Ann T Hill

US Patent:

51987457, Mar 30, 1993

Filed:

Aug 8, 1991

Appl. No.:

7/742881

Inventors:

Einar V. Larsen - Charlton NY
Ann T. Hill - Ballston Spa NY

Assignee:

Electric Power Research Institute - Palo Alto CA

International Classification:

H02K 1100

US Classification:

322 58

Abstract:

A dynamic braking system resistor for stabilizing a power system during power system disturbances includes a braking resistor for coupling with a power system bus. A controller monitors a power system parameter, such as the speed of a generator coupled with the power system bus, and determine therefrom a thyristor control signal. The controller uses the power system parameter to establish a desired modulation and then provides a bias to the desired modulation. The controller conditions the biased desired modulation signal to provide the thyristor control signal. A thyristor valve responsive to the thyristor control signal couples the braking resistor with a ground potential. A method is also provided of damping subsequent oscillations on a power system following a power system disturbance using the dynamic braking resistor.

US Patent:

54081718, Apr 18, 1995

Filed:

Jun 23, 1994

Appl. No.:

8/265491

Inventors:

Murray A. Eitzmann - Ballston Lake NY
Ann T. Hill - Ballston Spa NY

Assignee:

Electric Power Research Institute, Inc. - Palo Alto CA

International Classification:

G05F 116

US Classification:

323258

Abstract:

Disclosed is an End-Turn Solid-State Switching (ETSS) transfomer tap which makes use of a high-speed solid-state switching network to select either the end-turn lead or one of a number of non-isolated taps on a transformer regulating winding, and connects the selected tap to, while disconnecting the previously selected tap from, a single output conductor carrying the transformer load current. ETSS effectively changes the reference to one of the possible taps interfaced to a solid-state switching network. The same transformer regulating winding connected to ETSS can also be connected in series with a slow-speed mechanically-switched tap-changer (LTC). ETSS selects one connection point on the regulating winding while LTC operation selects the second point. A difference voltage is produced, depending on the number of turns between the ETSS selected tap and the LTC selected tap. The sign of the difference in voltage depends on whether the ETSS selected tap is higher or lower than the LTC selected tap.