Power Technologies, Inc.

John S Czuba

David W Parkinson

F Paul De Mello

Louis N Hannett

A microprocessor based, power systems stabilizer operating through excitation control wherein all required stabilizing information is derived from sampled values of voltage and current taken from potential and current transformers. The instantaneous values of terminal voltage and current are processed using algorithms in the accelerating power signal digital processor portion of the microprocessor to thereby develop a value of instantaneous internal voltage, the value of slip frequency of such voltages in relation to rated frequency and a digitally filtered value of electrical power. The accelerating power is calculated from the rate of change of slip and electrical power. The values of accelerating power are processed with digital algorithms in a stabilizing signal compute section of the microprocessor to yield a stabilizing signal which provides the desired modulating action for damping the machine oscillations of the synchronous generator. This modulating action is provided by switching the taps in an autotransformer being supplied from the potential transformer secondary measuring generator terminal voltage and feeding the voltage regulator and exciter for the generator. The selection of taps on the autotransformer is controlled by the microprocessor based stabilizer system at an appropriate rate, such as every one to ten milliseconds.

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New York, NY, United States of America

John S Czuba