Unit-connected generator with ground-fault neutralizer in generator neutral during ground-fault process

The 1st harmonic of the voltage zero-sequence component in the generator neutral during generator normal operation, during faults in the generator stator windings and in the power system and 3rd harmonic of the voltage zero-sequence component in generator neutral during normal operation and during ground-faults in stator winding are analysed. The influence of element grounding generator neutral on these all voltages for different parameters of the generator and transformer, the additional capacitance to ground of the generator breakers was determined. This influence was analyzed for generators with the ground-fault neutralizer (GFN) grounding generator neutral. The different resistances of the breakdown channel during ground-faults along the whole length of generator stator winding were considered in analysis. It has been found that for applied method of grounding the generator neutral, the level of neutralisation of the ground-fault current as well as the parameters of generator and transformer, the additional capacitance to ground of the generator breakers, level of fault resistance and ground-fault location have a substantial influence on these voltages. The voltage zero-sequence components in generator neutral and distribution of 3rd harmonic voltages in generator stator winding during normal generator operation and during ground-faults are determined mainly by these all parameters.