Undervoltage Mitigation in Unbalanced LV Grids with High Penetration of Electric Vehicles

Abstract

In this paper, a new strategy is proposed for controlling the on-load tap changer (OLTC) of medium-/low-voltage (MV/LV) transformers. The primary objective is the real-time voltage regulation of unbalanced, low-voltage (LV) distribution grids. Emphasis is placed on the mitigation of undervoltages that may occur during the charging of electric vehicles (EVs). Core of the proposed methodology is the identification of a critical bus that acts as a control reference for the proposed OLTC control scheme to determine the tap position that effectively alleviates undervoltages. The performance of the proposed control scheme is evaluated by performing quasi-static simulations on the IEEE European LV test feeder, assuming a high EV penetration scenario. In addition, a parametric analysis is conducted to identify the critical parameters that affect the ability of the proposed method to regulate the network voltage with reduced number of tap changes.