MV generator low-resistance grounding and stator ground fault damage

The purposes of This work are: 1) to examine the generator transient over-voltage and currents under the low-resistance ground fault conditions, and also to evaluate their corresponding stator ground fault damages, and 2) to establish an acceptable maximum system ground fault level. For comparison purposes, three versions of low-resistance grounding systems have been considered and they are: a low-resistance grounding system with a neutral breaker at the generator (hereinafter called a "neutral breaker system"); a low-resistance grounding system with the generator neutral low resistor being switched to a high-resistor after a stator ground fault (hereinafter called a "hybrid system"); and a low-resistance grounding system similar to the current practice (hereinafter called a "traditional system"). The simulation study is conducted with the aid of the electro magnetic transient program (EMTP). An experimental analog generator model is also used to verify the simulation results.