Volt-VAr Optimization of PV Smart Inverters in Unbalanced Distribution Systems

This paper proposes an operational scheduling model of distributed energy resources (DERs) and PV smart inverters with Volt-VAr controller using an accurate AC optimal power flow (ACOPF) in an unbalanced distribution network. A mathematical mixed-integer model of local Volt-VAr droop controller of the distributed mixed-phase PV smart inverters is proposed based on the IEEE 1547-2018 standard and is incorporated in the unbalanced ACOPF, which enables effective utilization of the Volt-VAr controllers to not only alleviate voltage issues locally but also at the feeder level. The proposed model is tested on two actual snapshots of a distribution feeder in Arizona. Also, the proposed operational scheduling method considering the Volt-VAr droop controller of PV smart inverters is compared with a recent work in scheduling of the PV smart inverters. The results illustrate that the PV smart inverters dispatches obtained by the proposed model can be practically implemented by local controller of inverters.