Field

The present invention generally relates to the field of energy storage systems for electrical energy and to the field of controlling energy storage systems.

Introduction

Storing electrical energy in stationary energy storage systems is becoming increasingly common due to the development of new and improved storage facilities. Operating an electrical energy storage system can be desirable due do a number of reasons: Provision of primary balancing power, peak shaving, provision of emergency power or trade with electricity, to name a few.

Particularly, provision of balancing power has seen an increase in demand owing to the steadily increasing share of renewable energies in the public electricity mix. Overall, this development leads to increasing fluctuations of the supplied electrical power due to the strong dependence on environmental conditions. However, an imbalance between supplied electrical power and recalled electrical power results in frequency and voltage fluctuations, which may damage electrical components connected to the power grid and in the worst case, result in a collapse of a power network.

Thus, increased flexibility of the network is required in order to compensate for the differences in supply and demand of electrical power within the power grid. These compensations are typically provided by means of electrical balancing power in order to stabilise the power grid frequency.

A common practice for providing primary balancing power is the use of gas-fired power plants which can ramp the produced power up and down relatively quickly. However, often this requires operation under non-ideal conditions which decreases efficiency and profitability.

Therefore, electrical energy storage units provide a valuable alternative for the supply of primary balancing power, which is known in the prior art. For example, EP 2777120 B1 discloses a method for delivering balancing power to stabilize an AC electricity network, the AC electricity network operating at a set frequency, comprising an energy storage that can take up and deliver electrical energy.

An increasing number of different energy storage systems have also been realised and are in operation to provide balancing power for stabilizing power grids. In particular, an increasing number of battery-based energy storage systems has become available.

However, as discussed above, energy storage systems can provide a plurality of functions. Some functions may be seasonally needed, so peak-shaving may be particularly reasonable for example during periods of higher energy consumption, in colder countries typically during winters (for lights and heating), in warmer countries rather during summers (for operating air conditioning installations). Of course, this also depends on the consumer whose consumption is peak-shaved.

Summary

An objective of the present invention is to provide an alternative or improved energy storage system and a method for control the system.

An optional objective of the present invention is to provide a method and system for providing different functions for a power grid by one energy storage system.

The invention is directed to an energy storage system that is configured to store and provide electrical energy and/or power. The system comprises at least one energy storage.

The at least one energy storage can be optionally at least one battery unit. The energy storage can be configured to store, that is to take in and to provide, electrical energy.

The energy storage can comprise at least one battery unit.

The energy storage can comprise at least one capacitor unit.

The energy storage system can comprise a fuel cell, a hydrogen storage and a device for electrolyse or another device configured to generate hydrogen using electricity. The fuel cell can also be the device for electrolyse, as discussed in "Reversible Brennstoffzellen: Stromspeicher mit Wasserstoff", Schmid, in : "Handelsblatt", 08.01.2019.

The system can comprise a power converter unit that is configured to control and/or convert electric power. The power converter unit can be configured to convert electrical power coming to/from the energy storage.

The power converter unit can be configured to convert direct current (DC) to alternating current (AC).

The power converter unit can be configured to convert alternating current (AC) to direct current (DC).

The power converter unit can adapt a voltage or current level of electrical power. The power converter unit can be configured to provide reactive power compensation statically.

The power converter can be configured to provide reactive power compensation statically by comprising power electronics.

Alternatively, the reactive power compensation of the power converter can be provided by a phase angle regulating transformer that the power converter can optionally comprise or be coupled to.

The power converter unit can be configured to provide reactive power compensation and to convert electric power to/from the energy storage at the same time.

That is, the power converter unit can be configured to provide reactive power compensation simultaneously to converting electrical power coming to/from the energy storage. That is, the power converter can be configured to provide a plurality of functions simultaneously.

Furthermore, the power converter unit can be configured to provide the functions simultaneously when the energy storage is charged/discharged with nominal power and/or under nominal operating parameters.

The system can further comprise an energy storage management system (ESMS). The ESMS can be configured to control the operation of the energy storage system and/or at least one of its components.

The energy storage management system can for example be and/or comprise a battery management system in a case where the energy storage is a battery unit.

The energy storage management system can be adapted to the concrete embodiment of the energy storage.

The ESMS can be configured to control the power converter unit.

The energy storage system can comprise a capacity in the range of 1 MWh to 500 MWh, preferably 2 MWh to 200 MWh, such as 50 MWh.

The energy storage system can comprise a C-rate in the range of 0.1C to IOC, preferably 0.5C to 5C, more preferably 1C to 5C. The C-rate can be a quotient of charging/discharging power per capacity. The system can comprise an energy management system (EMS) that is configured to interface with the ESMS. That is, the EMS can be configured to send and/or receive data from the ESMS, in particular to send commands/control data and/or to receive status data to/from the ESMS respectively.

The energy management system can be a physical system. The energy management system can be a computer program. The EMS can be a combination of a physical system and a program, it can be integrated into or run by hardware belonging to the energy storage system and/or by a server or a server system, such as a remote server or a cloud server system.

The energy management system can be configured for receiving requests. The requests can be requests for providing a grid-relevant function or a function that is beneficial for operating a power-grid, as discussed below in the context of the method. The requests can come from an operator of a power grid. The requests can come from a third party. The requests can come from a or be related to at least one electricity generator and/or an electricity consumer.

The energy storage system according to the preceding embodiment, wherein the requests are associated with a measure for a priority and/or a necessity of the respective request. This can be any measure for a priority and/or a necessity, and it can be added any party. For example, in a system where a price that is paid for delivering a function is depending on supply and demand, a real-time price can be an indicator for a real-time priority of a delivered function.

The requests can comprise requests that are signalled by and/or relative to the grid frequency. The grid frequency can for example be deduced from the frequency of a voltage in the grid or of a current in the grid. These requests can request balancing power. The requests can for example be requests to provide balancing power in reaction to shifts of a frequency of the power grid. The requests can also comprise a characteristic of the reaction to changes in the frequency of the power grid.

The requests can comprise requests that are signalled by and/or relative to a measure for reactive power in the grid. Such a measure can for example be a cos(phi) of power. Such a measure can also be a power of an electricity generator and a corresponding characteristic of required reactive power. The requests can comprise requests that are signalled by and/or relative to data from a third party. The data from a third party can be data relating to balancing power, for example if providers of balancing power are acting together. This can be optionally advantageous to facilitate a coupling to the power-grid, for example due to scale effects, or to provide a certain reliability that in compound is higher than if each energy storage system is operated independently. The data can also refer to times when the power grid needs to deliver high amounts of power. Said times can for instance be communicated by an operator of the power grid or by a provider or buyer of electrical energy. These data can also be other data, such as demands by other due to agreements to provide electrical power when said third party signals a need to do so. This can for example be optionally advantageous in case of electricity consumers such as industrial production facilities or municipal energy suppliers.

The requests can comprise requests that are relative to a consumption of an electricity consumer. The electricity consumer can comprise a plurality of electricity consumers, as detailed in the preceding paragraph - an industrial production facility or a municipal energy supplier both comprise or supply a plurality of consumers.

The requests can comprise requests that are relative to operating parameters of an electricity generator. These can for example be maximal operating times of electricity generators. These operating parameters can also be efforts for a start-up process of an electricity generator.

The electricity generator can be coupled to the energy storage system. The energy storage system can comprise the electricity generator. The electricity generator can generate electrical power based on renewable energies, such as wind, solar radiation, geothermal effects and/or combustion of renewable resources. The electricity generator can also generate electrical power based on combustion of fossil fuels and/or nuclear fission.

The requests can comprise requests that are relative to fuel availability parameters of an electricity generator. For example, depending on weather conditions, an availability of a fuel may be limited, such as under snowy conditions if the fuel is transported over streets, or under dry conditions when the fuel is transported over rivers, as seen in summer 2018 in Germany. A measure for such availability can for example be a delivery time or a price.

The requests can comprise requests that are signalled by and/or relative to an availability of electrical power/energy. Said request can be as mentioned above for example be issued by an operator of the power grid, parts, sections and/or subsections thereof. Said request can be signalled by and/or relative to a shortage or a surplus supply of electrical energy in the power grid, which can both be disadvantageous. Said availability can for example be signalled by voltages in certain parts of the power grid. Said availability can also be signalled by price-deviations of real-time power prices. Said availability can also be signalled by capacities of storages, for example in pumper-storage hydropower stations or battery-storage systems.

The energy management system can be configured for sending confirmations. These confirmations can in particular be regarding a provision of functions that are beneficial, relevant and/or critical to an operation of the power grid.

The energy management system can be configured for receiving prognosis data. This also comprises that a part of the EMS generates prognosis data that are used by the EMS.

The energy management system can be configured for receiving status data from the ESMS.

The energy management system can be configured for sending instruction data to the ESMS.

The energy storage system can be configured to provide balancing power for stabilizing the power grid to a pre-defined frequency based on a current frequency in the power grid.

The energy storage system (10) according to any of the preceding embodiments with the features of S5.1, wherein the energy storage system (10) is configured to provide balancing power for stabilizing a power grid (30) according to the requests (32).

The energy storage system can be configured for peak shaving, i.e. reducing the peak load of an electricity consumer.

The energy storage system can be configured for reducing the peak load by at least 2%, preferably at least 4%, more preferably at least 5%.

The energy storage system can be configured for reducing the peak load by at least 2% and at most 30%, preferably by at least 5% and at most 25% and more preferably by at least 10% and at most 20%.

The peak load can be a maximum power consumption. The peak load can also be a maximal ratio of consumed energy per predetermined time unit. The time unit can be for example 15 minutes. The energy storage system can be configured to be operated for reducing transmission in higher-level sections of the power grid. This can be achieved by storing electrical energy when there is an over-availability of electrical energy and supplying electrical energy when there is a higher demand of electrical energy. This can be optionally advantageous as it can reduce a need for adjustments in at least one or at least some higher-level sections of the power grid, for example in the transmission network.

The energy storage system can be configured for uninterruptible power supply (UPS).

The energy storage system can be configured for stand-alone operation. That is, it can be configured to function without a connection to the power grid or when the power grid is offline.

The energy storage system can be configured for an atypical network use. That is, the energy storage system can be configured for shifting the peak load out of a peak time window. The peak time window can be a time where a power consumption from the power grid is higher, as discussed above.

The energy storage system can be configured to provide reactive power compensation.

The energy storage system can be configured to provide reactive power compensation statically, that is by a static installation, such as by power electronics or a phase angle regulation transformer.

The energy storage system can be configured to provide reactive power compensation.

The energy storage system can be configured for local consumption optimization. That is, it can be configured to enable "self-consumption" of generated electricity. An optional advantage can be that power does not need to be drawn from the power grid.

The energy storage system can be configured to provide a black-start source.

The energy storage system can comprise an electricity generator. The electricity generator can be coupled to the energy storage, for example via the power converter unit. The electricity generator can be an electricity generator as discussed above.

The energy storage system can be a stationary energy storage system. The energy storage system can be directly linked to an electricity consumer, wherein the electricity consumer can be as discussed above. That is, the energy storage system can be linked to the electricity consumer without passing by the power grid and/or without passing by a higher-level section of the power grid. An example would be a production plant that integrates the energy storage system in a way so that power that is supplied from the energy storage system to the plant does not pass by the power grid and preferably also not by an electricity metering system of the plant so as not to perturbate its measuring. However, this concept could also be applied in case of a municipal electricity supplier: In such an example, the energy storage system can be integrated in the sub-section of the power grid that the supplier operates or uses, so that balancing, peak-shaving or other effects of the energy storage system can optionally advantageously reduce an impact of the municipal electricity supplier's section of the grid and the connected electricity consumers and/or producers on a higher-level power grid section. Power supplied by the energy storage system would in this example not need to transmitted by a connection of the sub-section of the network to the rest of the power grid.

This can be optionally advantageous as the subsection of the power grid can be stabilized and power does not need to be transmitted through other sections of the power grid that would thus become less stable.

The energy storage system can be configured to provide power to an electrical vehicle charging station. An optional advantage can be that, by supplying at least parts of power for rapid charging of electric vehicles (EV) from the energy storage system, peaks in power consumption are no immediately propagated to the power grid. An optional advantage can be that the power grid or a generator powering the energy storage system can provide an amount of corresponding electrical at a lower power over longer time.

The energy storage system can further be configured to carry out any step of the method discussed in the following or comprise any element necessary to carry out any step of the method.

The invention is furthermore directed towards a method for operating an energy storage system according to any of the energy storage system embodiments, wherein the method comprises providing a plurality of different grid-relevant functions operating the energy storage system.

At least some of the grid-relevant functions can be provided during same intervals of time. The grid-relevant functions can be provided simultaneously. This can also be referred to as "vertical stacking".

Different subsets of the plurality of grid-relevant functions can be provided at different intervals of time.

Each subset can comprise at least one different grid-relevant function. Each subset may in particular comprise a or exactly one grid-relevant function respectively.

Each subset can comprise a plurality of different grid-relevant functions.

At least one of the subsets can each comprise at least one different grid-relevant function, and others can comprise a plurality of different grid-relevant functions.

A plurality of the subsets can each comprise at least one different grid-relevant function, and others can comprise a plurality of different grid-relevant functions.

The grid-relevant functions can be at least one of

• Providing balancing power

• Providing emergency power

• Providing a black start source

• Providing an uninterruptible power supply

• Providing power independently from grid operation (e.g. in stand-alone operation)

• Avoiding peaks in power consumption or supply in the power grid (e.g. by peak shaving)

• Balancing mismatches of power consumption and power supply

• Compensating for a rise in power consumption or a decrease in power generation

• Compensating for a drop of power consumption or an increase in power generation

• Compensating reactive power

• Shifting loads to times where the overall demand is lower or the availability of power is higher

• Reducing power transmission in the power grid (e.g. by optimizing local power consumption, such as by storing and subsequently providing locally generated electrical energy)

• Shifting times of power generation, power transmission and/or power consumption (e.g. atypical network use)

The grid-relevant functions can be at least one of beneficial for the operation of the power grid, beneficial for a stability of the power grid and beneficial for a reliability, efficiency and/or a stability of a power supply of at least one electricity consumer which is supplied by the power grid during normal operation mode.

The stability of the power grid can for example refer to the frequency of the power grid, the voltage in the power grid or sections thereof, availability of power at all, power reserves and reactive power.

The stability of the power supply of the at least one electricity consumer which is supplied by the power grid during normal operation mode can refer to uninterruptible power supply or emergency-power supply of consumers, for example of hospitals, that are typically supplied by power from the power grid, however, they typically have access to supplementary emergency-power equipment. This can also refer to providing power for start-up of a thermal power plant, which is normally provided by the power-grid. However, if the power grid goes offline (blackout), then stored or generated energy must be made available for starting up the power plant.

The grid-relevant functions can correspond to the requests discussed in the context of the system above. The grid-relevant functions can correspond to the functions discussed in the preceding paragraphs discussing the method.

The method can comprise an instruction generation step that comprises generating instruction data for the ESMS

The step of generating instruction data for the ESMS can comprise determining constraints for operating the energy storage system based on the grid-relevant functions to be provided. The constraints can relate to the energy storage, for example thresholds for stored energy. The grid-relevant functions to be provided are grid-relevant functions that the energy storage system is either already providing and that shall be provided also in the immediate future, and/or grid-relevant functions that are planned to be provided in the future. That is, instructions for operating the energy storage system according to functions to be provided can be determined.

The step of generating instruction data for the ESMS can further comprise determining constraints for operating the energy storage system based on an impact of operations on the energy storage. Such an impact can for example in case of a battery system as energy storage be an operation mode that damages or overly degrades the battery system, such as a deep discharge or a discharge with an inadmissibly high discharge power. The constraints for operating the energy storage system can relate to a state of charge of the energy storage or a part or portion thereof. The constraints can also relate to a power with which the energy storage is charged/discharged and/or a power that is converted by the power converter unit.

The constraints for operating the energy storage system can further relate to at least one of a further variable regarding the energy storage, and further variable regarding the power converter unit. The further variable regarding the energy storage can be a parameter such as an admissible absolute temperature of the energy storage. The further variable regarding the power converter unit can be for a example an admissible overload, such as an overload within an I ² t-threshold.

Providing the plurality of different grid-relevant functions using the energy storage can comprise a storage controlling step, which comprises the ESMS controlling at least one of the energy storage and the power converter unit according to the instruction data sent to the ESMS.

The storage controlling step can further comprise receiving instruction data.

The instruction generation step can comprise generating the instruction data based on an estimation of a demand for the grid-relevant functions.

The instruction generation step can further comprise generating the estimation of the demand for the grid-relevant functions based on input data.

The instruction generation step can comprise receiving the input data.

The input data can comprise meteorological data. For instance, meteorological data can comprise data regarding a temperature, a humidity or a precipitation.

The input data can comprise meteorological prognosis data. Such data can be forecast data.

The input data can comprise meteorological measurement data.

The input data comprise measurements and/or a prognosis of a cloud cover. This can be optionally advantageous for estimation of power generated from solar power plants. The input data can comprise data and/or a prognosis relating to times of sunset, sunrise and/or other astronomical data relating to sunshine, such as data relating to solar eclipses. This can be optionally advantageous for estimation of power generated from solar power plants.

The input data can comprise measurements and/or a prognosis of wind direction and/or wind speed.

The input data can comprise data regarding at least one of a position, an orientation and a configuration of photovoltaic installations.

The input data can comprise data regarding at least one of position, orientation and configuration of wind turbines.

The input data can comprise data regarding a demand for reactive power.

The input data can comprise data regarding a demand for a relation of reactive power and active power generated by an electricity generator.

The input data can comprise information relating to an operation of the electricity consumer.

The input data can comprise a prognosis relating to an operation of the electricity consumer.

The input data can comprise information and/or a prognosis relating to a demand for thermal energy that can be generated by an operation of the electricity generator.

The electricity consumer comprises at least one or a plurality of electric vehicle charging station.

The electricity consumer can comprise production and/or processing machinery that is at least partially powered electrically. Said processing machinery can be mechanical machinery, but it can also be for chemical processing or electrical processing, or a continuous process.

The input data can relate to a generation of reactive power by the electricity consumer. Generating the estimation of the demand for the grid-relevant functions based on input data comprises using at least one prognosis model.

At least one of the at least one prognosis model(s) can be a data-driven model. A data- driven model can be for example a machine-learning model, a neuronal network or a model based on (computer) statistics. However, it is based on training data, historical data and/or analysis data. The training data can comprise historical data. The training data can comprise timestamped consumption data.

At least one of the at least one prognosis model(s) can be an engineering model. An engineering model is based on rules or laws of engineering or natural sciences or on approximations of such laws or rules.

The instruction generation step can further comprise generating the estimation of the demand for the grid-relevant functions based on historical data relating to the demand for the grid-relevant functions. Such historical data can for example be data regarding the grid frequency, the voltage of the grid, the reactive power in the grid, import or export of electrical power or energy, or a price of electrical power or a deviation thereof. For example, such historical data can be optionally advantageous to estimate daytime- dependant or seasonal availability or shortage of power, as they can for instance occur when solar power plants are used.

Generating the instruction data can comprise maximising a use of the Energy Storage System. A use of the energy storage system can for example relate to a use of its components, such as the power converter unit and the energy storage. "Use" does not need to be actual "active" use, but it can also be use as reserve.

Generating instruction data can comprise maximising a provision of the grid-relevant functions.

The maximising of the provision of the grid-relevant functions can comprise a maximising regarding constraints and/or weightings.

The constraints and/or weightings can be at least relating to a prioritisation of the grid relevant functions. The prioritisation can for example relate to operation of parts of the system for a purpose, or to the grid-relevant function as such. For example, a black-start or emergency power reserve may be prioritised higher than provision of balancing power and/or peak-shaving. The maximising the use and/or the maximising the provision can be based on the estimation of the demand for the grid-relevant functions.

The method can further comprise any method steps disclosed in the context of the system, in particular method steps for which elements of the energy storage system or the energy storage system are configured.

The invention is furthermore directed to a computer program product comprising instructions, which, when the program is executed by an energy storage system according to any of the energy storage system embodiments, causes the energy storage system to perform the method steps according to any of method embodiments, which have to be executed by the energy storage system.

Energy storage system embodiments

Below, reference will be made to energy storage system embodiments. These embodiments are abbreviated by the letter "S" followed by a number. Whenever reference is herein made to "energy storage system embodiments" or "system embodiments", these embodiments are meant.

51 An energy storage system (10) configured to store and provide electrical energy and/or power, the system comprising at least one energy storage (12).

52 The energy storage system (10) according to the preceding embodiment, wherein the at least one energy storage (12) is at least one battery unit.

53 The energy storage system (10) according to the penultimate embodiment, wherein the energy storage comprises (12) at least one battery unit.

54 The energy storage system (10) according to any of the preceding embodiments, wherein the energy storage (12) comprise at least one capacitor unit.

55 The energy storage system (10) according to any of the preceding embodiments, wherein the energy storage (12) comprises a fuel cell, a hydrogen storage and a device for generating hydrogen from electricity.

56 The energy storage system (10) according to any of the preceding embodiments, wherein the system comprises a power converter unit (16) that is configured to control and/or convert electric power. The energy storage system (10) according to the preceding embodiment, wherein the power converter unit (16) is configured to convert direct current (DC) to alternating current (AC). The energy storage system (10) according to any of the 2 preceding embodiments, wherein the power converter unit (16) is configured to convert alternating current (AC) to direct current (DC). The energy storage system (10) according to any of the three preceding embodiments, wherein the power converter unit (16) is configured to provide reactive power compensation statically. The energy storage system (10) according to any of the four preceding embodiments, wherein the power converter unit (16) is configured to provide reactive power compensation statically and to convert electric power to/from the energy storage (12) at the same time. The energy storage system (10) according to any of the preceding system embodiments, wherein the system further comprises an energy storage management system (ESMS) (14), configured to control the operation of the energy storage system (10) and/or at least one of its components. The energy storage system (10) according to the preceding system embodiment, wherein the ESMS (14) is configured to control the power converter unit (16). The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) comprises a capacity in the range of 1 MWh to 500 MWh, preferably 2 MWh to 200 MWh, such as 50 MWh. The energy storage system (10) according to any of the preceding system embodiments, wherein energy storage system (10) comprises a C-rate in the range of 0.1C to IOC, preferably 0.5C to 5C, more preferably 1C to 5C. The energy storage system (10) according to the any of the preceding embodiments with the features of Sll, wherein the system comprises a energy management system (EMS) (20) that is configured to interface with the ESMS (14). The energy storage system (10) according to the any of the preceding embodiments with the features of S15, wherein the energy management system (20) is configured for receiving requests (32). The energy storage system (10) according to the preceding embodiment, wherein the requests (32) are associated with a measure for a priority and/or a necessity of the respective request. The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are signalled by and/or relative to a grid frequency. The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are signalled by and/or relative to a measure for reactive power in the grid. The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are signalled by and/or relative to data from a third party. The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are relative to a consumption of an electricity consumer (50). The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are relative to operating parameters of an electricity generator (52). The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are relative to fuel availability parameters of an electricity generator (52). The energy storage system (10) according to the any of the preceding embodiments with the features of S16, wherein the requests (32) comprise requests that are signalled by and/or relative to an availability of electrical power/energy. The energy storage system (10) according to the any of the preceding embodiments with the features of S15, wherein the energy management system (20) is configured for sending confirmations (32). The energy storage system (10) according to the any of the preceding embodiments with the features of S15, wherein the energy management system (EMS) (20) is configured for receiving prognosis data (40). The energy storage system (10) according to the any of the preceding embodiments with the features of S15, wherein the energy management system (20) is configured for receiving status data from the ESMS (14). The energy storage system (10) according to the any of the preceding embodiments with the features of S15, wherein the energy management system (20) is configured for sending instruction data to the ESMS (14). The energy storage system (10) according to any of the preceding embodiments, wherein the energy storage system (10) is configured to provide balancing power for stabilizing a power grid (30) to a pre-defined frequency based on a current frequency in the power grid (30). The energy storage system (10) according to any of the preceding embodiments with the features of S16, wherein the energy storage system (10) is configured to provide balancing power for stabilizing a power grid (30) according to the requests (32). The energy storage system (10) according to any of the preceding embodiments, wherein the energy storage system (10) is configured for peak shaving, i.e. reducing the peak load of an electricity consumer (50). The energy storage system (10) according to the preceding system embodiment, wherein the energy storage system (10) is configured for reducing the peak load by at least 2%, preferably at least 4%, more preferably at least 5%. The energy storage system (10) according to any of the two preceding system embodiments, wherein the energy storage system (10) is configured for reducing the peak load by at least 2% and at most 30%, preferably by at least 5% and at most 25% and more preferably by at least 10% and at most 20%. The energy storage system (10) according to any of the preceding system embodiments, wherein the system is configured to be operated for reducing transmission in higher-level sections of the power grid. The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured for uninterruptible power supply (UPS). The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured for stand alone operation, i.e. it is configured to function without a connection to the power grid (30) or when the power grid (30) is offline. The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured for an atypical network use, i.e. shifting the peak load out of a peak time window. The energy storage system (10) according to any of the preceding embodiments, wherein the energy storage system (10) is configured to provide reactive power compensation. The energy storage system (10) according to the preceding embodiment, wherein the energy storage system (10) is configured to provide reactive power compensation statically. The energy storage system (10) according to any of the preceding embodiments with the features of S9, wherein the energy storage system (10) is configured to provide reactive power compensation. The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured for local consumption optimization. The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured to provide a black-start source. The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) comprises an electricity generator (52). 544 The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is a stationary energy storage system.

545 The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is directly linked to an electricity consumer (50).

546 The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured to provide power to an electrical vehicle charging station.

Method Embodiments

Below, method embodiments will be discussed. These embodiments are abbreviated by the letter "M" followed by a number. Whenever reference is herein made to "method embodiments", these embodiments are meant.

Ml A method for operating an energy storage system (10) according to any of the energy storage system embodiments, wherein the method comprises providing a plurality of different grid-relevant functions operating the energy storage system (10).

M2 The method according to the preceding method embodiment, wherein at least some of the grid-relevant functions are provided during same intervals of time.

M3 The method according to any of the preceding method embodiments, wherein the grid-relevant functions are provided simultaneously.

M4 The method according to any of the preceding method embodiments but the last, wherein different subsets of the plurality of grid-relevant functions are provided at different intervals of time.

M5 The method according to any of the preceding method embodiments with the features of M4, wherein each of the different subsets of different grid-relevant functions comprises at least one of the grid-relevant functions. M6 The method according to any of the preceding method embodiments with the features of M4, wherein at least one subset of the different subsets of the plurality of grid-relevant functions comprises a plurality of grid-relevant functions.

M7 The method according to any of the preceding method embodiments with the features of M4, wherein a plurality of subsets of the different subsets of the plurality of grid-relevant functions comprises a plurality of grid-relevant functions.

M8 The method according to any of the preceding method embodiments, wherein the grid-relevant functions are at least one of

(a) beneficial for an operation of the power grid (30),

(b) beneficial for a stability of the power grid (30) and

(c) beneficial for a reliability, efficiency and/or stability of a power supply of at least one electricity consumer (50) which is supplied by the power grid (30) during normal operation mode.

The grid-relevant functions can be the functions that correspond to the requests discussed in any of the system embodiments S18 to S24.

M9 The method according to any of the preceding method embodiments, wherein the method comprises an instruction generation step that comprises generating instruction data for the ESMS (14).

M10 The method according to the preceding method embodiment, wherein the step of generating instruction data for the ESMS (14) comprises determining constraints for operating the energy storage system (10) based on the grid-relevant functions to be provided.

Mi l The method according to any of the preceding method embodiments with the features of M9, wherein the step of generating instruction data for the ESMS (14) comprises determining constraints for operating the energy storage system (10) based on an impact of operations on the energy storage (12).

M12 The method according to any of the preceding method embodiments with the features of M10 or Mi l, wherein the constraints for operating the energy storage system (10) relate to at least one of

(a) a state of charge of the energy storage (12) or a part thereof,

(b) a power with which the energy storage (12) is charged/discharged, and

(c) a power that is converted by the power converter unit (16). M13 The method according to the preceding method embodiment, wherein the constraints for operating the energy storage system (10) further relate to at least one of

(a) a further variable regarding the energy storage (12), and

(b) a further variable regarding the power converter unit (16).

M14 The method according to any of the preceding method embodiments with the features of M9, wherein providing the plurality of different grid-relevant functions using the energy storage (10) comprises a storage controlling step, which comprises the ESMS (14) controlling at least one of the energy storage (12) and the power converter unit according to the instruction data sent to the ESMS (14).

M15 The method according to the preceding method embodiment, wherein the storage controlling step comprises furthermore receiving instruction data.

M16 The method according to any of the preceding method embodiments with the features of M9, wherein the instruction generation step comprises generating the instruction data based on an estimation of a demand for the grid-relevant functions.

M17 The method according to any of the preceding method embodiments with the features of M16, wherein the instruction generation step further comprises generating the estimation of the demand for the grid-relevant functions based on input data.

M18 The method according to any of the preceding method embodiments with the features of M17, wherein the instruction generation step comprises receiving the input data.

M19 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise meteorological data.

M20 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise meteorological prognosis data.

M21 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise meteorological measurement data. M22 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise measurements and/or a prognosis of a cloud cover.

M23 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise data and/or a prognosis relating to times of sunset, sunrise and/or other astronomical data relating to sunshine, such as data relating to solar eclipses.

M24 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise measurements and/or a prognosis of wind direction and/or wind speed.

M25 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise data regarding at least one of a position, an orientation and a configuration of photovoltaic installations.

M26 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise data regarding at least one of position, orientation and configuration of wind turbines.

M27 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise data regarding a demand for reactive power.

M28 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise data regarding a demand for a relation of reactive power and active power generated by an electricity generator (52).

M29 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise information relating to an operation of an electricity consumer (50).

M30 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise a prognosis relating to an operation of an electricity consumer (50). M31 The method according to any of the preceding method embodiments with the features of M17, wherein the input data comprise information and/or a prognosis relating to a demand for thermal energy that can be generated by an operation of an electricity generator (52).

M32 The method according to any of the preceding method embodiments with the features of M29 or M30, wherein an electricity consumer (50) comprises at least one or a plurality of electric vehicle charging station.

M33 The method according to any of the preceding method embodiments with the features of M29 or M30, wherein the electricity consumer (50) comprises production and/or processing machinery that is at least partially powered electrically.

M34 The method according to any of the preceding method embodiments with the features of M29 or M30, wherein the input data relate to a generation of reactive power by the electricity consumer (50).

M35 The method according to any of the preceding method embodiments with the features of M17, wherein generating the estimation of the demand for the grid relevant functions based on input data comprises using at least one prognosis model.

M36 The method according to any of the preceding method embodiments with the features of M35, wherein at least one of the prognosis model(s) is a data-driven model.

M37 The method according to any of the preceding method embodiments with the features of M36, wherein at least one of the at least one data-driven model is trained with historical data.

M38 The method according to any of the preceding method embodiments with the features of M36, wherein at least one of the at least one data-driven model is trained with timestamped consumption data.

M39 The method according to the preceding method embodiment, wherein at least one of the prognosis model(s) is an engineering model.

M40 The method according to any of the preceding method embodiments with the features of M16, wherein the instruction generation step further comprises generating the estimation of the demand for the grid-relevant functions based on historical data relating to the demand for the grid-relevant functions.

M41 The method according to any of the preceding method embodiments with the features of M9, wherein generating instruction data comprises maximising a use of the Energy Storage System (10).

M42 The method according to any of the preceding method embodiments with the features of M9, wherein generating instruction data comprises maximising a provision of the grid-relevant functions.

M43 The method according to the preceding method embodiment, wherein the maximising of the provision of the grid-relevant functions comprises a maximising regarding constraints and/or weightings.

M44 The method according to the preceding method embodiment, wherein the constraints and/or weightings are at least relating to a prioritisation of the grid relevant functions.

M45 The method according to any of the preceding method embodiments with the features of M41 or M42 and with the features of M16, wherein the maximising the use and/or the maximising the provision is based on the estimation of the demand for the grid-relevant functions.

Further System Embodiments

S47 The energy storage system (10) according to any of the preceding system embodiments, wherein the energy storage system (10) is configured to carry out the method according to any of the method embodiments.

Computer Program Product Embodiments

Below, computer program product embodiments will be discussed. These embodiments are abbreviated by the letter "P" followed by a number. Whenever reference is herein made to

"computer program product embodiments", these embodiments are meant.

PI A computer program product comprising instructions, which,

when the program is executed by an energy storage system according to any of the energy storage system embodiments,

causes the energy storage system to perform the method steps according to any of method embodiments, which have to be executed by the energy storage system. Figure description

Fig. 1 shows an overview of a possible embodiment of the disclosed system

Fig. 2 shows an example of multi-use of an energy storage system for peak-shaving, reactive power compensation and balancing power provision

Fig. 3 shows an example of a control-architecture to perform an embodiment of the disclosed method

Fig. 4 shows a schematized version of Fig. 2.

Figure 1 shows an energy storage system 10 comprising an energy management system 20, an energy storage 12; an energy storage management system (ESMS) 14, a power converter unit 16 and a connection to the power grid 30.

The system may optionally further comprise an electricity consumer 50 which may comprise at least one or a plurality of loads, such as buildings that require electrical energy, machines, air-conditioning, lighting, charging stations for electric vehicles etc.

The system may also optionally further comprise an electricity generator 52. This can be a photovoltaic system, a thermal power station, a generator relying on fossil fuel such as a diesel generator, a gas turbine power station or a combined heat and power plant.

Figure 2 shows an embodiment of a method of multiple simultaneous and sequential uses of an energy storage system. The vertical axis shows a power consumption of an electricity consumer 50 that is "peak-shaved" and a necessary power from the storage system to "shave" that consumption. That is, during consumption peaks of the electricity consumer 50, power is provided from the energy storage system in order to avoid a maximum power consumption from the power grid 30. The upper line shows the power consumption of the electricity consumer. Power above the "Peakshaving threshold" is provided by the energy storage system. The lower line shows the provided power from the storage. The scale regarding the vertical axis differs, as the power provided by the energy storage system corresponds to the consumption peaks of the electricity consumer above the Peakshaving threshold. The black vertical lines with crosses at their end also show power that is provided by the energy storage system, the crosses as well as the bold lines are for mere illustration and to distinguish the provided power from the consumed power.

The horizontal axis shows the time, it is scaled to one year. As becomes obvious, regarding peak-shaving alone, the energy storage system is inactive for the longest time of the year (intervals "II" and "III"). In the example, as the power consumption by the electricity consumer is not exactly predictable, intervals II are a reserved for peak-shaving as buffer interval. During interval III, the energy storage system could also provide other functions that are beneficial for the power grid 30, such as providing balancing power.

In parallel, the system can be designed to provide other functions in parallel. For example, a part of a capacity or stored energy of the energy storage system can reserved so as to provide an uninterruptible power supply. Alternatively or additionally, the power converter unit 16 of the system can be configured to provide reactive power compensation and the method can comprise providing said reactive power compensation.

Another parallel function of the storage (not shown) can be local consumption optimization, for example in a case where the energy storage system is further connected to an electricity generator, such as a photovoltaic installation.

Figure 3 shows possible input and output variables of a control method for the energy storage system.

Figure 4 shows a schematised version of Figure 2 for the sake of clarity and to point out particular features. However, the graphs for power consumption and power provision have been separated for better readability.

The power consumption graph shows the power consumption of an electricity consumer or a plurality of electricity consumers. The power provision graph shows power provided by the energy storage system to the energy consumer(s) for peak shaving.

The power provision graph corresponds to the parts of the power consumption above the peak shaving threshold.

The peak-shaving threshold may optionally be pre-defined.

Again, the energy storage system in Fig. 4 provides a plurality of functions: During period I, energy is provided for peak-shaving, so the energy storage system holds a respective reserve of energy and power. In parallel, another function or other functions, such as reactive power compensation, provision of balancing power and/or local consumption optimization, can be provided. The parallel function is indicated in the figure by IV. It can thus - for the sake of an example - be provided at all times (which may exclude down times of the energy storage system).

Furthermore, the energy storage system can be used for different functions at different times. Another function than peak shaving can for example be provided at times in a year during which the energy consumption of the consumer(s) is below the peak-shaving threshold. Such times are indicated by III in Fig. 4.

The intervals marked with II are optional buffer intervals when a need of peak shaving cannot be excluded with a sufficient probability.

Whenever a relative term, such as "about", "substantially" or "approximately" is used in this specification, such a term should also be construed to also include the exact term. That is, e.g., "substantially straight" should be construed to also include "(exactly) straight".

Whenever steps were recited in the above or also in the appended claims, it should be noted that the order in which the steps are recited in this text may be accidental. That is, unless otherwise specified or unless clear to the skilled person, the order in which steps are recited may be accidental. That is, when the present document states, e.g., that a method comprises steps (A) and (B), this does not necessarily mean that step (A) precedes step (B), but it is also possible that step (A) is performed (at least partly) simultaneously with step (B) or that step (B) precedes step (A). Furthermore, when a step (X) is said to precede another step (Z), this does not imply that there is no step between steps (X) and (Z). That is, step (X) preceding step (Z) encompasses the situation that step (X) is performed directly before step (Z), but also the situation that (X) is performed before one or more steps (Yl), ..., followed by step (Z). Corresponding considerations apply when terms like "after" or "before" are used.

While in the above, a preferred embodiment has been described with reference to the accompanying drawings, the skilled person will understand that this embodiment was provided for illustrative purpose only and should by no means be construed to limit the scope of the present invention, which is defined by the claims. Numbered Reference Elements

10 Energy storage system

12 Energy storage

14 Energy storage management system (ESMS)

16 Power converter unit

20 Energy management system (EMS)

30 Power Grid

32 Requests

34 Confirmations

40 Prognosis data

50 Electricity Consumer

52 Electricity generator