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

Abstract

A method and a control arrangement for controlling a renewable power plant (100) connected to a power grid (116) are presented. The method comprises, for each time frame of a sequence of time frames: - determining (210) one or more proactive policies (314pol) and corresponding priority indications (314pri) of a proactive control loop (310) associated with the renewable power plant (100); - determining (220) one or more run-time policies (322pol) and corresponding priority indications (322pri) of a run-time control loop (320) associated with the renewable power plant (100); - determining (230), by utilization of their priority indications (314pri, 322pri), a hierarchic order of the one or more proactive policies (314pol) and the one or more run-time policies (322pol); - determining (240) a control configuration (331) for the renewable power plant (100) based on the determined hierarchic order, the one or more proactive policies (314pol), and the one or more run-time policies (322pol); and - controlling (250) the renewable power plant (100) based on the determined control configuration (331).

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 for controlling a renewable power plant, to a control arrangement for controlling a renewable power plant, 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 comprise one or more renewable energy assets, comprising e.g. one or more wind turbine generators, one or more photovoltaic generators and / or one or more electric battery energy storage systems. Renewable power plants may also comprise one or more power-to-gas units, and may then be known as power-to-x plants. Besides electricity, the renewable power plants may include additional energy vectors, such as green hydrogen, produced from water, and other green synthetic fuels, such as methane, produced by mixing green hydrogen with additional chemical compounds and 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 thus comprises one or more electrical generators, such as on-site renewable energy sources, e.g., wind turbine generators and / or photovoltaic power generators. The renewable power plant may also comprise one or more electrolyzer systems arranged for breaking down water molecules into its constituents, i.e. to hydrogen and oxygen, by consuming electricity. Optionally, the renewable power plant may also comprise one or more plant extension units that can transform the produced hydrogen into other industrial products. The plant extension units comprise, e.g., chemical units / plants that utilize hydrogen and also possibly other compounds or elements, such as, e.g., nitrogen or carbon dioxide, to produce other industrial products and / or e-fuels. The produced industrial products and / or e- fuels may be stored locally, or may be provided for onward transportation / off-take. These entities, i.e. the electrical generators, the electrolyzer systems and the plant extension units, are coupled together via local electricity and gas grids within the renewable power plant.

[0007] Summary

[0008] The energy output of the renewable energy power plant should be controlled in order to optimize the most valuable operation of the renewable power plant. Conventional solutions for such control formulate optimal dispatch problems which generate reference- and / or set-points and assume that these reference- and / or set-points can be implemented at the renewable plant by a lower-level controller.

[0009] However, such conventional solutions are often infeasible, or at least result in an inaccurate control of the renewable power plant. One reason for this is the fluctuating nature of the one or more electrical generators due to varying wind and solar conditions, which requires the formulation of the dispatch problems to be run at high frequency. Another reason is that the communication connectivity to the renewable power plant may be intermittent, meaning that the dispatch signals, i.e. the reference- and / or set-points, may not be provided to the renewable power plant with the needed frequency for adapting to the fluctuations.

[0010] The renewable power plants further have a complex control structure of interlocked control loops, e.g. for human safety, grid compliance, environmental compliance and / or financial performance optimization. Thus, the conventional complex control structure, which comprises multiple control loops having differing objectives, creates decision-making conflicts for the renewable plant. These decision-making conflicts may become worse with insufficient and / or unreliable communication connectivity of the renewable power plant.

[0011] An object of the present invention is to provide a solution which mitigates or solves the above-mentioned problems related to the decision-making conflicts and / or the unreliable connectivity of the renewable plant. The above and further objects are solved by the subject matter of the aspects of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0012] According to a first aspect of the invention, a method for controlling a renewable power plant connected to a power grid, the renewable power plant comprising one or more renewable energy assets; the method comprising, for each time frame of a sequence of time frames:

[0013] - determining one or more proactive policies and corresponding priority indications of a proactive control loop associated with the renewable power plant;

[0014] - determining one or more run-time policies and corresponding priority indications of a run-time control loop associated with the renewable power plant;

[0015] - determining, by utilization of their priority indications, a hierarchic order of the one or more proactive policies and the one or more run-time policies;

[0016] - determining a control configuration for the renewable power plant based on the determined hierarchic order, the one or more proactive policies, and the one or more run-time policies; and

[0017] - controlling the renewable power plant based on the determined control configuration.

[0018] Hereby, control method which generates control configurations that lower-level control systems of the renewable power plant can follow in order to control the renewable power plant is provided. These control configurations may be determined based on one or more policies without constant need of network connection.

[0019] A configurable control of the renewable power plant is provided, which maximizes the value of the renewable power plant under the constraints of for example the compliance control loops being present on the renewable plant. Thus, a control configuration is generated in order to guide the low level control systems to the most valuable operation of the renewable power plant, while being constrained by the real run-time control system acting on the renewable plant under the current operation context for the renewable power plant. The renewable power plant comprises a cascade of control systems running independent control loops. For example, each asset has its own control system / loop, and there are various level control systems / loops in the renewable power plant. The presented method can manage / clear the possible conflicts between these control systems / loops, both of the forward looking / proactive control systems / loops and the run-time control systems / loops considering the current condition of the renewable power plant.

[0020] Generally, run-time control systems / loops are related / associated to control based on feedback from measured or calculated parameter values representing a current state of the renewable power plant and / or the grid. Such parameter values may for example comprise essentially any value which relates to the current operation conditions for the power plant, such as values associated with power output of wind turbines, power consumption of electrolyzers, or measurements of frequencies and / or voltages of the grid. Such values may also comprise essentially any value which relates to specific settings / conditions being associated with and / or indicating a current compliance with the grid codes. A run-time policy is a function which describes how the run-time control system / loop wants the renewable power plant to behave under the current conditions of the renewable power plant and / or the grid.

[0021] Proactive control systems / loops, however, relate to control of a future operation of the renewable power plant. Such forward-looking control may for example comprise controlling how the power produced by the renewable power plant should be distributed amongst the loads in the renewable power plant and / or the grid. A proactive policy describes how the proactive control system wants the renewable power plant to behave in its future operation given the information related to the renewable power plant being available over time.

[0022] The control configurations are therefore determined by utilizing a flexible conflict clearing between differing policies. The conflict clearing performed on the differing policies prioritizes control decisions according to a control hierarchy configuration of the renewable power plant when being applied to a current operation context for the renewable power plant. Hereby, the renewable power plant may be controlled in compliance with the complex control structure of the renewable power plant, comprising multiple interlocked control loops, e.g. for human safety, grid compliance, environmental compliance and / or financial performance optimization. The possibly conflicting objectives of the different layers of the complex control structure are solved by the conflict clearing applied to the policies, which may be performed also during insufficient and / or unreliable communication connectivity to the renewable power plant.

[0023] The conflict clearing of contradicting policies being utilized in the control of the renewable power plant may be used for maximizing the operational output and value of the renewable power plant, which may include any combination of wind-based power production, solar-based power production, storage systems, chemical production systems, e.g. power-to-x (P2X) systems producing for example hydrogen, ammonia and / or methanol, and loads of the renewal power plant, e.g. for mining systems. At the same time, the presented method ensures compliance to for example grid codes, environmental codes, and / or market requirements, by providing a configurable control hierarchy.

[0024] The policies, based on which the renewable power plant is controlled, may be varying over time, and may for example be affine and / or non-linear functions generated through an optimization algorithm. The policies are associated with meta-information related to the execution prioritization of the policy, utilized for performing the control of the renewable power plant. The policies may for example be mathematical functions that define a controller behavior depending on the current operation context, such as measurements, of the assets of the renewable power plant, e.g. wind or solar energy generation assets and / or energy consuming assets, e.g. electrolyzers or ammonia plants. These policies may thus capture the renewable power plant goals set up by a plant owner and how risk-willing the owner is with respect e.g. to failing market commitments, grid constraints, environmental constraints and behind the meter consumption constraints, given the uncertainty of the energy production of the renewable power plant and the potential for value generation. By application of the multi-tiered control approach of the presented method, the renewable power plant may control its power-to-x assets closer to an available energy, with reduced risk of energy shortfall, as compared to conventional setpointbased power plant control systems. The presented method for controlling the renewable power plant can easily be adapted to be market specific and implementation specific.

[0025] The presented method may also be utilized for integrating the renewable power plant with market systems and / or plant owner systems.

[0026] According to an embodiment of the present invention,

[0027] - the one or more proactive policies are comprised in a schedule of policies for the sequence of time frames; and

[0028] - each time frame of the schedule of policies comprises one or more proactive policies for that time frame.

[0029] Hereby, since each time frame is associated with one or more proactive policies, the one or more proactive policies on which the control of the renewable power plant is based may vary from time frame to time frame, i.e. may vary over time in order to adapt to varying conditions for the renewable power plant, without the need for constant network connection. The renewable power plant is hereby able to operate closer to an optimal configuration at all times, since the proactive policies are contingent on what happens in real-time in the renewable power plant.

[0030] According to an embodiment of the present invention, the one or more proactive policies reflect one or more in the group of:

[0031] - a long-term goal for the renewable power plant;

[0032] - a risk associated with the renewable power plant;

[0033] - an uncertainty associated with the renewable power plant;

[0034] - a forecast of energy pricing in the power grid; and

[0035] - a market interaction with the renewable power plant. Thus, the one or more proactive policies may take a large number of important parameters of various fields into account. The flexible conflict clearing provided by the presented control of the renewable power plant solves any possible conflicting interests associated with the one or more proactive policies and the one or more runtime policies, such that the most suitable control configuration is used as a basis for the control at any given point in time.

[0036] According to an embodiment of the present invention, the one or more run-time policies comprise one or more in the group of:

[0037] - at least one policy associated with a regulatory compliance control loop of the renewable power plant;

[0038] - at least one policy associated with a safety control loop of the renewable power plant;

[0039] - at least one policy associated with an environmental consideration control loop of the renewable power plant;

[0040] - at least one policy determined by a plant operator of the renewable power plant;

[0041] - at least one policy determined by an owner of the renewable power plant; and

[0042] - at least one policy determined by an operator of the power grid.

[0043] Thus, the one or more run-time policies may take a large number of important parameters related to e.g. human safety, grid compliance and / or environmental compliance into account. The flexible conflict clearing provided by the presented control of the renewable power plant solves any possible conflicting interests associated with the one or more run-time policies and the one or more proactive policies, such that the most suitable control configuration is used as a basis for the control at any given point in time.

[0044] According to an embodiment of the present invention,

[0045] - each of the one or more proactive policies and the one or more run-time policies defines a control behavior associated with one or more parameters of the renewable power plant; and

[0046] - the control behavior indicates how the renewable power plant should be configured when the one or more parameters fulfill corresponding conditions. Thus, the policies define a requested / wanted lower level control / controller behavior being dependent on, or associated with, one or more parameters associated with the current operation context of the renewable power plant, where these parameters e.g. may be measured, estimated, modelled and / or forecasted. Thus, the policies describe how to determine operational states for the renewable power plant from a current plant operational context over time, such that the renewable power plant is optimally controlled in respect of the policies, at every give point in time.

[0047] According to an embodiment of the present invention, each of the one or more proactive policies and the one or more run-time policies is one in the group of:

[0048] - a variable policy, which changes over a time frame; and

[0049] - a static policy, which is constant over a time frame.

[0050] In many implementations, the conditions for the renewable power plant and its asset may vary over time, due to e.g. varying wind and sun conditions. In such implementations, variable policies are useful. In other implementations, for which more constant conditions are present for the renewable power plant, static policies are useful.

[0051] According to an embodiment of the present invention, the control configuration comprises one or more in the group of:

[0052] - a maximum value for a control variable;

[0053] - a minimum value for a control variable;

[0054] - a reference value for a control variable;

[0055] - an identifier indicating an operation mode for the renewable power plant;

[0056] - an identifier indicating an operation mode for at least one of the one or more renewable energy assets of the renewable power plant;

[0057] - an indication of a lacking decision associated with a control variable;

[0058] - an identifier indicating a control behavior of a central control system of the renewable power plant;

[0059] - an identifier indicating a control behavior of a power plant controller of the renewable power plant; and - an identifier indicating a control behavior of at least one renewable asset controller of the renewable power plant.

[0060] The control configuration may comprise one or more values and / or identifiers that may be utilized for setting up the renewable power plant to perform according to a wanted behavior associated with one or more policies being used as a basis for determining the control configuration. Since various values and / or identifiers may be comprised in the control configuration, it is flexible and may easily be adapted to fit a currently controlled renewable power plant. Furthermore, the flexibility in the control configuration allows for a high-level control e.g. by setting of operation modes, such as delegating control decisions to lower level controllers, or for a fine-tuned control decision e.g. by setting specific reference values to low level control variables.

[0061] According to an embodiment of the present invention, the determination of the hierarchic order comprises:

[0062] - sorting the one or more proactive policies and the one or more run-time policies based on their priority indications.

[0063] The sorting of the one or more proactive policies and the one or more run-time policies based on their priority indications, that may be configured and / or dynamic, is a basis for the conflict avoiding control of the renewable power plant. Since the policies are arranged in their priority order, decision-making conflicts may easily, and efficiently be taken care of, with little computational complexity.

[0064] According to an embodiment of the present invention, the determination of the control configuration comprises:

[0065] - determining a control setting associated with each of the sorted one or more proactive policies and one or more run-time policies, in an order from a lowest priority policy to a highest priority policy; and

[0066] - merging each determined control setting with one or more previously determined control settings to determine the control configuration. The combination of sorting the policies and merging control settings associated with the sorted policies provides for an efficient and low complexity protection against policy-related conflicts. To merge the control setting according to a hierarchy like this ensures that the resulting control of the renewable power plant is constrained by the more important policies, such as e.g. the compliance control policies comprised in the run-time policies, while still trying to address the overall and / or economic parameters associated with the proactive policies. The compliance control loop may include a compliance control system and / or a safety control system. The proactive control system takes into consideration e.g. fulfilling owner’s goals and / or risk willingness, and market interactions. The proactive control system aims at maximizing the value of the renewable plant, by utilization of the proactive policies. Thus, the merging of the control settings utilizes the policies to maximize the value of the plant, while at the same time providing a conflict resolving function, such that the control of the renewable power plant is compliant to the control loops that are more important than value maximization, i.e. is compliant to the compliance control systems of the runtime control systems.

[0067] According to an embodiment of the present invention, the merging of each determined control settings comprises one or more in the group of:

[0068] - determining the control configuration based only on the highest priority policy;

[0069] - determining the control configuration based only on the highest priority policy and postpone control configuration determinations based on one or more lower priority policies;

[0070] - determining the control configuration based on a weighted combination of the highest priority policy and one or more lower priority policies, where the highest priority policy is given the highest weight in the weighted combination.

[0071] The herein presented embodiments for merging of the determined control settings provides for efficient and low complexity determinations of the control configuration, based on which the renewable power plant will be controlled by lower level control systems. According to an embodiment of the present invention, the controlling of the renewable power plant comprises:

[0072] - determining one or more parameters of the renewable power plant;

[0073] - determining operation states for the renewable power plant based on the determined control configuration and the determined one or more parameters; and

[0074] - controlling the renewable power plant towards the determined operation states.

[0075] Thus, the renewable power plant is controlled based on the determined control configuration and on the current operational conditions of the renewable power plant. Thus, the wanted behavior of the renewable power plant as defined by the one or more policies is applied to the current settings / conditions currently being experienced by the renewable power plant. Hereby, a flexible and well-adaptable control of the renewable power plant is provided.

[0076] According to an embodiment of the present invention, the method is sequentially performed for each time frame of the sequence of time frames, thereby resulting in a control of the renewable power plant varying over time.

[0077] To be able to change the control of the renewable power plant over time is important due to the often varying conditions for the renewable power plants and their renewable assets.

[0078] According to an embodiment of the present invention, the priority indications associated with the one or more proactive policies and / or the one or more run-time policies are configurable and / or dynamic.

[0079] Thus, the priority indications, and thus the importance of the policies may be configurable, e.g. by manual configuration, such that the control of the renewable power plant may be tailored by e.g. a plant operator or plant owner. The priority indications may also be dynamically changed, e.g. automatically according to a given context, if configured that way. The priority / control hierarchy can hereby be tailored to fit e.g. local regulations and / or needs / business motivations of the owner of the renewable power plant. According to a second aspect of the invention, a control arrangement for controlling a renewable power plant connected to a power grid is presented. The renewable power plant comprises one or more renewable energy assets. The control arrangement is configured to, for each time frame of a sequence of time frames:

[0080] - obtain one or more proactive policies and corresponding priority indications of a proactive control loop associated with the renewable power plant;

[0081] - determine one or more run-time policies and corresponding priority indications of a run-time control loop associated with the renewable power plant;

[0082] - determine, by utilization of their priority indications, a hierarchic order of the one or more proactive policies and the one or more run-time policies;

[0083] - determine a control configuration for the renewable power plant based on the determined hierarchic order, the one or more proactive policies, and the one or more run-time policies; and

[0084] - provide the determined control configuration to a central control system of the renewable power plant.

[0085] 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.

[0086] 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.

[0087] According to a third aspect of the invention, a renewable power plant is presented.

[0088] The renewable power plant comprises:

[0089] - one or more renewable energy assets; - a herein described control arrangement;

[0090] - a central control system configured to control the renewable power plant based on the determined control configuration provided by the control arrangement and on one or more parameters of the renewable power plant.

[0091] 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.

[0092] According to an embodiment of the present invention, the one or more renewable energy assets comprise one or more renewable electric power generating units in the group of:

[0093] - a wind turbine generator of the renewable power plant;

[0094] - a photo-voltaic generator of the renewable power plant; and

[0095] - an electric battery energy storage system of the renewable power plant.

[0096] By being able to utilize a number of different renewable power sources for producing renewable electric power, the renewable power plant may easily and quickly adapt to changing conditions, e.g., changing wind and / or sun conditions.

[0097] 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.

[0098] 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. Further advantageous embodiments of the method for controlling the renewable power plant, the control arrangement and the renewable power plant, and further advantages of the embodiments of the present invention, emerge from the detailed description of embodiments.

[0099] Brief Description of the Drawings

[0100] Aspects and embodiments of the invention are 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:

[0101] Fig. 1 is a schematic diagram illustrating an example of a renewable power plant, in which aspects and embodiments of the present invention may be implemented;

[0102] Fig. 2 is a flow chart diagram for a method according to various aspects and embodiments of the present invention;

[0103] Fig. 3 is a block diagram schematically illustrating some parts / systems / units / assets of various embodiments of the present invention; and

[0104] Figs. 4 schematically illustrates a control unit / arrangement according to some aspects and embodiments of the present invention.

[0105] Detailed Description

[0106] 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 energy assets utilized, and is not limited to implementation in the renewable power plant example in figure 1 .

[0107] 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 energy assets 106, including 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 103, such as, e.g., photo-voltaic panels 102. The wind turbine generators 101 and the photo-voltaic panels 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, may also be comprised in the renewable power plant 100. The renewable energy assets 106 of the renewable power plant 100 may also comprise one or more electric battery energy storage systems 105.

[0108] The renewable power plant 100 may be connected, or connectable, possibly via an internal grid 110 of the renewable power plan, to the external electric power grid 116 via a point of common coupling (PCC) 115. The renewable electric power generating units 103 feed / provide electric power 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.

[0109] The renewable power plant 100 may further, according to some embodiments, comprise one or more electrolyzer systems 121 comprised in corresponding one or more power-to-gas units 120, respectively. The one or more power-to-gas units 120 are configured to convert electric power to gas, wherein the gas comprises or consists of hydrogen, oxygen and / or methane.

[0110] An electrolyzer system 121 breaks down water molecules into its constituents, i.e. into hydrogen and oxygen, by consuming electricity. The one or more electrolyzer systems 121 may, e.g., comprise an alkaline electrolyzer, an unpressurized alkaline electrolyzer, a pressurized alkaline electrolyzer, a proton exchange membrane electrolyzer, an unpressurized proton exchange membrane electrolyzer, a pressurized proton exchange membrane electrolyzer, a polymer electrolyte membrane electrolyzer, an unpressurized polymer electrolyte membrane electrolyzer, a pressurized polymer electrolyte membrane electrolyzer and / or a solid oxide electrolyzer. The various electrolyzer technologies / types have differing operating efficiencies and ramping capabilities. Thus, the electrolyzer type being most efficient for the specific renewable power plant and / or for the current conditions may be utilized.

[0111] Optionally, the renewable power plant may also, according to some embodiments, comprise one or more plant extension units 130 that can transform the hydrogen produced by the electrolyzer systems 121 of the power-to-gas units 120 into other products by consuming electricity. The plant extension units 130 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 for provided for onward transportation.

[0112] 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 electrical generators 103 of the renewable power plant, which is not used by 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 electrolyzer systems 121 in the renewable power plant to a hydrogen or natural gas grid 126. Also, one or more interfaces 135 may be implemented to export industrial products, such as e-fuels, produced by the plant extension units 130 to a grid 136 for industrial products and / or e-fuels.

[0113] 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, may be comprised in, or be referred to as, a power plant controller (PPC) 160. As schematically illustrated in figure 1 , the power plant controller 160 controls the renewable power generating units 103, the battery system 105, the internal grid 110, the power to gas units 120, the plant extension units 130 and the product storage 131 . The power plant controller 160 may also communicate with the external electricity grid 116, the hydrogen or natural gas grid 126 and / or the grid 136 for industrial products and / or e-fuels. The herein described run-time control system 320 may, according to an embodiment, be comprised in the power plant controller 160 of the renewable power plant 100. The herein described conflict clearing system 330 and / or central control system 340 may also, according to various embodiments, be comprised in the power plant controller 160.

[0114] The renewable power plant 100 thus utilizes renewable energy sources 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, industrial products and / or e-fuels. The produced electricity, hydrogen, natural gas, industrial products and / or e-fuels may then be exported to external grids 116, 126, 136, respectively.

[0115] Due to rapid changes in the environment, such as changing wind strengths and changing sun conditions, the electric power produced by the wind turbine generators 101 and the photovoltaic power generators 102 may be rapidly changing. Such shortterm changes may occur in the time span of minutes or even seconds. The control of the energy output of the renewable energy power plant 100 should be controlled to optimize the most valuable operation of the renewable power plant 100. Conventional solutions for controlling the energy output are generally not able to sufficiently quickly adapt to such short-term changes.

[0116] Also, conventional control solutions rely on a complex control structure of interlocked control loops having differing objectives, comprising a cascade of controllers running independent control loops, e.g. for human safety, grid compliance, environmental compliance and / or financial performance optimization. Each asset may have its own controller, and there are various levels of controllers in the renewable power plant 100. This control structure may conventionally result in decision-making conflicts for the renewable plant 100.

[0117] These decision-making conflicts may become worse with insufficient and / or unreliable communication connectivity to the renewable power plant. For example, off-shore or remote power wind turbine generators 101 may lose its internet connection, e.g. by an underwater fibre connection being damaged.

[0118] Thus, conventional solutions for controlling the energy output are unable to provide a correct and reliable control of the energy output in some situations.

[0119] Figure 2 shows a flowchart illustrating some aspects and embodiments of a method 200 according to the present invention. Figure 3 shows a block chart schematically illustrating some aspects and embodiments of a control arrangement 150 according to the present invention.

[0120] The method 200 controls a renewable power plant 100 connected to a power grid 116. The renewable power plant 100 comprises one or more renewable energy assets 106.

[0121] The method comprises a first 210 step of determining, for each time frame of a sequence of time frames, one or more proactive policies 314pol and corresponding priority indications 314pri of a proactive control loop 310 associated with the renewable power plant 100. The one or more proactive policies 314pol and corresponding priority indications 314pri may for example be determined 210 by a proactive control system 310, working e.g. on an hourly time scale, as schematically illustrated in figure 3. The proactive control system 310 may be part of a proactive control loop, and may be provided with measurements 361 of the renewable power plant and / or the renewable assets 106.

[0122] In this document, a time frame may be a time period / window having a predetermined length, for example in an interval of 1 to 10 minutes, such as e.g. 5 minutes. The time frame could also extend further, into hours, days, weeks, etc. For example, there could be a policy that puts a turbine into maintenance mode for several days. The sequence of time frames may have a predetermined length, and may comprise a predetermined number of time frames. Generally, in this document, a policy defines a requested / wanted lower level control / controller behavior being dependent on, or associated with, one or more parameters of the renewable power plant. Thus, the policy may be a more or less complex mechanism, which describes how to determine operational states for the renewable power plant from a current plant operational context depending on measurements at the renewable power plant over time. According to various embodiments, the policies may for example comprise set points or mathematical functions, such as e.g. affine mathematical functions, linear mathematical functions or non-linear mathematical functions. The policies may also comprise or be associated with specific parameters of existing control loops, such as specific tuning / changes / adjustment of controller variables / parameters for e.g. PID controllers. The policies may also comprise or be associated with operation mode flags for assets, for example causing switching between predetermined operation modes for an asset, such as between e.g. wind turbine generator power modes. The policies may also comprise or be associated with complex models, such as Artificial Intelligence models or machine learning models, or may comprise or be associated with essentially any other suitable value, function or model.

[0123] Specifically, in this document, a proactive policy 314pol is a function which, given the available information associated with the renewable power plant 100 at a certain time, describes how the proactive control system 310 wants the renewable power plant 100 to behave. The proactive policies 314pol may be determined at a relatively low frequency, for example once every five minutes to once per year, or anywhere in this interval. Each proactive policy 314pol is assigned / given a category and a priority indication 314pri.

[0124] In a second step 220, one or more run-time policies 322pol and corresponding priority indications 322pri of a run-time control loop 320 associated with the renewable power plant 100 are determined for each time frame. The one or more run-time policies 322pol and corresponding priority indications 322pri may for example be determined 220 by a run-time control system 320 schematically illustrated in figure 3. The run-time control system 320 may be part of a run-time control loop, and may be provided with measurements 362 of the renewable power plant and / or the renewable assets 106.

[0125] In this document, a run-time policy 322pol is a function which, given the available information associated with the renewable power plant 100 at a certain time, describes how the run-time control system 320 wants the renewable power plant 100 to behave. The run-time policies 322pol may be determined at a relatively low frequency, for example once every five minutes to once per year, or anywhere in this interval. The run-time policies 322pol may also be determ ined / configured at commissioning of the renewable power plant, and may stay unchanged after that. Each run-time policy 322pol is assigned / given a category and a priority indication 322pri.

[0126] Thus, the one or more proactive policies 314pol are determined by the proactive control system 310 and the one or more run-time policies 322pol are determined by the run-time control system 320, i.e. they are determined by different control systems. The proactive control system 310 and the run-time control system 320 may have differing views on how the renewable power plant 100 should behave, i.e. should be controlled, possibly leading to conflicting one or more proactive policies 314pol and one or more run-time policies 322pol.

[0127] Therefore, in a third step 230, a hierarchic order of the one or more proactive policies 314pol and the one or more run-time policies 322pol is determined by utilization of their priority indications 314pri, 322pri, respectively, for each time frame. The hierarchic order may for example be determined 230 by a conflict clearing system 330 working e.g. on a seconds time scale and being provided with the one or more proactive policies 314pol and the one or more run-time policies 322pol and their priority indications 314pri, 322pri from the proactive control system 310 and the runtime control system 320, respectively, as schematically illustrated in figure 3. The conflict clearing system 330 may also be provided with measurements 361 of the renewable power plant and / or the renewable assets 106. According to an embodiment, the conflict clearing system 330 determines if any of the one or more proactive policies 314pol or the one or more run-time policies 322pol should be activated. The conflict clearing system 330 may for example determine that the current measurements / conditions do not trigger a specific proactive control policy, e.g. due to low wind conditions, while other policies are still relevant / activated. Thus, the conflict clearing system 330 determines which proactive policies and run-time policies are active, and then sorts the active policies according to a hierarchy.

[0128] It should be noted that all control inputs from the proactive control system 310 and the run-time control system 320 to the conflict clearing system 330 are in the form of policies, i.e. are the one or more proactive policies 314pol and the one or more runtime policies 322pol. Thus, even plant external signals, such as inputs 321 from operators or owners of the renewable power plant 100 and / or the power grid 116 are converted into policy representations internally being used in the conflict clearing system 330.

[0129] In a fourth step 240, a control configuration 331 for the renewable power plant 100 is determined for each time frame based on the determined hierarchic order, the one or more proactive policies 314pol, and the one or more run-time policies 322pol. The control configuration 331 may for example be determined 240 by the conflict clearing system 330 schematically illustrated in figure 3.

[0130] The control configuration 331 hereby provided is cleared of any possible conflicts, such as schedule conflicts between the proactive control loop and existing schedulebased control loops of the renewable power plant 100, e.g. environmental control loops, and non-schedule conflicts between e.g. proactive control decisions and grid compliance control loops. The provided single control configuration 331 is ready to be easily executed by lower level control systems, without risking running in to any conflicts.

[0131] The control configuration 331 may define a limitation or a desired reference associated with the central control system 340 of the renewable power plant 100. As a non-limiting example, a control configuration 331 may specify that e.g. a reference power at point of common coupling should be maintained, while limiting the generation wind power, but neither specifying any limitations on the generation of solar power nor on the power consumption in the renewable power plant 100.

[0132] In a fifth step 250, the renewable power plant 100 is for each time frame controlled based on the determined control configuration 331 . The control 250 of the renewable power plant 100 is performed by a central control system 340 and a lower level asset control system 250, where the central control system 340 is provided with the control configuration 331 from the conflict clearing system 330, as schematically illustrated in figure 3.

[0133] The central control system 340 and the asset control system 250 may e.g. work on a milli-second time scale, and may also be provided with measurements 361 of the renewable power plant and / or the renewable assets 106.

[0134] The central control system 340 is configured to control the renewable power plant, including wind turbine generators 101 , photovoltaic panels 102, batteries 105, electrolyzers 121 , or other relevant renewable energy assets 106, according to the control configuration 331 during each specific time frame. The central control system 340 uses e.g. local measurements 361 and the current provided control configuration 331 to determine the best operation point for the renewable energy assets 106. The central control system 340 may provide a high level asset control signal 341 to the lower level asset control system 350.

[0135] The asset control system 350, for example comprising a set of renewable asset controllers, such as e.g. wind turbine generator controllers or photovoltaic panel controllers, provide a low lever control signal 351 to the renewable energy asset 360 / 106 being controlled. This control signal 351 may override asset-internal control loops if the control hierarchy is configured this way. The lower level control signal 351 may for example comprise set points, reference points and / or control mode flags intended for the individual assets 360 / 106.

[0136] According to an embodiment, the herein described method 200, i.e. the herein described method aspects and embodiments, including the herein described steps 210, 220, 230, 240, 250, 232, 242, 243, 244, 245, 246, is sequentially performed for each time frame of the sequence of time frames. This sequentially performed execution of the method 200 results in in a control of the renewable power plant 100 which varies over time.

[0137] It should be noted that the method steps illustrated in figure 2 and described herein do not necessarily have to be executed in the order illustrated in figure 2. The steps may essentially be executed in any suitable order, as long as the physical requirements and the information needed to execute each step is available when the step is executed.

[0138] According to an embodiment, the one or more proactive policies 314pol, possibly provided by the proactive control system 310, are comprised in a schedule of policies for the sequence of time frames. Each time frame of the schedule of policies then comprises one or more proactive policies 314pol for that time frame. Thus, a set of at least one proactive policy 314pol is defined for each time frame of the schedule of policies. These proactive policies 314pol may be conditionally triggered e.g. based on local measurements 361 of the renewable power plant 100. For each policy, a prioritization identifier 214pri is defined, such that if two or more policies are to be triggered simultaneously, the conflict resolution system 330 will use these prioritization identifiers 214pri to prioritize one policy over another, as explained herein.

[0139] Each of the one or more proactive policies 314pol may define a control behavior associated with one or more parameters 361 of the renewable power plant 100. The control behavior then indicates how the proactive control system 310 wants the renewable power plant 100 to be configured when the one or more parameters 361 fulfill corresponding conditions.

[0140] The one or more proactive policies 314pol may for example reflect a short-term, midterm or long-term goal for the renewable power plant 100, a risk associated with the renewable power plant 100 and / or an uncertainty associated with the renewable power plant 100. Such proactive policies 314pol may be determined based on information 311 associated with goals and risk willingness of an owner of the renewable power plant 100 being input to the proactive control system 310. The one or more proactive policies 314pol may also reflect a forecast of energy pricing and / or an actual / current pricing known e.g. 12-36 hours before operation, in the power grid 116 being comprised in forecasting information 312 being input to the proactive control system 310. The forecasting information 312 may, according to various embodiments, also comprise information associated with weather and / or power generation forecasting. The one or more proactive policies 314pol may also reflect a market interaction with the renewable power plant 100 being included in market interaction information 313 being input to the proactive control system 310.

[0141] According to various embodiments, each of the one or more proactive policies 314pol may be a variable policy, which changes / varies over / during / within a time frame, or may be a static policy, which is constant / stable over / during / within a time frame. According to an embodiment, the priority indications associated with the one or more proactive policies 314pol are configurable and / or dynamic.

[0142] The priority indications being configurable herein means that the control hierarchy may be adapted e.g. to local regulations, such as regarding grid compliance versus environmental compliance. For example, in some countries, providing ancillary services like frequency containment reserves are a market product, thus having a lower priority compared to environmental compliance, and in other countries, similar ancillary services form part of a grid code, thus having a higher priority than some environmental compliance functions. The priority indications are therefore configured to fit local laws for operating the plant. Also, by some plant owners, proactive policies that try to extend the lifetime of the energy assets may be regarded as less important than some short-term economic policies, such as e.g. changing the power mode of a set of turbines, while other plant owners may prefer lifetime management policies to be more important than short-term economic gain. In cases where these two kinds of policies are in conflict, the prioritization is determined by what the plant owner has deemed preferrable. The priority indications being dynamic means that systems can adapt the priority indications according to their context. For example, shadow flickers are allowed up to certain amount of hours per year. Therefore, if it is possible keep track of these allowed hours, an economic policy may be dynamically up-prioritized over environmental compliance for these hours.

[0143] According to an embodiment, the one or more run-time policies 322pol comprise at least one policy associated with a regulatory compliance control loop of the renewable power plant 100, schematically illustrated by the feedback loop 362 in figure 3. According to an embodiment, the one or more run-time policies 322pol comprise at least one policy associated with a safety control loop of the renewable power plant 100, schematically illustrated by the feedback loop 362. According to an embodiment, the one or more run-time policies 322pol comprise at least one policy associated with an environmental consideration control loop of the renewable power plant 100, schematically illustrated by the feedback loop 362.

[0144] Each of the one or more run-time policies 322pol defines a control behavior associated with one or more parameters of the renewable power plant 100, where the control behavior indicates how the run-time control system 320 wants the renewable power plant 100 to be configured when the one or more parameters 361 fulfill corresponding conditions.

[0145] According to various embodiments, each of the one or more run-time policies 322pol may be a variable policy, which changes / varies over / during / within a time frame, or may be a static policy, which is constant / stable over / during / within a time frame.

[0146] According to an embodiment, the priority indications associated with the one or more run-time policies 322pol are configurable, as explained above. The chosen prioritization is, according to an embodiment, an absolute prioritization across all control loops. Thus, the proactive policies can be of higher or lower priority than the runtime policies, resulting in a priority list where both types of policies are mixed, i.e. where proactive policies and runtime policies are interleaved. According to an embodiment, the one or more run-time policies 322pol comprise at least one policy determined by a plant operator of the renewable power plant 100, schematically illustrated as a plant operator input 321 to the run-time control system 320. According to an embodiment, the one or more run-time policies 322pol comprise at least one policy determined by an owner of the renewable power plant 100, schematically illustrated as a plant owner input 321 to the run-time control system 320. According to an embodiment, the one or more run-time policies 322pol comprise at least one policy determined by an operator of the power grid 116, schematically illustrated as a power grid operator input 321 to the run-time control system 320. The operator of the power grid 116 may her be e.g. a transmission system operator (TSO), a distribution system operator (DSO) and / or a utility company.

[0147] Generally, the run-time policies 322pol are often given a higher priority 322pri than the priority 314pri of the proactive policies 314pol, due to the nature of the run-time control loops, including e.g. compliance and safety control loops.

[0148] According to an embodiment, the above-mentioned determination 230 of the hierarchic order comprises the step of sorting 232 the one or more proactive policies 314pol and the one or more run-time policies 322pol based on their priority indications 314pri, 322pri.

[0149] Thus, based on the priority indications 314pri, 322pri, the one or more proactive policies 314pol and the one or more run-time policies 322pol are arranged in an order reflecting their importance for the renewable power plant 100. For example, the one or more proactive policies 314pol and the one or more run-time policies 322pol may be arranged / sorted from the least important policy 314 / 322low to the most important policy 314 / 322high, in accordance with their respective priority indications 314pri, 322pri.

[0150] As mentioned above, there are a number of control systems / loops configured for controlling the renewable power plant 100 by utilization of specific functions associated with these control systems / loops. These functions are arranged in a control hierarchy. This control hierarchy of the control functions is reflected in the priority indications 314pri, 322pri assigned to the policies, such that a policy provided by a specific control function being higher in the control hierarchy is given a priority indication indicating that it is more important than a policy provided by another control function being lower in the control hierarchy. Correspondingly, a policy provided by a control function being lower in the control hierarchy is given a priority indication indicating that it is less important than a policy provided by a control function being higher in the control hierarchy. Thus, if the one or more proactive policies 314pol and the one or more run-time policies 322pol are then sorted from the least important policy to the most important policy, in accordance with their respective priority indications 314pri, 322pri, the hierarchy of the functions is reflected in the order of the sorted one or more proactive policies 314pol and the one or more run-time policies 322pol.

[0151] It should be noted that the the specific control functions are the ones being sorted in the control hierarchy. For example, the same proactive control system may generate a policy that is purely economic, and another policy intended to prevent dangerous situations due to potential ice formation. The second policy may be more important than run-time policies, since it more desirable to avoid throwing ice pieces off the blade, possibly endangering human lives, rather than maintain a high-power output due to an under frequency, e.g. for grid compliance. Thus, the prioritization of a policy depends on the importance of its function / purpose, e.g. its end goal, rather than depending on the system generating the function / purpose.

[0152] According to an embodiment, the determination 240 of the control configuration 331 includes a step of determining 242 a control setting associated with each of the sorted 232 one or more proactive policies 314pol and one or more run-time policies 322pol. For each of the one or more proactive policies 314pol and one or more runtime policies 322pol being sorted in an order from a lowest priority policy 314 / 322low to a highest priority policy 314 / 322high, a suitable control setting is here sequentially determined 242. Thus, the control settings are determined 242 in an order from the policy being least important, i.e. from the lowest priority policy 314 / 322low, to the policy being most important, i.e. to the highest priority policy 314 / 322high.

[0153] The control configuration 331 is determined 240 by sequentially merging 243 each determined 242 control setting with one or more previously determined control settings.

[0154] Thus, during execution of a time frame, all proactive policies 314pol and run-time policies 322pol that are valid and activated for this time frame, e.g. due to the current context of the renewable power plant 100, are listed and sorted according to on their priority indications 314pri, 322pri. The list is traversed from the least important policy 314 / 322low to the most important policy 314 / 322high, and the policies 314pol, 322pol are evaluated, generating a control setting for each policy 314pol, 322pol. As the list is traversed, the resulting control setting associated with each policy evaluation is merged onto a previously determined control setting, such that when the last, and thus most important policy 314 / 322high has been evaluated, the resulting control configuration 331 has the final word on what the central control system 340 can and should do.

[0155] The merging 243 of each determined control settings with one or more previously determined control settings, which is used for determining the control configuration 331 , may be performed in a number of ways, according to various embodiment.

[0156] According to an embodiment, the merging 243 is performed such that the control configuration 331 is determined 244 based only on the highest priority policy 314 / 322high. Thus, the merging 243 here overwrites previously determined control settings with the control setting associated with the highest priority policy 314 / 322high, and then uses these resulting control settings as a basis for the control configuration 331 .

[0157] According to an embodiment, the merging 243 is performed such that the control configuration 331 is initially determined 245 based only on the highest priority policy 314 / 322high, and such that control configuration determinations based on one or more lower priority policies is postponed. Thus, the merging 243 here initially neglects all the lower priority policies, but keeps them for later usage.

[0158] According to an embodiment, the merging 243 is performed such that the control configuration 331 is determined 246 based on a weighted combination of the highest priority policy 314 / 322high and one or more lower priority policies, where the highest priority policy 314 / 322high is given the highest weight in the weighted combination. Thus, the merging 243 here combines control settings associated with two or more policies, where these control settings are weighted in accordance with the importance of the respective policies.

[0159] Thus, the control configuration 331 to be used for the time frame may be determined 240 by sequentially evaluating the policies, such that the least important policy 314 / 322low is first evaluated, then the second least important policy, and so on until the most important policy 314 / 322high is evaluated. The control setting associated with each policy is merged with one or more previously determined control settings, resulting in the control configuration 331 .

[0160] The merging of the determined control settings may be simple, e.g. discarding, postponing and / or overwriting previous control settings, or may be more complex / advanced, e.g. weighted combinations of control settings, as mentioned above. The merging of two control setting may for example comprise overwriting previously determined control settings with the control setting associated with a most important policy 314 / 322high as dictated by the priority indications. The merging may also for example comprise to using advanced decision-making rules that determine a final control configuration 331 that satisfies fully the most important policy 314 / 322high, while fulfilling fully or partially the needs of one or more less important policies, e.g. by moving the execution of one policy in time, or determining a superset value that satisfies both policies needs on a specific control variable.

[0161] Some complex merging methods may result in a control configuration 331 varying over time within the time frame. For example, if the time frame is 1 h, the first half hour and the second half hour may have different control configurations 331. Also, if a high priority policy is input, e.g. a policy based on a plant operator input 321 , a plant owner input 321 , or a power grid operator input 321 , this high priority policy should be followed directly, also within the time frame, and should then quickly be reflected in the control configuration 331 for the renewable power plant 100.

[0162] When all control settings from the relevant policies have been merged into a control configuration 331 , the control configuration 331 is sent to the central control system 340 of the renewable power plant 100, as explained above.

[0163] Thus, the evaluation determines if the policy is relevant or not for the current power plant context 361. The hereby provided control of the renewable power plant 100 is flexible in term of differences related to a geographical region and / or context / implementation of the renewable power plant 100. For example, in some countries and / or some time periods, it is according to the legislation more important to protect wildlife, such as e.g. bats, than to ensure power grid stability, whereas in it is the other way around in other countries and / or other time periods, which may be taken into consideration in the herein described control of the renewable power plant 100. As another example, wind plant operation may exceed established noise limits for a limited number of hours over a year. If during a period of high prices, there is still remaining time of the allowed number of hours of noise exceedance, then an economic policy may be dynamically rated to have higher importance to create value for the plant. The method 200 for controlling the renewable power plant 100 can also easily be adapted to be market specific and implementation specific.

[0164] According to various embodiments, the control configuration 331 may comprise various parameters. For example, the control configuration 331 may comprise a maximum, minimum and / or reference value for a control variable. The control configuration 331 may further comprise an identifier indicating an operation mode for the renewable power plant 100 and / or an identifier indicating an operation mode for at least one of the one or more renewable energy assets 106 of the renewable power plant 100. The control configuration 331 may further comprise an indication of a lacking decision associated with a control variable. The control configuration 331 may further comprise an identifier indicating a control behavior of the central control system 340 of the renewable power plant 100, an identifier indicating a control behavior of a power plant controller 150 of the renewable power plant 100 and / or an identifier indicating a control behavior of at least one renewable asset controller 350 of the renewable power plant 100.

[0165] According to an embodiment, the control 250 of the renewable power plant 100 based on the determined control configuration 331 comprises the step of determining 252 one or more parameters 361 of the renewable power plant 100, where these one or more parameters 361 may e.g. be measured locally in the renewable power plant 100, may be estimated and / or modelled for the renewable power plant 100, and / or may be forecasted for the renewable power plant 100.

[0166] The control 250 of the renewable power plant 100 further comprises the steps of determining 254 operation states for the renewable power plant 100, based on the determined control configuration 331 and the determined one or more parameters 361 , and controlling 256 the renewable power plant 100 towards the determined operation states.

[0167] Thus, the control 150 of the renewable power plant 100, is based on the determined control configuration 331 , for which possible policy-related conflicts have been solved. The operation states, towards which the renewable power plant 100, is controlled 350 are then determined by the control configuration 331 being conditionally triggered by the values of the one or more parameters 361 of the renewable power plant 100, being e.g. one or more locally measured parameters 361.

[0168] According to an aspect, control arrangement 150 for controlling the renewable power plant 100 is presented. The renewable power plant 100 the renewable power plant 100 comprising one or more renewable energy assets 106.

[0169] The control arrangement 150, illustrated in figures 1 and 4 is configured to execute / provide / implement the herein described aspects and embodiments of the method for controlling the renewable power plant 100.

[0170] The control arrangement 150 is thus configured to, e.g., it comprises means / devices 410 to, for each time frame of a sequence of time frames, obtain 210 one or more proactive policies 314pol and corresponding priority indications 314pri of a proactive control loop 310 associated with the renewable power plant 100. The obtained one or more proactive policies 314pol and / or corresponding priority indications 314pri may here be determined by the control arrangement 150 itself. The obtained one or more proactive policies 314pol and / or corresponding priority indications 314pri may also, or partially, be determined by an off-plant entity, such as e.g. a cloud computing platform external from the renewable power plant, and may then be provided to the control arrangement 150.

[0171] The control arrangement 150 is further configured to, e.g., it comprises means / devices 420 to, for each time frame of a sequence of time frames, determine 220 one or more run-time policies 322pol and corresponding priority indications 322pri of a run-time control loop 320 associated with the renewable power plant 100.

[0172] The control arrangement 150 is further configured to, e.g., it comprises means / devices 430 to, for each time frame of a sequence of time frames, determine 230, by utilization of their priority indications 314pri, 322pri, a hierarchic order of the one or more proactive policies 314pol and the one or more run-time policies 322pol.

[0173] The control arrangement 150 is further configured to, e.g., it comprises means / devices 440 to, for each time frame of a sequence of time frames, determine 240 a control configuration 331 for the renewable power plant 100 based on the determined hierarchic order, the one or more proactive policies 314pol, and the one or more run-time policies 322pol.

[0174] The control arrangement 150 is further configured to, e.g., it comprises means / devices 450 to, for each time frame of a sequence of time frames, provide 250 the determined control configuration 331 to a central control system 340 of the renewable power plant 100. The control arrangement 150 may further be configured to, e.g., it comprises units / means / devices 432, 442, 443, 444, 445, 446, 452, 454 to, execute / provide / implement the further herein mentioned method steps 232, 242, 243, 244, 245, 246, 252, 254 according to various above-described embodiments.

[0175] According to an aspect, a renewable power plant 100 connected to a power grid 116 is presented. The renewable power plant 100, being schematically illustrated in figures 1 and 2, comprises one or more renewable energy assets 106, and a control arrangement 150 as herein described. The renewable power plant 100 further comprises a central control system 340 configured to control the renewable power plant 100 based on the determined control configuration 331 provided 250 by the control arrangement 150 and on one or more parameters 361 of the renewable power plant 100.

[0176] 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 4) 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.

[0177] Figure 4 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, 220, 230, 240, 250, 232, 242, 243, 244, 245, 246, 252, 254. 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.

[0178] 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 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.

[0179] 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, 220, 230, 240, 250, 232, 242, 243, 244, 245, 246, 252, 254, 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.

[0180] With reference to figure 1 , the control arrangement 150, which may include one or more control units or control entities 410, 420, 430, 440, 450, 432, 442, 443, 444, 445, 446, 452, 454, 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.

[0181] As mentioned above, the one or more proactive policies 314pol and / or corresponding priority indications 314pri may also be determined 210 by an off-plant entity, such as e.g. a cloud computing platform external from the renewable power plant. The off- plant entity then comprises one or more control units or control entities 410, such as for example one or more devices, controllers or control devices, arranged to perform the determination 210 of the one or more proactive policies 314pol and / or corresponding priority indications 314pri.

[0182] The herein described aspects and embodiments may be applied also in other renewable power plants than the renewable power plant mentioned herein. 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) connected to a power grid (116), the renewable power plant (100) comprising one or more renewable energy assets (106); the method comprising, for each time frame of a sequence of time frames:- determining (210) one or more proactive policies (314pol) and corresponding priority indications (314pri) of a proactive control loop (310) associated with the renewable power plant (100);- determining (220) one or more run-time policies (322pol) and corresponding priority indications (322pri) of a run-time control loop (320) associated with the renewable power plant (100);- determining (230), by utilization of their priority indications (314pri, 322pri), a hierarchic order of the one or more proactive policies (314pol) and the one or more run-time policies (322pol);- determining (240) a control configuration (331 ) for the renewable power plant (100) based on the determined hierarchic order, the one or more proactive policies(314pol), and the one or more run-time policies (322pol); and- controlling (250) the renewable power plant (100) based on the determined control configuration (331).

2. The method according to claim 1 , wherein- the one or more proactive policies (314pol) are comprised in a schedule of policies for the sequence of time frames; and- each time frame of the schedule of policies comprises one or more proactive policies (314pol) for that time frame.

3. The method according to any one of claims 1-2, wherein the one or more proactive policies (314pol) reflect one or more in the group of:- a long-term goal for the renewable power plant (100);- a risk associated with the renewable power plant (100);- an uncertainty associated with the renewable power plant (100);- a forecast of energy pricing in the power grid (116); and- a market interaction with the renewable power plant (100).

4. The method according to any one of claims 1-3, wherein the one or more run-time policies (322pol) comprise one or more in the group of:- at least one policy associated with a regulatory compliance control loop of the renewable power plant (100);- at least one policy associated with a safety control loop of the renewable power plant (100);- at least one policy associated with an environmental consideration control loop of the renewable power plant (100);- at least one policy determined by a plant operator of the renewable power plant (100);- at least one policy determined by an owner of the renewable power plant (100); and- at least one policy determined by an operator of the power grid (116).

5. The method according to any one of claims 1-4, wherein- each of the one or more proactive policies (314pol) and the one or more run-time policies (322pol) defines a control behavior associated with one or more parameters (361 ) of the renewable power plant (100); and- the control behavior indicates how the renewable power plant (100) should be configured when the one or more parameters (361 ) fulfill corresponding conditions.

6. The method according to any one of claims 1 -5, wherein each of the one or more proactive policies (314pol) and the one or more run-time policies (322pol) is one in the group of:- a variable policy, which changes over a time frame; and- a static policy, which is constant over a time frame.

7. The method according to any one of claims 1-6, wherein the control configuration (331 ) comprises one or more in the group of:- a maximum value for a control variable;- a minimum value for a control variable;- a reference value for a control variable;- an identifier indicating an operation mode for the renewable power plant (100);- an identifier indicating an operation mode for at least one of the one or more renewable energy assets (106) of the renewable power plant (100);- an indication of a lacking decision associated with a control variable;- an identifier indicating a control behavior of a central control system (340) of the renewable power plant (100);- an identifier indicating a control behavior of a power plant controller (150) of the renewable power plant (100); and- an identifier indicating a control behavior of at least one renewable asset controller (350) of the renewable power plant (100).

8. The method according to any one of claims 1-7, wherein the determination (230) of the hierarchic order comprises:- sorting (232) the one or more proactive policies (314pol) and the one or more runtime policies (322pol) based on their priority indications (314pri, 322pri).

9. The method according to claim 8, wherein the determination (240) of the control configuration (331) comprises:- determining (242) a control setting associated with each of the sorted (232) one or more proactive policies (314pol) and one or more run-time policies (322pol), in an order from a lowest priority policy (314 / 322low) to a highest priority policy (314 / 322high); and- merging (243) each determined control setting with one or more previously determined control settings to determine the control configuration (331 ).

10. The method according to claim 9, wherein the merging (243) of each determined control settings comprises one or more in the group of:- determining (244) the control configuration (331) based only on the highest priority policy (314 / 322high);- determining (245) the control configuration (331) based only on the highest priority policy (314 / 322high) and postpone control configuration determinations based on one or more lower priority policies;- determining (246) the control configuration (331) based on a weighted combinationof the highest priority policy (314 / 322high) and one or more lower priority policies, where the highest priority policy (314 / 322high) is given the highest weight in the weighted combination.11 . The method according to any one of claims 1 -10, wherein the controlling (250) of the renewable power plant (100) comprises:- determining (252) one or more parameters (361) of the renewable power plant (100);- determining (254) operation states for the renewable power plant (100) based on the determined control configuration (331 ) and the determined one or more parameters (361 ); and- controlling (256) the renewable power plant (100) towards the determined operation states.

12. The method according to any one of claims 1-11 , being sequentially performed for each time frame of the sequence of time frames, thereby resulting in a control of the renewable power plant (100) varying over time.

13. The method according to any one of claims 1-12, wherein the priority indications associated with the one or more proactive policies (314pol) and / or the one or more run-time policies (322pol) are configurable and / or dynamic.

14. A computer program (503) 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 claims 1 to 13.

15. A control arrangement (150) for controlling a renewable power plant (100) connected to a power grid (116), the renewable power plant (100) comprising one or more renewable energy assets (106); wherein the control arrangement (150) is configured to, for each time frame of a sequence of time frames:- obtain (210) one or more proactive policies (314pol) and corresponding priorityindications (314pri) of a proactive control loop (310) associated with the renewable power plant (100);- determine (220) one or more run-time policies (322pol) and corresponding priority indications (322pri) of a run-time control loop (320) associated with the renewable power plant (100);- determine (230), by utilization of their priority indications (314pri, 322pri), a hierarchic order of the one or more proactive policies (314pol) and the one or more run-time policies (322pol);- determine (240) a control configuration (331 ) for the renewable power plant (100) based on the determined hierarchic order, the one or more proactive policies(314pol), and the one or more run-time policies (322pol); and- provide (250) the determined control configuration (331 ) to a central control system (340) of the renewable power plant (100).

16. A renewable power plant (100) connected to a power grid (116), the renewable power plant (100) comprising:- one or more renewable energy assets (106);- a control arrangement (150) as claimed in claim 15;- a central control system (340) configured to control the renewable power plant (100) based on the determined control configuration (331 ) provided (250) by the control arrangement (150) and on one or more parameters (361) of the renewable power plant (100).

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