Distribution system grounding impacts on fault responses

One of the main concerns of utilities, nowadays, is grounding the distribution systems. Distribution systems are usually three phase systems with a returning current neutral wire. Grounding the neutral wire will affect the power quality and characteristics of distribution systems during unbalanced conditions, specially phase to ground faults. In this paper several case studies have been done to investigate the impacts of different types of grounding the distribution systems on fault responses. The fault responses are fault current, voltage swell, substation ground potential rise and neutral wire voltages and currents. Some sensitivity studies are also performed to see the effects of grounding parameters on fault responses. The results are presented in graphical and tabular forms.