EPRI analysis: Smart inverter grid support functions can save utilities money
An analysis by the Electric Power Research Institute (EPRI) shows that new operational capabilities offered by smart inverters can provide technical and economic gains when those capabilities are activated and properly configured by utilities.
The assessment, part of an Electric Program Investment Charge (EPIC)-funded Pacific Gas and Electric Company (PG&E) project, provides one of the most comprehensive analyses of the potential impacts of smart inverters’ grid support functions on electric distribution systems in which rooftop distributed photovoltaic (PV) panels are extensively deployed.
“In areas where we see significant private PV installation, the potential increases for effects on power quality within the distribution system,” explained Jouni Peppanen, a technical leader in EPRI’s Power Systems Studies and a principal researcher of the effort. “PG&E wanted to better understand if and how smart PV inverters could address these PV-driven power quality problems and if smart inverters could be deployed at a cost lower than that of traditional network upgrades. This analysis addresses these questions.”
EPRI’s model expanded typical distribution engineering modeling of the primary, medium voltage system (the poles and wires at the street level) to examine low-voltage secondary circuits in detail (the private resident level). This comprehensive and detailed modeling enabled researchers to quantify more accurately the effects of smart inverter functions extensively deployed on distributed residential rooftop PV.
Researchers used EPRI’s OpenDSS software to model the technical impacts and economic value of volt-var and volt-Watt functions defined in California Electric Rule 21 (CA Rule 21), Hawaiian Electric Rule 14 (HI Rule 14), and IEEE 1547-2018 for smart inverters. The researchers performed a detailed comparison of the industry-recommended default settings defined in CA Rule 21 and HI Rule 14.
“We modeled more than 15,000 scenarios across six feeders using multiple technology penetration levels, load conditions, and PV generation profiles,” said Miguel Hernandez from EPRI’s Power Systems Studies group and another principal researcher of the effort. “Based on our extensive literature review, we believe this is the first report to take a holistic approach to the distribution system — from the grid to the home, and back — when modeling impacts of PV and smart PV inverters. This bigger picture could inform distribution network investments for utilities around the world.
While the six distribution feeders’ characteristics reflect the diversity of PG&E’s distribution system, they represent a very small portion of the total system. The effort’s findings suggest measurable gains for electric utilities that address the effects of smart inverters on distribution systems with extensive PV penetration and support further investigation.
The report, “EPIC 2.03A: Smart Inverters: Modeling Report,” is available to the public through PG&E’s Electric Program Investment Charge Project Reports webpage.
News item from the Electric Power Research Institute