Volt/VAR Support and Demand Response Co-Optimization in Distribution Systems with Adaptive Droop Control of Inverters

This paper proposes a hierarchically-coordinated Volt/VAR support scheme to cooperatively minimize operation costs and voltage deviations. The scheme uses the two-step droop control of smart inverters as well as scheduling of slow response capacitor banks and transformer tap changers. The peak shaving objective is also combined with the Volt/VAR support model to reduce dependency on traditional voltage regulators while minimizing operating costs. The problem is formulated as two-stage stochastic programming subject to day-ahead Volt/VAR device technical constraints. The results are used in a short-time probabilistic model for voltage deviation minimization by sub-hourly updating the forecasting signals. Finally, the competence of the proposed Volt/VAR support framework enabling the utilities to optimize the characteristic of inverters effectively and use the advantages of demand response (DR) and legacy devices is verified on three-phase distribution feeders. The results show that the proposed method leads to less voltage deviation and loss minimization compared to traditional strategies.