Energy storage module comprising a DC link

• US 9,825,504 B2
• Filed: 06/20/2014
• Issued: 11/21/2017
• Est. Priority Date: 06/24/2013
• Status: Active Grant

• Current Assignee: Enrichment Technology Company Limited
• Original Assignee: Enrichment Technology Company Limited
• Inventors: Schfer, Christoph, Vor Dem Esche, Rainer, Spangenberg, Arne
• Primary Examiner(s): Wells, Kenneth B
• Application Number:
  US14/896,109
• Publication Number:
  US 20160118859A1
• Time in Patent Office: 1,250 Days
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 11/00 Circuit arrangements for providing service supply to auxiliaries of stations in which electric power is generated, distributed or converted
• CPC Class Codes: H02J 15/007 involving storage in the form of mechanical energy, e.g. fly-wheels
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02J 9/066 characterised by the use of dynamo-electric machines H02J9/08 takes precedence
• CPC Class Codes: H02K 7/025 for power storage
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids
• CPC Class Codes: Y02P 90/50 Energy storage in industry with an added climate change mitigation effect

Abstract

An energy storage module for the reversible storage of electric energy is provided that comprises several flywheel energy storage units that are electrically connected in parallel via a shared DC link. A first regulation system is connected to the DC link and that, during normal operation (NO), connects the DC link to one or more external power networks in order to absorb (En) energy from or release (Ep) energy into the external power network(s). A second regulation system includes an input side and an output side, whereby the input side is connected to at least the DC link while the output side is connected to an internal supply network for purposes of supplying one or more electrically powered operating aggregates that are needed to operate the flywheel energy storage units.

Claims

1. An energy storage module for the reversible storage of electric energy, comprising several flywheel energy storage units that are electrically connected in parallel via a shared DC link, comprising a first regulation system that is connected to the DC link and that, during normal operation (NO), connects the DC link to one or more external power networks (ES1, ES2) in order to absorb (En) energy from or release (Ep) energy into the external power network(s) (ES1, ES2), and comprising a second regulation system having an input side and an output side, whereby the input side is connected to at least the DC link while the output side is connected to an internal supply network for purposes of supplying one or more electrically powered operating aggregates that are needed to operate the flywheel energy storage units, whereby the second regulation system is configured to connect the DC link to the internal supply network, at least during emergency operation (NF) when the external power network is absent, and to supply the supply network with the requisite supply power (VL) only from the DC link in order to ensure the continued operation of the flywheel energy storage units, at least during a first time interval (T).

2. The energy storage module according to claim 1, characterized in that, during emergency operation (NF), the second regulation system regulates the supply network voltage (VS) in the internal supply network in an essentially constant manner in that, depending on the demand, it supplies power from the DC link.

3. The energy storage module according to claim 2, characterized in that the input side of the second regulation system is additionally connected to an external power network (ES2) and the second regulation system is configured to provide the supply power for the internal supply network from the external power network during normal operation (NO), and from the DC link during emergency operation.

4. The energy storage module according to claim 3, characterized in that the energy storage module is configured to continuously monitor the direct voltage in the DC link, and the flywheel energy storage units each have motor control means which, independently of a module control unit for controlling the flywheel energy storage units during normal operation, are configured so that, in the case of emergency operation (NF)—

at least on the basis of the monitored direct voltage (GS)—

they do not allow the direct voltage (GS) in the DC link to fall below a lower threshold value (SW2) in that they release (EFp) energy from the appertaining flywheel energy storage units, at least as long as the amount of energy stored in the appertaining flywheel energy storage units has not fallen below a minimum energy level.

5. The energy storage module according to claim 4, characterized in that there is at least one measuring device in the DC link for purposes of measuring the direct voltage (GS) in the DC link, and said device is connected at least to the appertaining motor control means of the flywheel storage units.

6. The energy storage module according to claim 5, characterized in that the motor control means of the individual flywheel storage units are connected directly to each other, independently of the module control unit, and they each comprise a flywheel control means which is configured to carry out a jointly coordinated support operation (SB) of the direct voltage (GS) in the DC link by all of the flywheel storage units during emergency operation (NF).

7. The energy storage module according to claim 6, characterized in that the energy storage module comprises one or more measuring units to continuously measure the voltage quality of the external power networks connected to the energy storage module, whereby the measuring unit or units are configured to emit an emergency operation signal (NFS) within the energy storage module in case of an overvoltage or an undervoltage in at least one of the connected external power networks, and the second regulation system is configured to switch over from normal operation (NO) to emergency operation (NF) as an automatic response to the emergency operation signal (NFS).

8. The energy storage module according to claim 7, characterized in that the first regulation system is configured to disconnect the DC link from the external power network in response to the emergency operation signal (NFS), and/or the second regulation system is configured to disconnect the internal supply network from the external power network in response to the emergency operation signal (NFS).

9. The energy storage module according claim 8, characterized in that the measuring units are configured to send a normal operation signal (NOS) within the energy storage module once the external power network is available again, and the energy storage module is configured to change over from emergency operation (NF) to normal operation (NO) as an automatic response to the normal operation signal (NOS) and to connect the DC link and the internal supply network to the external power network(s).

10. A method for controlling an energy storage module according to claim 1, comprising the following steps:

energy from a shared DC link to which several flywheel storage units are electrically connected in parallel is released (Ep) into or absorbed (En) from one or more external power networks that are connected to the DC link via a first regulation system, and

the one or more operating aggregates needed to operate (BT) the flywheel storage units are supplied with the energy required to operate (BT) the operating aggregates during the normal operation (NO) of the energy storage module via an internal supply network, whereby the supply network is connected to an output side of a second regulation system whose input side is connected at least to the DC link, and

the energy storage module is switched over from normal operation (NO) to emergency operation (NF) when the external power network is absent, and

the internal supply network is supplied (V) with the supply power (VL) for the continued operation (BT) of the flywheel storage units when the external power network is absent, and this is done only from the DC link, at least during a first time interval (T).

11. The method according to claim 10, comprising the following additional step:

the supply network voltage (VS) of the internal supply network is regulated (R) to a constant value in that, depending on the demand, power is supplied from the DC link by means of the second regulation system.

12. The method according to claim 11, comprising the following additional steps:

the direct voltage (GS) of the DC link is continuously monitored, preferably by means of at least one measuring device arranged in the DC link, and

independently of a module control unit for controlling the flywheel storage units during normal operation (NO), in case of emergency operation (NF), the flywheel storage units are controlled (ST) by means of appertaining motor control means in the individual flywheel storage units on the basis of the monitored direct voltage (GS), so that, due to the release (EFp) of energy from the appertaining flywheel storage units into the DC link, its direct voltage (GS) does not fall below a lower threshold value (SW2), at least as long as the amount of energy stored in the flywheel storage units does not fall below a minimum energy level, preferably by stipulating time-related torque specifications (DV) for the appertaining flywheel storage units.

13. The method according to claim 12, comprising the following additional steps:

a jointly coordinated support operation (SB) of all flywheel storage units is carried out by means of the motor control means in order to regulate the direct voltage (GS) in the DC link to a constant value during emergency operation (NF) in that each motor control means encompasses flywheel control means, and the individual motor control means of the flywheel storage units are connected to each other, independently of the module control unit, and

individual flywheel storage units are systematically excluded from the shared support operation (SB) in order to provide a minimum amount of energy for a controlled ramp-down of the flywheel storage units.

14. The method according to claim 13, comprising the following additional step:

the internal supply network is disconnected from the DC link by means of the second regulation system once the amount of energy stored in the flywheel storage units has fallen below a minimum energy level.

15. The method according to claim 10, comprising the following additional steps:

the voltage quality in the external power networks that are connected to the energy storage module is continuously measured (KM) employing one or more measuring units of the energy storage module,

an emergency operation signal (NFS) is emitted within the energy storage module by one measuring unit in case of an overvoltage or an undervoltage in at least one of the connected external power networks,

the external power network(s) is/are disconnected at least from the DC link by means of the first regulation system,

the flywheel storage units are switched over from normal (NO) operation to emergency operation (NF) and the internal supply network is supplied with the requisite supply power (VL) from the DC link by means of the second regulation system as an automatic response to a drop in the direct voltage (GS) in the DC link or as an automatic response to the emergency operation signal (NFS),

a normal operation signal (NOS) is emitted by the measuring units once the external power network becomes available once again,

the energy storage module is switched over from emergency operation (NF) to normal operation (NO), and

the internal supply network is connected to the external power network(s), preferably by means of the second regulation system, as an automatic response to the normal operation signal (NOS).