A method for controlling a decentralized heat pump system for providing heating to an indoor area of one or more buildings

Abstract

The disclosure relates to a method (500) for controlling a decentralized heat pump system (100). The system (100) comprising: a first set (110) of one or more heat pump modules; and one or more second sets (120a-c) of one or more heat pump modules (121, 122, 123, 124); the method (500) 5 comprising: determining (S502) at least one of an outdoor temperature, and data pertaining to an electric grid status of an electric grid (150, 160a-c), determining (S504), based on at least one of said outdoor temperature, and said data pertaining to the electric grid status, and, optionally, a specification of the system (100): an ambient side fluid recirculation loop temperature set 10 point of a working fluid of an ambient side fluid recirculation loop (102); detecting (S506) a temperature of the working fluid of the fluid recirculation loop (102); and controlling (S508) an operation of the first set (110) to adjust the first working temperature of the working fluid of the fluid recirculation loop (102) to match said ambient side fluid recirculation loop temperature set point.

Description

[0001] A METHOD FOR CONTROLLING A DECENTRALIZED HEAT PUMP SYSTEM FOR PROVIDING HEATING TO AN INDOOR AREA OF ONE OR MORE BUILDINGS

[0002] Field of the disclosure

[0003] The present disclosure relates to a method for controlling a decentralized heat pump system for providing heating to an indoor area of one or more buildings.

[0004] Background art

[0005] Nearly all large, developed cities in the world have at least two types of energy grids incorporated in their infrastructures; one grid for providing electrical energy and one grid for providing space heating and hot tap water preparation. Today a common grid used for providing space heating and hot tap water preparation is a gas grid providing a burnable gas, typically a fossil fuel gas. The gas provided by the gas grid is locally burned for providing space heating and hot tap water. In order to reduce the carbon dioxide emissions there are plans to replace such gas grid with more “green” energy efficient energy systems.

[0006] One such energy efficient energy system is cold thermal grids. Cold thermal grids are an evolution of district heating and district cooling systems, where combined district heating and district cooling system with aid of using heat pumps for heating and cooling can provide both cooling, heating and tap water preparation to buildings.

[0007] In order to succeed with the replacement of gas grids, where the respective gas boiler is replaced by a heat pump, the heat pumps used need to be smaller, less costly, easier to control and with lower technical complexity, e.g., with fewer and / or less complex sensors for measuring the space heat and tap water energy consumption than presently used heat pumps. The conventional energy systems are associated with several drawbacks and there is thus a need in the art of making energy systems more flexible and optimized for the occasion.

[0008] Summary

[0009] It is an object to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination. These and other objects are at least partly met by the invention as defined in the independent claims. Preferred embodiments are set out in the dependent claims.

[0010] According to a first aspect there is provided a method for controlling a decentralized heat pump system for providing heating to an indoor area of one or more buildings, the decentralized heat pump system comprising: a first set of one or more heat pump modules wherein each heat pump module of the first set is configured to be directly connected to a cold side fluid recirculation loop at a first side thereof and to be directly connected to an ambient side fluid recirculation loop at a second side thereof, wherein each heat pump module of the first set is powered by a first electric grid; and one or more second sets each comprising one or more heat pump modules wherein each heat pump module of each of the one or more second sets is configured to be directly connected, or connected via a respective further fluid recirculation loop, to the ambient side fluid recirculation loop, at a first side thereof and to be directly connected to a respective hot side fluid recirculation loop at a second side thereof for providing heating to at least a part of the indoor area, and wherein each heat pump module of each of the one or more second sets is powered by a respective second electric grid of one or more second electric grids; the method comprising: determining at least one of an outdoor temperature, and data pertaining to an electric grid status of the first electric grid and / or the one or more second electric grids, and determining, based on at least one of said outdoor temperature, and said data pertaining to the electric grid status of the first electric grid and / or the one or more second electric grids, and, optionally, a specification of the decentralized heat pump system and / or structures / systems to which it is connected: an ambient side fluid recirculation loop temperature set point of a working fluid of the ambient side fluid recirculation loop; detecting a first working temperature of the working fluid of the ambient side fluid recirculation loop; and controlling an operation of the first set of one or more heat pump modules to adjust the first working temperature of the working fluid of the ambient side fluid recirculation loop to match said ambient side fluid recirculation loop temperature set point.

[0011] Each second set of the one or more second sets may be introduced in at least the respective indoor area of the one or more buildings. Each heat pump module of each set of the one or more second sets may be introduced in a respective part of the respective indoor area of the one or more buildings. Each heat pump module may be configured to cover, i.e. being able to heat and / or provide tap water, to the respective part of the respective indoor area. The part may be a part of an apartment or a whole apartment of the one or more buildings. The part may be a part of a building or a whole building of the one or more buildings. Each of the respective further fluid recirculation loops may be arranged in the respective indoor area of the one or more buildings.

[0012] As readily appreciated by the person skilled in the art, each heat pump module of the present disclosure comprises a refrigerant circulation loop which includes a first heat exchanger unit, a compressor, a second heat exchanger unit and an expander which may be connected to one another in a sequence. Such a heat pump module is configured to transfer energy from a cold side to a hot side by means of a refrigeration cycle.

[0013] By a heat pump module being “directly connected” to a fluid recirculation loop is herein meant that said fluid recirculation loop passes through a heat exchanger of the heat pump module such that the heat pump module can transfer energy directly to, or from, a working fluid transported within that fluid recirculation loop.

[0014] By a heat pump module being “connected via a further fluid recirculation loop” to the ambient side fluid recirculation loop is herein meant that said further fluid recirculation loop passes through a heat exchanger of the heat pump module such that the heat pump module can transfer energy directly to, or from, a working fluid transported within said further fluid recirculation loop. It further implies that energy can be transported between the further fluid recirculation loop and the ambient side fluid recirculation loop. The latter may be achieved by a heat transfer means. The heat transfer means may be a heat exchanger. The heat transfer means may alternatively be a heat pump. This will be discussed in more detail later.

[0015] The method for controlling the decentralized heat pump system may be advantageous as it allows for controlling the operation of the first set of one or more heat pump modules in an efficient way, fulfilling the efficiency needs for the case with one or more buildings of various types and use cases. This is achieved by controlling the operation of the first set of one or more heat pump modules by adjusting the first working temperature to the ambient side fluid recirculation loop set point. Thus, by controlling the first working temperature using the first set of one or more heat pump modules improves the energy efficiency of the entire decentralized heat pump system.

[0016] The decentralized heat pump system may be a scalable decentralized heat pump system architecture and the method of the first aspect may be further advantageous as it allows for controlling the scalable decentralized heat pump system. Thus, the method of the first aspect may be able to control the decentralized heat pump system in a desirous way although one or more second sets of one or more heat pump modules may be connected and disconnected to / from the decentralized heat pump system, i.e. to / from the ambient side fluid recirculation loop. The method of the first aspect may be further able to control the decentralized heat pump system in a desirous way although connecting and disconnecting one or more heat pump modules to / from the respective second set, i.e. to / from the further fluid recirculation loop.

[0017] The method may be further advantageous as it allows for controlling the decentralized heat pump system such that energy is transferred between different fluid recirculation loops which the sets of heat pump modules of the decentralized heat pump system are connected to in an optimized and efficient way.

[0018] The method may be yet further advantageous as it allows for controlling the operation of the first set of one or more heat pump modules based on one or more parameters. Thus, a flexible method for controlling the decentralized heat pump system may be achieved.

[0019] It should be noted that the outdoor temperature and the electric grid status of the first and / or the one or more second grids may be variable parameters which may depend on external factors, such as e.g. weather conditions, regional or national electricity supply, etc. With “electric grid status” is herein meant the status of the electric grid at the current point in time or at least a time period close thereto, and could include parameters such as grid frequency, grid voltage, grid power or grid current. These parameters are typically detected and input to the heat pump system on a regular basis.

[0020] It should be further noted that the specification of the decentralized heat pump system and / or structures / systems to which it is connected may be static parameter(s) which is / are not affected or dependent on external factors. The specification may be obtained at design of the system or at commissioning of the system. The structures / systems to which the decentralized heat pump system is connected may be for example one or more buildings, one or more heat sinks, one or more electric grids, etc.

[0021] The specification of the of the decentralized heat pump system and / or structures / systems to which it is connected may include a specification of the first electric grid and / or the one or more second electric grids. This implies that the specification may comprise data such as a maximum allowed current, a wire standard of electric cables, a maximum allowed power etc. The specification of the of the decentralized heat pump system and / or structures / systems to which it is connected may alternatively or additionally include data pertaining to an energy performance of the indoor area. This implies that the specification may include data pertaining to a thermal insulation performance of a building or a part of a building, such as e.g. wall thicknesses, insulation standards, window area and thermal transmittance (U) thereof, any kind of measured or estimated coefficients of thermal conductivity (A), thermal resistance (R) and thermal transmittance (U) of walls, roof, doors and windows, etc.

[0022] Direct electric heaters may be provided to contribute to the heating provided by the second set of one or more heat pump modules. Such a direct electric heater may be provided in each heat pump module of the second set. Alternatively, or additionally, a direct electric heater may be provided outside of said heat pump module of the second set.

[0023] According to an embodiment, the respective hot side fluid recirculation loop may further include a hot water accumulator tank. A direct electric heater may be placed in the hot water accumulator tank. Thus, the respective hot side fluid recirculation loop may also include the direct electric heater. The provision of the direct electric heater may be advantageous as it allows to provide a faster heating which thus improves comfort for the user. In particular, the provision of the direct electric heater allows to better tailor the operation of the respective heat pump module to particular conditions. As an example, when the outside temperature is low, the heat transfer provided by the heat pump module may have to be directed to the radiators only. The direct electric heater may then be used to selectively heat the hot tap water.

[0024] By way of example, if the outdoor temperature is low, the ambient side fluid recirculation loop set point may be determined to be high and the first set of one or more heat pump modules may be operated to match the first working temperature with the high ambient side fluid recirculation loop set point. As a consequence, the one or more heat pump modules of the one or more second sets may be able to achieve a higher coefficient of performance (COP) and reducing a risk for high electricity peaks. This may be advantageous as it allows excluding the direct electric heater but still being able to deliver a desired heat capacity to the one or more buildings and or to the part of the one or more buildings. This may in turn be advantageous as it allows for reducing the risk for high electricity peaks. The same may hold if the specification of the decentralized heat pump system and / or structures / systems to which it is connected falls within ranges which suggests a low efficiency / capability (for example if building(s) has a low thermal insulation or if electric grid(s) has a low maximum electric current, etc.) or if the electric grid status of the first electric grid and / or the second electric grid may be low. As an opposite, if the outdoor temperature is high, the ambient side fluid recirculation loop set point may be determined to be low and the first set of one or more heat pump modules may be operated to match the first working temperature with the low ambient side fluid recirculation loop set point. As a consequence, the one or more heat pump modules of the one or more second sets may be able to achieve a higher coefficient of performance (COP) and reducing a risk for high electricity peaks. This is advantageous as it allows for an efficient decentralized heat pump system. The same may hold if the specification of the decentralized heat pump system and / or structures / systems to which it is connected falls within ranges which suggests a high efficiency / capability (for example if building(s) has a high thermal insulation or if electric grid(s) has a high maximum electric current, etc.) or if the electric grid status of the first electric grid and / or the second electric grid may be high.

[0025] This is advantageous as it allows driving the complete decentralized heat pump system by electricity instead of by combustion as in conventional systems, i.e. it allows an electrified solution based on renewable energy instead of combustion solutions as in conventional system.

[0026] Although individual second electric grids may be provided, it is alternatively conceivable that two or more of the one or more second sets of one or more heat pump modules is configured to be connected to a respective second electric grid. For some embodiments, there is only one second electric grid. For such embodiments, all of the one or more second sets of one or more heat pump modules is configured to be connected to the (sole) second electric grid.

[0027] According to the disclosed method, the operation of the first set of heat pumps is controlled to adjust the first working temperature of the working fluid of the ambient side fluid recirculation loop. Thus, the method will control the temperature in respect of which the one or more second sets operate, either directly or indirectly via the further fluid recirculation loop. This implies that the operation of the heat pump modules of the one or more second sets does not necessarily need to be related to the disclosed method, i.e. the heat pump modules of the one or more second sets may be set out to operate independent on the proposed method, i.e. in a slave mode. It is however conceivable that the operation of the heat pump modules of the one or more second sets is taken into account by the proposed method. As an example, in a case where the operation of the heat pump modules of the one or more second sets is forced to operate in an inefficient manner as a result from its boundary conditions, which boundary conditions includes the temperature of the ambient loop, which is controlled by the disclosed method, this may be taken into account by the disclosed method. In other words, the step of determining an ambient side fluid recirculation loop temperature set point of the working fluid of the ambient side fluid recirculation loop may be further based on a status of the heat pump modules of the one or more second sets.

[0028] The first set of one or more heat pump modules may be configured to transfer energy from the cold side fluid recirculation loop to the ambient side fluid recirculation loop, i.e. a temperature of a working fluid of the ambient side fluid recirculation loop may increase due to the energy transferred from the cold side fluid recirculation loop to the ambient side fluid recirculation loop. The one or more second sets of one or more heat pump modules may be configured to transfer energy from the ambient side fluid recirculation loop to the respective hot side fluid recirculation loop, i.e. a temperature of a working fluid of the respective hot side fluid recirculation loop may increase due to the energy transferred from the ambient side fluid recirculation loop to the respective hot side fluid recirculation loop. The one or more second sets of one or more heat pump modules may be configured to transfer energy from the ambient side fluid recirculation loop to the respective hot side fluid recirculation loop via the respective further fluid recirculation loop. This design may be advantageous as it allows providing energy to the part of the indoor area of the one or more buildings in an efficient way.

[0029] It should however be noted that the decentralized heat pump system may be able to transfer energy in different directions than previously described. For embodiments where the one or more second sets are directly connected to the ambient side fluid recirculation loop, each heat pump module of the one or more second sets may be reversed such that each heat pump module of the one or more second sets are configured to transfer energy from the hot side fluid recirculation loop to the ambient side fluid recirculation loop. For embodiments where the one or more second sets are connected to the ambient side fluid recirculation loop via the further fluid recirculation loop, each heat pump module of the one or more second sets may be reversed such that each heat pump module of the one or more second sets are configured to transfer energy from the hot side fluid recirculation loop to the further fluid recirculation loop. This design may be advantageous as it allows retrieving energy from the part of the indoor area of the one or more buildings if needed. It should be further noted that if a second set comprises two or more heat pump modules, the heat pump modules may be configured to operate in different ways, i.e. one or more heat pump modules may be configured to transfer energy to the hot side fluid recirculation loop and one or more heat pump modules may be configured to be reversed such that energy is retrieved from the hot side fluid recirculation loop. This may be advantageous as it allows for a flexible heat pump system in which different heat pump modules may be arranged in different ways depending on needs, e.g. for heating some areas and cooling others.

[0030] It should be further noted that also the one or more heat pump modules of the first set may be reversed such that energy is transferred from the ambient side fluid recirculation loop to the cold side fluid recirculation loop. This may be the case if a temperature of the working fluid of the ambient side fluid recirculation loop is determined to be too high, i.e. above a predetermined threshold value.

[0031] The fluid recirculation loops are closed loop circuits. Thus, the fluid recirculation loops are all hydraulically disconnected from each other when the system is in use. In other words, the cold side fluid recirculation loop is hydraulically isolated from the ambient side fluid recirculation loop when the system is in use. Further, the ambient side fluid recirculation loop is hydraulically isolated from the respective further fluid recirculation loop when the system is in use. The respective further fluid recirculation loop is hydraulically isolated from the respective hot side fluid recirculation loop when the system is in use. In other words, the fluid recirculation loops are operatively disconnected from one and other, such that no fluid is transferred between any two of said fluid recirculation loops when in use. It should however be understood that the above does not rule out the possibility that there are means to transfer working fluid to, from or even between the different refrigeration loops.

[0032] With the term “cold side fluid recirculation loop” is herein meant a closed circuit through which a constant volume of working fluid is circulated. The cold side fluid recirculation loop may be arranged to retrieve, or provide, heat from a heat sink. The heat sink may be for example one or more of: ambient air, an aquifer, a bore hole, and industrial waste heat. The term “cold side fluid recirculation loop” as used herein is a non-limiting term to describe one of the recirculation loops to which the first set of one or more heat pump modules are connected to and the term is chosen to reflect how said recirculation loop most commonly will relate to the other recirculation loops temperature-wise. The term should however not be interpreted as requiring that the cold side fluid recirculation loop have a working fluid which always has a lower temperature than the working fluids of the other recirculation loops.

[0033] With the term “hot side fluid recirculation loop” is herein meant a closed loop circuit through which a constant volume of working fluid is circulated. The hot side fluid recirculation loop may be located in a part of an indoor area of one or more buildings. The hot side fluid recirculation loop may be arranged to provide heating and / or hot tap water to the indoor area of the one or more buildings. The term “hot side fluid recirculation loop” as used herein is a nonlimiting term to describe a recirculation loop to which a heat pump module of one of the second sets is connected to and the term is chosen to reflect how said recirculation loop most commonly will relate to the other recirculation loops temperature-wise. The term should however not be interpreted as requiring the hot side fluid recirculation loop to have a working fluid with temperature being higher than temperatures of working fluids of the other recirculation loops.

[0034] An electrical grid is typically described as an interconnected network for electricity delivery from producers to consumers. An electrical grid may consist of power stations, electrical substations to step voltage up and down, electric power transmission to carry power long distances and electrical power distribution to individual customers, where voltage is stepped down again to required service voltage(s). However, in the context of this application, an electrical grid may be less extensive and complex than what is implied from the above general definition, and as used herein the term should be construed as limited only in so far as having its own well-defined boundaries and characteristics in relation to adjacent electrical grids. Thus, each electrical grid according to the disclosure may be operably independent on parallel electrical grids, have its own defined operating voltage, frequency and so on. Typically, an electrical grid, as used herein, is a sub distribution grid. As such, it may have its own interface for receiving electrical power from another electrical grid further upstream thereof.

[0035] If the decentralized heat pump system comprises a plurality of second sets of one or more heat pump modules and each second set is arranged in a respective building, the respective building may comprise a plurality of second electric grids such that the heat pump modules of each second set may be connected to different second electric grid.

[0036] According to some embodiments, the first set of one or more heat pump modules is configured to be connected to a control unit which may be configured to control the operation of the first set of one or more heat pump modules.

[0037] This implies that each heat pump module of the first set of one or more heat pump modules is connected to the control unit. This may be advantageous as it allows optimizing an efficiency of the first set of one or more heat pump modules. The control unit may be configured to control the operation of the first set of one or more heat pump modules based on various parameters such as outdoor temperature, capabilities of the electric grids the heat pump modules are connected to, energy characteristics of the part of the indoor area of the one or more buildings, and so forth. The control unit may be configured to be connected (wired or wireless) to one or more sensors comprised in the decentralized heat pump system and configured to determine data pertaining to the various parameters. The one or more sensors may be a temperature sensor or a current sensor or the like.

[0038] This may be further advantageous in that a robust decentralized heat pump system is achieved. This may be yet further advantageous as it improves the efficiency of the decentralized heat pump system since the control unit is configured to control the operation of the first set of one or more heat pump modules, and as a consequence, the temperature of the working fluid of the ambient side fluid recirculation loop. This may be yet further advantageous as it allows controlling the first set of one or more heat pump modules in a viable, flexible, and effective way.

[0039] With the term “control unit” is herein meant any device or unit configured to control an operation of the first set of one or more heat pump modules. Preferably, the system comprises one control unit which is configured to control the operation of each heat pump module of the first set of one or more heat pump modules. It should however be noted that each heat pump module of the first set may have a respective further control unit which is configured to, together with the control unit, control the operation of the associated heat pump module. The control unit may be e.g., a microprocessor or a central processing unit, CPU. The control unit may be configured to control the power and enablement of the heat pump module operation of the first set. The control unit may be wired, or wireless connected to each of the heat pump modules of the first set.

[0040] Each heat pump module of the one or more second sets may be configured to be connected to the control unit which is configured to control an operation of each heat pump module of the one or more second sets. The control unit may be configured to control the operation of each heat pump module of the second sets based on the operation of the first set of one or more heat pump modules. By way of example, if each heat pump module of the one or more second sets is connected to the control unit, it may be possible to prevent use of the direct electric heater if not needed.

[0041] If the energy transfer means is the heat pump, the heat pump may be configured to be connected to the control unit which is configured to control an operation of the heat pump. The control unit may be configured to control the operation of the heat pump based on the operation of the first set of one or more heat pump modules.

[0042] According to some embodiments, the specification of the decentralized heat pump system and / or structures / systems to which it is connected includes a specification of the first electric grid and / or the one or more second electric grids, and wherein the step of determining the ambient side fluid recirculation loop temperature set point is further based on said specification of the first electric grid and / or the one or more second electric grids.

[0043] This may be advantageous in that it allows for optimizing the operation of the first set of one or more heat pump modules as well as optimizing the operation of the entire decentralized heat pump module. This is achieved by determining the ambient side fluid recirculation loop set point in a flexible and efficient way. It should be noted that the specification of the first electric grid and / or the one or more second electric grids may be static parameter(s) which is not affected or dependent on external factors.

[0044] According to some embodiments, the specification of the decentralized heat pump system and / or structures / systems to which it is connected includes data pertaining to an energy performance of the indoor area, and wherein the step of determining the ambient side fluid recirculation loop temperature set point is further based on said data pertaining to the energy performance of the indoor area.

[0045] This may be advantageous in that it allows for optimizing the operation of the first set of one or more heat pump modules as well as optimizing the operation of the entire decentralized heat pump system. This is achieved by determining the ambient side fluid recirculation loop set point in a flexible and efficient way. It should be noted that the data pertaining to an energy performance of the indoor area may be static parameter(s) which are not affected or dependent on external factors.

[0046] If the data pertaining to the energy performance of the indoor area falls within a range which suggests a low efficiency (for example if the building(s) within which the indoor area is situated have a low thermal insulation, etc.), the ambient side fluid recirculation loop temperature set point may be set to a somewhat higher temperature to better compensate for the low efficiency.

[0047] According to some embodiments, the step of determining at least one of an outdoor temperature, and data pertaining to an electric grid status of the first electric grid and / or the one or more second electric grids comprises determining frequency data for the first electric grid and / or the one or more second electric grids, and wherein the ambient side fluid recirculation loop temperature set point is determined such that a deviation between the frequency data of the first electric grid and / or the one or more second electric grids and a predetermined frequency data set point is lowered during operation of the decentralized heat pump system.

[0048] By way of example, in European interconnected electric grids may the predetermined frequency data set point be 50 Hz, i.e. the standard frequency in Europe’s electrical grids is 50 Hz. In North America and parts of Japan is the standard frequency in the electrical grids 60 Hz, i.e. the predetermined frequency data set point may be 60 Hz. Thus, the value of the predetermined frequency data set point may be dependent on where in the world the decentralized heat pump system is located.

[0049] This may be advantageous as it allows for optimizing the operation of the first electric grid and / or the one or more second electric grids and stabilizing the frequency of the first electric grid and / or the one or more second electric grids. By way of example, if the frequency data of the one or more second electric grids is determined to be higher than the predetermined frequency data set point, the first set of one or more heat pump modules may be controlled to operate with a reduced capacity. As a consequence, the one or more heat pump modules of the one or more second sets may be controlled to operate with an increased capacity, thereby increasing the load which may allow the grid frequency to decrease towards the predetermined frequency data set point. If, on the other hand, the frequency data of the one or more second electric grids is determined to be lower than the frequency data set point, the first set of one or more heat pump modules may be controlled to operate with an increased capacity. As a consequence, the one or more heat pump modules of the one or more second sets may be controlled to operate with a reduced capacity, thereby decreasing the load which may allow the grid frequency to increase towards the predetermined frequency data set point.

[0050] According to some embodiments, the one or more heat pump modules of each of the one or more seconds sets are configured to be connected via the respective further fluid recirculation loop to the ambient side fluid recirculation loop, and wherein the decentralized heat pump system further comprises, for at least one set of the one or more second sets: a respective further heat pump module configured to be directly connected to the ambient side fluid recirculation loop at a respective first side thereof and directly connected to the respective further fluid recirculation loop of said at least one of the second sets at a second side thereof, the method further comprising: determining, for said at least one set of the one or more second sets, and based on at least one of the outdoor temperature, the data pertaining to the electric grid status of the first electric grid and / or the one or more second electric grids, and, optionally, the specification of the decentralized heat pump system and / or structures / systems to which it is connected, a respective further fluid recirculation loop temperature set point of a working fluid of the respective further fluid recirculation loop; detecting a temperature of the working fluid of the respective further fluid recirculation loop; and controlling an operation of the respective further heat pump module to adjust the temperature of the working fluid of the respective further fluid recirculation loop to match said respective further fluid recirculation loop temperature set point.

[0051] This may be advantageous as it allows for controlling the decentralized heat pump system in a more efficient and flexible way. The method may be further advantageous as it allows for controlling the decentralized heat pump system such that energy is transferred between the ambient side fluid recirculation loop and the further fluid recirculation loop in a more efficient and flexible way. The method may be yet further advantageous as it allows for controlling the operation of the respective further heat pump module based on one or more parameters.

[0052] The respective further fluid recirculation loop temperature set point may be determined based on the operation of the first set of one or more heat pump modules. The respective further fluid recirculation loop temperature set point may be determined based on the first working temperature of the working fluid of the ambient side fluid recirculation loop.

[0053] By way of example, if the building is a badly insulated building, the heat pump module may be introduced such that a more efficient and controllable heating may be achieved to increase (or decrease) the temperature of the working fluid of the further fluid recirculation loop for optimized operation of the heat pump modules of the second set in this building. Thus, the heat pump may be advantageous in that it allows adapting the temperature of the working fluid of the ambient side fluid recirculation loop and the further fluid recirculation loop such that the method is arranged to control the decentralized heat pump system such that an optimal efficiency of the decentralized heat pump system may be achieved. According to some embodiments, the specification of the first electric grid and / or the one or more second electric grids comprises one or more of: a maximum allowed current of the first electric grid and / or the one or more second electric grids, a maximum allowed power of the first electric grid and / or the one or more second electric grids, and a maximum allowed voltage of the first electric grid and / or the one or more second electric grids.

[0054] This is advantageous as it allows for controlling the decentralized heat pump system, and especially the operation of the first set of one or more heat pump modules, in a flexible way, wherein the controlling of the operation may be based on a plurality of parameters.

[0055] According to some embodiments, the data pertaining to the energy performance of the indoor area comprises one or more of: an insulation range of the indoor area, and an insulation type of the indoor area.

[0056] This is advantageous as it allows for controlling the operation of the first set of one or more heat pump modules based on how the insulation or inertia of the indoor area is provided, i.e. if the indoor area is good or bad isolated or if the inertia of the climate shield is high or low.

[0057] According to some embodiments, the data pertaining to the electric grid status of the first electric grid and / or the one or more second electric grids comprises data pertaining to a deficiency of electricity in the first electric grid and / or the one or more second electric grids, data pertaining to a surplus of electricity in the first electric grid and / or the one or more second electric grids, and frequency data for the first electric grid and / or the one or more second electric grids.

[0058] In this context, the data pertaining to the deficiency of electricity in the first electric grid and / or the one or more second electric grids may be interpreted as a time period in which an energy price is higher than a daily average price. This may be referred to as the electric grid status of the first electric grid and / or the one or more second electric grids is low. Further in this context, the data pertaining to the surplus of electricity in the first electric grid and / or the one or more second electric grids may be interpreted as a time period in which an energy price is lower than a daily average price. According to some embodiments, the one or more second sets of one or more heat pump modules comprise a plurality of second sets of one or more heat pump modules.

[0059] This is advantageous as it allows for a scalable decentralized heat pump system architecture.

[0060] According to some embodiments, each of the plurality of second sets are located in a respective building which each defines a respective part of the indoor area.

[0061] This is advantageous as it allows for controlling the decentralized heat pump system such that the decentralized heat pump system is able to provide heating and / or tap water to the respective building.

[0062] According to some embodiments, the ambient side fluid recirculation loop temperature set point is different from each of the at least one respective further fluid recirculation loop temperature set points.

[0063] This is advantageous in that it allows to control the decentralized heat pump system to transfer energy between the ambient side fluid recirculation loop to the respective further fluid recirculation loop.

[0064] According to some embodiments, the ambient side fluid recirculation loop temperature set point is smaller than each of the at least one respective further fluid recirculation loop temperature set points.

[0065] This is advantageous in that it allows to control the decentralized heat pump system to transfer energy from the ambient side fluid recirculation loop to the respective further fluid recirculation loop.

[0066] According to some embodiments, the one or more heat pump modules of each of the one or more second sets are configured to be connected via the respective further fluid recirculation loop to the ambient side fluid recirculation loop, and wherein the decentralized heat pump system further comprises, for at least one of the second sets, a respective heat exchanger configured to be directly connected to the ambient side fluid recirculation loop at a first side thereof and directly connected to the respective further fluid recirculation loop of said at least one of the second sets at a second side thereof. The heat exchanger is configured to transfer energy between the ambient side fluid recirculation loop and the further fluid recirculation loop. This may be advantageous in that, it provides a less expensive and more reliable energy transfer and, depending on building energy characteristics, the efficiency of the system may be improved since the ambient loop temperature may be controlled for the in-door area with best insulation for optimized use of power needed for the one or more heat pump modules of the second set configured to cover that indoor area.

[0067] Effects and features of the second and third aspects are largely analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second aspect and third aspects. It is further noted that the inventive concepts relate to all possible combinations of features unless explicitly stated otherwise.

[0068] A further scope of applicability of the present disclosure will become apparent from the detailed description given below. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.

[0069] Hence, it is to be understood that this disclosure is not limited to the particular component parts of the device described or steps of the methods described as such device and method may vary. It is also to be understood that the terminology used herein is for purpose of describing particular embodiments only, and is not intended to be limiting. It must be noted that, as used in the specification and the appended claim, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of the elements unless the context clearly dictates otherwise. Thus, for example, reference to "a unit" or "the unit" may include several devices, and the like. Furthermore, the words "comprising", "including", "containing" and similar wordings does not exclude other elements or steps. Brief descriptions of the drawings

[0070] The disclosure will by way of example be described in more detail with reference to the appended schematic drawings, which shows presently preferred embodiments of the disclosure.

[0071] Figure 1 illustrates a decentralized heat pump system.

[0072] Figure 2 is a detailed illustration of one heat pump module of a second set of one or more heat pump modules.

[0073] Figure 3 is a detailed illustration of three heat pump modules of a second set of one or more heat pump modules.

[0074] Figure 4 illustrates a heat pump module.

[0075] Figure 5 is a flowchart illustrating a method for controlling a decentralized heat pump system.

[0076] Detailed description

[0077] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the disclosure to the skilled person.

[0078] With reference to Fig. 1 , a decentralized heat pump system 100 is illustrated by way of example. The decentralized heat pump system 100 is configured to transfer heat from one side of the system 100 to another side of the system 100. The decentralized heat pump system 100 is configured to transfer heat within the system 100. The decentralized heat pump system 100 comprises a first set 110 of one or more heat pump modules 111 and three second sets 120a, 120b, 120c of one or more heat pump modules 121 , 122, 123, 124. Throughout the application text, the phrase “first set of one or more heat pump modules” and the phrase “first set” are both referring to the first set of one or more heat pump modules. The phrase “one or more second sets of one or more heat pump modules” and the phrase “second sets” are both referring to the one or more second sets of one or more heat pump modules.

[0079] As depicted in Fig. 1 , the first set 110 comprises one heat pump module 111. The heat pump module 111 of the first set 110 is directly connected to a cold side fluid recirculation loop 101 at a first side 111a thereof and to an ambient side fluid recirculation loop 102 at a second side 111b thereof. The cold side fluid recirculation loop 101 may be a closed circuit through which a constant volume of working fluid is circulated. The working fluid may have a fluid temperature in the range of 0-40°C, preferably 5-25°C, more preferably 5-15°C. The cold side fluid recirculation loop may be arranged to retrieve, or provide, heat from a heat sink 107. The heat sink 107 may be for example one or more of: ambient air, an aquifer, a bore hole, and industrial waste heat. The ambient side fluid recirculation loop 102 may be a closed circuit through which a constant volume of working fluid is circulated. The working fluid may have a fluid temperature in the range of 0-40°C, preferably 5-25°C, more preferably 10-20°C. The ambient side fluid recirculation loop 102 may be arranged below ground. The heat pump module 111 of the first set 110 is configured to transfer energy between the cold side fluid recirculation loop 101 and the ambient side fluid recirculation loop 102. The heat pump module 111 of the first set 110 may have an operating power of 20 - 20000 kW.

[0080] As indicated above, the decentralized heat pump system 100 comprises three second sets 120a, 120b, 120c of one or more heat pump modules 121 , 122, 123, 124. Second set 120a comprises one heat pump module 121. Second set 120b comprises three heat pump modules 122, 123, 124. Second set 120c comprises three heat pump modules 122, 123, 124. The decentralized heat pump system 100 may comprise more than three second sets 120a, 120b, 120c or less than three second sets 120a, 120b, 120c.

[0081] The heat pump module 121 of second set 120a is connected to the ambient side fluid recirculation loop 102 at a first side 121a thereof and to a hot side fluid recirculation loop 104 at a second side 121 b thereof. Thus, the heat pump module 121 is configured to transfer energy between the ambient side fluid recirculation loop 102 and the hot side fluid recirculation loop 104. The heat pump module 121 of second set 120a and the hot side fluid recirculation loop 104 are arranged in a first building 140a and are configured to provide heating and / or tap water to an indoor area of the first building 140a. The operating power of the heat pump module 121 may be 10-1000 kW depending on a size of the first building 140a. However, it should be noted that the operating power of the heat pump module 121 of the first second set 120a is smaller than the operating power of the heat pump module 111 of the first set 110.

[0082] The heat pump modules 122, 123, 124 of second set 120b are connected to a further fluid recirculation loop 103 at a respective first side 122a, 123a, 124a thereof and to a respective hot side fluid recirculation loop 104 at a respective second side 122b, 123b, 124b thereof. Thus, the heat pump modules 122, 123, 124 of second set 120b are configured to transfer energy between the respective further fluid recirculation loop 103 and the respective hot side fluid recirculation loop 104. The heat pump modules 122, 123, 124 of second set 120b and the respective hot side fluid recirculation loops 104 are arranged in a second building 140b and are configured to provide heating and / or tap water to a respective indoor area of the second building 140b. The further fluid recirculation loop 103 may also be arranged in the second building 140b. By way of examples, each heat pump module 122, 123, 124 and the respective hot side fluid recirculation loop 104 may be configured to provide heating and / or tap water to a respective apartment (i.e. a respective part of an indoor area) of the second building 140b. The operating power of the heat pump modules 122, 123, 124 may be 3-20 kW depending on a size of the respective indoor area of the second building 140b. However, it should be noted that the operating power of the heat pump modules 122, 123, 124 of second set 120b is smaller than the operating power of the heat pump module 111 of the first set 110.

[0083] The decentralized heat pump system 100 further comprises energy transfer means 130. The energy transfer means 130 is connected to the ambient side fluid recirculation loop 102 at a first side 130a thereof and to the further fluid recirculation loop 103 of second set 120b at a second side 130b thereof. The energy transfer means 130 of the second building 140b is a heat exchanger 131a and may be configured to transfer energy from the ambient side fluid recirculation loop 102 to the further fluid recirculation loop 103.

[0084] The heat pump modules 122, 123, 124 of second set 120c are connected in a similar way as the heat pump modules 122, 123, 124 of second set 120b and comprises similar components and features as described above for second set 120b. The heat pump modules 122, 123, 124 of second set 120c and the respective hot side fluid recirculation loops 104 are arranged in a third building 140c and are configured to provide heating and / or tap water to a respective indoor area of the third building 140c. The further fluid recirculation loop 103 may also be arranged in the third building 140c. By way of examples, each heat pump module 122, 123, 124 and the respective hot side fluid recirculation loop 104 may be configured to provide heating and / or tap water to a respective apartment (i.e. an indoor area) of the third building 140c. The operating power of the heat pump modules 122, 123, 124 may be 3-20 kW depending on a size of the respective indoor area of the third building 140c. However, it should be noted that the operating power of the heat pump modules 122, 123, 124 of second set 120c is smaller than the operating power of the heat pump module 111 of the first set 110.

[0085] As indicated above, the decentralized heat pump system 100 further comprises energy transfer means 130. The energy transfer means 130 of the third building 140c is a heat pump 131 b and may be configured to transfer energy from the ambient side fluid recirculation loop 102 to the further fluid recirculation loop 103.

[0086] The respective further fluid recirculation loops 103 may be a closed circuit through which a constant volume of working fluid is circulated. The working fluid may have a fluid temperature in the range of 0-40°C, preferably 5-25°C, more preferably 10-30°C. The respective hot side fluid recirculation loop 104 may be a closed circuit through which a constant volume of working fluid is circulated. The working fluid may have a fluid temperature in the range of 30-70°C.

[0087] Thus, the first set and the second sets are connected to the ambient side fluid recirculation loop 102 in one way or another, either directly connected or via energy transfer means, wherein the decentralized heat pump system 100 may be configured to transfer energy from the cold side fluid recirculation loop 101 to the hot side fluid recirculation loop 104 via the ambient side fluid recirculation loop 102 and the respective further fluid recirculation loop 103, if any.

[0088] As best illustrated in Figs 2 and 3, the respective hot side fluid recirculation loop 104 includes a radiator circuit or an underfloor heating circuit 104a and a tap water exchange circuit 104b. The respective hot side fluid recirculation loop 104 is configured such that the second side 121 b, 122b, 123b, 124b of each heat pump module 121 , 122, 123, 124 of each of the second sets 120a, 120b, 120c is in fluid communication with either the radiator circuit 104a for providing room heating or with the tap water heat exchange circuit 104b for heating tap water. It should be noted that the heat pump modules 121 , 122, 123, 124 are physically connected to both the radiator circuit 104a and the tap water exchange circuit 104b at all times. As depicted in Fig. 2, the heat pump module 121 is in fluid communication with the radiator circuit 104a (illustrated as a solid line) and is not in fluid communication with, but physically connected to, the tap water exchange circuit 104b (illustrated as a dotted line). As depicted in Fig. 3, the first heat pump module 122 and the second heat pump module 123 are in fluid communication with the tap water exchange circuit 104b (illustrated as a solid line) and is not in fluid communication with, but physically connected to, the radiator circuit 104a (illustrated as a dotted line). The third heat pump module 124 is in fluid communication with the radiator circuit 104a (illustrated as a solid line) and is not in fluid communication with, but physically connected to, the tap water exchange circuit 104b (illustrated as a dotted line).

[0089] With reference to Fig. 4, the heat pump modules 111 , 121 , 122, 123, further detail. Each heat pump module 111 , 121 , 122, 123, 124 comprises first inlet and outlet ports 431 a, 431 b at the respective first side 111a, 121a, 122a, 123a, 124a thereof and second inlet and outlet ports 432a, 432b at the respective second side 111 b, 121 b, 122b, 123b, 124b thereof. Each heat pump module 111 , 121 , 122, 123, 124 further comprises a refrigerant circulation loop 434. The refrigerant recirculation loop 434 comprises a first heat exchanger unit 435 and a second heat exchanger unit 437 as well as a compressor 436 and an expander 438.

[0090] The first inlet and outlet ports 431a, 431 b are connected to a fluid recirculation loop 101 , 102, 103 (depending on the heat pump module as discussed above). The second inlet and outlet ports 432a, 432b are connected to another fluid recirculation loop 102, 103, 104 (depending on the heat pump module as discussed above). The first heat exchanger unit 435 is fluidly connected to the first inlet and outlet ports 431a, 431 b. The second heat exchanger unit 437 is fluidly connected to the second inlet and outlet ports 432b, 432a. The refrigerant circulation loop 434 preferably circulates a refrigerant through the first heat exchanger unit 435, the compressor 436, the second heat exchanger unit 437 and the expander 438. The refrigerant and the working fluid of the fluid recirculation loop 101 , 102, 103 are configured to exchange thermal energy between each other in the first heat exchanger unit 435 such that a temperature of the refrigerant increases and a temperature of the working fluid decreases. The refrigerant is circulated from the first heat exchanger unit 435 to the compressor 436 which is configured to increase the temperature and pressure of the refrigerant even further before supplying the refrigerant to the second heat exchanger unit 437. The refrigerant and the working fluid of the other fluid recirculation loop 102, 103, 104 are configured to exchange thermal energy between each other in the second heat exchanger unit 437 such that a temperature of the refrigerant decreases and a temperature of the working fluid increases. The refrigerant is circulated from the second heat exchanger unit 437 to the expander 438 which is configured to control an amount of refrigerant released into the first heat exchanger unit 435. The working fluid is circulated from the second heat exchanger unit 437 to a further heat pump module 121 , 122, 123, 124 or to the respective radiator circuit 104a or the respective tap water exchange circuit 104b.

[0091] If the energy transfer means 130 is a heat pump module, the heat pump module comprises similar features and is operating in a similar way as described for the heat pump modules 111 , 121 , 122, 123, 124 of the decentralized heat pump system 100 above.

[0092] One or more of the heat pump devices 121 , 122, 123, 124 of the second sets 120a, 120b, 120c may further comprise a direct electric heater 406. When the heat pump devices 121 , 122, 123, 124 of the second set 120a, 120b, 120c comprises the direct electric heater 406, the maximum operating power of the heat pump device 121 , 122, 123, 124 of the second set 120a, 120b, 120c will be the sum of the maximum operating power of the respective compressor 436 and the maximum operating power of the respective direct electric heater 406. As a non-limiting example, if the maximum operating power of the compressor 436 is 5 kW and the maximum operating power of the direct electric heater 406 is 6 kW, the maximum operating power of the heat pump device 121 , 122, 123, 124 will be 11 kW. The provision of the direct electric heater 406 allows to better tailor the operation of the heat pump module 121 , 122, 123, 124 to particular conditions. As an example, when the outside temperature is low, the heat transfer provided by the refrigerant circulation loop 434 may have to be directed to the radiators only. The direct electric heater 406 may then be used to selectively heat the hot tap water. The direct electric heater 406 may be placed in an accumulator tank 407 and the heat pump device 121 , 122, 123, 124 may in this case also include the accumulator tank 407.

[0093] Referring back to Fig. 1 , the ambient side fluid recirculation loop 102 and the further fluid recirculation loop 103 are operatively disconnected from one another. Thus, no fluid is transferred between the two fluid recirculation loops 102, 103 when energy is transferred between the two fluid recirculation loops 102, 103 during use of the decentralized heat pump system 100. The decentralized heat pump system 100 further comprises a process water refilling circuit system 105. As can be seen in Fig. 1 , the process water refilling circuit system 105 interconnects the ambient side fluid recirculation loop 102 and the further fluid recirculation loop 103 of the second building 140b. Although not illustrated, the process water refilling circuit system 105 may interconnect the ambient side fluid recirculation loop 102 with more than one, or with each, respective further fluid recirculation loop 103. As can be further seen in Fig. 1 , the process water refilling circuit system 105 interconnects the ambient side fluid recirculation loop 102 and one of the respective hot side fluid recirculation loops 104 of the second building 140b. Although not illustrated, the process water refilling circuit system 105 may interconnect the ambient side fluid recirculation loop 102 with more than one, or with each, respective hot side fluid recirculation loop 104. The process water refilling circuit system 105 is configured to allow, selectively, to supply process water from the ambient side fluid recirculation loop 102 to the respective further fluid recirculation loop 103 and / or to the respective hot side fluid recirculation loop 104 for refilling the respective further fluid recirculation loop 103 and / or the respective hot side fluid recirculation loop 104. This is provided by a respective valve 106 arranged in the process water refilling circuit system 105.

[0094] As best illustrated in Fig. 3, the respective further fluid recirculation loop 103 and the respective hot side fluid recirculation loop 104 are operatively disconnected from one another. Thus, no fluid is transferred between the two fluid recirculation loops 103, 104 when energy is transferred between the two fluid recirculation loops 103, 104 during use of the decentralized heat pump system 100. The decentralized heat pump system 100 further comprises a further process water refilling circuit system 115. As illustrated in Fig. 3, the further process water refilling circuit system 115 interconnects the further fluid recirculation loop 103 and the hot side fluid recirculation loop 104 of the second building 140b. Although not illustrated, the further process water refilling circuit system 115 may interconnect the respective further fluid recirculation loop 103 with more than one, or with each, respective hot side fluid recirculation loop 104. The further process water refilling circuit system 115 is configured to allow, selectively, to supply process water from the respective further fluid recirculation loop 103 to the respective hot side fluid recirculation loop 104 for refilling the respective hot fluid recirculation loop 104. This is provided by a respective valve 116 arranged in the further process water refilling circuit system 115.The first set 110 of one or more heat pump modules is connected to a first electric grid 150. Each of the second set 120 of one or more heat pump modules are connected to a respective second electric grid 160a, 160b, 160c. This may be advantageous in that it allows separated electrical grids which may be beneficial because it makes the system 100 less vulnerable. By way of example, this is achieved by that the first and second electric grids may be different local area network.

[0095] The decentralized heat pump system 100 further comprises a control unit 170. The first set 110 of one or more heat pump modules is connected to the control unit 170, wherein the control unit 170 is configured to control an operation of the first set 110 of one or more heat pump modules 110. Although the control unit 170 is illustrated as being remote from the first set 110 of one or more heat pump modules, the control unit 170 may be comprised in the first set 110 of one or more heat pump modules. The control unit 170 may be comprised in one heat pump module 111 of the first set 110 of one or more heat pump modules. The control unit 170 may be wired, or wireless connected to the first set 110 of one or more heat pump modules 111. As further depicted, the second sets 120a, 120b, 120c of one or more heat pump modules are connected to the control unit 170. The control unit 170 may be comprised in one of the second sets 120a, 120b, 120c of one or more heat pump modules. The control unit 170 may be comprised in one heat pump module 121 , 122, 123, 124 of the second sets 120 of one or more heat pump modules. The control unit 170 may be wired, or wireless connected to the second sets 120a, 120b, 120c of one or more heat pump modules. The control unit 170 may be arranged to be distributed over a plurality of heat pump modules such that a mesh network (well-known in the art by the skilled person) is formed. With reference to Fig. 5, a flowchart illustrating a method 500 for controlling a decentralized heat pump system 100 is shown by way of example. The decentralized heat pump system 100 corresponds to the decentralized heat pump system 100 as depicted in Fig. 1. As introduced above, the decentralized heat pump system 100 comprises a first set 110 of one or more heat pump modules and one or more second sets 120a-c, each comprising one or more heat pump modules 121 , 122, 123, 124. Thus, the one or more second sets 120a-c of one or more heat pump modules may comprise a plurality of second sets 120a-c of one or more heat pump modules. Each of the plurality of second sets 120a-c may be located in a respective building 140a-c. Each of the one or more heat pump modules 121 , 122, 123, 124 of the respective second set 120a-c may be located in a respective part of the respective indoor area.

[0096] The method 500 comprises determining S502 at least one of an outdoor temperature, and data pertaining to an electric grid status of the first electric grid 150 and / or the one or more second electric grids 160a-c.

[0097] It should be noted that the outdoor temperature and the electric grid status of the first electric grid 150 and / or the one or more second grids 160a-c may be variable parameters which may depend on external factors, such as e.g. weather conditions, regional or national electricity supply, etc. With “electric grid status” is herein meant the status of the electric grid 150, 160a-c at the current point in time or at least a time period close thereto, and could include parameters such as grid frequency, grid voltage or grid current. These parameters are typically detected and input to the heat pump system 100 on a regular basis.

[0098] Optionally, the step of determining S502 at least one of an outdoor temperature, and data pertaining to the electric grid status of the first electric grid 150 and / or the one or more second electric grids 160a-c may comprise determining frequency data for the first electric grid 150 and / or the one or more second electric grid 160a-c.

[0099] Optionally, the data pertaining to the electric grid status of the first electric grid 150 and / or the one or more second electric grids 160a-c may comprise data pertaining to a deficiency of electricity in the first electric grid 150 and / or the one or more second electric grids 160a-c, and data pertaining to a surplus of electricity in the first electric grid 150 and / or the one or more second electric grids 160a-c.

[0100] Thereafter, the method 500 comprises determining S504, based on at least one of said outdoor temperature, and said data pertaining to the electric grid status of the first electric grid 150 and / or the one or more second electric grids 160a-c, and, optionally, a specification of the decentralized heat pump system 100 and / or structures / systems to which it is connected: an ambient side fluid recirculation loop temperature set point of a working fluid of the ambient side fluid recirculation loop 102.

[0101] It should be noted that the specification of the decentralized heat pump system 100 and / or structures / systems to which it is connected may be static parameter(s) which is / are not affected or dependent on external factors. The specification may be obtained at design of the system 100 or at commissioning of the system 100. The structures / systems to which the decentralized heat pump system 100 may be connected may be for example one or more buildings 140a-c, one or more heat sinks 107, one or more electric grids 150, 160a-c, etc.

[0102] The specification of the decentralized heat pump system 100 and / or structures / systems to which it is connected may include a specification of the first electric grid 150 and / or the one or more second electric grids 160a-c. This implies that the specification may comprise data such as a maximum allowed electric current, a wire standard of electric cables, a maximum allowed power etc.

[0103] Optionally, the step of determining S504 the ambient side fluid recirculation loop set point may be further based on the specification of the first electric grid 150 and / or the one or more second electric grids 160a-c.

[0104] The specification of the decentralized heat pump system 100 and / or structures / systems to which it is connected may include data pertaining to an energy performance of the indoor area. This implies that the specification may include data pertaining to a thermal insulation performance and inertia of a building 140a-c or a part of a building 140a-c, such as e.g. wall thicknesses, insulation standards, window area and thermal transmittance (U) thereof, any kind of measured or estimated coefficients of thermal conductivity (A), thermal resistance (R) and thermal transmittance (U) of walls, roof, doors and windows, etc.

[0105] Optionally, the step of determining S504 the ambient side fluid recirculation loop set point may be further based on the data pertaining to the energy performance of the indoor area.

[0106] Optionally, the ambient side fluid recirculation loop set point may be determined such that a deviation between the frequency data of the first electric grid 150 and / or the one or more second electric grids 160a-c and a predetermined frequency data set point is lowered during operation of the decentralized heat pump system 100. Thus, the method 500 may be configured to control the operation of the first set 110 of one or more heat pump modules such that the deviation between the frequency data of the first electric grid 150 and / or the one or more second electric grids 160a-c and the predetermined frequency data set point is lowered.

[0107] Thereafter, the method 500 comprises detecting S506 a first working temperature of the working fluid of the ambient side fluid recirculation loop 102.

[0108] Thereafter, the method 500 comprises controlling S508 an operation of the first set of one or more heat pump modules 110 to adjust the first working temperature of the working fluid of the ambient side fluid recirculation loop 102 to match said ambient side fluid recirculation loop temperature set point.

[0109] Optionally, the method 500 may further comprise, if the decentralized heat pump system 100 comprises a further heat pump modules 131 b, determining S510, for said at least one set of the one or more second sets 120a-c, and based on at least one of the outdoor temperature, the data pertaining to the electric grid status of the first electric grid 150 and / or the one or more second electric grids 160a-c, and, optionally, the specification of the decentralized heat pump system 100, a respective further fluid recirculation loop temperature set point of a working fluid of the respective further fluid recirculation loop.

[0110] Thereafter, the method 500 may further comprise, detecting S512 a temperature of the working fluid of the respective further fluid recirculation loop 103.

[0111] Thereafter, the method 500 may further comprise, controlling S514 an operation of the respective further heat pump module 150b to adjust the temperature of the working fluid of the respective further fluid recirculation loop to match said respective further fluid recirculation loop temperature set point.

[0112] The ambient side fluid recirculation loop temperature set point may be different from each of the at least one respective further fluid recirculation loop temperature set points. The ambient side fluid recirculation loop temperature set point may be smaller than each of the at least one respective further fluid recirculation loop temperature set points. The decentralized heat pump system 100 may comprise a heat exchanger 131a as introduced in connection with Fig. 1 .

[0113] The person skilled in the art realizes that the present disclosure by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed, from a study of the drawings, the disclosure, and the appended claims.

Claims

CLAIMS1 . A method (500) for controlling a decentralized heat pump system (100) for providing heating to an indoor area of one or more buildings (140a- c), the decentralized heat pump system (100) comprising: a first set (110) of one or more heat pump modules wherein each heat pump module (111 ) of the first set (110) is configured to be directly connected to a cold side fluid recirculation loop (101 ) at a first side (111a) thereof and to be directly connected to an ambient side fluid recirculation loop (102) at a second side (111b) thereof; and one or more second sets (120a-c) each comprising one or more heat pump modules (121 , 122, 123, 124) wherein each heat pump module (121 , 122, 123, 124) of each of the one or more second sets (120a-c) is configured to be directly connected, or connected via a respective further fluid recirculation loop (103), to the ambient side fluid recirculation loop (102), at a first side (121a, 122a, 123a, 124a) thereof and to be directly connected to a respective hot side fluid recirculation loop (104) at a second side (121 b, 122b, 123b, 124b) thereof for providing heating to at least a part of the indoor area, wherein each heat pump module (111 ) of the first set (110) is powered by a first electric grid (150), and each heat pump module (121 , 122, 123, 124) of each of the one or more second sets (120a-c) is powered by a respective second electric grid (160a-c) of one or more second electric grids (160a-c); and wherein the method (500) comprises: determining (S502) at least one of an outdoor temperature, and data pertaining to an electric grid status of the first electric grid (150) and / or the one or more second electric grids (160a-c), and determining (S504), based on at least one of said outdoor temperature, and said data pertaining to the electric grid status of the first electric grid (150) and / or the one or more second electric grids (160a-c), and, optionally, a specification of the decentralized heat pump system (100) and / or structures / systems to which it is connected:an ambient side fluid recirculation loop temperature set point of a working fluid of the ambient side fluid recirculation loop (102); detecting (S506) a first working temperature of the working fluid of the ambient side fluid recirculation loop (102); and controlling (S508) an operation of the first set (110) of one or more heat pump modules to adjust the first working temperature of the working fluid of the ambient side fluid recirculation loop (102) to match said ambient side fluid recirculation loop temperature set point.

2. The method (500) according to claim 1 , wherein said specification includes a specification of the first electric grid (150) and / or the one or more second electric grids (160a-c), and wherein the step of determining (S504) the ambient side fluid recirculation loop temperature set point is further based on said specification of the first electric grid (150) and / or the one or more second electric grids (160a-c).

3. The method (500) according to claim 1 or 2, wherein said specification includes data pertaining to an energy performance of the indoor area, and wherein the step of determining (S504) the ambient side fluid recirculation loop temperature set point is further based on said data pertaining to the energy performance of the indoor area.

4. The method (500) according to any one of claim 1 to 3, wherein the step of determining (S502) at least one of an outdoor temperature, and data pertaining to an electric grid status of the first electric grid (150) and / or the one or more second electric grids (160a-c) comprises determining frequency data for the first electric grid (150) and / or the one or more second electric grids (160a-c), and wherein the ambient side fluid recirculation loop temperature set point is determined such that a deviation between the frequency data of the firstelectric grid (150) and / or the one or more second electric grids (160a-c) and a predetermined frequency data set point is lowered during operation of the decentralized heat pump system (100).

5. The method (500) according to any one of the preceding claims, wherein the one or more heat pump modules (121 , 122, 123, 124) of each of the one or more seconds sets (120a-c) are configured to be connected via the respective further fluid recirculation loop (103) to the ambient side fluid recirculation loop (102), and wherein the decentralized heat pump system (100) further comprises, for at least one set of the one or more second sets (120a-c): a respective further heat pump module (131b) configured to be directly connected to the ambient side fluid recirculation loop (102) at a respective first side thereof (130a) and directly connected to the respective further fluid recirculation loop (103) of said at least one of the second sets (120a-c) at a second side (130b) thereof, the method (500) further comprising: determining (S510), for said at least one set of the one or more second sets (120a-c), and based on at least one of the outdoor temperature, the data pertaining to the electric grid status of the first electric grid (150) and / or the one or more second electric grids (160a-c), and, optionally, the specification of the decentralized heat pump system (100) and / or structures / systems to which it is connected, a respective further fluid recirculation loop temperature set point of a working fluid of the respective further fluid recirculation loop (103); detecting (S512) a temperature of the working fluid of the respective further fluid recirculation loop (103); and controlling (S514) an operation of the respective further heat pump module (131 b) to adjust the temperature of the working fluid of the respective further fluid recirculation loop (103) to match said respective further fluid recirculation loop temperature set point.

6. The method (500) according to any one of claims 2 to 5, wherein the specification of the first electric grid (150) and / or the one or more second electric grids (160a-c) comprises one or more of:- a maximum allowed current of the first electric grid (150) and / or the one or more second electric grids (160a-c),- a maximum allowed power of the first electric grid (150) and / or the one or more second electric grids (160a-c), and- a maximum allowed voltage of the first electric grid (150) and / or the one or more second electric grids (160a-c).

7. The method (500) according to any one of claims 3 or 4-6 when dependent on claim 3, wherein the data pertaining to the energy performance of the indoor area comprises one or more of: an insulation range of the indoor area, and an insulation type of the indoor area.

8. The method (500) according to any one of the preceding claims, wherein the data pertaining to the electric grid status of the first electric grid (150) and / or the one or more second electric grids (160a-c) further comprises data pertaining to a deficiency of electricity in the first electric grid (150) and / or the one or more second electric grids (160a-c), and data pertaining to a surplus of electricity in the first electric grid (150) and / or the one or more second electric grids (160a-c).

9. The method (500) according to any one of the preceding claims, wherein the one or more second sets (120a-c) of one or more heat pump modules comprise a plurality of second sets (120a-c) of one or more heat pump modules.

10. The method (500) according to claim 9, wherein each of the plurality of second sets (120a-c) are located in a respective building (140a-c) which each defines a respective part of the indoor area.11 . The method (500) according to any one of claims 5 or 6-10 when dependent on claim 5, wherein the ambient side fluid recirculation loop temperature set point is different from each of the at least one respective further fluid recirculation loop temperature set points.

12. The method (500) according to claim 11 , wherein the ambient side fluid recirculation loop temperature set point is smaller than each of the at least one respective further fluid recirculation loop temperature set points.

13. The method (500) according to any one of claims 9 to 12, wherein the one or more heat pump modules (121 , 122, 123, 124) of each of the one or more second sets (120a-c) are configured to be connected via the respective further fluid recirculation loop (103) to the ambient side fluid recirculation loop (102), and wherein the decentralized heat pump system (100) further comprises, for at least one of the second sets (120a-c), a respective heat exchanger (131a) configured to be directly connected to the ambient side fluid recirculation loop (102) at a first side (130a) thereof and directly connected to the respective further fluid recirculation loop (103) of said at least one of the second sets (120a-c) at a second side (130b) thereof.

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