Study on Resistance Grounded System of 110vK

Generally, neutrals of 110kv distribution system in China are directly grounded. When single phase-to-earth fault occures, there is a serious voltage sag in load side and the short-circuit current is very high, in some case it´s even higher than three-phase short-circuit current. 110kv resistance grounded system has been studied in this paper. Results show that this mode can inhibit the single-phase short-circuit current and reduce voltage sag of load side to improve power quality. The overvoltage level will not exceed the insulation level of existing electrical equipment if we reasonablely choose the value of neutral grounded resistance. PSCAD simulation has verified that.