Optimal Reactive Power Allocation for Photovoltaic Inverters to Limit Transformer Tap Changes

This paper combines an iterative approach based voltage control algorithm for allocating the reactive power outputs of distributed energy sources (DERs) with an Augmented Lagrangian voltage deviation optimization model that takes tap positions into consideration. The approach is applied to a modified IEEE 123 bus distribution test system with several PVs of varying output. Voltage variations due to the intermittent nature of the PVs in the distribution system are constrained by scheduling reactive power injections from the inverters. Allocating reactive power outputs of PVs and changing transformer tap positions allows the proposed approach to be used as an alternative to traditional distribution voltage control approaches. Simulation results show that the proposed method is able to keep voltage magnitudes in the normal voltage magnitude range with few tap operations.