Asea Brown Boveri Ab

Abb Power Td & Company

Kevin J Timko

Aftab H Khan

John G Reckleff

Hisham A Othman

Willie K Wong

A trigger control system for a thyristor-controlled series capacitor (TCSC) is disclosed. In one application, a power system 10 is coupled to a load 12 by a series capacitor 14 connected in parallel to a thyristor unit 16 and inductor 17. The thyristors are triggered by the control system 18, which includes a first circuit 20 that generates signals proportional to the peak of the line currents, a stabilizer circuit 22, an adder 24, a look-up table 26, a conversion circuit 28, a pulse generator 30, a phase-locked loop (PLL) 32, a ramp generator 34, a trigger window circuit 36, and a three input AND gate 38 the output of which is a grid pulse signal 40 that triggers the thyristor unit 16. The control system diminishes power swing oscillations and subsynchronous resonance oscillations.

Thyristor-controlled series capacitor triggering system

A dynamic mechanically-switched damping (DMSD) system is described which utilizes one or more mechanical switches and appropriate controls to switch series or shunt reactive impedances in order to provide power oscillation damping in power systems. The DMSD system provides a controller which can be configured based on the number of mechanical switches in the DMSD system, the type of reactive impedances interfaced to the power system by each switch and the magnitude of each of the reactive impedance. The DMSD system monitors parameters of the power system and the controller generates a modulation signal based on the monitored parameters. The modulation signal is processed to identify a reactive impedance of the available DMSD system reactive impedances required to damp power oscillations. Appropriate switches are selected for supplying the required reactive impedance. A switching control signal is generated and output to each of the selected switches to synchronously open or close the switch at a predetermined instant.

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Apex, NC, United States of America

Kevin J Timko