicted future state of the gas transmission network (126); and based on the one or more obtained parameters of the gas transmission network (126), controlling (220) the one or more power-to-gas units (120) to convert electric power at least partly provided by the one or more renewable electric power generating units (103) to gas for an introduction of at least a portion of the converted gas into the gas transmission network (126).

Description

[0001] A METHOD AND A CONTROL ARRANGEMENT FOR CONTROLLING A RENEWABLE POWER PLANT

[0002] Technical field

[0003] Aspects of the present invention relate to a method and a control arrangement for controlling a renewable power plant comprising one or more renewable electric power generating units and one or more power-to-gas units, the renewable power plant being connected to a gas transmission network. Further aspects of the invention relate to a renewable power plant comprising the control arrangement, and to a computer program or a computer-readable medium implementing the method.

[0004] Background

[0005] Renewable power plants rely on renewable energy sources such as wind and / or sun to produce electricity by usage of wind turbine generators and / or photovoltaic power generators. Renewable power plants may also comprise one or more power-to-gas units, and may then also be known as power-to-x plants. Besides electricity, the renewable power plants may produce additional energy vectors, such as green hydrogen, produced from water, and other green synthetic fuels, produced by mixing green hydrogen with additional chemical compounds and / or elements. Byproducts of renewable power plants may include recoverable low-grade heat and oxygen, both resulting from the electrolysis of water.

[0006] The renewable power plant may be connected via one or more interfaces to an external electricity grid, an external hydrogen or natural gas grid, an external heat distribution network and / or a grid for industrial products, such as e-fuels.

[0007] The integration of multiple energy vectors / products provides the renewable power plants with the possibility of exchanging different kinds of energy vectors via one or more energy exchange nodes. For example, electricity, hydrogen and / or heat may be exchanged in such nodes. The interfaces may be implemented as a physical point where the flow of energy between the renewable power plant and the surroundings, such as for example external grids of various kinds, is formally regulated. Thus, an energy vector may only be exchanged to another energy vector if it has a specific set of attributes, for example a certain voltage, frequency, pressure, flow, and / or temperature, depending on the energy vector. This specific set of attributes may correspond to, be comprised in, or comprise, network / grid codes for one or more energy vectors.

[0008] Summary

[0009] Over time, the supply and demand of gas in the gas transmission / distribution network may change. Also, the supply and demand for electric power in the electric power grid may change over time. Such changes in the supply and / or demand may in some situations cause balancing problems in the gas transmission / distribution network and / or in the electric power grid. Further, depending on the available power resources, the prices of electric power and / or gas also vary over time with the changing supplies and demands.

[0010] The demand for gas may for example change because one or more large gas consumption units in the gas transmission / distribution network are being started or stopped. The supply of gas in the gas transmission / distribution network may change due to varying conditions for producing gas in the gas transmission / distribution network and / or in external gas suppliers. Further, the conditions for producing electric power in the renewable power plant may vary, and the consumption of elective power in the electric power grid may also vary, whereby the electric power being available for conversion to gas in the renewable power plant is also varying. These changes in the supply and / or demand of gas may cause balancing problems in the gas transmission / distribution network.

[0011] An object of the invention is to provide a solution which mitigates or solves such balancing problems.

[0012] An object of the invention is to provide a solution which mitigates or solves the drawbacks and problems of conventional solutions. The above and further objects are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0013] According to a first aspect of the invention, a method for controlling a renewable power plant comprising one or more renewable electric power generating units and one or more power-to-gas units, the renewable power plant being connected to a gas transmission network, is presented. The method comprises: obtaining one or more parameters of the gas transmission network, the one or more parameters of the gas transmission network being generated based on a predicted future state of the gas transmission network; and based on the one or more obtained parameters of the gas transmission network, controlling the one or more power-to-gas units to convert electric power at least partly provided by the one or more renewable electric power generating units to gas for an introduction of at least a portion of the converted gas into the gas transmission network.

[0014] Hereby, gas may in the renewable power plant be produced by converting electric power to gas in one or more power-to-gas units. The gas may then be introduced into the gas transmission network. The production of gas and the introduction of the produced gas into the gas transmission network is based on the one or more obtained parameters of the gas transmission network, which may indicate a risk for future balancing problems in the gas transmission network.

[0015] Thus, if the gas transmission network is predicted to run into balancing problems, the predicted instability may be proactively counteracted by the preventive introduction of the produced gas into the gas transmission network. The renewable power plant may thus reduce the risk for, or avoid, future balancing problems in the gas transmission network.

[0016] Since the production of gas and the introduction of the produced gas into the gas transmission network is based on the one or more obtained parameters of the gas transmission network, that are generated based on a predicted future state of the gas transmission network, a proactive balancing of the gas transmission network is achievable by the renewable power plant.

[0017] By forecasting / predicting the future states and / or conditions of the gas transmission network and by basing the conversion of electric power to gas on these forecasts / predictions, the conversion of electric power to gas may be performed depending on the available power sources over time. Thus, depending on the forecasts / predictions, the conversion may be controlled such that it balances the supply of and the demand for gas in the gas transmission network over time.

[0018] Thus, forecasts / predictions of future states and / or conditions of the gas transmission network may be utilized for controlling the conversion of electric power to gas. Such forecasted / predicted future states and / or conditions may for example be associated with pressures, flow, rates, flow directions, volumes and / or quantities of the gas in the gas transmission network. The future states and / or conditions may also be associated with a number of gas consumers, and a volume of gas consumed by the consumers. The future states and / or conditions may also be associated with the volume and / or character of available gas from external gas suppliers. The future states and / or conditions may also be associated with a set point for the renewable power plant. Thus, one or more of these features of the future states and / or conditions of the gas transmission network may be taken into consideration when forecasting / predicting the supply and / or demand of gas in the gas transmission network. To control the conversion of electric power to gas based on such information associated with future situations of the gas transmission network makes it possible to proactively balance the supply and demand of gas in the gas transmission network.

[0019] Thus, based on the forecast / predictions, the renewable power plant may decide when in time it is favorable to produce electric power and when in time it is favorable to produce gas. For example, if the weather forecast indicates that there will first be strong winds and sunny, and after that wind still and very cold, it may be advantageous to first produce electric power by wind turbine generators and photovoltaic generator when there is a lot of wind and sun, and to convert some of the hereby produced available electric power to gas, which is stored. Then, the gas may be traded on the market when there is little wind and cold weather. Hereby, the gas may be produced at a low cost, when there is plenty of available electric power, and may be sold at a high price when there is less electric power available and when there is a high demand for gas.

[0020] According to an embodiment of the first aspect, the one or more obtained parameters of the gas transmission network are generated based on one or more in the group of:

[0021] • predicted future requirements of the gas transmission network; and

[0022] • a predicted future gas consumption of the gas transmission network.

[0023] To control the conversion of electric power to gas based on predicted future requirements and / or predicted future gas consumption of the gas transmission network makes it possible to proactively counteract imbalance between supply and demand of gas in the gas transmission network.

[0024] According to an embodiment of the first aspect, the method further comprises: predicting, based on the one or more obtained parameters of the gas transmission network, a future instability of the gas transmission network; and controlling the one or more power-to-gas units to convert electric power to gas based on the predicted future instability of the gas transmission network.

[0025] By predicting that there will a future instability of the gas transmission network, and by, based on this predicted upcoming instability, preventively converting electric power to gas and to timely introduce the converted gas into the gas transmission network, the predicted future instability of the gas transmission network is efficiently counteracted and / or avoided before it occurs.

[0026] According to an embodiment of the first aspect, the future instability is predicted if at least one of the one or more obtained parameters of the gas transmission network fluctuates with an amplitude A exceeding a fluctuation amplitude threshold Ath; A>Ath. Some of the one or more obtaining parameters of the gas transmission network have naturally fluctuating values. The fluctuation amplitude threshold Ath is utilized for identifying the parameters that fluctuate too much, i.e. that fluctuate abnormally, thereby indicating that there will be a future instability problem in the gas transmission network.

[0027] According to an embodiment of the first aspect, the renewable power plant is connected to an electric power grid, wherein the method further comprises: based on the one or more obtained parameters of the gas transmission network, importing electric power from the electric power grid to the renewable power plant; and based on the one or more obtained parameters of the gas transmission network, controlling the one or more power-to-gas units to convert, in addition to the electric power provided by the one or more renewable electric power generating units, at least a portion of the electric power imported from the electric power grid to gas.

[0028] When the renewable power plant is connected to the electric power grid, more possibilities to proactively counteract future instability of the gas transmission network are available. Electric power available for conversion into gas may then be provided by both the one or more renewable electric power generating units of the renewable power plant and the electric power grid. Thus, electric power may be imported from the electric power grid to the renewable power plant, and this imported electric power may, in addition to the electric power produced by the one or more renewable electric power generating units of the renewable power plant, be converted into gas.

[0029] A higher level of flexibility is hereby achieved for the renewable power plant. For example, when the wind turbine generators and / or the photovoltaic power generators do not produce enough electric power to stabilize the gas transmission network, for example when there is little wind and / or at night or during cloudy days, the future instability of the gas transmission network may still be proactively counteracted and / or improved by converting imported electric power into gas and introducing the converted gas into the gas transmission network. According to an embodiment of the first aspect, the method further comprises: obtaining one or more parameters of the electric power grid; and based on the one or more obtained parameters of the electric power grid, importing electric power from the electric power grid to the renewable power plant for the conversion of at least a portion of the electric power imported from the electric power grid to gas.

[0030] By taking also the one or more obtained parameters of the electric power grid into consideration when importing electric power from the electric power grid, the current state and / or condition of the electric power grid, and / or a future state and / or condition of the electric power grid, are also utilized as a basis for the decisions associated with electric power import. Thus, the current and / or future states and / or conditions of both of the gas transmission network and the electric power grid are take into consideration when the electric power is imported from the electric power grid. The import of electric power, and thus also the conversion of the imported electric power into gas, may hereby optimized to the current and / or future situations of one or both of the gas transmission network and the electric power grid.

[0031] According to an embodiment of the first aspect, the one or more power-to-gas units are controlled to only convert electric power provided by the one or more renewable electric power generating units to gas.

[0032] Thus, no electric power is here imported for the conversion of electric power to gas. The conversion of electric power to gas may hereby be performed without the need for possibly expensive import of electric power. This way, i.e. without import, it is also assured that the electric power only originates from the renewable electric power generating units, i.e. from renewable power sources.

[0033] According to an embodiment of the first aspect, the one or more obtained parameters of the gas transmission network are fluctuating over time, the fluctuations being indicative of a stability of the gas transmission network. By analyzing the naturally fluctuating values for the one or more obtained parameters of the gas transmission network, the parameters changing in an abnormal way may be identified as an indication of future instability, while normally changing parameters are detected as an indication of future stability for the gas transmission network.

[0034] According to an embodiment of the first aspect, the method further comprises: based on the one or more obtained parameters of the gas transmission network, allocating a power producing capability of the renewable power plant; controlling the one or more renewable electric power generating units to produce electric power by utilization of the allocated power producing capability; and controlling the one or more power-to-gas units to convert at least a part of the produced electric power to gas.

[0035] Hereby, a power backup is created by this allocation of power producing capability, which can be utilized for producing gas, if needed. Thus, a reserve of power is allocated for gas conversion, where the converted gas then may be introduced in the gas transmission network to compensate for upcoming instability / imbalance in the gas transmission network.

[0036] According to an embodiment of the first aspect, the one or more obtained parameters of the gas transmission network comprise one or more of the group of:

[0037] • a pressure of the gas transmission network;

[0038] • a gas flow rate of the gas transmission network;

[0039] • a gas flow direction of the gas transmission network;

[0040] • a gas volume of the gas transmission network;

[0041] • one or more quantities of gas at one or more locations in the gas transmission network;

[0042] • an amount of gas consumers connected to the gas transmission network;

[0043] • a gas volume consumed by gas consumers connected to the gas transmission network;

[0044] • a character of available gas provided by one or more external gas supplies to the gas transmission network; a volume of available gas provided by one or more external gas supplies to the gas transmission network; and a set point for the renewable power plant.

[0045] Thus, various parameters of the gas transmission network may be utilized as a basis for the conversion of electric power to gas and / or for the preventive introduction of the converted gas into the gas transmission network, which offers a flexibility and reliability for the proactive production and / or introduction of gas. The one or more obtained parameters of the gas transmission network may be generally fluctuating parameters. The one or more obtained parameters of the gas transmission network may correspond to, may be comprised in, and / or may be part of the network / grid codes for the gas transmission network, i.e. may define a specific set of attributes that the gas distributors must fulfill on the energy market.

[0046] According to an embodiment of the first aspect, each of the one or more power-togas units is configured to convert electric power to gas by utilization of an electrolyzer system.

[0047] Electrolyzer systems provides for an efficient conversion of electric power into gas, which has a small amount of conversion losses.

[0048] According to an embodiment of the first aspect, the method further comprises: based on the one or more obtained parameters of the gas transmission network, controlling the one or more power-to-gas units to convert electric power to a gas or gas mixture comprising or consisting of one or more of the group of:

[0049] • hydrogen;

[0050] • oxygen; and

[0051] • methane.

[0052] Hydrogen, oxygen and / or methane gases may be utilized in a large number of implementations. Also, these gases may be transformed in one or more plant extension units into other products by consuming electricity from the renewable power plant. The gases and possibly other compounds or elements, such as e.g. nitrogen or carbon dioxide, may here by utilized for producing other industrial products, such as e.g. e-fuel, ammonia and / or a methanol products.

[0053] According to an embodiment of the first aspect, the one or more renewable electric power generating units comprise one or more in the group of:

[0054] • a wind turbine generator of the renewable power plant;

[0055] • a photo-voltaic generator of the renewable power plant;

[0056] • an electric battery energy storage system of the renewable power plant; and

[0057] • a fuel cell of the renewable power plant.

[0058] The renewable power plant may thus comprise a number of different renewable electric power generating units utilizing a corresponding number of different renewable power sources, respectively. Hereby, renewable electric power may be produced by the renewable power plant under various weather conditions, for example under varying wind and sun conditions.

[0059] According to an embodiment of the first aspect, the method further comprises: obtaining the one or more parameters at / for a point of interest where one or more requirements of the gas transmission network are to be fulfilled; based on the one or more obtained parameters at / for the point of interest, dispatching one or more references to the renewable power plant; based on the one or more dispatched references, controlling the one or more power-to-gas units to convert electric power to gas for a fulfillment of at least one of the one or more requirements at the point of interest.

[0060] When the one or more parameters of the gas transmission network are obtained at / for the point of interest where the renewable power plant and the gas transmission network are connected, the requirements may correspond to and / or be comprised in gas transmission network / grid codes. The dispatched references may correspond to, or comprise, set points intended for control of the entire renewable power plant and / or reference points intended for control of individual entities of the renewable power plant.

[0061] Thus, based on gas transmission networks / grid codes, gas is here produced by conversion of electric power, and the gas is then proactively introduced into the gas transmission network. Hereby, the renewable power plant is controlled to produce gas which is introduced into the gas transmission network such that the gas transmission will comply with its network / grid codes in the future. In other words, the gas transmission network is proactively balanced by the renewable power plant based on its gas grid codes, such that the gas transmission network will securely provide gas complying with its specific set of attributes, such as for example flow and / or pressure attributes.

[0062] According to a second aspect of the invention, a control arrangement for controlling a renewable power plant, wherein the renewable power plant comprises one or more renewable electric power generating units and one or more power-to-gas units, and is connected to a gas transmission network, is presented. The control arrangement is configured to:

[0063] Obtain one or more parameters of the gas transmission network, the one or more parameters of the gas transmission network being generated based on a predicted future state of the gas transmission network; and based on the one or more obtained parameters of the gas transmission network, control the one or more power-to-gas units to convert electric power at least partly provided by the one or more renewable electric power generating units to gas for the introduction of at least a portion of the converted gas into the gas transmission network.

[0064] The control arrangement of the second aspect has corresponding advantages as the ones mentioned above for the method for controlling a renewable power plant according to the first aspect of the invention.

[0065] It is to be appreciated that all the embodiments described for the method aspect of the invention are applicable also to the control arrangement aspect of the invention. Thus, all embodiments described for the method aspect of the invention may be performed by the control arrangement, which may include one or more controllers, control units, or control devices. The embodiments of the control arrangement have advantages corresponding to advantages mentioned above for the method and its embodiments.

[0066] According to a third aspect of the invention, a renewable power plant is presented. The renewable power plant comprises one or more renewable electric power generating units and one or more power-to-gas units, and is connected to a gas transmission network. The renewable power plant further comprises a herein described control arrangement.

[0067] The renewable power plant of the third aspect has corresponding advantages as the ones mentioned above for the method for controlling a renewable power plant according to the first aspect of the invention and its embodiments.

[0068] According to a fourth aspect of the invention, the above mentioned and other objects are achieved with a computer program or a computer-readable medium comprising instructions which, when the program or the instructions is / are executed by a computer, cause the computer to carry out one or more of the methods according to any one of the aspects and embodiments disclosed above or below. Advantages of the computer program or the computer-readable medium according to the fourth aspect correspond to advantages of the method according to the first aspect and its embodiments mentioned above or below.

[0069] According to an aspect of the present invention, the above-mentioned computer program and / or the computer-readable medium are / is configured to implement the method and its embodiments described herein.

[0070] The above-mentioned features and embodiments of the method, the computer program, the computer-readable medium, the control arrangement and the renewable power plant, respectively, may be combined in various possible ways providing further advantageous embodiments. Further advantageous embodiments of the method for controlling the renewable power plant and the control arrangement, and further advantages of the embodiments of the present invention, emerge from the detailed description of embodiments.

[0071] Brief Description of the Drawings

[0072] Embodiments of the invention will now be illustrated, for exemplary purposes, in more detail by way of embodiments and with reference to the enclosed drawings, where similar references are used for similar parts, in which:

[0073] Figure 1 is a schematic diagram illustrating an embodiment of a renewable power plant, to which herein described embodiments may be applied;

[0074] Figure 2 is a schematic diagram illustrating an embodiment of a wind turbine generator of the power plant of figure 1 ;

[0075] Figure 3 is a schematic diagram illustrating an embodiment of a Power-to-X unit of the power plant of figure 1 ;

[0076] Figure 4 is a schematic flow chart illustrating methods according to various aspects and embodiments of the invention; and

[0077] Figure 5 is a schematic diagram illustrating an embodiment of a control arrangement according to the second aspect of the invention, in which a method according to any one of the herein described aspects and embodiments may be implemented.

[0078] Detailed Description

[0079] Figure 1 schematically illustrates a non-limiting example of a renewable power plant 100, in which aspects and embodiments of the present invention may be implemented. The aspects and embodiments of the present invention may, of course be implemented in any suitable renewable power plant, in which one or more renewable electric power generating units and one or more power-to-gas units are utilized, and is connected to a gas transmission network. The aspects and embodiments of the present invention are thus not limited to implementation in the renewable power plant example in figure 1 . The renewable power plant 100 is arranged for providing electric power, or electrical energy, to an electric power grid 116. The renewable power plant 100 includes one or more renewable electric power generating units 103, such as wind turbine generators 101. According to some embodiments, the renewable power plant 100 may also comprise one or more other renewable electric power generating units / assets 103, for example a photo-voltaic generator 102, such as a photo-voltaic panel, a solar panel, or a solar cell panel. The wind turbine generators 101 and the photo-voltaic generator 102 may also be generally described as renewable power sources 103 of the renewable power plant 100, or as renewable power generators 103 of the renewable power plant 100. Other renewable electric power generating units 103, such as e.g. one or more fuel cells 104, may also be comprised in the renewable power plant 100. The one or more fuel cells 104 may for example comprise one or more hydrogen fuel, and may be configured for converting hydrogen and oxygen into electric power by utilizing redox reactions. The hydrogen used in this conversion may for example be produced by a power-to-gas (P2G) 120 in the renewable power plant 100, and may possibly be stored in an internal hydrogen storage 122 of the renewable power plant 100, as explained below. The renewable power plant 100 may also comprise one or more additional renewable power sources or power generators 103, such as one or more electric battery energy storage systems 106, which may comprise an electric battery energy storage system, possibly including one or more electric battery units.

[0080] The renewable power plant 100 may also comprise further assets / units / components, such as for example one or more harmonic filters and / or one or more reactive power compensation units. Such further assets / units / components are schematically referred to as further assets / units / components 107 in figure 1 .

[0081] The renewable power plant 100 may be connected, or connectable, possibly via an internal grid 110 of the renewable power plant 100, to the electric power grid 116 via a point of common coupling (PCC) 115. The renewable electric power generating units 103 feed / provide electric power produced by them to the internal grid 110, which is connected via the point of common coupling 115 to the external electric power grid 116. For some embodiments, the electric power grid 116 may be referred to as a utility grid, an electrical grid, a power grid, or an electric power network.

[0082] The renewable power plant 100 further comprises one or more power-to-x units, including one or more power-to-gas units 120. The power-to-x units are configured to convert electric power from the renewable power plant 100 to x, i.e. to gas in this case. The power-to-x unit may thus comprise a power-to-gas (P2G) unit 120, including an electrolyzer system 121 configured to convert electric power from the renewable power plant 100 to gas. The power-to-gas units 120 may be described as dynamic electrical loads. The one or more electrolyzer systems 121 are arranged to break down water molecules into its constituents, i.e. into hydrogen and oxygen, by consuming electricity. The power-to-gas units 120, each comprising one or more electrolyzer systems 121 , may also produce heat in the electrolysis process.

[0083] Optionally, the renewable power plant 100 may also comprise one or more plant extension units 130 that can transform hydrogen produced by the one or more power-to-gas units 120, i.e. produced by the one or more electrolyzer systems 121 , respectively, into other products by consuming electricity. The plant extension units 130 may be described as static or semi-static electric loads, and may comprise one or more chemical units / plants that utilize hydrogen and possibly other compounds or elements, such as e.g. nitrogen or carbon dioxide, to produce other industrial products, such as e.g. e-fuels. The plant extension units 130 may also comprise e.g. an ammonia production plant and / or a methanol production plant. The produced industrial products, e.g. e-fuels, may be stored locally in a product storage 131 , or may be provided for direct onward transportation.

[0084] One or more interfaces, such as the point of common coupling, 115 to the external electricity grid 116, may provide the possibility to export surplus power produced by the renewable electrical generators 103 of the renewable power plant, which is not used by the one or more power-to-gas units 120, including the electrolyzer systems 121 , and the downstream plant extension units 130, to the electricity grid 116. Corresponding one or more external interfaces 125 may be implemented to export hydrogen produced by the power-to-gas units 120, i.e. by the electrolyzer systems 121 , in the renewable power plant 100 to a hydrogen or natural gas grid 126, i.e. to a gas transmission / distribution network / grid 126. One or more external interfaces 127 may further be implemented to export heat produced by the one or more power-togas units 120 in the renewable power plant to a heat grid 128, i.e. to a heat transmission / distribution network 128. Also, one or more interfaces 135 may be implemented to export industrial products, such as for example e-fuels, produced by the plant extension units 130 to a grid 136 for industrial products such as e.g. e-fuels.

[0085] The one or more interfaces 115 to the external electricity grid 116, may also provide the possibility to import electric power from the external power grid 116 to the renewable power plant 100. Correspondingly, the one or more external interfaces 125 to the gas transmission / distribution network 126 may provide the possibility to import gas from the gas transmission / distribution network 126 to the renewable power plant 100. Further, the one or more external interfaces 127 to the heat transmission / distribution network 128 may provide the possibility to import heat from the heat transmission / distribution network 128 to the renewable power plant 100. Also, the one or more interfaces 135 to the grid 136 for industrial products may provide the possibility to import industrial products from the grid 136 for industrial products to the renewable power plant 100.

[0086] The renewable power plant 100 may include a control arrangement 150 configured to control the renewable power plant 100. According to some embodiments, the control arrangement 150 may comprise, or be referred to as, a power plant controller (PPC). As schematically illustrated in figure 1 , the control arrangement 150 in form of a power plant controller controls the renewable power generating units 103, the battery system 106, the further assets / units / components 107, the internal grid 110, the one or more power-to-gas units 120, the plant extension units 130 and / or the product storage 131 . The power plant controller 150 may also communicate with the external electric power grid 116, the gas transmission network 126, the heat grid 128 and / or the grid 136 for industrial products, and / or their respective interfaces 115, 125, 127, 135. Also, measurements, for example of electric power or other system parameters and / or attributes, are provided to the control arrangement 150 from one or more of the renewable power generating units 103, the battery system 106, further assets / units / components 107, the internal grid 110, the one or more power-to-gas units 120, the plant extension units 130, and the product storage 131. Measurements may also be provided by one or more of the external electric power grid 116, the gas transmission network 126, the heat transmission / distribution 128 and the grid 136 for industrial products, and / or from their respective interfaces 115, 125, 127, 135.

[0087] The renewable power plant 100, which may also be called a power-to-x plant, thus utilizes renewable energy sources, such as wind and sun, for producing electricity by the use of renewable electrical generators 103, such as the wind turbine generators 101 and / or the photovoltaic power generators 102. The produced electricity may be provided to the external electricity grid 116 and / or may be used for producing hydrogen, natural gas, heat, and / or industrial products such as for example e-fuels. The produced electricity, hydrogen, natural gas, heat and / or industrial products may then be exported to the external electric power grid 116, the external gas transmission network 126, the external heat transmission / distribution 128 and / or an external industrial product grid 136, respectively.

[0088] In figure 2, an embodiment of the wind turbine generator 101 of the renewable power plant 100 of figure 1 is schematically illustrated. The wind turbine generator 101 may comprise a rotor 161 including one or more blades 162, or rotor blades 162, for example two or more blades 162, such as three blades, or more. The wind turbine generator 101 may comprise a tower 163 and a nacelle 164 mounted to the top of the tower 163. The rotor 161 may be connected, such as rotatably connected or mounted, to the nacelle 164. The wind turbine generator 101 may comprise an electric generator 165 to which the rotor 161 is connected. The rotor 161 is configured to drive the electric generator 165. The nacelle 164 may house the electric generator 165.

[0089] The rotor 161 is rotatable by action of the wind. The wind-induced rotational energy of the blades 162 and rotor 161 may be transferred via a coupling 166, for exampling including one or more shafts, to the electric generator 165. Thus, the wind turbine generator 101 may be described to be configured to convert kinetic energy of the wind to mechanical energy, or rotational energy, by way of the blades 162 and, subsequently, to electric power by way of the electric generator 165. The wind turbine generator 101 may comprise one or more power converters 167 connected to the electric generator 165. The wind turbine generator 101 and / or the electric generator 165 may be connected to the electric power grid 116 via the one or more power converters 167. The one or more power converters 167 may comprise a first power converter for converting AC power from the electric generator 165 to DC power. The one or more power converters 167 may comprise a second power converter for converting DC power from the first power converter to AC power to be provided to the electric power grid 116. The nacelle 164 may house the one or more power converters 167, or the one or more power converters 167 may be located elsewhere.

[0090] The wind turbine generator 101 may be controlled by, or may comprise, a control arrangement 168 for controlling the wind turbine generator 101. The control arrangement 168 of the wind turbine generator 101 may comprise a wind turbine generator controller. The control arrangement 168 of the wind turbine generator 101 may be configured to communicate with and / or be connected to, or be part of, the control arrangement 150 of the power plant 100. For some embodiments, the wind turbine generator 101 may be referred to as a variable-speed wind turbine generator. It is to be understood that the wind turbine generator 101 may include further units, components and / or devices, such as for example sensors, required for a wind turbine generator 101. For some embodiments, and as schematically illustrated in figure 2, the power-to-x units 120, i.e. the power-to-gas unit 120s, may be connected, more specifically electrically connected, to a connection point of the wind turbine generator 101 , such that it may draw electric power produced by the wind turbine generator 101 for producing x. For some embodiments, the wind turbine generator 101 and the power-to-x unit 120 may be arranged together as a unit. However, for some embodiments, the power-to-x unit 120 may be located and / or connected elsewhere in the renewable power plant 100.

[0091] Figure 3 schematically discloses an embodiment of the power-to-x (P2X) unit, here being a power-to-gas unit (P2G) 120 of the power plant 100 of figure 1 , which is configured to convert electric power from the renewable power plant 100 to gas. According to various herein described embodiments, the power-to-gas unit 120 may be configured to convert electric power produced by the renewable power plant 100 itself, and / or may be configured to use imported electric power, to produce a gas or gas mixture comprising or consisting of hydrogen, oxygen and / or methane. In the embodiment illustrated in figure 3, the power-to-gas unit 120 is configured to convert electric power from the renewable power plant 100, i.e. electric power produced within and / or imported to the renewable power plant 100, to a gas mixture comprising hydrogen and oxygen. The power-to-gas unit 120 may be described to be configured to use electricity to break water into hydrogen and oxygen in a process called electrolysis in an electrolyzer system 121. Thus, through the electrolysis, hydrogen is created, which may be used for example as a fuel. The power-to-gas unit 120 may include a container 322 configured to hold or contain water. The power-to-gas unit 120, i.e. the electrolyzer system 121 , may include one or more anodes 323 and one or more cathodes 324 separated from one another by a membrane 325. The container 322 may include an outlet 326 for hydrogen and an outlet 327 for oxygen. The produced hydrogen may be stored in an internal hydrogen storage 122 of the renewable power plant 100.

[0092] With reference to figure 3, for some embodiments, the power-to-gas unit 120 comprises an electrolyzer system 121 comprising one or more of the group of:

[0093] - an alkaline electrolyzer;

[0094] - an unpressurized alkaline electrolyzer;

[0095] - a pressurized alkaline electrolyzer;

[0096] - a proton exchange membrane electrolyzer;

[0097] - an unpressurized proton exchange membrane electrolyzer;

[0098] - a pressurized proton exchange membrane electrolyzer;

[0099] - a polymer electrolyte membrane electrolyzer;

[0100] - an unpressurized polymer electrolyte membrane electrolyzer;

[0101] - a pressurized polymer electrolyte membrane electrolyzer; and

[0102] - a solid oxide electrolyzer (SOEC).

[0103] As illustrated in figures 2 and 3, for some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point of the wind turbine generator 101 . For some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point of the renewable power plant 100. For some embodiments, the power-to-gas unit 120 may be connected, more specifically electrically connected, to a connection point / external interface, such as the point of common coupling 115, between the renewable power plant 100 and the electric power network / grid 116, and to a connection point / external interface 125 between the renewable power plant 100 and the gas transmission / distribution network 126.

[0104] It is to be understood that the power-to-gas unit 120 may include further units than the ones herein described, such as e.g. other components and / or devices, for example pumps, vents, storage tanks and / or separators, required for the power-to- gas unit 120 to work efficiently. It is to be understood that other embodiments of the power-to-gas unit 120 than the one disclosed in figure 3 are possible.

[0105] The regulation of renewable power plants may for example be controlled by one or more transmission system operators for electricity or gas, which may be responsible for regulating the energy nodes configured for exchanging electricity and gaseous fuels, such as hydrogen. The one or more transmission system operators may in some countries include national transmission system operators. Also, a local district heating company may regulate / control energy nodes configured for exchanging low- grade heat. Since the energy exchange may cross national borders, the national transmission system operators for electricity or gas may be coordinated by supranational bodies.

[0106] Depending on the configuration of the renewable power plant and the available energy infrastructure, it is necessary to develop control systems and control strategies that can simultaneously comply with network / grid codes of electricity and gas distribution systems, as well as potential heat distribution systems. Thus, renewable power plants are required to produce energy with a specific set of attributes, such as for example voltage, frequency, flow, pressure and / or temperature, depending on the energy vector, for a reliable operation of the renewable power plant. For example, in a European context, the energy nodes configured for exchanging electricity and gaseous fuel of renewable power plants may be regulated by the European national transmission system operators for electricity or gas. Also, energy nodes configured for exchanging low-grade heat may be regulated by the European local district heating company. The European national transmission system operators for electricity and gas are coordinated by supranational bodies, such as the European Network of Transmission System Operators for Electricity (ENTSO-E) and European Network of Transmission System Operators for Gas (ENTSO-G).

[0107] Both the ENTSO-E and the ENTSO-G monitor and analyze the implementation of network codes that clearly define the specific set of attributes that electricity and gas distributors must fulfill to have a harmonized and integrated energy market within the European Union.

[0108] The renewable power plants within Europe may thus have to comply with network codes of the ENTSO-E, the ENTSO-G, both of the ENTSO-E and the ENTSO-G, or none of the ENTSO-E and the ENTSO-G, depending on the configuration of the renewable power plant 100 and on the energy infrastructure available. Outside of Europe, corresponding organizations / bodies may determine corresponding network codes for other countries / regions / continents, which must be complied with by renewable power plants in those countries / regions / continents.

[0109] It may thus be necessary to develop control systems and control strategies that can simultaneously comply with network codes for electricity, gas and / or heat distribution transmission / distribution networks / grids. In cases where no network codes are enforced by regulators, renewable power plants 100 will still need to produce energy with a specific set of attributes, such as for example voltage, frequency, pressure and / or temperature, depending on the energy vector, for a reliable operation of the renewable power plant 100.

[0110] Imbalances in the external gas transmission / distribution network 126 to which the renewable power plant 100 is connected, are not allowed according to the network codes for the gas transmission / distribution network 126. For example, instable gas flow, instable gas pressure and / or varying amounts of gas in the gas transmission / distribution network 126 due to such imbalances may cause the gas transmission / distribution network 126 not to comply with its network codes.

[0111] In certain situations, balancing problems in the gas transmission network 126 to which the renewable power plant 100 is connected, may occur. The supply and demand of gas in the gas transmission network 126 may change over time, and depending on the available power resources, the prices of gas will also vary correspondingly over time with the changing supply and demand.

[0112] The demand for gas may for example change because one or more large gas consumption units in the gas transmission network 126 are being started or stopped. The supply of gas in the gas transmission network 126 may change due to varying gas production in the gas transmission network 126 and / or in external gas suppliers. The supply of gas in the gas transmission network 126 may also change due to varying conditions for producing electric power in the renewable power plant 100, and thus due to varying electric power being available for conversion to gas in the renewable power plant 100. Such changes, and possibly also other changes, in the supply of and / or demand for gas may cause balancing problems in the gas transmission network 126, and may also influence the prices of gas.

[0113] Correspondingly, the supply of and demand for electric power in the electric power grid 116 may change over time. Such changes in the supply and / or demand may in some situations cause balancing problems in the electric power grid 116, and may, depending on the available power resources, influence the prices of electric power.

[0114] Figure 4 shows a flow chart diagram for a method 200 for controlling the renewable power plant 100, where the renewable power plant 100 comprises one or more renewable electric power generating units 103 and one or more power-to-gas units 120. The renewable power plant 100 is further connected to a gas transmission network 126, as explained above.

[0115] In a first step 210 of the method 200, one or more parameters of the gas transmission network 126 are obtained. The one or more parameters of the gas transmission network 126 are here generated based on a predicted future state of the gas transmission network 126.

[0116] According to various embodiments, to obtain the one or more parameters of the gas transmission network 126 may comprise that the renewable power plant, i.e. the control arrangement 150, at least partly forecasts / predicts the one or more parameters of the gas transmission network 126 and / or may comprise that the one or more parameters of the gas transmission network 126 are at least partly provided by the gas transmission network 126, whereby the gas transmission network 126 provides for example corresponding forecasts, predictions, reference point points and / or set points that are received by the renewable power plant 100.

[0117] According to various embodiments, the one or more determined parameters of the gas transmission network 126, which are generated based on a predicted future state of the gas transmission network, may comprise pressure of the gas transmission network 126, a gas flow rate of the gas transmission network 126, a gas flow direction of the gas transmission network 126, a gas volume of the gas transmission network 126, one or more quantities of gas at one or more locations in the gas transmission network 126, an amount of gas consumers connected to the gas transmission network 126, a gas volume consumed by gas consumers connected to the gas transmission network 126, a character of available gas provided by one or more external gas supplies to the gas transmission network 126, a volume of available gas provided by one or more external gas supplies to the gas transmission network 126 and / or a set point for the renewable power plant 100. At least some of the one or more determined parameters may be generally fluctuating / non-stationary parameters, that vary relatively slowly over time. At least one of the one or more determined parameters may correspond to at least one of the network codes for the gas transmission network 126.

[0118] According to an embodiment, the one or more obtained parameters of the gas transmission network 126 are generated based on predicted future requirements of the gas transmission network 126 and / or on a predicted future gas consumption of the gas transmission network 126. The one or more obtained parameters of the gas transmission network may be determined by the gas transmission network 126, which then provides them to the renewable power plant 100. The gas transmission network 126 may then predict / forecast a future state and / or behavior of the gas transmission network 126 based on measured and / or calculated states and / or conditions of the gas transmission network 126. The gas transmission network 126 may also predict / forecast a future gas consumption and / or production in the gas transmission network 126. The gas transmission network 126 may also be configured to generate and send references / parameters / values based on these predictions / forecasts to the renewable power plant 100.

[0119] Alternatively, the renewable power plant 100, i.e. the control arrangement 150, may according to some embodiments, be configured to itself generate references / parameters / values based on the predictions / forecasts provided by the gas transmission network 126. The renewable power plant 100, i.e. the control arrangement 150, may also be configured to itself predict / forecast the future gas consumption and / or production in the gas transmission network 126, and then to generate references / parameters / values based on these predictions / forecasts.

[0120] In a second step 220, the one or more power-to-gas units 120 are, based on the one or more obtained parameters of the gas transmission network 126 that are generated based on a predicted future state of the gas transmission network, controlled to convert electric power at least partly provided by the one or more renewable electric power generating units 103 to gas for an introduction of at least a portion of the converted gas into the gas transmission network 126. According to various embodiments, the one or more power-to-gas units 120 are thus controlled 220, based on the one or more determined parameters of the gas transmission network 126, to convert electric power to a gas or gas mixture comprising or consisting of hydrogen, oxygen and / or methane.

[0121] The one or more power-to-gas units 120 are therefore connected to the one or more renewable electric power generating units 103, and are configured to draw electric power generated by the one or more renewable electric power generating units 103 when producing gas. Thus, the power-to-gas unit 120 may be configured to convert electric power to gas, where the electric power is provided by the one or more renewable power sources / assets / units 103 of the renewable power plant 100, comprising e.g. one or more the wind turbine generators 101 and / or one or more photovoltaic power generators 102. Also, for some below described embodiments, the power-to-gas unit 120 may be connected to the electric power grid 116, and may be configured to convert electric power imported from the electric power grid 116 to gas.

[0122] According to some embodiments, the method further comprises a third step 230, in which the renewable power plant 100 is, based on the one or more obtained parameters of the gas transmission network 126, controlled to introduce at least a portion of the converted gas into the gas transmission network 126 so as to improve a stability of the gas transmission network 126. Thus, the renewable power plant 100 here provides / injects gas into the gas transmission network 126, and hereby counteracts the imbalance / instability of the gas transmission network 126, possibly caused by varying supply of and / or demand for gas in the gas transmission network 126.

[0123] According to an embodiment illustrated by the flow chart of figure 4, the method 200 further comprises the step of predicting, based on the one or more obtained parameters of the gas transmission network 126, a future instability of the gas transmission network 126. The prediction 211 of such future instability / imbalance may comprise detecting if the one or more determined parameters of the gas transmission network 126, having been generated based on a predicted future state of the gas transmission network 126, exceed their respective limits / thresholds.

[0124] It should be noted that at least one of the one or more obtained parameters is a generally fluctuating / varying parameter. The fluctuations / variations of the parameter values may then be indicative of the level of a future stability of the gas transmission network 126. For such generally fluctuating / varying parameters, corresponding limits / thresholds may be defined to detect if the obtained parameters fluctuate / vary too much. Thus, according to an embodiment, the limits / thresholds for normally fluctuating parameters may indicate an amplitude Ath for some of these fluctuations / variations that should not be exceeded by the amplitude A of the parameters. In other words, the gas transmission network 126 is predicted 211 to become instable / imbalanced if at least one of the one or more obtained parameters of the gas transmission network 126 fluctuates with an amplitude A exceeding its fluctuation amplitude threshold Ath; A>Ath. Further, the limits / thresholds may also indicate a change over time for some of these fluctuations / variations that should not be exceeded by the parameters, respectively.

[0125] After the possible instability / imbalance has been predicted / forecasted 211 , the control 220 of the one or more power-to-gas units 120 to convert electric power to gas is based on the predicted future instability of the gas transmission network 126, such that the predicted future instability may be counteracted by the introduction 230 of the converted gas into the gas transmission network 126.

[0126] According to an embodiment illustrated by the flow chart of figure 4, the renewable power plant 100 is connected to an electric power grid 116, as illustrated in figure 1 . The method 200 then further comprise the step of importing 212 electric power from the electric power grid 116 to the renewable power plant 100 based on the one or more obtained parameters of the gas transmission network 126.

[0127] Then, the one or more power-to-gas units 120 are controlled to convert at least a portion of the electric power imported from the electric power grid 116 to gas. The one or more power-to-gas units 120 are here also controlled to convert electric power provided by the one or more renewable electric power generating units 103 to gas. The conversion of electric power imported from the external electric power grid 116 and electric power produced by the one or more renewable electric power generating units 103 of the renewable power plant 100 to gas is based on the one or more obtained parameters of the gas transmission network 126. The converted gas is then introduced 230 into the gas transmission network.

[0128] According to an embodiment illustrated by the flow chart of figure 4, the method 200 further comprises the step of obtaining 213 one or more parameters of the electric power grid 116, in addition to the obtained one or more parameters of the gas transmission network 126. Then, the import 214 of electric power from the electric power grid 116 to the renewable power plant 100 for the conversion of at least a portion of the imported electric power to gas is based also on the one or more obtained parameters of the electric power grid 116. Thus, electric power is here imported 214 from the electric power grid based on obtained parameters of the gas transmission network 126 and on obtained parameters of the electric power grid. Then, electric power imported 214 from the electric power grid is converted to gas based on the obtained parameters of the gas transmission network 126. At least a portion of the converted gas is then introduced 230 into the gas transmission network based on obtained parameters of the gas transmission network 126.

[0129] Correspondingly as for the obtained parameters of the gas transmission network 126, the obtained parameters of the electric power grid 116 may according to various embodiments, be generated based on predicted future requirements of the electric power grid 116 and / or on a predicted future electric power consumption of the electric power grid 116. The one or more obtained parameters of the electric power grid 116 may be determined by the electric power grid 116, and may be provided to the renewable power plant 100. The electric power grid 116 may then predict / forecast a future state and / or behavior of the electric power grid 116, and may also predict / forecast a future electric power consumption in the electric power grid 116. The electric power grid 116 may further be configured to generate and send references / parameters / values based on these predictions / forecasts to the renewable power plant 100.

[0130] Alternatively, the renewable power plant 100, i.e. the control arrangement 150, may according to some embodiments, be configured to itself generate references / parameters / values based on the predictions / forecasts provided by the electric power grid 116. The renewable power plant 100, may also be configured to itself predict / forecast the future electric power consumption in the electric power grid 116, and then to generate references / parameters / values based on these predictions / forecasts. According to an embodiment, the above mentioned control 220 of the one or more power-to-gas units comprises controlling the one or more power-to-gas units to avoid importing electric power, and instead to only convert electric power produced / provided by the one or more renewable electric power generating units to gas. The hereby converted gas may then, based on the one or more determined parameters of the gas transmission network 126, be at least partially introduced into the gas transmission network 126 so as to improve a stability of the gas transmission network 126. Since no electric power is here imported for the conversion of electric power to gas, it is assured that the electric power only originates from renewable power sources.

[0131] According to an embodiment illustrated by the flow chart of figure 4, the method 200 further comprises the step of allocating 215 a power producing capability of the renewable power plant 100 based on the one or more obtained parameters of the gas transmission network 126. This allocation is provided by controlling the renewable power plant 100 to run in a so-called derated mode, i.e. in a reduced / non- maximal production mode for which not all of the production capabilities of the renewable power plant are fully utilized. Then, the one or more renewable electric power generating units 103 are controlled 216 to produce electric power by utilization of the allocated power producing capability. The one or more power-to-gas units 120 are controlled 220 to convert at least a part of the hereby produced electric power to gas, which may then be introduced 230 into the gas transmission network 126.

[0132] Thus, a possible / imaginary power backup / reserve is hereby created / released in the renewable power plant 100, which can be utilized for producing gas if needed. In other words, a reserve of power is allocated, which is possible to utilize for production of gas, which may be introduced in the gas transmission network 126 if needed.

[0133] According to an embodiment illustrated in by the flow chart of figure 4, the one or more parameters are obtained 210 at a point of interest 125 where one or more requirements of the gas transmission network 126 are to be fulfilled. According to some embodiments, the requirements may correspond to and / or may be comprised in gas transmission network / grid codes. In this document, all of the points of interest, the point of common connection (PCC), and the point of interconnection, refers to a point, e.g. a point / node / place / location where at least two networks meet, for example the point at which the obligations / responsibilities of the renewable power plant 100 terminates and obligations / responsibilities of the gas provider and / or transmission network 126 starts. This may also be described as the point at which the renewable power plant 100 stops and the gas network 126 starts.

[0134] Then, based on the one or more obtained parameters at the point of interest 125, one or more references are dispatched 221 to the renewable power plant 100. According to an embodiment, the dispatched references may be, correspond to and / or comprise set points intended for the entire renewable power plant 100 and / or reference points intended for individual entities of the renewable power plant 100. According to an embodiment, the step of dispatching 221 the references further comprises calculating the references based on the one or more obtained parameters at the point of interest 125.

[0135] In the renewable power plant 100, the one or more power-to-gas units 120 are then controlled 222, based on the one or more dispatched references, to convert electric power to gas. Thus, the dispatched references are received by the renewable power plant 100, and are used for controlling the conversion of electric power to gas in the one or more power-to-gas units 120.

[0136] Then, the renewable power plant 100 is controlled 230, based on the one or more determined parameters at the point of interest 125, to introduce at least a portion of the converted gas into the gas transmission network 126, so as to fulfil one or more requirements at the point of interest 125.

[0137] According to a second aspect, a control arrangement 150 configured for controlling a renewable power plant 100 is presented. As mentioned above, the renewable power plant 100 comprises one or more renewable electric power generating units 103 and one or more power-to-gas units 120. The renewable power plant 100 is connected to a gas transmission network 126. The control arrangement 150 is configured to obtain 210 one or more parameters of the gas transmission network 126. The one or more parameters of the gas transmission network 126 are generated based on a predicted future state of the gas transmission network 126, as described above.

[0138] The control arrangement 150 is further configured to control 220, based on the one or more obtained parameters of the gas transmission network 126, the one or more power-to-gas units 120 to convert electric power at least partly provided by the one or more renewable electric power generating units 103 to gas for the introduction of at least a portion of the converted gas into the gas transmission network 126, as described above.

[0139] According to some embodiments, the control arrangement 150 is further configured to control 230, based on the one or more obtained parameters of the gas transmission network 126, the renewable power plant 100 to introduce at least a portion of the converted gas into the gas transmission network 126.

[0140] With reference to Figure 1 , the renewable power plant 100 may comprise a control arrangement 150 for controlling the power plant 100 according to any one of the aspects and / or embodiments disclosed herein. The control arrangement 150 may comprise, or be referred to as, a power plant controller (PPC).

[0141] According to a third aspect, a renewable power plant 100 is presented. The renewable power plant 100 comprises one or more renewable electric power generating units 103 and one or more power-to-gas units 120, and is connected to a gas transmission network 126, as schematically illustrated in figure 1. The renewable power plant 100 further comprises a control arrangement 150 as herein described.

[0142] The control arrangement 150 may further be configured to, e.g. it comprises units / means / devices 410, 411 , 412, 413, 414, 415, 416, 420, 421 , 422, 430 to, execute / provide / implement the further herein mentioned method steps 210, 211 , 212, 213, 214, 215, 216, 220, 221 , 222, 230 according to various above-described embodiments.

[0143] The person skilled in the art will appreciate that the herein described method aspects and embodiments of the control arrangement controlling a renewable power plant 100 may also be implemented in a computer program, which, when it is executed in a computer, instructs the computer to execute the method. The computer program is usually constituted by a computer program product 503 (shown in figure 5) stored on a non-transitory / non-volatile digital storage medium, in which the computer program is incorporated in the computer-readable medium of the computer program product. The computer-readable medium comprises a suitable memory, such as, for example: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc.

[0144] Figure 5 shows in schematic representation an embodiment of the control arrangement 150 according to an aspect of the invention, which may include a control unit 500, which may be arranged / configured for performing / executing one or more of the above-mentioned method steps 210, 211 , 212, 213, 214, 215, 216, 220, 221 , 222, 230. The control unit 500 may comprise a computing unit 501 , which can be constituted by essentially any suitable type of processor or microcomputer, for example a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit having a predetermined specific function (Application Specific Integrated Circuit, ASIC). The computing unit 501 is connected to a memory unit 502 arranged in the control unit 500. The memory unit 502 provides the computing unit 501 with, for example, the stored program code and / or the stored data which the computing unit 501 requires to be able to perform computations. The computing unit 501 is also arranged to store partial or final results of computations in the memory unit 502.

[0145] In addition, the control unit 500 may be provided with devices 511 , 512, 513, 514 for receiving and transmitting input and output signals. These input and output signals may comprise waveforms, impulses, or other attributes which, by means of the devices 511 , 513 for the reception of input signals, can be detected as information and can be converted into signals which can be processed by the computing unit 501 . These signals are then made available to the computing unit 501 . The devices 512, 514 for the transmission of output signals are arranged to convert signals received from the computing unit 501 in order to create output signals by, for example, modulating the signals, which, for example, can be transmitted to other parts and / or systems of, or associated with, the electric power grid 116, the gas transmission network 126, the heat transmission / distribution network 128, the grid 136 for industrial products and / or the renewable power plant 100 (see figure 1 ). Each of the connections to the devices for receiving and transmitting input and output signals can be constituted by one or more of a cable, a data bus, and a wireless connection.

[0146] Here and in this document, control units are often described as being provided for performing steps of the method according to herein described aspects and embodiments of the invention. This also includes that the units are designed to and / or configured to perform these method steps. For example, the control units may comprise one or more control entities arranged for performing one or more of the herein described method steps 210, 211 , 212, 213, 214, 215, 216, 220, 221 , 222, 230, respectively. These control entities may for example correspond to groups of instructions, which may be in the form of programming code, that are input into, and are utilized / executed by the processor / computing unit 501 of the control unit 500 when the entities are active and / or are utilized for performing their method steps, respectively. Such control entities may be implemented as separate entities in multiple control units, or may be logically separated but physically implemented in the same control unit, or may be both logically and physically arranged together.

[0147] With reference to figure 1 , the control arrangement 150, which may include one or more control units or control entities 410, 411 , 412, 413, 414, 415, 416, 420, 421 , 422, 430, such as for example one or more devices, controllers or control devices, may be arranged to perform all of the method steps mentioned above, in the claims, and in connection with the herein described aspects and embodiments. The control arrangement 150 is associated with the above-described advantages for each respective embodiment of the method. The herein described aspects and embodiments may be applied also in other power plant domains than the renewable / power-to-x plant domains mentioned herein. For example, the herein described aspects and embodiments may be applied to virtual power plants or aggregations of flexible energy loads with their corresponding constraints.

[0148] The present invention is not limited to the above-described embodiments. Instead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.

Claims

Claims1. A method (200) for controlling a renewable power plant (100) comprising one or more renewable electric power generating units (103) and one or more power-togas units (120), the renewable power plant (100) being connected to a gas transmission network (126), wherein the method (200) comprises: obtaining (210) one or more parameters of the gas transmission network (126), the one or more parameters of the gas transmission network (126) being generated based on a predicted future state of the gas transmission network (126); and based on the one or more obtained parameters of the gas transmission network (126), controlling (220) the one or more power-to-gas units (120) to convert electric power at least partly provided by the one or more renewable electric power generating units (103) to gas for an introduction of at least a portion of the converted gas into the gas transmission network (126).

2. A method (200) according to claim 1 , wherein the one or more obtained parameters of the gas transmission network (126) are generated based on one or more in the group of:• predicted future requirements of the gas transmission network (126); and• a predicted future gas consumption of the gas transmission network (126).

3. A method (200) according to any one of claims 1 -2, further comprising: predicting (211 ), based on the one or more obtained parameters of the gas transmission network (126), a future instability of the gas transmission network (126); and controlling (220) the one or more power-to-gas units (120) to convert electric power to gas based on the predicted future instability of the gas transmission network (126).

4. A method (200) according to claim 2, wherein the future instability is predicted (211 ) if at least one of the one or more obtained parameters of the gas transmission network (126) fluctuates with an amplitude A exceeding a fluctuation amplitude threshold Ath; A>Ath.

5. A method (200) according to any one of claims 1 -4, wherein the method (200) further comprises: based on the one or more obtained parameters of the gas transmission network, controlling (230) the renewable power plant (100) to introduce at least a portion of the converted gas into the gas transmission network (126) so as to improve a stability of the gas transmission network (126).

6. A method (200) according to any one of claims 1-5, wherein the renewable power plant (100) is connected to an electric power grid (116), wherein the method (200) further comprises: based on the one or more obtained parameters of the gas transmission network (126), importing (212) electric power from the electric power grid (116) to the renewable power plant (100); and based on the one or more obtained parameters of the gas transmission network (126), controlling (220) the one or more power-to-gas units (120) to convert, in addition to the electric power provided by the one or more renewable electric power generating units (103), at least a portion of the electric power imported from the electric power grid (116) to gas.

7. A method (200) according to claim 6, wherein the method (200) further comprises: obtaining (213) one or more parameters of the electric power grid (116); and based on the one or more obtained parameters of the electric power grid (116), importing (214) electric power from the electric power grid (116) to the renewable power plant (100) for the conversion of at least a portion of the electric power imported from the electric power grid (116) to gas.

8. A method (200) according to any one of claims 1-5, wherein the one or more power-to-gas units (120) are controlled (220) to only convert electric power provided by the one or more renewable electric power generating units (103) to gas.

9. A method (200) according to any one of claims 1-8, wherein the one or more obtained parameters of the gas transmission network (126) are fluctuating over time, the fluctuations being indicative of a stability of the gas transmission network (126).

10. A method (200) according to any one of claims 1-9, wherein the method (200) further comprises: based on the one or more obtained parameters of the gas transmission network (126), allocating (215) a power producing capability of the renewable power plant (100); controlling (216) the one or more renewable electric power generating units (103) to produce electric power by utilization of the allocated power producing capability; and controlling (220) the one or more power-to-gas units (120) to convert at least a part of the produced electric power to gas.

11. A method (200) according to any one of claims 1 -10, wherein the one or more obtained parameters of the gas transmission network (126) comprise one or more of the group of:• a pressure of the gas transmission network (126);• a gas flow rate of the gas transmission network (126);• a gas flow direction of the gas transmission network (126);• a gas volume of the gas transmission network (126);• one or more quantities of gas at one or more locations in the gas transmission network (126);• an amount of gas consumers connected to the gas transmission network (126);• a gas volume consumed by gas consumers connected to the gas transmission network (126);• a character of available gas provided by one or more external gas supplies to the gas transmission network (126);• a volume of available gas provided by one or more external gas supplies to the gas transmission network (126); and• a set point for the renewable power plant (100).

12. A method (200) according to any one of claims 1-11 , wherein each of the one or more power-to-gas units (120) is configured to convert electric power to gas by utilization of an electrolyzer system (121 ).

13. A method (200) according to any one of claims 1-12, wherein the method (200) further comprises: based on the one or more obtained parameters of the gas transmission network (126), controlling (220) the one or more power-to-gas units (120) to convert electric power to a gas or gas mixture comprising or consisting of one or more of the group of:• hydrogen;• oxygen; and• methane.

14. A method (200) according to any one of claims 1 -13, wherein the one or more renewable electric power generating units (103) comprise one or more of the group of:• a wind turbine generator (101 ) of the renewable power plant (100);• a photo-voltaic generator (102) of the renewable power plant (100);• an electric battery energy storage system (106) of the renewable power plant (100); and• a fuel cell (104) of the renewable power plant (100).

15. A method (200) according to any one of claims 1-14, wherein the method (200) further comprises:obtaining (210) the one or more parameters at a point of interest (125) where one or more requirements of the gas transmission network (126) are to be fulfilled; based on the one or more obtained parameters at the point of interest (125), dispatching (221 ) one or more references to the renewable power plant (100); based on the one or more dispatched references, controlling (222) the one or more power-to-gas units (120) to convert electric power to gas for a fulfilment of at least one of the one or more requirements at the point of interest (125).

16. A computer program (703) or a computer-readable medium comprising instructions which, when the program or the instructions is / are executed by a computer, cause the computer to carry out the method according to any one of the claims 1 to 15.

17. A control arrangement (150) for controlling a renewable power plant (100), wherein the renewable power plant (100) comprises one or more renewable electric power generating units (103) and one or more power-to-gas units (120), and is connected to a gas transmission network (126), wherein the control arrangement (150) is configured to: obtain (210) one or more parameters of the gas transmission network (126), the one or more parameters of the gas transmission network (126) being generated based on a predicted future state of the gas transmission network (126); and based on the one or more obtained parameters of the gas transmission network (126), control (220) the one or more power-to-gas units (120) to convert electric power at least partly provided by the one or more renewable electric power generating units (103) to gas for the introduction of at least a portion of the converted gas into the gas transmission network (126).

18. A renewable power plant (100) comprising one or more renewable electric power generating units (103) and one or more power-to-gas units (120), and being connected to a gas transmission network (126), wherein the renewable power plant (100) comprises a control arrangement (150) according to claim 17.

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