Analysis of switching transients in domestic installations with grid-tied microgeneration

With ambitious 2020 targets for increased energy efficiency and utilisation of sustainable energy sources fast approaching, the UK´s electricity networks will need to adapt in order to integrate the vast amounts of small, distributed energy sources required. Microgeneration sources rated below 16A per phase will likely make a significant contribution to meet these targets, and as such a great deal of research has focused on maximising the time-value and energy yield of such sources. Little attention, however, has yet been paid to electromagnetic transient phenomena relating directly to their use. This paper details work undertaken to determine the severity of switching transients arising as a result of the UK standard G83/1 grid disconnect requirements. The construction of a generic domestic supply model in ATP-EMTP is presented, and a systematic switching overvoltage study is performed at the consumer distribution panel and at the terminals of the LV transformer. It was found that a combination of high generator output and low instantaneous local load led to overvoltage magnitudes of approximately 1.4 p.u. Worst case scenarios were flagged for further detailed study, and a number of model refinements identified.