Investigation of Temporary Overvoltage on Microgrid with Emphasis on Ferroresonance

摘要

Temporary overvoltages caused by primary and secondary islanding due to a fault on a hybrid microgrid of a wind energy and PV system that was connected to the grid, was considered in this study. Symmetry opening of three poles opening and nuisance opening of circuit breaker leading to ferroresonance were investigated using ATP/EMTP. The findings show that during primary islanding an overvoltage of 5.60 P.U. was observed and 7.05 P.U. during secondary islanding. An overvoltage of 3.43 P.U. was experienced during an event of ferroresonance, which could be suppressed by transposing the cable and by connecting a resistive load which is 1% of rated transformer. The effect of the length of the cable on the ferroresonant overvoltage was also studied and found to decrease with the increase of the length of cable.