WO2017084792A1

WO2017084792A1 - Energy storage system

Info

Publication number: WO2017084792A1
Application number: PCT/EP2016/072612
Authority: WO
Inventors: Dirk Vahle
Original assignee: Robert Bosch Gmbh
Priority date: 2015-11-20
Filing date: 2016-09-22
Publication date: 2017-05-26
Also published as: DE102015222983A1

Abstract

The invention relates to an energy storage system (1) for temporarily storing electrical energy with an electric machine (4) which is drive-connected to a hydraulic machine (5), and with a pneumatic-hydraulic piston-cylinder arrangement (10) which is arranged by interposing valve devices between the hydraulic machine (5) and a gas storage unit (8). In order to optimize the storage of electrical energy with an electrical machine, the pneumatic-hydraulic piston-cylinder arrangement (10) comprises at least one gas piston pump (12), which has two pneumatic connectors (33, 34) and two hydraulic connectors (23, 24) which can be connected or are connected to the hydraulic machine (5) by interposing a hydraulic valve device (26).

Description

description

title

Energy Storage System The invention relates to an energy storage system for buffering electrical energy with an electric machine drivingly connected to a hydraulic machine, and to a pneumatic-hydraulic piston-cylinder assembly interposed between valve means between the hydraulic machine and a gas storage device. The invention further relates to a method for operating such an energy storage system. The invention also relates to a system for buffering electrical energy with such an energy storage system. State of the art

From the German patent application DE 10 2013 105 186 AI a compressed air energy storage system with a compressed air reservoir, a compressor arrangement for supplying compressed air to the compressed air reservoir, and with a pneumatic-hydraulic device with at least one pneumatic-hydraulic piston-cylinder arrangement for generating a hydraulic pressure is known hydraulic machine for driving a load can be supplied, wherein the at least one pneumatic-hydraulic

Piston cylinder arrangement at least two cylinders, each with one

Pneumatic chamber for relaxing compressed air, wherein the pneumatic chambers are connected in series with an outlet of the compressed air reservoir. US Pat. No. 7,832,207 B2 discloses a method and a system for storing and recovering energy, wherein hydraulic-pneumatic accumulators for open air together with

Amplifier arrangements are used, in which at least one Accumulator and at least one amplifier with a high-pressure gas storage reservoir is in communication, wherein a fluidic machine is coupled on a fluid side with an electric machine. Disclosure of the invention

The object of the invention is the storage of electrical energy with an electric machine, which is drivingly connected to a hydraulic machine, and with a pneumatic-hydraulic

Piston cylinder arrangement, which is arranged with the interposition of valve means between the hydraulic machine and a gas storage device, in particular with regard to the space requirement, the efficiency and / or with regard to thermodynamic losses to optimize. The object is achieved in an energy storage system for temporarily storing electrical energy with an electric machine, which is drivingly connected to a hydraulic machine, and with a pneumatic-hydraulic piston-cylinder arrangement, which is arranged with the interposition of valve means between the hydraulic machine and a gas storage device, thereby achieved that the pneumatic-hydraulic

Piston cylinder assembly comprises at least one gas piston pump having two pneumatic connections and two hydraulic connections, the lower

Intermediate circuit of a hydraulic valve device with the hydraulic machine can be connected or connected. The electric machine can be operated as an electric motor or as a generator. The hydraulic

Machine can be operated as a hydraulic pump or as a hydraulic motor. With the help of the at least one gas piston pump can be provided in a simple manner, a very efficient compressed air storage system for electrical energy. With the energy storage system can by compressing gas, in particular ambient air, pneumatic energy in one

Magnitude of one hundred to seven hundred bar in the

Gas storage device are stored. For energy generation, the stored pneumatic energy, in particular the stored air or compressed air, relaxed in the environment and drives the hydraulic machine operated as a hydraulic motor and the connected thereto acting as a generator electric machine. The generator returns the generated electrical energy to a consumer. The at least one gas piston pump is an air compressor, which is driven by hydraulic pressure, in particular hydraulic oil pressure, which in turn is provided by the working as a hydraulic pump hydraulic machine.

While the gas, in particular the air, is compressed and conveyed into the gas storage device on one side of the gas piston pump, gas, in particular air, is drawn in from the environment on the other, in particular opposite or opposite, side of the gas piston pump. By a suitable reversal of valve devices that the

Pneumatic connections or the hydraulic connections are assigned, conveying and suction areas of the gas piston pump can be operated alternately from one to the other side of the gas piston pump. to

Recovery of the stored pneumatic energy is the pressurized gas, in particular the pressurized air, from the

Gas storage device drained via the gas piston pump. In a compression of the hydraulic medium, in particular a hydraulic fluid in a double piston of the gas piston pump can then be driven in a simple manner operating as a hydraulic motor hydraulic machine. By coupling with the electric machine, the stored

Pneumatic energy are given over the working as an electric generator electric machine in the form of electrical energy back to the consumer. The control or reversing takes place by means of suitable hydraulic and pneumatic switching valves.

A preferred embodiment of the energy storage system is characterized in that the gas piston pump comprises two separated by a separating element inner hydraulic cylinder chambers, which are separated by two pistons of outer pneumatic cylinder chambers, which

Interposition of pneumatic valve devices with the

Gas storage device or an environment connectable or connected. This allows a simple forced return of the piston of the gas piston pump in a simple manner. The

Energy storage system with the hydraulic machine and the

Gas piston pump is hydraulically sealed in itself. By the arrangement of Hydraulic cylinder chambers and the pneumatic cylinder chambers in combination with the two pistons and the separator in the gas piston pump allows a simple system design. In addition, a particularly compact design with relatively few control valves is possible. By targeted control of the control valves unwanted energy losses in the thermodynamic gas process can be kept low.

A further preferred exemplary embodiment of the energy storage system is characterized in that the two pistons are coupled to one another by a piston rod which extends through the separating element such that a forced return of the pistons results during operation of the gas piston pump. The separating element is designed, for example, as a partition in a cylinder in which the pistons coupled to one another by the piston rod are guided to and fro. The pistons limit with mutually facing piston surfaces, the hydraulic cylinder chambers through the

Separating element are separated. With their piston surfaces facing away from each other, the pistons limit the pneumatic cylinder chambers. The cylinder of the gas piston pump has, for example, substantially the shape of a straight, closed hollow cylinder.

A further preferred embodiment of the energy storage system is characterized in that throttle check valves between the

pneumatic-hydraulic piston-cylinder arrangement and the environment associated pneumatic valve devices are connected. The

Throttling check valves are advantageous to the unwanted

To further reduce energy losses in the storage process. The

Throttle check valves can be regulated or unregulated.

By using the throttle check valves can be particularly advantageous to dispense with a mutual control of the pneumatic valve devices. The throttle check valves provide the advantage that the

Pneumatic valve devices can remain open during a relaxation process.

Another preferred embodiment of the energy storage system is characterized in that the gas storage device a gas storage which is surrounded by a temperature storage system. Of the

Gas storage, in particular air storage, is advantageously located in a temperature storage system of a liquid or solid material. The temperature storage system is advantageous to heat of compression

temporarily. The temperature storage system returns the stored

Heat demand-dependent controlled or uncontrolled back to the gas storage, in particular air storage, back to heat the stored gas, in particular the stored air before their relaxation. As a result, the energy losses during operation of the energy storage system can be further reduced.

A further preferred embodiment of the energy storage system is characterized in that the gas storage device is associated with at least one heat exchanger. Through the at least one heat exchanger, the unwanted energy losses during operation of the

Energy storage system can be further reduced. The at least one

Heat exchanger is installed, for example, in or on the gas storage device. In a compression process, the at least one heat exchanger advantageously takes over the resulting heat of compression and transports it, for example, to another heat exchanger in the environment. There, a transport medium of the heat exchanger cools off and is returned to the

Gas storage device out. In the relaxation process of

Gas storage device is then advantageously transported heat from the environment in the direction of the gas storage device. As a result, the relaxing gas, in particular the relaxing air, can be heated in a simple manner. The process described above can be advantageously supported by an active fan on the heat exchanger environment.

In a method of operating a previously described

Energy storage system, the above object is alternatively or additionally achieved in that in one of the pneumatic cylinder chambers of the pneumatic-hydraulic piston-cylinder assembly gas, in particular air, is compressed, while in the other pneumatic cylinder space of the

pneumatic-hydraulic piston-cylinder arrangement gas, in particular air, is sucked from the environment. The compressed gas is in the Gas storage device promoted. Due to the intermediate storage, the unwanted energy losses during operation of the energy storage system can be advantageously reduced.

A preferred embodiment of the method is characterized

in that the pneumatic cylinder chambers assigned to the pneumatic-hydraulic piston-cylinder arrangement

Pneumatic valve devices are mutually switched on / off so that gas is slowly released from the gas storage device. This prevents the gas, especially the air, from cooling too much during the expansion process. As a result, the undesirable energy losses during operation of the energy storage system can be further reduced.

In a system for temporary storage of electrical energy with an energy storage system described above, the above object is alternatively or additionally achieved in that the system comprises at least two gas piston pump and gas storage gas cylinders in a system cabinet, in which accommodated also the electric machine and the hydraulic machine are. The gas cylinders are particularly advantageous for conventional gas cylinders. The electric machine and the hydraulic machine are advantageously housed in a lower portion of the plant cabinet.

The invention further relates to a gas piston pump, a hydraulic machine and / or an electric machine for a previously described energy storage system, in particular for a previously described system for temporary storage of electrical energy.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, various embodiments are described in detail.

Short description of the drawing

Show it: Figure 1 is an illustration of the energy storage system with a gas piston pump and a gas storage device in the form of a hydraulic circuit diagram;

Figure 2 is a pV diagram to the energy storage system of Figure 1;

FIG. 3 shows a section of FIG. 1 with an additional throttle control;

FIG. 4 shows a pV diagram for the energy storage system from FIG. 3;

Figure 5 shows a detail of the energy storage system of Figure 1 with a temperature storage system, which is associated with the gas storage device;

FIG. 6 shows a pV diagram for the energy storage system from FIG. 5;

FIG. 7 shows a section of the energy storage system from FIG. 1 with an additional heat exchanger, which is assigned to the gas storage device;

FIG. 8 shows a pV diagram for the energy storage system from FIG. 7;

9 shows a system cabinet with an energy storage system, as shown in Figure 1, and

Figure 10 is a view into the plant cabinet of Figure 9 showing an arrangement of gas cylinders and gas piston pumps.

Description of the embodiments

1 shows an energy storage system 1 with an electric machine 4 and a hydraulic machine 5 in the form of a hydraulic circuit diagram. By a plus symbol and a minus symbol is indicated in Figure 1, that the electric machine 4 to an electrical supply device connected. The electric machine 4 can be operated both as an electric motor and as a generator.

The hydraulic machine 5 is drivingly connected to the electric machine 4 and can be operated as a hydraulic motor or as a hydraulic pump, as symbolically indicated by arrowheads in Figure 1. If the electric machine 4 works as an electric motor, then as

Hydraulic pump operating hydraulic machine 5 are driven by the electric machine 4. When the hydraulic machine 5 as

Hydraulic motor works, then it can be driven with it working as a generator electric machine 4.

The energy storage system 1 further includes a

Gas storage device 8, with the gas, especially air, can be stored under pressure. A pneumatic-hydraulic

Piston cylinder assembly 10 is connected between the hydraulic machine 5 and the gas storage device 8.

The pneumatic-hydraulic piston-cylinder assembly 10 comprises a gas piston pump 12 with a cylinder 14. In the cylinder 14 of the

Gas piston pump 12 are two pistons 15, 16 movable back and forth, that is movable in Figure 1 upwards and downwards, arranged. The two pistons 15, 16 are coupled together by a piston rod 18, that is rigidly connected to each other in the case of the gas piston pump 12.

The piston rod 18 is guided through a separating element 19. By the separating element 19, the cylinder 14 is divided inside in two halves. By the separating element 19, a first inner hydraulic cylinder space 21 is separated from a second inner hydraulic cylinder space 22. The first inner one

Hydraulic cylinder space 21 is limited in Figure 1 upwards of the piston 15. The second inner hydraulic cylinder space 22 is limited in Figure 1 downwardly from the piston 16.

The first inner hydraulic cylinder space 21 of the glass piston pump 12 is connected via a hydraulic connection 23 to a hydraulic valve device 26 connected. The second inner hydraulic cylinder space 22 is connected to the hydraulic valve device 26 via a hydraulic connection 24.

The hydraulic valve device 26 is designed as a 4/3-way valve with four connections and three switching positions. By symbolically indicated springs is the

Hydraulic valve device 26 biased in its illustrated center position. The hydraulic valve device 26 is electromagnetically actuated.

On the right in Figure 1 side of the hydraulic valve device 26, the two hydraulic ports 23, 24 of the gas piston pump 12 are connected. To the in

1 left side of the hydraulic valve device 26, the hydraulic machine 5 and a hydraulic medium reservoir 28 are connected.

The gas piston pump 12 comprises in the cylinder 14 a first outer pneumatic cylinder space 31 and a second outer pneumatic cylinder space 32. The first outer pneumatic cylinder space 31 is delimited by the piston surface of the piston 15 facing away from the separating element 19. The second outer pneumatic cylinder space 32 is delimited by the piston surface of the piston 16 facing away from the separating element 19.

The first pneumatic cylinder chamber 31 is assigned a pneumatic connection 33. The second pneumatic cylinder chamber 32 is assigned a pneumatic connection 34. The pneumatic connection 33 communicates with a pneumatic branch 35. The pneumatic port 34 communicates with a pneumatic branch 36.

To the pneumatic branch 35 two pneumatic valve devices 41, 42 are connected. To the pneumatic branch 36 are two

Pneumatic valve devices 43, 44 connected. The

Pneumatikventileinrichtungen 41 to 44 are as 2/2 way valves with a

Check valve position and an opening valve position executed. By symbolically indicated springs, the pneumatic valve devices 41 to 44 are all biased in their check valve position. The pneumatic valve means 41 and 43 are between the respective associated pneumatic branch 35, 36 and an environment of

Gas piston pump 12 connected. In the check valve position of

Pneumatic valve devices 41 and 43, a connection to the environment is interrupted.

The pneumatic valve devices 42, 44 are connected between the respectively associated branch 35, 36 and a pneumatic branch 48. The gas storage device 8 is connected to the pneumatic branch 48

connected. In the illustrated check valve position of

Pneumatic valve devices 42, 44, an escape of gas from the gas storage device 8 is interrupted or prevented.

FIG. 2 shows a pV diagram for the energy storage system 1 from FIG. On an x-axis is a compression volume V in a suitable

Volume unit applied. With V _s a start volume is designated. VE is a final volume. With ps / ε a starting pressure and a final pressure are indicated, which are the same and the start volume V _s and the final volume VE are assigned. Ps is a memory pressure. With pv is a

Referred to compaction pressure.

By a dashed curved arrow 51, a relaxation process is indicated. By a dashed curved arrow 52 is a

Densification process indicated. By a curve 53, an isothermal compression process is indicated. Due to an increase in temperature during compression and cooling after compression during the expansion, energy losses 54 result in the real storage process. The

Memory losses result from the difference between pv minus ps and the difference Vs minus V _e .

In the energy storage system 1 shown in Figure 1 is carried out by a mutual switching on and off of the pneumatic valve devices 41 to 44, a slow relaxation of the air from the gas storage 8, which is also referred to as an air reservoir. The slow relaxation prevents the air in the relaxation process from cooling too much and thus with it associated energy loss undesirably reduces the efficiency of the energy storage system 1.

In the compression process is prevented by a slow hydraulic pressure build-up in the corresponding hydraulic cylinder chamber 21, 22 of the gas piston pump 12 that the temperature in the air reservoir 8 increases too much.

In order to obtain a highly efficient thermodynamic gas process, care must be taken in the design of the energy storage system 1 that the pneumatic components of the energy storage system 1 allow rapid temperature compensation in the environment. The can

Gas piston pump 12, the associated piping, the

Pneumatic devices 41 to 44 and the gas storage device 8 with special construction elements, such as cooling fins, the

Enlargement of the surface to be equipped.

FIG. 3 shows a section from FIG. 1 with the gas piston pump 12 and the gas storage device 8 and the pneumatic valve devices 41 through 44 according to a further exemplary embodiment of the energy storage system. In Figure 3 is between the branches 35, 36 and the

Pneumatic valve devices 41, 43 each one

Throttle check valve 61, 62 connected.

The throttle check valves 61, 62 are regulated in their illustrated embodiment, but may also be carried out unregulated. With the

Throttle check valves 61, 62, a mutual control of the pneumatic valve devices 41, 43 is no longer required. Both

Pneumatic valve means 41, 43 can during the

Relaxation process remain open. Depending on the set throttling, the relaxation process is automatically slowed down.

FIG. 4 shows the associated pV diagram. By an arrow 65 is indicated that the point VE in the thermodynamic gas process by the previously described slowdown of the expansion process further in Moved toward Vs. This can reduce energy loss in the

Storage process can be further reduced.

FIG. 5 shows the same detail from FIG. 1 as in FIG. 3 according to a further exemplary embodiment. In FIG. 5, the

Gas storage device 8 for a further reduction of

Memory energy losses associated with a temperature storage system 74. The temperature storage system 74 is formed, for example, from liquid or solid materials and surrounds a gas storage 70 of the

Gas storage device 8.

The temperature storage system 74 has the task of buffering heat of compression. If desired, the stored heat may be controlled or returned uncontrolled back into the gas storage 70 to heat the air stored in the gas storage 70 prior to its relaxation.

In FIG. 6, an isothermal compression process is indicated by a curve 53. In the thermodynamic gas process results from the

Temperature entry by means of the temperature storage system 74 after compression, a maintenance of the pressure in the gas storage or

Air storage 70 (pv = ps). The intermediate storage results in a further reduction of the storage energy loss 76. An arrow 78 indicates a further shift from VE to Vs. FIG. 7 shows the same section of the energy storage system 1 from FIG. 1 as in FIGS. 3 and 5 according to a further exemplary embodiment. In FIG. 7, a heat exchanger 82 is arranged in the gas storage device 8. The heat exchanger 82 in the gas storage device 8 is connected to a heat exchanger 81 in the environment.

The heat exchanger 81 in the area is associated with a fan 84. The heat exchanger 82 takes over resulting in the compression process

Compressive heat and transported to the heat exchanger 81 in the environment. There, the transport medium cools off and is led back to the heat exchanger 82 in the gas storage device 8. In the expansion process of the gas storage device 8, heat is transported from the environment in the direction of the gas storage device 8. As a result, the air relaxed in the gas storage device 8 is heated. The fan 84 supports this process.

In FIG. 8, a curve 53 shows an isothermal compression process. By arrows 88, 89 is indicated in Figure 8 that the characteristics of the compression and expansion process is the isothermal

Compression process 86 are approximated. This results in a reduced storage energy loss 87.

In Figure 9, a system 100 for the energy storage system 1 of Figure 1 is shown by way of example. The plant 100 comprises a plant cabinet 102 with feet 104, 105. The plant has, for example, a height of almost two meters and a width of about sixty centimeters. At the top of that

Plant cabinet 102, an air connection pipe 108 is provided.

In a lower portion of the plant cabinet 102, an electric machine 114 and a hydraulic machine 115 are arranged. Above the two machines 114, 115, a hydraulic medium reservoir 116 is arranged. A gas storage device 118 occupies a majority of an interior of the plant cabinet 102. The gas storage device 118 comprises a total of six gas cylinders 121 to 126. The gas cylinders 121 to 126 are combined with two gas piston pumps 131, 132.

FIG. 10 shows a cross section of the plant cabinet 102 from FIG. In the cross section you can see how the total of six gas cylinders 121 to 126, together with the two gas piston pumps 131, 132 are arranged in a particularly space-saving manner in the system cabinet 102.

Claims

claims

An energy storage system (1) for temporarily storing electrical energy with an electric machine (4; 114) drivingly connected to a hydraulic machine (5; 115) and a pneumatic-hydraulic piston-cylinder arrangement (10) interposed

Valve means between the hydraulic machine (5, 115) and a gas storage device (8, 118) is arranged, characterized in that the pneumatic-hydraulic piston-cylinder arrangement (10) comprises at least one gas piston pump (12, 131, 132), the two pneumatic connections (33,34 ) and two hydraulic connections (23, 24) which can be connected or connected to the hydraulic machine (5, 115) with the interposition of a hydraulic valve device (26).

2. Energy storage system according to claim 1, characterized in that the gas piston pump (12, 131, 132) comprises two inner hydraulic cylinder chambers (21, 22) which are separated from one another by a separating element (19) and which are separated by two pistons (15, 16) from outer pneumatic cylinder chambers (31 , 32) are separated with the interposition of pneumatic valve devices (41-44) with the

Gas storage device (8; 118) or an environment connectable

or are connected.

3. energy storage system according to claim 2, characterized in that the two pistons (15,16) by a piston rod (18) which extends through the separating element (19) through, are coupled together so that during operation of the gas piston pump (12 131, 132) results in a forced return of the pistons (15, 16).

4. energy storage system according to claim 2 or 3, characterized in that throttle check valves (61,62) between the pneumatic-hydraulic piston-cylinder assembly (10) and those associated with the environment

Pneumatic valve devices (41,43) are connected.

5. Energy storage system according to one of claims 2 to 4, characterized

characterized in that the gas storage device (8; 118) comprises a gas reservoir (70) surrounded by a temperature storage system (74).

6. Energy storage system according to one of claims 2 to 5, characterized

characterized in that the gas storage device (8; 118) at least one

Heat exchanger (81,82) is assigned.

7. A method for operating an energy storage system (1) according to any one of the preceding claims, characterized in that in one of the pneumatic cylinder chambers (31,32) of the pneumatic-hydraulic

Piston cylinder assembly (10) gas, in particular air, is compressed, while in the other pneumatic cylinder space of the pneumatic-hydraulic

Piston cylinder assembly (10) gas, in particular air, is sucked from the environment.

8. The method according to claim 7, characterized in that the

Pneumatic cylinder chambers (41-44) of the pneumatic-hydraulic

Piston cylinder assembly (10) associated pneumatic valve means (41-44) are mutually switched on / off, that gas from the

Gas storage device (8; 118) is slowly relaxed.

9. system (100) for temporarily storing electrical energy with a

Energy storage system (1) according to one of claims 1 to 6, characterized in that the plant (100) at least two gas piston pumps (12; 131,132) and gas storage device (8; 118) gas bottles (121-126) in a plant cabinet (102) in which also the electric machine (114) and the hydraulic machine (115) are housed.

10. Gas piston pump (12, 131, 132), hydraulic machine (5, 115) and / or

Electric machine (4, 114) for an energy storage system (1) according to one of Claims 1 to 6, in particular for a system (100) for buffering electrical energy according to Claim 9.