Controller for energy supply systems

1. A method of operating an energy supply system comprising an energy storage unit and an energy production unit, comprising the steps of:

predetermining a time frame in which the energy supply system will be functioning, calculating costs for operating the energy supply system in advance of operation for all time instants within the time frame and storing the calculated costs for each time instant in a table,

the calculating of the costs for the table starting from assigning a terminal cost function which assigns a cost for operating the energy supply system to each of a plurality of values related to energy stored in the energy storage unit and stores the terminal cost function in the table, and then, working backwards in time from the terminal cost function, defining at each time interval optimal heat flux which gives a lowest cost for operating the energy supply system for every value related to the energy stored in the energy storage unit thus defining a new cost function at each time interval of the complete time frame and storing each new cost function in the table; and

controlling and applying the amount of energy supplied by the energy storage unit so that at any time instant of the predetermined time frame, the energy storage unit is adapted to supply energy,

wherein the step of controlling and applying the amount of energy supplied by the energy storage unit comprises:

selecting from the table the optimal amount of energy to be supplied by the energy storage unit defined by the cost function stored for each time instant which minimizes the cost for operating the energy supply system at each time interval and applying the selected optimal amount of energy from the table for controlling the operation of the energy storage unit for continuous operation of the energy storage unit during the predetermined time frame.

2. The method according to claim 1 , wherein the cost for operating is calculated for each portion of demanded flux that can be supplied by the energy storage unit.

3. The method according to claim 1 , wherein the cost for operating is calculated for each value of the demanded flux within a predetermined range of said demanded flux.

4. The method according to claim 1 , wherein the step of calculating the cost for operating is carried out in advance for all time instants within the time frame and stored in a table and wherein the selecting step comprises looking up the portion of demanded flux in the table.

5. A method of operating an energy supply system comprising an energy storage unit and an energy production unit, comprising the steps of:

predetermining a time frame in which the energy supply system will be functioning, wherein costs for operating the energy supply system are calculated in advance of operation for all time instants within the time frame and stored, by starting with assigning a terminal cost function which assigns a cost for operating the energy supply system to each of a plurality of values related to the energy stored in the energy storage unit and, working backwards in time from the terminal cost function, defining and storing at each time interval an optimal heat flux which gives a lowest cost for operating the energy supply system for every value related to the energy stored in the energy storage unit thus defining a new cost function at each time interval of the complete time frame; and

controlling and applying the amount of energy supplied by the energy storage unit by selecting control parameters associated with the lowest cost so that at any time instant of the predetermined time frame, the energy storage unit is configured to supply energy,

wherein the selected control parameters are applied to control the operation of the energy storage unit for continuous operation of the energy storage unit during the predetermined time frame,

wherein the energy storage unit is an underground thermal energy storage system.

6. The method according to claim 5 , wherein said time frame is the year round.

7. A controller adapted to operate an energy supply system comprising an energy storage unit and an energy production unit, the controller being configured to carry out a method of operating an energy supply system comprising an energy storage unit and an energy production unit, comprising the steps of:

predetermining a time frame in which the energy supply system will be functioning, wherein costs for operating the energy supply system are calculated in advance of operation for all time instants within the time frame and stored, by starting from assigning a terminal cost function which assigns a cost for operating the energy supply system to a plurality of values related to the energy stored in the energy storage unit and, working backwards in time from the terminal cost function, defining and storing at each time interval an optimal heat flux which gives a lowest cost for operating the energy supply system for every value related to the energy stored in the energy storage unit thus defining a new cost function at each time interval of the complete time frame; and

controlling and applying the amount of energy supplied by the energy storage unit by selecting control parameters associated with the lowest cost defined by the cost function so that at any time instant of the predetermined time frame, the energy storage unit is adapted to supply energy,

wherein the selected control parameters are applied to control the operation of the energy storage unit for continuous operation of the energy storage unit during the predetermined time frame.

8. The controller according to claim 7 , wherein the system is a system for heating and/or air conditioning a building.

9. The controller according to claim 7 , wherein the system is a system for providing power to a vehicle.

10. A method of operating, over a time frame, an energy supply system comprising an energy production unit and an energy storage unit, the method comprising, at time instants in the time frame:

selecting the energy flux to be removed from the energy storage unit by calculating and storing costs for operating the energy supply system in advance of operation for all time instants within the time frame, by starting from assigning a terminal cost function which assigns a cost for operating the energy supply system to each of a plurality of values related to the energy stored in the energy storage unit and, working backwards in time from the terminal cost function, defining and storing at each time interval an optimal heat flux which gives the lowest cost for operating the energy supply system for every value related to the energy stored in the energy storage unit thus defining and storing a new cost function at each time interval of the complete time frame;

selecting at any time instant an optimal amount of energy supplied by the energy storage unit which minimizes the cost for operating the energy supply system defined by the cost function;

applying the selected optimal amount of energy for controlling the operation of the energy storage unit for continuous operation of the energy storage unit during all time instants in the time frame; and

extracting the selected energy flux from the energy storage unit.

11. The method according to claim 10 , wherein the system is a system for heating and/or air conditioning a building.

12. The method according to claim 10 , wherein the energy storage unit is a thermal energy storage system.

13. The method according to claim 10 , wherein the indication of the energy contained within the energy storage unit is the temperature of the thermal energy storage system.

14. A method of operating, over a time frame, an energy supply system comprising an energy production unit and an energy storage unit, the method comprising, at time instants in the time frame:

selecting the energy flux to be removed from the energy storage unit by calculating and storing costs for operating the energy supply system in advance of the operation for all time instants within the time frame, by starting from assigning a terminal cost function which assigns a cost for operating the energy supply system to each of a plurality of values related to the energy stored in the energy storage unit and, working backwards in time from the terminal cost function, defining and storing at each time interval an optimal heat flux which gives the lowest cost for operating the supply system for every value related to the energy stored in the energy storage unit thus defining and storing a new cost function at each time interval of the complete time frame;

selecting the optimal amount of energy supplied by the storage unit which minimizes the cost for operating the energy supply system at any time instant;

applying the selected optimal amount of energy for controlling the operation of the energy storage unit for continuous operation of the energy storage unit during all time instants in the time frame; and

extracting the selected energy flux from the energy storage unit,

wherein the energy storage unit is a thermal energy storage system and the energy storage unit is an underground thermal energy storage system.

15. The method according to claim 14 , wherein said time frame is the year round.

16. A controller adapted to operate, over a time frame, an energy supply system comprising an energy storage unit and an energy production unit so as to, at time instants in the time frame:

select the energy flux to be removed from the energy storage unit by selecting the optimal amount of energy to be supplied by the storage unit which minimizes the cost for operating the energy supply system as defined by a cost function calculated and stored for each time instant, and

applying the selected optimal amount of energy for controlling the operation of the energy storage unit for continuous operation of the energy storage unit during all time instants in the time frame,

wherein an optimal amount of energy is calculated in advance by calculating and storing costs for operating the energy supply system in advance of operation for all time instants within the time frame by starting from assigning a terminal cost function which assigns a cost for operating the energy supply system to each of a plurality of values related to the energy stored in the energy storage unit at each time instant and, working backwards in time from the terminal cost function, at each time interval defining and storing an optimal heat flux which gives the lowest cost for operating the energy supply system for every value related to the energy stored in the energy storage unit at each time instant thus defining a new cost function at each time interval of the complete time frame.