Method, system and controller for controlling a plurality of heat pumps operated in a locally distributed manner in a network

Abstract

The invention relates to a method for controlling a plurality of heat pumps operated in a locally distributed manner in a network, at least one thermal store being assigned to one heat pump, which thermal store at least temporarily enables local operation at at least one first point in time and temporarily enables network operation, in particular network operation providing system services referred to as "ancillary service obligation", at at least one second point in time, in which at least one group comprising at least two heat pumps from the plurality of heat pumps is assigned, wherein at least one control function is assigned to this group in such a way that the control function controls at least one heat pump of the group based on at least one input variable, in particular the result, of at least one actual / target value comparison, in particular by specifying at least one target value correlating at least to a physical size of the network, at first and / or second points in time, in particular at transitions from first to second points in time, and vice versa. The invention further relates to a system and to a controller for controlling a plurality of heat pumps operated in a locally distributed manner in a network.

Description

[0001] Description

[0002] Method, system and controller for controlling a large number of locally distributed heat pumps in a network

[0003] The invention relates to a method for controlling a plurality of heat pumps operated locally distributed in a network according to the preamble of claim 1, a system for controlling a plurality of heat pumps operated locally distributed in a network according to the preamble of claim 15, and a controller for controlling a plurality of heat pumps operated locally distributed in a network according to the preamble of claim 16.

[0004] It is known that heat pumps are devices that use electricity for heating. It is also known that they are usually installed in combination with thermal storage systems. This allows for flexible operation, enabling them, for example, to also be used to provide ancillary services to the electricity grid without compromising user comfort.

[0005] It is also known that heat pumps can be switched off during periods of high demand, while they can be switched on during periods of low demand or high feed-in to relieve the grid. With such a practice, if a large number of heat pumps are suddenly relieved of such a system service obligation, they can then place a new load on the grid. This effect, also known as the "rebound effect," typically manifests itself in the fact that if the heat pumps were previously switched on, they are likely to be switched off, and conversely, if they were switched off, they are likely to be switched on immediately. If this sudden change is carried out simultaneously by a large number of heat pumps, the electricity grid is strained.

[0006] The object underlying the invention is to provide a technical solution that overcomes the disadvantages of the prior art, in particular it is to provide a solution for the operation of heat pumps in a power grid that enables a minimized load on the power grid.

[0007] The task is based on the procedure for controlling a large number of devices in a single system.

[0008] Network locally distributed heat pumps according to the preamble of claim 1, by its characterizing features, starting from the system for controlling a plurality of locally distributed heat pumps in a network according to the preamble of claim 15, by its characterizing features, and starting from the controller for controlling a plurality of locally distributed heat pumps in a network according to the preamble of claim 16, by its characterizing features.

[0009] In the inventive method for controlling a plurality of locally distributed heat pumps in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least temporary local operation at least at a first time and temporary network operation, in particular a system service operation referred to as an "ancillary service obligation", at least one group comprising at least two heat pumps is assigned from the plurality of heat pumps, wherein at least one control function is assigned to this group such that the control function, based on at least one input variable, in particular the result of at least one actual / setpoint comparison, controls at least one heat pump of the group, in particular by specifying at least one setpoint that correlates with at least one physical quantity of the network.in first and / or second points in time, especially during transitions from first to second points in time and vice versa, regulates.

[0010] One advantage of the method according to the invention is, among other things, that it enables the bundled use of heat pumps with thermal storage in the electricity grid for system services and minimizes, and in particular completely avoids, rebound effects in the context of such grid services, because groups of heat pumps are formed and at least one control function is available for each group based on at least one input variable, so that negative effects in the context of grid operation, in particular switching to and from grid operation, can be detected based on the input variable and countermeasures can be initiated by the control function influencing one and / or more heat pumps, thermal storage units and / or loads.

[0011] The system according to the invention for controlling a plurality of heat pumps operated locally distributed in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least a first time at least temporarily local operation and at least a second time temporarily network operation, in particular a system service operation referred to as a so-called "ancillary service obligation", is characterized by means for carrying out the method and / or one of its further developments.

[0012] The controller according to the invention for controlling a plurality of heat pumps operated locally distributed in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least a first time at least temporarily local operation and at least a second time temporarily network operation, in particular a system service operation referred to as a so-called "ancillary service obligation", is designed to perform at least one control function according to the method and / or one of its further developments.

[0013] The system according to the invention for controlling a plurality of heat pumps operated locally distributed in a network, as well as the controller according to the invention for controlling a plurality of heat pumps operated locally distributed in a network, are characterized in that they contribute to the implementation and, mutatis mutandis, thus to the realization of the advantages mentioned in connection with the method, since they are designed for carrying out the method according to the invention and / or one of its further developments, or have the means for carrying it out.

[0014] Further advantageous embodiments and developments of the invention are specified in the dependent claims.

[0015] The advantages mentioned below do not necessarily have to be achieved by the subject matter of the independent patent claims. Rather, they may also be advantages that are achieved solely by individual embodiments, variants, or further developments. The same applies to the following explanations.

[0016] According to an advantageous embodiment of the inventive method, a control function is assigned to each heat pump in at least a first part of the group. This embodiment can advantageously be used when limited or no information about the group of heat pumps is acquired, yet still achieve the inventive effect of preventing the rebound effect. The input variable could, for example, be information about whether a network service starts or stops. This embodiment is particularly suitable for large, homogeneous groups of heat pumps. Alternatively, or, for example, additionally for only partially homogeneous groups, the inventive method can be further developed such that a control function is assigned to at least a subset of the heat pumps in the group.This is particularly advantageous if the network target or setpoint is based on at least one common measurement variable, for example the network frequency.

[0017] Preferably, the method according to the invention is further developed in such a way that the physical quantity used is a frequency or an aggregated current profile of the grouping of heat pumps, local values ​​such as the current in a local part of the network and / or other measurable parameters of the network and / or its parts, which are controlled by the at least one setpoint, so that the advantage can arise that at least one common measured quantity is given.

[0018] Alternatively or additionally, the inventive method is further developed such that at least one state of the heat pump is detected at at least one point in time and fed to the control function in such a way that it forms the basis for generating the at least one setpoint. This also means that the state of the heat pump itself is used as the basis for the control, which offers further optimization possibilities for preventing the rebound effect.

[0019] Preferably, the method according to the invention is further developed in such a way that at least temporarily a plurality of setpoint values, in particular successively changed by discrete values, are specified in such a way that a transition from the first time to the second time and / or the transition from the second time to the first time takes place step by step until the actual / setpoint value is reached, thereby avoiding negative effects, in particular short-term high loads.

[0020] According to a further development of the method according to the invention, the control is carried out such that a setpoint is selectively specified for each heat pump, wherein the specification is such that a transition from the first time point to the second time point and / or the transition from the second time point to the first time point occurs depending on a property, in particular at least one operating state, the dimension, or comparable correlating physical quantities, of the heat pump. This allows a priority queue to be created such that the heat pumps can be individually released from their network service according to one or more of their properties. According to a further development of the method according to the invention, a temperature, in particular of the thermal storage, is specified as the setpoint, wherein the current temperature is provided as the actual value for the control function.This is advantageous, for example, when the temperature setpoints are to be adjusted, especially gradually, in order to enable a gradual compensation of a deviation from the network setpoint.

[0021] For this purpose, it is advantageous to further develop the method according to the invention such that the temperature setpoint is stored and the setting is carried out in such a way that the setpoint is gradually increased from the current temperature, such that the specified setpoint is increased successively, in particular by discrete values, and this continues as long as a threshold comparison between the current temperature and the stored temperature setpoint ensures that the current temperature is less than or equal to the temperature setpoint. This prevents the temperature setpoint from being exceeded.

[0022] According to a further embodiment of the inventive method, the control function determines the energy requirement for increasing the setpoint based on the volume of the thermal storage and / or a load predicted for a specific time period. This allows the time required to reach the temperature setpoint to be calculated, taking into account the heat output of the controlled heat pump.

[0023] In a further development of the inventive method, the control function limits a power gradient of the group accumulated over a determined period at the beginning and / or end of network operation; this offers a further approach to reduce or prevent the rebound effect.

[0024] This also applies if the inventive method is further developed in such a way that the control function sets a maximum power of the heat pump and / or a maximum power gradient based on at least one controlled variable, in particular an on / off setpoint for heat pumps, at least one temperature setpoint for the thermal storage and / or loads.

[0025] According to a further development of the inventive method, at least one control function is provided by at least one controller, and alternatively or additionally, the inventive method is further developed such that the at least one control function is provided by a combination of a plurality of controllers. This ensures that at least one controller is dedicated to the control function and / or that the control function runs on one or more controllers, i.e., parts of the functions are implemented by controllers distributed throughout the system and connected to the system.

[0026] Further advantages and details of the invention, as well as further developments of the invention, are explained in more detail below with reference to an exemplary embodiment shown in the single figure. It shows the

[0027] Figure (FIG) schematically shows an exemplary process for controlling a large number of heat pumps operated locally distributed in a network according to one of the possible embodiments of the method according to the invention.

[0028] The embodiment described below in the figure (FIG) is a preferred embodiment, the advantages of which, as well as further embodiments or developments of the invention, are explained in more detail.

[0029] In particular, the following explanations merely show exemplary implementation possibilities of how such implementations of the teaching according to the invention could look, since it is impossible and also not helpful or necessary for understanding the invention to name all these implementation possibilities.

[0030] Furthermore, a person skilled in the art, with knowledge of the independent claims, will of course be aware of all the possibilities for realizing the invention that are customary in the prior art, so that in particular there is no need for a separate disclosure in the description.

[0031] In the exemplary embodiment(s), the described components of the embodiments each represent individual features of the invention that can be considered independently of one another, which further develop the invention independently of one another and can therefore also be regarded as part of the invention individually or in a combination other than that shown.

[0032] Furthermore, the described embodiments can also be supplemented by further features of the invention already described. The single figure (FIG) schematically shows a flowchart of a first embodiment of the method, as well as an embodiment of the arrangement of the invention for carrying out the method.

[0033] In the illustrated embodiment, it can be seen that in a first step S1, a network target value is recorded and fed to a device for comparing the actual and setpoint values. Any deviation is then detected in a second step S2 and forwarded as an input signal to a controller for grouped heat pumps according to the invention.

[0034] This control system can be a single controller that controls all heat pumps in a group of heat pumps, or it can be a group of controllers or a group of controller functions provided by one or more controllers, so that each controller and / or controller function is assigned to and controls one heat pump in the group.

[0035] For the control of the group, in a third step S3, at least one signal is generated based on the detected deviation, with which at least one heat pump of the group is controlled in such a way that the current contribution to the network value of the group is set to a target value.

[0036] The signal or multiple signals can be generated in such a way that this occurs step by step, for example, individual heat pumps are activated one after the other with a time delay and / or the setting of the target value for each heat pump results in a step by step approaching the target value.

[0037] The specification of one or more signals for setting the setpoint is therefore schematically summarized as a setpoint specification taking place in a fourth step S4.

[0038] Based on this setpoint specification or one or more signals for controlling at least one of the heat pumps in the group, the group of heat pumps, with its contribution to the network value, ideally approaches the setpoint and / or a difference remains. To determine this, the contribution to the network value made by the group of heat pumps is fed to the aforementioned device for actual-setpoint comparison in a sixth step S6. It can be seen that this is a control loop, meaning that the aforementioned steps S1...S6 are continuously repeated during operation. Furthermore, it can be seen that, according to a further development of the invention, the control system of the grouped heat pump can also be continuously supplied with status information, for example, the status of individual or all heat pumps and / or other parameters of the group suitable for effective control.This can be done optionally; therefore, this feedback is shown as a dashed line in the diagram.

[0039] The invention, and in particular the embodiment, makes it possible to bundle heat pumps on a large scale and use them for providing ancillary network services without unduly burdening the network.

[0040] Further advantages and details of the illustrated embodiment, partly in different words, but also of other embodiments, will become clear below.

[0041] The invention, in particular the embodiment described above, requires at least one dedicated heat pump controller which is integrated, as shown in the figure, into a network which has a plurality of heat pumps that form at least one grouping or pool of heat pumps.

[0042] With this dedicated controller, instead of immediately activating all the pool's heat pumps as described in the introduction, the deviation between a measured network value and a target network value can be compensated for S1...S6.

[0043] At least one network parameter can serve as the network value. For example, according to a further development of the invention, a global value such as the frequency, an aggregated electricity consumption of the entire heat pump fleet, a local value such as the current in a local part of the network, and / or other suitable network parameters can be provided, i.e., defined.

[0044] As already explained, the controller then provides a setpoint S4 to the pooled heat pumps and can (optionally) receive information about the status of each heat pump.

[0045] The invention can further be developed such that the controller gradually releases the heat pumps from ancillary service obligations to the system / network. This further development is easy to implement, as it achieves the advantages of the invention without requiring information about the pooled heat pumps. Furthermore, this development has the advantage of being particularly well-suited for large and homogeneous pools of heat pumps.

[0046] Alternatively or additionally, a priority queue can be created according to further training. This can be derived when information about the size and operating status of the heat pumps, such as "on," "off," or current electricity consumption, etc., is available, allowing for more differentiated control. For example, larger systems can be released when there is a large deviation from the ancillary performance obligation, and smaller systems when there is a small deviation.

[0047] In the example shown, the third step S3 can be performed by a controller that specifies the setpoints for all heat pumps in a group or pool. According to a further embodiment of the invention, the method and arrangement according to the invention can be designed such that a controller, i.e., a regulator, implemented in particular by one or more, for example distributed, processors, is used for each heat pump in the group of pooled heat pumps.

[0048] According to further training, each controller can then, for example, adjust the temperature setpoints, such as those of the hot water storage tank connected to the heat pump, or the setpoints of thermally active building systems (TABS), in particular stepwise, to compensate for the deviation from the network setpoint, in particular stepwise.

[0049] This approach is advantageously further developed by sharing a temperature measurement with the corresponding controller. This further development can usually be implemented with minimal adjustments if the hot water storage tank's temperature controller is part of the heat pump controller, which is often the case. This controller must also store the original temperature setpoint to prevent exceeding this temperature.

[0050] This further development is directly applicable if the network target value, first step S1, is based on a measurement of one or more operating parameters common to all heat pumps, for example, the network frequency. The further development can advantageously be designed alternatively or additionally such that, in the event that, for example, a cumulative power is specified as the setpoint, a further control layer is provided by the inventive method or arrangement, which calculates individual network target values ​​for each heat pump controller based on the capacity of the respective installed heat pump in the group.

[0051] Alternatively or additionally, the invention can be further developed in such a way that, in addition to the described temperature setpoints, further parameters, for example so-called anti-Legionella cycles, defrosting processes and / or electric heating elements, are taken into account in order to reduce the rebound effect.

[0052] The anti-Legionella cycle represents an additional load. According to the invention, this load can be forced to occur at a specific time by the at least one controller per pool, thereby increasing the overall system load, or its execution can be postponed to reduce the overall load. Defrosting is another process that, according to the invention, can be postponed in time to either relieve or increase the load on the network.

[0053] The inclusion of heating elements is particularly advantageous as a further development when the grouped heat pumps are part of a monoenergetic heating system, which is usually the case, and which then regularly includes an electric heating element. According to the heating system, this electric heating element is mainly used on extremely cold days, as it reduces investment costs compared to a larger heat pump. This electric heating element is less energy-efficient than the heat pump, but according to the invention, it can be used or switched on to introduce an additional electrical load when this is beneficial for the power grid.

[0054] The control mechanism according to the invention and its further developments can be integrated with common controllers, in particular into the Siemens Climatix OEM controller and / or in a cloud-based controller.

[0055] For better understanding, the mechanisms and relationships of the inventive method and arrangement, or its further developments, are described below using specific values. However, the invention and its further developments are not limited to these values. They are arbitrarily selected values ​​used only as examples. If a hot water storage tank associated with a pool heat pump is operated, for example, at a temperature of 48 °C, which generally corresponds to the highest point in the tank, the set temperature can be temporarily increased by the inventive control system, for example, to 60 °C, when flexibility is required as part of a system service. In this case, it is likely that the heat pump will switch on to heat the storage tank to the set temperature.

[0056] According to the invention, the energy requirement for this temperature increase can be determined, for example, by estimation, based on the volume of the storage tank and the predicted load during the coming minutes / hours. Taking into account the heat output of the heat pump, the time required to reach the set temperature can be calculated according to the invention. The same can be done when the flexibility requirement no longer exists and the system is to return to the original setpoint. When switching from flexibility requirement to normal operation, the storage tank has a higher temperature than required, for example, the specified 60 °C instead of 48 °C, which causes the heat pump to switch off. Without the invention, this abrupt shutdown of all heat pumps involved can negatively impact the grid due to the rebound effect.

[0057] A further embodiment of the invention, which at least reduces the rebound effect and even prevents it under ideal conditions, consists in the control system limiting the cumulative power gradient of all participating heat pumps when the flexibility request is started or stopped. For example, if 1 MW of additional power is requested, the embodiment can further reduce this power within a period of 10 minutes after the request, resulting in a gradient of approximately 100 kW per minute.

[0058] Conversely, after a load reduction, for example by lowering the storage setpoint temperature from 48 °C to 44 °C, and subsequently resetting the storage setpoint temperature to its original value, all heat pumps are switched on. According to a further development of the inventive method, an additional restriction can be imposed so that they do not exceed 100 kW per minute for the next 10 minutes. Alternatively or additionally, a dynamic maximum slope can be imposed to adapt to transient grid behavior. Again, alternatively or additionally, according to a further development, the additional load exceeding the previous loads of the heat pumps can be limited, for example to 10%.The invention addresses the characteristic that arises when heat pumps are used for system services (providing flexibility) after a flexibility request: before a specific flexibility request exists, not all heat pumps may run simultaneously, but they will likely start when the storage tank's setpoint temperature is raised again, unless explicitly controlled as provided by the invention. The initial power consumption of all heat pumps in the flexibility heat pump pool can be 2 MW; after the flexibility is provided, the power should not exceed 2.2 MW.

[0059] According to a further embodiment of the invention, these additional restrictions can be implemented by the described controller. By using the aforementioned control variables, for example, on / off setpoints for heat pumps, temperature setpoints for connected storage units and / or loads, the maximum power outputs and maximum power gradients can be controlled in order to reduce the problems caused by the rebound effect.

[0060] One of the key advantages and applications of the embodiment where a controller is responsible for a group or pool of heat pumps is its ability to manage a large pool with limited (or even no) information about the individual heat pump states. In contrast, the embodiment where each heat pump has its own controller employs a more technically sophisticated control logic that requires more information but also reduces the feedback loop. It is conceivable that for some applications, a combination of these two embodiments—where individual heat pumps are controlled by one controller and multiple heat pumps are controlled by one controller—could be advantageous.

[0061] The examples shown have in common that they provide at least one dedicated controller to mitigate the rebound effect after the provision of heat pump grid system services, instead of abruptly disconnecting all heat pumps from their grid system supply. The invention is therefore not limited to the described embodiments, but encompasses all variants falling within the scope of protection defined by the claims that include this common feature and offer the advantage of gradually relieving the heat pumps and thus also relieving the strain on the electricity grid. Also included are all variants resulting from the aforementioned further developments and embodiments that fall within the scope of protection of the claims. Regardless of the grammatical gender of a particular term, persons of male, female, or other gender identities are included.

Claims

Patent claims 1. A method for controlling a plurality of heat pumps operated locally distributed in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least temporary local operation at at least one time point and temporary network operation, in particular a system service operation referred to as an "ancillary service obligation", characterized in that at least one group comprising at least two heat pumps is assigned from the plurality of heat pumps, wherein at least one control function is assigned to this group such that the control function, based on at least one input variable, in particular the result of at least one actual / setpoint comparison, controls at least one heat pump of the group, in particular by specifying at least one setpoint that correlates with at least one physical quantity of the network.in first and / or second points in time, especially during transitions from first to second points in time and vice versa, regulates.

2. Method according to the preceding claim, characterized in that for at least a first part of the heat pumps of the group, a control function is assigned to each heat pump.

3. Method according to one of the preceding claims, characterized in that a control function is assigned to at least a second part of the heat pumps of the group, at least for a subset of heat pumps of the group.

4. Method according to one of the preceding claims, characterized in that the physical quantity is a frequency or an aggregated current profile of the grouping of heat pumps, local values ​​such as the current in a local part of the network and / or other measurable parameters of the network and / or its parts, which are controlled by at least one setpoint.

5. Method according to one of the preceding claims, characterized in that at least one state of the heat pump is detected at at least one time and supplied to the control function in such a way that it is used as the basis for generating the at least one setpoint.

6. Method according to one of the preceding claims, characterized in that the regulation is carried out in such a way that at least temporarily a plurality of setpoint values, in particular successively changed by discrete values, are specified in such a way that a transition from the first time to the second time and / or the transition from the second time to the first time takes place step by step until the actual / setpoint value is reached.

7. Method according to one of the preceding claims, characterized in that the control is carried out in such a way that a setpoint is selectively specified for each heat pump, wherein the specification is carried out in such a way that a transition from the first time to the second time and / or the transition from the second time to the first time takes place depending on a property, in particular at least one operating state, the dimension or comparable correlating physical quantities, of the heat pump.

8. Method according to one of the preceding claims, characterized in that a temperature, in particular of the thermal storage, is specified as the setpoint, wherein the current temperature is provided as the actual value of the control function.

9. Method according to the preceding claim, characterized in that the temperature setpoint is stored and the setting is carried out in such a way that a stepwise increase of the setpoint from the current temperature takes place in such a way that a successive, in particular by discrete values, increase of the specified setpoint takes place, wherein this takes place as long as a threshold comparison of current temperature and stored temperature setpoint ensures a current temperature less than or equal to the temperature setpoint.

10. Method according to the preceding claim, characterized in that the control function determines an energy requirement for increasing the setpoint based on the volume of the thermal storage and / or a load predicted for a determined time range.

11. Method according to one of the preceding claims, characterized in that the control function limits a value exceeding a certain value. The cumulative power gradient of the group is measured over a determined period at the beginning and / or end of network operation.

12. Method according to one of the preceding claims, characterized in that the control function sets a maximum power of the heat pump and / or a maximum power gradient based on at least one controlled variable, in particular an on / off setpoint for heat pumps, at least one temperature setpoint for the thermal storage and / or loads.

13. Method according to one of the preceding claims, characterized in that at least one control function is provided by at least one controller.

14. Method according to one of the preceding claims, characterized in that the at least one control function is provided by a combination of a plurality of controllers.

15. System for controlling a plurality of heat pumps operated locally distributed in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least a first time at least temporarily local operation and at least a second time temporarily network operation, in particular a system service operation referred to as a so-called "ancillary service obligation", characterized by means for carrying out the method according to one of the preceding claims.

16. Controller for controlling a plurality of heat pumps operated locally distributed in a network, wherein at least one thermal storage unit is assigned to each heat pump, which enables at least temporary local operation at least at a first time and temporary network operation, in particular a system service operation referred to as an "ancillary service obligation", characterized in that it is designed to perform at least one control function according to the method according to one of claims 1 to 13.

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