Effective VOLT/VAR control in low voltage grids with bulk loads such as electric vehicle garages

Abstract

The growing share of distributed energy resources aggravates voltage control in distribution grids. The X(U) local control and its combination with Q-Autarkic customer plants are the most effective and reliable Volt/var control strategies in low voltage grids with high prosumer share. However, these strategies may need adaptations to guarantee voltage limit compliance when bulk loads such as electric vehicle parking garages are connected to the low voltage feeders. This paper extends the X(U) local control concept to involve bulk loads in Volt/var control and analyzes the resulting load flows in a real low voltage grid. Results show that the extended control scheme reliably removes all voltage limit violations by increasing the reactive power flows through the low voltage feeders and distribution substations.