Method for improved utilization of energy grids

Abstract

A local heating system is presented. The local heating system comprising: a first heat source (10) connectable to a heating grid (110) and arranged to extract heat from the heating grid (110); a second heat source (20) connectable to an electrical energy grid (120) and to transform electricity feed through the electrical energy grid (120) into heat; a heat emitting device (30); a distribution system (40) for circulating heat transfer fluid between the heat emitting device (30) and the first and second heat sources (10, 20); and a controller (50) configured to control the first and second heat source's (10, 20) relative outtake of heat from the heating grid (110) and the electrical energy grid (120), respectively.

Claims

1. A method for controlling a primary local heating system comprising a first heat source connected to a heating grid, a second heat source connected to an electrical energy grid, one or more heat emitting devices for providing comfort heating, and a distribution system for circulating heat transfer fluid between said one or more heat emitting devices and the first and second heat sources, the method comprising: determining a temporally resolved heating control parameter (TRHCP), the TRHCP indicating a temporally resolved overall heating consumption need of a plurality of local heating systems in relation to a temporally resolved overall available heating capacity of the heating grid, wherein the plurality of local heating systems are connected to the heating grid, determining a temporally resolved electric power control parameter (TREPC), the TREPC indicating a temporally resolved overall electric power need in relation to a temporally resolved overall available electric power of the electrical energy grid to which the second heat source is connected, comparing the TRHCP to the TREPC to generate a comparison result; and based on the comparison result, controlling an outtake of heat from the first heat source (heat outake.sub.1) and an outtake of heat from the second heat source (heat outake.sub.2) to minimize a performance parameter (P), wherein P=(the TRHCP? the heat outake.sub.1)+(the TREPC? the heat outake.sub.2).

2. The method according to claim 1, wherein the TRHCP comprises information pertaining to an amount of emitted greenhouse gases per energy unit of heat provided via the heating grid.

3. The method according to claim 1, wherein the TRHCP comprises information pertaining to an efficiency of the first heat source's capability to transfer heat from the heating grid to the heat transfer fluid of the distribution system.

4. The method according to claim 1, wherein the TRHCP comprises information pertaining to cost per energy unit of heat provided via the heating grid.

5. The method according to claim 1, wherein the TREPC comprises information pertaining to amount of emitted greenhouse gases per energy unit of electricity of the electrical energy grid.

6. The method according to claim 1, wherein the TREPC comprises information pertaining to an efficiency of the second heat source's capability to transform electric energy from the electrical energy grid to heat in the heat transfer fluid of the distribution system.

7. The method according to claim 1, wherein the TREPC comprises information pertaining to cost per energy unit of electricity of the electrical energy grid.

8. The method according to claim 1, wherein the first heat source is a heat exchanger or a heat pump connected to the heating grid.

9. The method according to claim 1, wherein the second heat source is a resistive electric heater.

10. A local heating system, comprising: a first heat source connectable to a heating grid and arranged to extract heat from the heating grid; a second heat source connectable to an electrical energy grid and to transform electricity feed through the electrical energy grid into heat; a heat emitting device; a distribution system for circulating heat transfer fluid between the heat emitting device and the first and second heat sources; and a controller configured to determine a temporally resolved heating control parameter (TRHCP), the TRHCP indicating a temporally resolved overall heating consumption need of a plurality of local heating systems in relation to a temporally resolved overall available heating capacity of the heating grid, wherein the plurality of local heating systems are connected to the heating grid, determine a temporally resolved electric power control parameter (TREPC), the TREPC indicating a temporally resolved overall electric power need in relation to a temporally resolved overall available electric power of the electrical energy grid to which the second heat source is connected, compare the TRHCP to the TREPC to generate a comparison result; and based on the comparison result, control an outtake of heat from the first heat source (heat outake.sub.1) and an outtake of heat from the second heat source (heat outake.sub.2) to minimize a performance parameter (P), wherein P=(the TRHCP? the heat outake.sub.1)+(the TREPC? the heat outake.sub.2).

11. The local heating system according to claim 10, wherein the second heat source is arranged in the distribution system.

12. The local heating system according to claim 10, wherein the second heat source is an electric resistive heater.

13. The local heating system according to claim 10, wherein the first heat source is a heat exchanger or a heat pump.

14. A controller configured to control a relative outtake of heat from a first heat source connected to a heating grid and a second heat source connected to an electrical energy grid, the first and second heat sources belonging to a local heating system; wherein the controller is configured to determine a temporally resolved heating control parameter (TRHCP), the TRHCP indicating a temporally resolved overall heating consumption need of a plurality of local heating systems in relation to a temporally resolved overall available heating capacity of the heating grid, wherein the plurality of local heating systems are connected to the heating grid, determine a temporally resolved electric power control parameter (TREPC), the TREPC indicating a temporally resolved overall electric power need in relation to a temporally resolved overall available electric power of the electrical energy grid to which the second heat source is connected, compare the TRHCP to the TREPC to generate a comparison result; and based on the comparison result, control an outtake of heat from the first heat source (heat outake.sub.1) and an outtake of heat from the second heat source (heat outake.sub.2) to minimize a performance parameter (P), wherein P=(the TRHCP? the heat outake.sub.1)+(the TREPC? the heat outake.sub.2).

15. The controller according to claim 14, further configured to determine at least one of the TRHCP or the TREPC locally.

16. The controller according to claim 14, further configured to control the first heat source's outtake of heat from the heating grid by controlling a control valve.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other aspects of the present invention will now be described in more detail, with reference to appended drawings showing embodiments of the invention. The figures should not be considered limiting the invention to the specific embodiment; instead they are used for explaining and understanding the invention.

(2) As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention.

(3) FIG. 1 is a schematic view of a local heating system comprising a first heat source and a second heat source.

(4) FIG. 2 is block diagram of a method 200 for controlling a relative outtake of heat from the first and second heat sources of the local heating system of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(5) The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention 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 to fully convey the scope of the invention to the skilled person.

(6) With reference to FIG. 1 a local heating system 1 will be discussed. The local heating system 1 comprises a first heat source 10, a second heat source 20, a heat emitting device 30, and a distribution system 40 for circulating heat transfer fluid between the heat emitting device 30 and the first and second heat sources 10, 20.

(7) The first heat source 10 is connected to a heating grid 110. The heating grid 110 is configured to distribute heat to the first heat source 10.

(8) The heating grid 110 may be a district heating system. The district heating system comprises a hydraulic network comprising a district feed conduit for an incoming flow of district heat transfer fluid and a district return conduit for a return flow of district heat transfer fluid. In the district heating system, a driving pressure difference between district feed conduit and district return conduit of the hydraulic network creates a so called pressure cone whereby the pressure in the district feed conduits is higher than the pressure in the return conduits. This pressure difference circulates district heat transfer fluid in the hydraulic network between a central heat production plant and the local heating systems connected to the district heating system. Further, one or more district grid circulation pumps are arranged in the district heating system in order to provide the driving pressure difference. In case the heating grid 100 is a district heating system, the first heat source 10 is a heat exchanger. Again, this is the embodiment illustrated in FIG. 1.

(9) Alternatively, the heating grid 110 may be a district thermal energy distribution system as defined in WO 2017/076868. In this case, the first heat source 10 is a thermal energy consumer heat exchanger as defined in WO 2017/076868 and/or WO2017/076866.

(10) Yet alternatively, the heating grid 110 may be gas distribution grid configured to distribute a burnable gas. In this case, the first heat source 10 is a gas burner.

(11) The distribution system 40 comprises a feed line 42 and a return line 44. The distribution system 40 may further comprise a circulation pump 46. The first heat source 10 is fluidly connected to the feed line 42 and the return line 44 for letting heat transfer fluid flow from the return line 44 via the first heat source 10 and into the fed line 42. While doing so the first heat source 10 is configured to heat heat transfer fluid of the distribution system 40 flowing through the first heat source 10. Hence, the first heat source 10 is configured to transfer heat from the heating grid 110 to heat transfer fluid of the distribution system 40.

(12) The second heat source 20 is connected to an electrical energy grid 120. The second heat source 20 is typically an electric resistive heater. The second heat source 20 is arranged in the distribution system 40. Preferably, the second heat source 20 is arranged on the feed line 42.

(13) The heat emitting device 30 is configured to provide comfort heating. The heat emitting device 30 may be a radiator. The local heating system 1 may comprise a plurality of heat emitting devices 30. The heat emitting device 30 is configured to emit heat to its surroundings. Typically, the heat emitting device 30 is arranged in a room of a building.

(14) The first heat source 10 may transmit heat from heat transfer fluid of the heating grid 110 to heat transfer fluid in the distribution system 40 of the local heating system 1. In this way, heat can be generated remotely in a large scale heat production plant (not shown) and emitted locally, far away from the plant. The plants may for example use geothermal energy or energy from other processes such as combustion of household garbage. The produced heat is then distributed through the heating grid 110 to a plurality of local heating systems where it is taken out by heat sources connected to the heating grid 110.

(15) In addition to, or instead of using heat from the first heat source 10, heat can be generated locally in the local heating system 1 using the second heat source 20 by feeding electricity from the electrical energy grid 120 into second heat source 20 which then heats the heat transfer fluid of the distribution system 40 of the local heating system 1.

(16) Since the electrical energy grid 120 operates differently from the heating grid 110, negative effects of a shortage or malfunction of either the heating grid 110 or the electrical energy grid 120 can be mitigated by increasing the utilization of the other respective heat source 10, 20. The decisions about which heat source to use and to what extent, can be controlled locally at each local heating system 1, or centrally by a controller connected to each respective local heating system 1 connected to the heating grid 110 and/or the electrical energy grid 120.

(17) The local heating system may further comprise a controller 50 configured to control the first and second heat sources 10, 20 outtake of heat. The controller 50 is configured to control the first and second heat sources 10, 20 relative outtake of heat from the heating grid 110 and the electrical energy grid 120, respectively. The relative control does not mean the first and second heat sources 10, 20 have to be used one at a time; Rather they can be used either one at a time or simultaneously, and to varying degree of relative energy outtake from each heat source 10, 20.

(18) The controller 50 is configured to control a relative outtake of heat from the first and second heat sources 10, 20. The controller 50 is configured to base the control on a comparison of a temporally resolved heating control parameter and a temporally resolved electric power control parameter. The temporally resolved heating control parameter is indicative of a temporally resolved overall heating consumption need of a plurality of local heating systems, connected to the heating grid 110, in relation to a temporally resolved overall available heating capacity of the heating grid 110. The controller 50 may be configured to determine the temporally resolved heating control parameter locally. Alternatively, the controller 50 may be feed with the temporally resolved heating control parameter from a central server (not shown) configured to determine the temporally resolved heating control parameter. The temporally resolved electric power control parameter is indicative of a temporally resolved overall electric power need in relation to a temporally resolved overall available electric power of the electrical energy grid 120. The controller 50 may be configured to determine the temporally resolved electric power control parameter locally. Alternatively, the controller 50 may be feed with the temporally resolved electric power control parameter from a central server (not shown) configured to determine the temporally resolved electric power control parameter.

(19) The controller 50 is further configured to control the relative outtake of heat from the first and second heat sources 10, 20 such that the temporally resolved heating control parameter times the outtake of heat from the first heat source plus the temporally resolved electric power control parameter times the outtake of heat from the second heat source is optimized. According to one example, the relative outtake may me optimized such that the temporally resolved heating control parameter times the outtake of heat from the first heat source, plus the temporally resolved electric power control parameter times the outtake of heat from the second heat source, is minimized. By minimized is in this context not limited to an actual minimum in the function for the relative outtake. It is enough that one comes sufficiently close to the actual minimum. For example, within 20% of the actual minimum. Preferably, within 10% of the actual minimum.

(20) The first heat source's 10 outtake of heat from the heating grid 110 may be controlled by controlling a control valve 12. By controlling the control valve 12 the flow of heat transfer fluid of the heating grid into the first heat source 10 is controlled. The controller 50 may be configured to control the control valve 12. The control valve 12 may as in the in FIG. 1 shown embodiment be located at a return line arranged to return heat transfer fluid from the first heat source 10 to the heating grid. This set-up may e.g. be used in the case of the heating grid 110 is a grid configured to heated heat transfer fluid in a grid configured to transport thermal heat. Alternatively, the control valve 12 may be located at a feed line arranged to feed heat transfer fluid from the heating grid 110 to the first heat source 10. This set-up may e.g. be used if the heating grid 110 is a grid providing a burnable gas and the first heat source 10 is a gas burner.

(21) Hence, the control of the relative outtake of heat from the first and second heat sources 10, 20 may be based on data analysis. Optionally the control of the relative outtake of heat from the first and second heat sources 10, 20 may be based on data analysis in combination with manual decisions and overrides.

(22) With reference to FIG. 2 a method 200 for controlling a relative outtake of heat from the first and second heat sources 10, 20 of a local heating system 1 according to above will be discussed. The method 200 comprises determining S202 a temporally resolved heating control parameter indicating a temporally resolved overall heating consumption need of a plurality of local heating systems, connecting to the heating grid, in relation to a temporally resolved overall available heating capacity of the heating grid. Temporally resolved overall heating consumption need of a plurality of local heating systems could comprise information as to how much energy is needed for heating of the plurality of local heating systems over a predetermined period of time. This could be based on historical data but also based on forecasting. The temporally resolved overall available heating capacity of the heating grid may for example be determined upon historical data but also based on forecasting such as based on weather forecasts. Local sensors for each local heating system could be used to report local weather data, such as outdoor temperature, wind and outdoor humidity, which data could then be used to assist in determining temporally resolved overall or local heating consumption need.

(23) The method 200 further comprises determining S204 a temporally resolved electric power control parameter indicating a temporally resolved overall electric power need in relation to a temporally resolved overall available electric power of the electrical energy grid to which the second heat source is connected.

(24) Further, the method 200 comprises controlling S206, based on a comparison of the temporally resolved heating control parameter and the temporally resolved electric power control parameter, a relative outtake of heat from the first and second heat sources. The outtake is controlled such that the temporally resolved heating control parameter times the outtake of heat from the first heat source, plus the temporally resolved electric power control parameter times the outtake of heat from the second heat source, is optimized. According to one example, the relative outtake may me optimized such that the temporally resolved heating control parameter times the outtake of heat from the first heat source, plus the temporally resolved electric power control parameter times the outtake of heat from the second heat source, is minimized. By minimized is in this context not limited to an actual minimum in the function for the relative outtake. It is enough that one comes sufficiently close to the actual minimum. For example, within 20% of the actual minimum. Preferably, within 10% of the actual minimum.

(25) The predetermined period of time for temporal analysis depends on the circumstances of each energy distribution grid, such as the resolution and delay of data collected from local heating systems, heat production plants or electricity production plants. For example, the predetermined period of time may be 1 hour, 2 hours, 6 hours or 24 hours. Other periods of time are also possible within the scope of the present disclosure.

(26) Overall available heating capacity relates to all produced heating, i.e. not taking consumed heating into account. Similarly, overall available electric power relates to all produced electric power, i.e. not taking consumed electric power into account.

(27) The temporally resolved heating control parameter may comprise information pertaining to an amount of emitted greenhouse gases per energy unit of heat provided via the heating grid.

(28) The temporally resolved heating control parameter may comprise information pertaining to an efficiency of the first heat source's capability to transfer heat from the heating grid to the heat transfer fluid of the distribution system.

(29) The temporally resolved heating control parameter may comprises information pertaining to cost per energy unit of heat provided via the heating grid.

(30) The temporally resolved electric power control parameter may comprise information pertaining to amount of emitted greenhouse gases per energy unit of electricity of the electrical energy grid.

(31) The temporally resolved electric power control parameter may comprise information pertaining to an efficiency of the second heat source's capability to transform electric energy from the electrical energy grid to heat in the heat transfer fluid of the distribution system.

(32) The temporally resolved electric power control parameter may comprises information pertaining to cost per energy unit of electricity of the electrical energy grid.

(33) The person skilled in the art realizes that the present invention 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.

(34) For example, the controller 50 may be embodied in many different ways. According to one example the controller 50 may be a single controller configured to control both the first and second heat sources 10, 20. According to another example, the controller 50 may be a distributed controller comprising two or more controller modules. For example, a first controller module may be configured to control the first heat source 10 and a second controller module may be configured to control the second heat source 20. The first and second controller modules are configured to communicate with each other and exchange data. The communication may be wired or wireless.

(35) Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.