Schweitzer Engineering Laboratories, Inc.

Douglas I Taylor

Bogdan Zdzislaw Kasztenny

Normann Fischer

Dale S Finney

Ritwik Chowdhury

The present application discloses systems and methods related to protection of a reactor in an alternating current (AC) electric power system. In one embodiment, a system may include a protective action subsystem to implement a protective action based on identification of a fault condition associated with a reactor. A frequency determination subsystem may determine when a frequency of the AC voltage is outside of a range defined by a lower threshold and an upper threshold and may identify a change in the frequency associated with de-energization of a line in electrical communication with the reactor. A supervisory subsystem may restrain implementation of the protective action when the frequency is outside of the range or when the change in the frequency is associated with de-energization of the line in electrical communication with the reactor.

Line reactor protection security using local frequency measurement

Protection of an electrical generator includes determining a rotor and stator components using rotor and stator electrical signals, calculating a unbalance and/or differential component using the stator and rotor components, and determining a stator or rotor fault based on the unbalance and/or differential component. Further, the faulted phase and/or zone of a stator fault may be determined using the stator positive sequence voltage and negative sequence current.

Systems and methods for monitoring and protecting an electric power generator

Disclosed herein are systems for detecting a location of a fault on an electric power transmission line using a state-of-polarization traveling wave in an optical ground wire. Various embodiments may also detect a traveling wave on a conductor of the transmission system. The arrival times of the state-of-polarization traveling wave and the electrical traveling wave may be compared. Using the difference in times and the known propagation velocities of the traveling waves, a distance to the fault may be calculated. Arrival time of the state-of-polarization traveling wave may be calculated using electrical signals from photodetectors in an optical channel with polarizing filters at different orientations or reference frames.

Transmission line protection using traveling waves in optical ground wire fiber

Disclosed herein are systems for detecting a location of a fault on an electric power transmission line using a state-of-polarization traveling wave in an optical ground wire Various embodiments may also detect a traveling wave on a conductor of the transmission system. The arrival times of the state-of-polarization traveling wave and the electrical traveling wave may be compared. Using the difference in times and the known propagation velocities of the traveling waves, a distance to the fault may be calculated. Arrival time of the state-of-polarization traveling wave may be calculated using electrical signals from photodetectors in an optical channel with polarizing filters at different orientations or reference frames.

A system for reducing inrush current in a three phase utility transformer upon energization of the transformer by an applied three phase voltage utilizes a pre-flux circuit for establishing residual flux levels in the core segments of the primary windings of the transformer which are near the prospective flux levels established in the core segments by the applied voltage. The pre-flux circuit includes a pre-fluxing capacitor which, after being charged to a predetermined voltage level, is discharged serially through two of the primary windings to establish the predetermined flux levels in the core segments of the two windings, and a reduced flux level in the core segment of the remaining primary winding. The transformer is energized at the instant of positively-referenced peak phase voltage to the third primary winding such that prospective and residual flux approach a near-equal level in all three core segments and inrush current is reduced. The method may be applied to the secondary or tertiary windings instead of the primary windings. Additionally, an alternative method allows application of the pre-fluxing circuit to a delta-connected set of transformer windings.

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Pullman, WA, United States of America

Douglas I Taylor