Low-energy storage fast-start uninterruptible power supply system and method

• US 6,507,128 B2
• Filed: 05/23/2001
• Issued: 01/14/2003
• Est. Priority Date: 05/23/2001
• Status: Expired due to Term

• Current Assignee: ABB Schweiz AG (ABB Limited)
• Original Assignee: General Electric Company
• Inventors: King, Robert Dean, Sinha, Gautam
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/681,697
• Publication Number:
  US 20020175660A1
• Time in Patent Office: 601 Days
• Field of Search: 290/40.R, 290/40.A, 290/40.B, 290/40.C, 290/11, 290/24, 322/4, 322/7, 307/64
• US Class Current: 290/40.00C
• CPC Class Codes: H02J 3/30 using dynamo-electric machines coupled to flywheels
• CPC Class Codes: H02J 9/08 requiring starting of a prime-mover
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02E 60/16 Mechanical energy storage, e.g. flywheels or pressurised fluids
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

An uninterruptible power supply system has standby and backup modes and can change to backup mode upon detection of a grid fault. In both modes an alternator rotates at synchronous-speed so that backup mode capability is ready. An energy storage unit through a DC-AC inverter remains coupled to the grid in standby mode so that it is charged, ready to supply power when changed to backup mode. In standby mode, first and third clutches are disengaged and engaged, transmitting alternator rotary motion to a flywheel but not therefrom to a heat engine. In backup mode, first and third clutch are engaged and disengaged to permit the alternator, via a second clutch, to overrun the flywheel and allow transmitting of flywheel torque to accelerate the heat engine to starting speed for driving the alternator to supply power to the grid after the engine is at operating speed and coupled to the alternator through a locked second clutch and an engaged third clutch.

Claims

1. An uninterruptible power supply system having a standby mode of operation and a backup mode of operation, said system comprising:

a heat engine having a crankshaft;

an alternator having an input shaft and an output electrically connected to an electrical power grid;

a flywheel disposed between said crankshaft of said heat engine and said input shaft of said alternator;

a first motion transmitting mechanism disposed between said flywheel and said crankshaft of said heat engine and actuatable between engaged and disengaged conditions for correspondingly drivingly coupling and decoupling said flywheel to and from said crankshaft of said heat engine;

a second motion transmitting mechanism providing a one-way drive coupling between said flywheel and said input shaft of said alternator such that in a first direction from said alternator to said flywheel said second motion transmitting mechanism operates in an overrun mode in which said input shaft of said alternator can rotate at a speed faster than that of said flywheel whereas in a second direction, opposite said first direction, from said flywheel to said alternator said second motion transmitting mechanism operates in a locked mode in which said flywheel can rotate up to the same speed as that of said input shaft of the alternator so as to transmit drive torque from said flywheel to said alternator;

a third motion transmitting mechanism disposed between said flywheel and said input shaft of said alternator and actuatable between engaged and disengaged conditions for correspondingly drivingly coupling and decoupling said flywheel to and from said input shaft of said alternator such that when said third motion transmitting mechanism is in said disengaged condition said second motion transmitting mechanism permits said input shaft of said alternator to overrun said flywheel such that no driving torque is transmitted from said input shaft of said alternator to said flywheel whereas when said third motion transmitting mechanism is in said engaged condition said input shaft of said alternator and said flywheel are drivingly coupled to one another such that said drive torque can be transmitted in either direction between said flywheel and input shaft of said alternator so that said input shaft of said alternator and said flywheel can rotate at the same speed;

a source of AC electrical energy provided by an energy storage source and a DC-AC inverter connected to the electrical power grid; and

an uninterruptible power supply system control connected to the electrical power grid and to said heat engine and said first and third motion transmitting mechanisms for controlling operation of said heat engine and said first and third motion transmitting mechanisms so as to change said system from a standby mode of operation to a backup mode of operation such that in said standby mode said source of AC electrical energy is charging, and ready to supply power to the power grid and said first and third motion transmitting mechanisms are respectively in disengaged and engaged conditions so as to transmit alternator rotary motion to said flywheel but not therefrom to said heat engine, whereas in said backup mode said source of AC electrical energy is supplying power to the power grid in response to said control detecting of a fault in the power grid and said first and third motion transmitting mechanisms are respectively in engaged and disengaged conditions so as to permit said alternator, via said second motion transmitting mechanism, to overrun said flywheel and allow transmitting of flywheel torque to accelerate said heat engine to a starting speed for driving said alternator to supply the power to the power grid.

2. The system of claim 1 in which in absence of said control detecting a fault in the power grid, said control is operable to maintain said system in said standby mode of operation such that said alternator rotates at said predetermined speed so as to be in a constant state of readiness for facilitating starting of said heat engine in response to said control changing said system from said standby mode to said backup mode.

3. The system of claim 1 in which in absence of said control detecting a fault in the power grid, said source of AC electrical energy remains coupled to the power grid to receive electrical energy therefrom sodas to be charged and ready to supply electrical energy to the power grid upon said control changing said system from said standby mode to said backup mode.

4. The system of claim 1 in which in absence of said control detecting a fault in the power grid, said control is operable to maintain said system in said standby mode of operation in which said first motion transmitting mechanism is maintained in said disengaged condition such that said flywheel is decoupled from said heat engine.

5. The system of claim 1 in which in absence of said control detecting a fault in the power grid, said control is operable to maintain said system in said standby mode of operation in which said third motion transmitting mechanism is maintained in said engaged condition such that said input shaft of said alternator rotatably drives said flywheel via said third motion transmitting mechanism.

6. The system of claim 1 in which in response to said control detecting a fault in the power grid, said control is operable to change said system from said standby mode of operation to said backup mode of operation in which said control actuates said third motion transmitting mechanism to said disengaged condition.

7. The system of claim 1 in which in response to said control detecting a fault in the power grid, said control is operable to change said system from said standby mode of operation to said backup mode of operation in which said first motion transmitting mechanism is actuated to said engaged condition driving coupling said flywheel to said crankshaft of said heat engine which permits said second motion transmitting mechanism to allow said flywheel to decrease in speed as said flywheel transfers torque to said crankshaft of said heat engine via said first motion transmitting mechanism to initiate and increase the speed of rotation of said heat engine to a predetermined speed where said heat engine is started by said control.

8. The system of claim 7 in which in response to said control detecting a fault in the power grid, said control is operable to change said system from said standby mode of operation to said backup mode of operation in which said control actuates said third motion transmitting mechanism to said engaged condition once said heat engine and said flywheel reach said speed of said input shaft of said alternator.

9. The system of claim 1 in which said first and third motion transmitting mechanisms are friction clutches.

10. The system of claim 1 in which said second motion transmitting mechanism is a one-way overrun clutch.

11. The system of claim 1 in which said first motion transmitting mechanism has a disk part which is attached to said crankshaft of said heat engine and a pressure plate part which is attached to said flywheel and is actuatable to drivingly couple and decoupled said flywheel to and from said crankshaft of said heat engine when said disk part and pressure plate part correspondingly are engaged with and disengaged from one another.

12. The system of claim 1 in which said second motion transmitting mechanism has an outer annular part attached to said flywheel and an inner annular part attached to said input shaft of said alternator, said one-way drive coupling being provided between said outer annular part and said inner annular part such that said inner annular part rotating with said input shaft of said alternator can rotate faster than said outer annular part rotating with said flywheel but said outer annular part cannot rotate faster than said inner annular part.

13. The system of claim 12 in which said third motion transmitting mechanism has a disk part attached to said input shaft of said alternator, an outer annular part of said second motion transmitting mechanism and a pressure plate part attached to said flywheel and actuatable to drivingly couple and decoupled said flywheel to and from said input shaft of said alternator when said disk part and pressure plate part correspondingly are engaged with and disengaged from one another.

14. The system of claim 1 wherein said source of AC electrical power includes:

a DC electrical energy storage unit; and

a DC-AC inverter connected between said energy storage unit and the electrical power grid for converting DC energy to AC energy and supplying the AC energy to the power grid.