APPARAT FOR ATT SKYDDA ETT KRAFTSYSTEM MOT VERKNINGARNA AV UNDERSYNKRONA STROMSVENGNINGAR

摘要

Apparatus for protecting a power system or a portion thereof against the effects of subsynchronous current oscillations is disclosed. A signal representative of or proportional to the subsynchronous current is developed via synchronous modulation and bandpass filter techniques. This signal is fully rectified to produce a waveform from which information can be garnered from both the positive and negative half-cycles.