Testing Ground Fault Protection of Generating Units With Frequency-Selective Grounding
S. A. Saleh, Razzaqul Ahshan, Marcelo E. Valdes, D. Jewett, Claudio S. Mardegan, Julian Meng, Sergio Panetta
Abstract
This paper experimentally evaluates responses of ground fault protection for synchronous generators, which are grounded using frequency-selective grounding. Frequency-selective grounding is designed to provide a low ground impedance path (similar to solid grounding) for high frequency zero-sequence current components. This grounding system also provides an impedance similar to a low-resistance grounding for low frequency zero-sequence current components. The frequency-dependent equivalent impedance of frequency-selective grounding can affect ground potential and current, which are typically used as inputs for ground fault protective relays. Effects of frequency-selective grounding on ground fault protection are experimentally evaluated using a 7.5 kVA synchronous generator. Experimental tests are conducted for different implementations of ground fault protection, when responding to fault and non-fault events. Evaluation results detailed in this paper demonstrate the negligible effects of frequency-selective grounding on responses of different ground fault protective relays.