Switching transient analysis of small distributed generators in low voltage networks

This paper details work undertaken to determine the severity of switching transients arising as a result of the G83/1 grid disconnect requirements of type-tested microgeneration equipment. Models of a generic domestic electricity supply and simple urban and rural low voltage networks are constructed in ATP-EMTP, and a series of generator switching operations simulated. It was found that, on the customer supply side, the combination of high generator output and low instantaneous domestic load led to overvoltage magnitudes of 1.4 p.u. At distribution level, a direct correlation was found to exist between the number of generators on a feeder and peak overvoltage magnitudes on that feeder. Worst case scenarios were identified for further detailed study, and a number of model refinements would be required.