CAISO is moving forward with an initiative meant to ease the integration of distributed resources into its markets.
The main goal of the program: to make it easier for grid-connected resources such as rooftop solar, energy storage, plug-in electric vehicles and demand response to participate in the ISO’s market operations, creating more system flexibility and reducing carbon dioxide emissions.
“The number and diversity of these resources are growing and represent an increasingly important part of the resource mix,” CAISO said in its revised proposal.
On May 4, CAISO provided an update on phase two of its Energy Storage and DER initiative, which will propose changes that are due to be reviewed by the Energy Imbalance Market (EIM) Governing Body on July 13 and submitted to the ISO’s Board of Governors for approval during its July 26-27 meeting.
The proposals involve improving the accuracy of DR contributions through alternative energy usage baselines, distinguishing between charging energy and station power for storage resources, and developing a net benefits test for DR resources that participate in the EIM.
Expanded Baseline Options
According to CAISO, a majority of market participants support a set of baselines to assess the performance of proxy demand resources — DR aggregations of retail customers — that was developed by a stakeholder working group.
While the current “10-in-10” baseline methodology is considered accurate for many large commercial and industrial customers, stakeholders don’t think it is appropriate for all customer types, prompting the working group to propose additional baselines. Using the 10-in-10 methodology, the ISO calculates a baseline by examining the 45 days prior to a trade date and finding 10 “like” days in which no DR was required. The ISO then uses hourly average meter data to create a baseline representing a typical load profile, and the resource is paid for reducing usage below the baseline.
Under the new proposal, baselines for residential resources would be based on a four-day weather match that estimates what electricity use would have been in absence of DR dispatch under similar weather and on similar days, and using a control group of similar users.
Commercial baselines would be based on the 10-in-10 method with a 20% adjustment cap, an average of the previous five days and a control group. Baselines are adjusted using actual load data in the hours preceding a DR event to better reflect variables that might not be present in the historical data.
“Stakeholders who supported the proposal stated that the use of additional baselines for residential and commercial customers would improve the accuracy and reduce bias when compared to the 10-in-10 baseline,” CAISO said.
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