Skip to Main Content

Variable Resource Integration and System Flexibility Needs

Our state-of-the-art PSO modeling tool is well-designed to simulate the operation of variable resources and corresponding system flexibility needs to incorporate them.

We are able to model system operations down to a minute-by-minute basis, capturing all the intra-hour variability of these intermittent resources and load. Additionally, we are able to model the interaction between the day-ahead and real-time decision cycles and forecast error between cycles. This capability is important for assessing system design needs and the full costs of integrating renewables, as well as the benefits of storage, real-time coordination across RTOs, and other strategies to integrate renewables. Furthermore, we are able capture a full range of feasible renewable integration strategies by customizing operating reserves characteristics and modeling storage resources and demand response to optimize system flexibility.


Below is a list of representative engagements for our Variable Resource Integration and System Flexibility Needs practice.

Benefit-cost analysis of ERCOT's proposed Future Ancillary Services design

For the Electric Reliability Council of Texas (ERCOT), we evaluated the benefits of its proposal to unbundle ancillary services, enable broader participation by load resources and new technologies, and tune its procurement amounts to system conditions. We worked with ERCOT staff to assess each ancillary service and how generation, load resources, and new technologies could participate. We also directed their simulation of the market using PLEXOS, and evaluated other benefits outside of the model.

Renewable integration for Aruba and other island systems

Island power planning faces distinct problems not observed in larger markets. Brattle experts prepared a study for W.E.B. Aruba, the power generation and water provider on the island, on integrating 30 percent of wind energy and 10 percent of other renewables, including solar and biogas. The study included development of different ancillary service requirements, detailed operational simulations accounting for renewables and load forecast uncertainty and variability, generator maintenance and forced outages, economic cost, and benefit evaluations of renewables integration. Several technologies were analyzed to improve wind integration, including different types of storage and demand management solutions. Including the approved second wind plant, several solar plants, and other innovative technology options, Aruba is expected to attain nearly 50 percent energy from renewable resources by 2018. Brattle experts are now being asked to help prepare a roadmap for Aruba to achieve the ultimate goal of becoming 100 percent oil-fuel free (for energy and water production). Similar analyses have been prepared for several other islands.

Renewable integration analysis and model development

For a utility in the Western U.S., Brattle experts assessed the potential compensating resource needs and costs associated with integrating intermittent resources into the regional system. We designed and managed the development of the first user-interactive evaluation tool to estimate the investment and operational cost associated with increasing regulation, load-following, day-ahead scheduling, and ramping services that will be needed with increasing intermittent resources that have generation output that can be unpredictable and variable in nature. The framework and mechanics of the model have been presented before the California Public Utility Commission’s Stakeholder workshops, with results of scenarios discussed at various forums.

Benefits and cost analysis of implementing a Western U.S.-wide energy market

In 2016, Brattle experts led a team of multiple consulting companies to help California ISO evaluate ISO regionalization and transitioning the Western Interconnection into a locational marginal cost-based full “Day-2” energy market with centralized optimized day-ahead unit commitment and real-time dispatch. Our role included using PSO to develop West-wide nodal production cost simulations for 2020 through 2030 to assess impacts on ratepayers, emissions, grid operations, and the ability to integrate large amounts of variable renewable generation across the region. We also analyzed the findings of other regional markets that have gone through similar transitions, reviewing two dozen ex-post and ex-ante studies of the costs and benefits of regionalization, transitioning from zonal to nodal market design, and migrating from a real-time imbalance market to a full day-ahead market with optimized unit commitments and ancillary services markets. Our work culminated in a public report and several presentations to stakeholder groups across the West and in California. It provided the analytical foundation for active ongoing multi-state discussions about ISO regionalization.

News & Knowledge