A Two-Stage Approach for PV Inverter Engagement in Power Factor Correction and Voltage Regulation

Rapid integration of distributed energy resources, such as solar photovoltaic (PV), can lead to overvoltage challenges in distribution feeders due to reverse power flow and low power factor at the substation interface. While existing literature extensively explores the utilization of smart inverter capabilities for reactive power flexibility using volt-var curve (VVC), obtaining time-varying operating points of such curves in real-time is challenging due to computational demands and communications requirements. Similarly, employing optimization-based approaches for reactive power control and active voltage regulation in large-scale distribution feeders is difficult due to the complexity of the problem and the challenges in effectively engaging customer-owned resources. This paper proposes a two-stage strategy to harness smart inverters for reactive power support. The first stage formulates short-term planning by optimally designing VVCs (sub-daily basis) for large-scale solar PVs based on projected system needs and communicating optimal curves to smart inverters in advance. Subsequently, the second stage employs a transactive-based method to involve customer-owned PVs for reactive power support, effectively enhancing overall system performance and addressing real-time demands. The efficacy of this approach will be demonstrated using real-world distribution circuits provided by Vermont Electric Power Company (VELCO) and Vermont Electric Cooperative (VEC).