Sub-hourly Grid Modeling Capabilities with PLEXOS

from the June 2011 Issue of Up to Wind Speed, a newsletter published by the National Renewable Energy Laboratory (NREL)

NREL plans to use PLEXOS in the Western Wind and Solar Integration Study - Phase 2 to examine the impacts of variable generation on conventional units, and in the Eastern Wind Integration and Transmission Study - Phase 2 to examine the ability of demand response to help integrate variable generation.

Traditional production cost modeling uses hourly time steps; however, many of the effects of renewable generation are apparent at the sub-hourly level. In the second phase of the integration studies, NREL researchers and analysts will refine the level of analysis, with sub-hourly grid modeling tools such as PLEXOS.

PLEXOS is a next-generation, optimization-based simulation solution that uses linear programming capabilities. It is used by industry analysts and power companies to resolve regional reserve allocations, resource expansions, emission values, and market prices for energy and reserves.

The PLEXOS software models a 5-minute real-time energy and ancillary-service market dispatch, for areas as large and complex as the Eastern Interconnect, at a nodal level. It can be used to analyze the impact of variable generation on economic dispatch and the impact of variable generation on reserves. It offers more detailed modeling of conventional generator emissions that are the result of ramping events. It allows the analysts to examine the benefits of faster markets, balancing area cooperation, and shorter time horizon forecasting techniques.

NREL's Transmission and Grid Integration Group is comprised of experts on power grid integration of renewable power sources such as wind, photovoltaics, and concentrating solar power. With the use of new tools like PLEXOS, NREL can analyze unit scheduling at sub-hourly levels to utilize the most recently available information on variable output and the demand response to variable energy generation.