Stealing Vars In Broad Daylight: Inverter-Based Solar Challenges On The Distribution Grid

The recent rapid expansion of inverter-based resources (IBRs), particularly solar, has shifted from the transmission grid to the distribution grid due to limited transmission hosting capacity. However, the distribution grid was not originally designed to interconnect generation, creating significant operational challenges for utilities. According to ANSI C84.1, Distributed Generation (DG) interconnections are limited by the maximum voltage rise the distribution feeders can support without damaging customer and utility equipment. High voltage conditions are the leading challenge posed by DG, followed by thermal limitations and reverse power flow concerns. Additionally, phase imbalance challenges arise when dealing with single-phase versus three-phase solar sites.

This paper examines the challenges typically encountered with capacitor operation when integrating solar generation into distribution feeders. Modeled circuit examples illustrate how optimized capacitor placement and operation using IEEE 1547-compliant smart inverters can improve voltage regulation, enhance power factor, and increase solar hosting capacity on distribution feeders.