Westinghouse Electric Corporation

Electric Power Research Institute Incorporated

Miklos Sarkozi

Laszlo Gyugyi

Robert C Miller

Colin D Schauder

Michael B Brennen

Charles W Edwards

Eugene G Vaerewyck

Paul G Kennedy

Nicholas Yaroshuk

Nick Yaroshuk

A solid-state circuit breaker with fault current conduction is described. The circuit includes a power sensor connected to a power line having an up-stream side and a down-stream side. The output of the power sensor is conveyed to a switch selection circuit that identifies a line disturbance on the power line. In response to a line disturbance, the switch selection circuit generates a set of output signals. The output signals force the opening of a fault current interruption circuit including a set of turn-off thyristors. The turn-off thyristors respond to the line disturbance within a fraction of a power signal cycle to provide isolation between the up-stream side and downstream side of the power line. An alternate power source may then be applied to the down-stream side of the power line. If the line disturbance exists on the down-stream side of the power line, the output signals force the closing of a fault current conduction circuit including a set of thyristors connected in series with a reactor. The closing of the fault current conduction circuit forces the conduction of a fault current from the reactor that allows the activation of circuit breakers positioned on the down-stream side of the power line. As a result, a conventional hierarchical circuit breaker control strategy is maintained.

Solid-state circuit breaker with fault current conduction

A system and method is provided compensating utility distribution line transients such as voltage sags in a dynamic manner, by inserting a voltage signal in series with the distribution signal having a magnitude and phase to effectively cancel out the voltage deviation caused by a network disturbance. An energy storage device such as a storage capacitor is used to provide energy to an inverter circuit which is controlled to generate the series-inserted signal. Preferably a converter such as a chopper is utilized between the storage element and the inverter, to provide a constant dc input to the inverter. A controller generates a corrective error signal based upon the deviation between the utility supply voltage as affected by the disturbance, and the nominal ideal voltage signal, and adjusts the insertion voltage so as to optimize real power delivery to the utility distribution line.

Apparatus and method for dynamic voltage restoration of utility

A static VAR generator for providing reactive compensation incorporating a malfunction detector. The static VAR generator comprises a reactance which is linearly responsive to a first linearized control signal and produces an output signal proportional to the reactive compensation which provides a feedback signal. A director control uses the feedback signal and an adjustable reference signal to provide the first linearized control signal based on the difference between the reference and feedback signals. A tracker controller provides a second linearized control signal based on the reference and feedback signals. The second control signal is compensated by an equalizer that determines the difference between the first and second control signals. The compensation counters the difference between the first and second control signals caused by the offset and component tolerances in the two controllers and makes the second control signal substantially equal to and track the first control signal. A first comparator conpares the compensated second control signal with the first control signal. Whenever these two control signals are not substantially equal, a fault has occurred in one of the two controllers. A second comparator compares the first control signal with the output signal. Whenever these two signals are not substantially equal, a fault has occurred in the generator. In an alternate embodiment an additional tracker control, comparators and default decoder provide a 2 out of 3 polling system for indicating when one of the three controllers is malfunctioning.

Malfunction detector for static VAR controllers

In a static frequency changer controlled by adjusting the time of conduction of the bilateral switching units forming static converters, the time of conduction is split into n time intervals of conduction of respective subdurations adding-up to be equivalent to the effective time of conduction of the controlled switching unit, and such subdurations are spread and distributed throughout the time period of control of the switching unit within the original switching pattern of the converters, thereby to improve the quality of the output and input currents.

Unrestricted frequency changer system and adjustable frequency AC motor

This invention is a system of automatically classifying defects both for sorting defective products (metallic surfaces, especially tube surfaces) as to the reworking operation required for correcting the defect, and for classifying the defect as to the preceding manufacturing operation which is the most probable cause of that defect and sending a signal to that operation to provide for adjustments to minimize future defects. The system uses a source of electromagnetic radiation (typically a laser beam which is scanned across the surface) and at least two sensors (adjusted such that the radiation is reflected from a defect-free surface principally received by one of the sensors but that there is a measured amount of radiation in the other sensor). An average signal of the principal sensor is developed as a function of scan position. Threshold circuitry detects when the ratio of sensor signal to average signal varies by a predetermined amount. Special circuitry is used to detect the essentially simultaneous occurrence of at least two different preselected combinations of signal variations to identify the type of defect.

Processing system for detection and the classification of flaws on

This invention is an improved method for scanning for flaws on a surface utilizing dynamic correction. Each individual scan signal is divided into a large number of increments, each increment representing a predetermined position in the scan. A dynamic average is computed for each of the scan positions and flaws are detected by comparing the increment signals to the dynamic average signal for the same position. This technique is especially useful to detect flaws on high quality tubing, such as used for nuclear reactor fuel rods or for nuclear reactor steam generator tubing.

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Murrysville, PA, United States of America

Miklos Sarkozi