A Cloud on the Horizon: Power quality assessment in distribution grids with rapid photovoltaic fluctuations and mitigation strategies using Electric Vehicles

Abstract

Cloud transient can cause rapid fluctuations in photovoltaic (PV) generation output, which could significantly affect the voltage levels in distribution grids with high PV penetration. This could concern distribution system operators (DSOs), as they are responsible for compliance to the EN-50160 power quality standards in distribution grids. This thesis analyzes the effect of rapid PV fluctuations on voltage levels and voltage fluctuations in the distribution grid by performing load flow simulations for an existing distribution grid in the Netherlands using PV data with a 20-second resolution. The analysis considers different electric vehicle (EV) charging strategies and scenarios corresponding to three different years (2017, 2030 and 2050), different seasons (summer and winter) and different levels of PV fluctuation. In addition, an optimization framework for the mitigation of PV fluctuations through EVs has been proposed and tested. The results show that voltage fluctuations induced by PV fluctuations are minor in 2017, but are considerably high in 2050. However, the voltage fluctuations are largely dependent on the location in the distribution grid, the grid configuration and the installed PV capacity. In 2050, the reported voltage fluctuations can lead to regular visible and annoying light flicker. The analysis also shows that implementation of the proposed mitigation framework with EVs reduces the amount of light flicker and that EV availability is sufficient in 2050 to act as a reliable mitigation technology, although this comes with additional charging costs.