Uninterruptible power supply and method of use

Patent metadata

Field	Value
Publication number	US-2016359361-A1
Application number	US-201514732215-A
Country	US
Kind code	A1
Filing date	Jun 5, 2015
Priority date	Jun 5, 2015
Publication date	Dec 8, 2016
Grant date	—

Abstract

An uninterruptible power supply (UPS) includes a line terminal, a load terminal, a double-conversion circuit coupled in series, and further includes a bypass circuit, and a synchronize circuit. The line terminal couples to a doubly fed induction generator (DFIG). The load terminal couples to a load having a demanded power. The double-conversion circuit regulates grid power from the line terminal to the demanded power at the load terminal. The bypass circuit is coupled between the line terminal and the load terminal, and configured to deliver regulated power generated by the DFIG to the load terminal when the grid power is lost. The synchronize circuit is coupled between the double-conversion circuit and the DFIG, and, when the grid power is lost, the synchronize circuit injects a current through the double-conversion circuit and into the DFIG, synchronizing the regulated power generated by the DFIG to the demanded power.

First claim

What is claimed is:

1 . An uninterruptible power supply (UPS) comprising:
a line terminal configured to be coupled to a doubly fed induction generator (DFIG) and an electric grid, the electric grid configured to transmit grid power to said line terminal, the DFIG configured to generate regulated power; a load terminal configured to be coupled to a load that has a demanded power; a double-conversion circuit configured to be coupled to said line terminal and said load terminal, said double-conversion circuit further configured to regulate grid power transmission from said line terminal to said load terminal; a bypass circuit configured to be coupled to said line terminal and said load terminal, said bypass circuit further configured to deliver the regulated power to said load terminal when the grid power is unavailable; and a synchronize circuit configured to be coupled to said double-conversion circuit and the DFIG, said synchronize circuit further configured to inject a current from said double-conversion circuit into the DFIG when the grid power is unavailable, the current configured to synchronize the regulated power generated by the DFIG to the demanded power.

2 . The UPS in accordance with claim 1 , wherein said double-conversion circuit comprises:
an alternating current-to-direct current (AC/DC) converter; and a direct current-to-alternating current (DC/AC) converter serially coupled to said AC/DC converter.

3 . The UPS in accordance with claim 2 further comprising a battery coupled to said double-conversion circuit, said battery configured to provide the demanded power to said load terminal when transitioning between the grid power and the regulated power.

4 . The UPS in accordance with claim 3 , wherein said battery is further configured to supply the current injected into the DFIG, the current transmitted through the AC/DC converter and said synchronize circuit.

5 . The UPS in accordance with claim 4 further comprising a first switch positioned between said line terminal and said double-conversion circuit, said first switch configured to close when the grid power is present and open when the grid power is not present.

6 . The UPS in accordance with claim 5 , wherein said bypass circuit comprises a second switch between said line terminal and said load terminal, said second switch configured to open when the grid power is present.

7 . The UPS in accordance with claim 6 , wherein said second switch is further configured to:
open when said battery provides the demanded power to said load terminal; and close to deliver the regulated power generated by the DFIG to said load terminal.

8 . The UPS in accordance with claim 7 , wherein said second switch is further configured to close when said battery provides the demanded power, said battery configured to provide cranking power through said second switch to the DFIG.

9 . A method of operating an electrical distribution system configured to be coupled to an electric grid and receive grid power therefrom, said method comprising:
detecting a loss of grid power on a line terminal; disconnecting a double-conversion circuit from the line terminal; starting-up a doubly fed induction generator (DFIG) and generating regulated power; delivering the regulated power to a load comprising bypassing the double-conversion circuit; and feeding back the regulated power, through the double-conversion circuit, to the DFIG, thereby synchronizing the regulated power to a desired frequency, phase, and amplitude for the load.

10 . The method in accordance with claim 9 further comprising:
delivering battery power to the load when transitioning from the grid power to the regulated power; and
feeding back the battery power, through at least a portion of the double-conversion circuit, to the DFIG, thereby synchronizing the regulated power to the desired frequency, phase and amplitude.

11 . The method in accordance with claim 9 , wherein starting-up the DFIG comprises:
delivering battery power to a stator of the DFIG comprising bypassing the double-conversion circuit before energizing a rotor of the DFIG; cranking the rotor and a primer coupled thereto by induction to a desired speed; applying the battery power to the rotor, through at least a portion of the double-conversion circuit, thereby synchronizing the regulated power generated by the DFIG to the desired frequency, phase, and amplitude; removing the battery power from the stator; and driving the primer with a variable speed drive.

12 . The method in accordance with claim 9 further comprising:
disconnecting, at an automatic transfer switch, the line terminal from a grid that provides the grid power, upon detecting the loss of the grid power; and
connecting, at the automatic transfer switch, the line terminal to a stator of the DFIG.

13 . The method in accordance with claim 9 further comprising:
regulating the grid power, at the double-conversion circuit, to the desired frequency, phase, and amplitude before detecting the loss of the grid power; and
delivering the grid power through the double-conversion circuit to the load before detecting the loss of the grid power.

14 . The method in accordance with claim 9 further comprising delivering the regulated power through the double-conversion circuit to a battery, thereby charging the battery.

15 . An electrical distribution system comprising:
a doubly fed induction generator (DFIG) comprising a rotor and a stator, said DFIG configured to generate a regulated power at said stator; an automatic transfer switch configured to decouple from a grid and couple to said stator upon detection of a loss of grid power; and an uninterruptible power supply (UPS) configured to:
receive a regulated power through said automatic transfer switch from said DFIG;
deliver a first portion of the regulated power to a load; and
deliver a second portion of the regulated power to said rotor to synchronize the regulated power to a desired frequency, phase, and amplitude for the load.

16 . The electrical distribution system in accordance with claim 15 , wherein said UPS comprises:
a double-conversion circuit configured to:
regulate and deliver the grid power to the load; and
regulate and deliver the regulated power, generated by said stator, to said rotor; and
a battery coupled to said double-conversion circuit, said double-conversion circuit further configured to deliver a direct current (DC) charging power to said battery.

17 . The electrical distribution system in accordance with claim 16 , wherein said UPS further comprises a bypass circuit coupled in parallel to said double-conversion circuit, said bypass circuit configured to:
open when the grid power is present; and close when receiving the regulated power from said DFIG.

18 . The electrical distribution system in accordance with claim 17 , wherein said battery is configured to deliver battery power to the load during a transition between the grid power and the regulated power from said DFIG.

19 . The electrical distribution system in accordance with claim 18 , wherein said bypass circuit is further configured to close during the transition, said battery further configured to deliver battery power to said stator to crank said rotor by induction.

20 . The electrical distribution system in accordance with claim 19 , wherein said UPS further comprises a switch coupled between said double-conversion circuit and said rotor of said DFIG, said switch configured to:
c

Assignees

• Gen Electric

Inventors

• Tiwari Arvind Kumar
• Kolhatkar Yashomani Y
• Colombi Silvio

Classifications

• H02J9/08

  requiring starting of a prime-mover · CPC title

• H02J9/066 Primary

  characterised by the use of dynamo-electric machines (H02J9/08 takes precedence) · CPC title

• H02J11/00

  Circuit arrangements for providing service supply to auxiliaries of stations in which electric power is generated, distributed or converted · CPC title

• H02J9/04 Primary

  in which the distribution system is disconnected from the normal source and connected to a standby source · CPC title