Method and system for controlling energy streams

Abstract

The invention relates to a method and to a corresponding system for controlling energy streams in order to connect operations of an electricity distribution network (1) and a heat distribution network (2) by means of an intermediate energy storage unit (3). According to the invention, the power balance and quality of current and voltage of the electricity distribution network (1) are adjusted by supplying the losses provided by adjustment of the electricity distribution network to the energy storage unit (3) in the form of heat, and from the energy storage unit the heat is extracted to the heat distribution network (2) according to the heat requirement of the heat distribution network.

Claims

1. A method for controlling energy streams in order to connect operations of an electricity distribution network and a heat distribution network by means of an intermediate energy storage unit, and the energy storage unit comprises an electrical resistor as a supply means for supplying electrical energy released by adjustment of the electricity distribution network to the energy storage unit directly, and a heat exchanger circuit which comprises a first heat exchanger in the energy storage unit and a second heat exchanger in the heat distribution network for supplying thermal energy in a controlled manner from the energy storage unit to the distribution network, characterized in that the power balance and quality of current and voltage of the electricity distribution network are adjusted by supplying the losses provided by adjustment of the electricity distribution network to the energy storage unit in the form of heat, and from the energy storage unit, the heat is extracted to the heat distribution network according to the heat requirement of the heat distribution network.

2. The method according to claim 1, characterized in that the energy storing material used in the energy storage unit is a substance having a phase transition temperature between the highest and the lowest operating temperatures of the energy storage unit.

3. The method according to claim 2, characterized in that the phase transition used in the energy storage unit is from solid into liquid and back.

4. The method according to claim 1, characterized in that the energy storage unit is a salt storage unit in the temperature range of 90-450° C.

5. The method according to claim 1, characterized in that the energy storage unit is a water storage unit.

6. The method according to claim 1, characterized in that the losses provided by adjustment of the electricity distribution network are supplied directly to an electrical resistor inside the energy storage unit.

7. The method according to claim 1, characterized in that the losses provided by adjustment of the electricity distribution network are supplied to a liquid take from where the heat generated is transferred to the energy storage unit by means of a liquid circuit.

8. A system for controlling energy streams in order to connect operations of an electricity distribution network and a heat distribution network by means of an intermediate energy storage unit, characterized in that the energy storage unit comprises an electrical resistor as a supply means for supplying electrical energy released by adjustment of the electricity distribution network to the energy storage unit directly, and a heat exchanger circuit comprises a first heat exchanger in the energy storage unit and a second heat exchanger in the heat distribution network for supplying thermal energy in a controlled manner from the energy storage unit to the distribution network, the energy storage unit is a water storage unit or a mass storage unit applying a phase transition process for the storage of energy, the control system comprises an adjustment means for maintaining optimal conditions of the electricity distribution network, and the supply means for supplying energy released by the adjustment to the energy storage unit, and the heat exchanger circuit between the energy storage unit and the heat distribution network with controls for supplying thermal energy to the heat distribution network in a controlled manner.

9. The system according to claim 8, characterized in that the energy storage unit is a salt storage unit, and the salt is sodium nitrate NaNO.sub.3 or potassium nitrate KNO.sub.3 or their mixture.

10. The system according to claim 8, characterized in that the supply means comprise a liquid tank provided with an electrical resistor in communication with the electricity distribution network, and a liquid circuit provided with a pump between the liquid tank and the energy storage unit, and the energy storage unit is provided with the first heat exchanger through which the liquid from the liquid tank circulates and transfers the heat to the energy storage unit.

11. The system according to claim 10, characterized in that the pump is configured to circulate liquid in a controlled manner by means of valves between the liquid tank, the energy storage unit and the heat distribution network.

12. The system according to claim 8, characterized in that the heat distribution network is a district heating network.

13. The system according to claim 8, characterized in that power supplied to electrical resistors is implemented by means of power electronics, a frequency changer or an IGBT.

14. The system according to claim 8, characterized in that the energy storage unit is used as a heat load by charging it up to a certain heat level from the heat distribution network.

15. The system according to claim 8, characterized in that the energy storage unit is a movable, detached unit that is displaceable and connectable to the heat distribution network near the energy consumption site.

Description

LIST OF FIGURES

(1) FIG. 1 represents one system for controlling energy according to the invention.

(2) FIG. 2 represents another system for controlling energy according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(3) The method and the system according to the invention will now be described in detail with reference to the accompanying drawings 1 and 2 representing schematic diagrams of some systems according to the invention.

(4) In one system for controlling energy according to the invention as shown in FIG. 1, between an electricity distribution network 1 and a heat distribution network 2 there is provided a mass storage unit serving as an energy storage unit 3, which in this embodiment is a salt storage unit. The salt is preferably sodium nitrate NaNO.sub.3 or potassium nitrate KNO.sub.3 or their mixture. Thus, the energy capacity of the heat storage unit can be increased, as it is possible to apply the phase transition of the salts between a solid and a liquid state, which is known to be greatly energy absorbing or releasing.

(5) In the system according to the invention, adjustment and control of the electricity distribution network 1 is carried out by means of suitable adjustment means 4, including a transformer 18 and a rectifier 19, such that all surplus power is recovered. These operations performed in the network include at least power adjustment, i.e. use of surplus power, voltage adjustment, frequency adjustment, and reactive power adjustment or compensation. Supply means 5 provided in the system for supplying the power obtained to the energy storage unit 3 comprise a liquid tank 8 including an electrical resistor 7 to which the electrical power obtained by the adjustments is supplied. It is also possible to place another electrical resistor in the energy storage unit 3 directly, such that in certain situations, the energy obtained is supplied directly to the energy storage unit 3.

(6) From the liquid tank 8 there is provided a liquid circuit 10, by means of which thermal energy from the liquid tank 8 may be transferred optionally to the energy storage unit 3 and/or to the heat distribution network 2. For the purpose of this heat transfer, the liquid circuit 10 comprises a first heat exchanger 11 in the energy storage unit 3, and a second heat exchanger 12 in communication with the heat distribution network 2. Further, the liquid circuit 10 is provided with a pump 9 arranged to pump liquid from the liquid tank 8 between the heat exchangers. The pump takes its operating energy between the transformer 18 and the rectifier 19.

(7) From the pump 9, conduit 20 extends via valve 14 to the first heat exchanger 11 of the energy storage unit 3, from where conduit 21 goes to valve 16, via which through conduit 22 the liquid is able to return back from the energy storage unit 3 to the liquid tank 8. Thus, heat from the liquid tank 8 may be transferred to the energy storage unit 3. If energy is to be transferred directly to the heat distribution network 2 by the pump 9, valve 14 will be closed, such that conduit 10 would lead to valve 13, from where conduit 23 extends to the second heat exchanger 12 and further to conduit 24, which via valve 17 opens into conduit 22 and back to the liquid tank 8. Thus, the hot liquid from the liquid tank 8, the water of the like, transfers thermal energy directly to the heat distribution network 2.

(8) When energy from the energy storage unit 3 is transferred to the heat distribution network 2, the liquid circuit is as follows. The liquid circulates from the pump 9 via valve 14 to conduit 20 and through heat exchanger 11 to conduit 21. From there, valve 16 closed and valve 15 opened, the circuit proceeds via conduit 23 to heat exchanger 12 in communication with the heat distribution network. From here the liquid returns via conduit 24, valve 17 and conduit 22 to the liquid tank 8.

(9) In one system for controlling energy according to the invention as shown in FIG. 2, between the electricity distribution network 1 and the heat distribution network 2 there is provided a water storage unit serving as the energy storage unit 3. The material of the water storage unit is water.

(10) In the system according to the invention, adjustment and control of the electricity distribution network 1 is carried out by means of suitable adjustment means 4, including the transformer 18 and the rectifier 19, such that all surplus power is recovered. These operations performed in the network include at least power adjustment, i.e. use of surplus power, voltage adjustment, frequency adjustment, and reactive power adjustment or compensation. In the system, the energy storage unit 3 is provided with an electrical resistor 7 to which the electrical power obtained by the adjustments is supplied. The electrical resistor 7 functions as the supply means 5 for supplying energy released by the adjustment to the energy storage unit.

(11) Between the energy storage unit 3 and the heat distribution network 2 there is provided a heat exchanger circuit 28 with controls for supplying thermal energy to the heat distribution network. From the energy storage unit 3 there is provided a liquid circuit 25 by means of which thermal energy from the energy storage unit 3 may be transferred to the heat distribution network 2. For the purpose of this heat transfer the liquid circuit 25 comprises a heat exchanger 26 in communication with the heat distribution network 2. Alternatively the heat exchanger circuit 28 may comprise a first heat exchanger in the energy storage unit 3 and a second heat exchanger in communication with the heat distribution network 2, and a closed liquid circuit between them. Further, the liquid circuit 25 of FIG. 2 is provided with a pump 27 arranged to pump liquid from the energy storage unit 3 to the heat exchanger 26 provided in the heat distribution network. The pump takes its operating energy between the transformer 18 and the rectifier 19. Thus, the water from the energy storage unit 3, or alternatively the liquid provided in the liquid circuit 25, transfers thermal energy to the heat distribution network 2 directly.

(12) The invention has been described above by way of examples with reference to the accompanying drawings; however, various embodiments of the invention are possible within the scope defined by the claims.