GENERAL
Why does MISO want to reform accreditation methodology?
The purpose of MISO’s accreditation reform is to adopt accreditation methodology that is consistent across all resource types and that will remain stable as the mix of MISO resources and system risks continue to evolve.
What is the primary goal of MISO Resource Adequacy construct?
As an RTO, one of MISO’s key functions is to facilitate the availability of adequate resources to reliably meet the demand in the MISO region. MISO’s Resource Adequacy construct complements the jurisdiction that regulatory authorities have in determining the necessary level of adequacy and works in concert with Load Serving Entities that provide demand forecasts that help drive the development of local and regional requirements using Loss of Load Expectation (LOLE) metric of 1 day in 10 years.
Why are Load Serving Entity (LSE) obligations also tied to the portfolio of the entire system?
The MISO system has consistently been modeled as a whole interconnected system when establishing the Planning Reserve Margin Requirement, which is dependent on the performance of all the resources in the MISO fleet. Resource Accreditation should reflect resource performance during the times of system need to ensure reliability of the system as a whole.
Does this Accreditation reform contain capacity replacement requirements?
No, replacement capacity is not included in this proposal.
Why does MISO look at all Resource Adequacy (RA) hours as being equal?
MISO believes that considering all hours in the analysis serves to strengthen the reliability analysis. The RA hours identify situations when the operation of the system was approaching critical conditions. High demand is still a main driver of results, but the modeling also considers other systems risk, which are essential to understand.
DIRECT LOSS-OF-LOAD METHODOLOGY (DLOL)
What is the Direct Loss-of-Load Methodology?
Direct Loss-of-Load (DLOL) is a methodology to calculate the marginal capacity value of resources in resource adequacy studies. It measures the marginal contribution of a resource to reliability, by calculating the average generation of said resource during critical times in the system, also known as loss-of-load (LOL) hours.
Which hours of the year are considered in the DLOL methodology?
MISO’s probabilistic analysis, and thus DLOL, includes the simulation of all hours of the year. The DLOL method captures a resource’s availability during LOL hours (when reliability is at the highest risk).
Why are RA hours and modeled DLOL hours different?
DLOL hours capture a broader set of system conditions than RA hours (dozens of load/weather years, hundreds of resource outage patterns, etc.). RA hours only reflect one possible scenario of hundreds that are covered in the probabilistic model. While DLOL hours capture the expected contribution of resources under a wider range of conditions, RA hours examine actual performance of the resources during historical high-risk hours. The methodology combines both to recognize the importance of both and how they complement each other.
Are LOL hours the same for all resources?
Yes, the LOL hours are determined by the reliability model and are consistent across all resource types in determining DLOL.
Does MISO’s proposal for DLOL apply to all non-emergency resource types?
Yes, the DLOL methodology is being proposed for all non-emergency resource types.
Does the DLOL methodology capture portfolio effects?
Portfolio effects only need to be separately accounted for with average-type accreditation methods. For marginal accreditation approaches, such as the DLOL approach, portfolio effects are captured by explicitly modeling the expected energy mix without changing the risk profile because it is not necessary to remove an entire resource class from the system.
Will MISO be sharing LOL hours similar to RA hours?
Yes, MISO will be sharing LOL hours.
Will MISO be providing the class level DLOL values?
MISO is evaluating a 5GW, 10GW, and 15GW solar scenario, as well as 5GW wind scenario. MISO will be sharing class level DLOL values for simulated scenarios when they are available.
When will MISO be making future DLOL estimates available?
The future year estimates are planned to be provided annually as part of the Regional Resource Assessment (RRA) Study starting in 2024.
Will the transition to the DLOL methodology be gradual?
MISO has proposed a 3-year transition period prior to full adoption of DLOL accreditation methodology, during which MISO will provide stakeholder with indicative results.
Will the Reliability Demand Curve (RDBC) proposed reform impact the DLOL methodology?
MISO is committed to evaluating any potential interdependencies between different reform efforts that are being worked on in parallel. With respect to the RBDC proposal that is being considered, there is no direct impact on the proposed DLOL accreditation methodology.
Will MISO be providing preliminary data for alternative accreditation methods?
This data is not readily available and cannot be provided within the scope of MISO’s proposed accreditation methodology.
HYBRID RESOURCES
How will hybrid accreditation be assessed in both co-located and DIR configurations?
Accreditation will be determined by the performance of the component resources. The Market Participant’s chosen operation of the component resources can result in different performance outcomes.
How will component level metering be defined?
Component resources will be defined by their underlying generation technology, such as wind, solar, steam, etc.
How will performance be measured for a DIR hybrid?
Performance will be measured by Real-Time offers, which are based on the DIR forecast. Hybrid DIR must provide their own forecast and cannot use the MISO forecast.
Why is MISO capping the aggregated accredited value of hybrid and co-located resources?
The independent treatment of the hybrid components will provide an upper bound of their contribution of system reliability, so the combined modeling will not exceed the sum of the parts. Even if separate component capabilities could exceed the interconnection service limit, the interconnection limit provides a total upper bound on possible contribution according to the interconnection agreement.
STORAGE RESOURCES
Why does MISO expect the accreditation values of storage to decrease?
Storage accreditation is expected to decrease because right now storage is modeled assuming full state of charge at the time of loss of load which may not match the behavior of storage in operations. MISO plans to work with stakeholders on further improvements to LOLE modeling, including how storage should be modeled in the LOLE analysis to align with its expected operations in Real-Time.
Will an 8-hour battery and 4-hour battery be placed in the same storage class?
Unit-level values will be set depending on the capabilities of those units in Tier 1 and 2 hours. If the battery with a larger reservoir provides a better alignment, its resulting individual accreditation allocation from the overall resource class will be higher.
LOSS-OF-LOAD EXPECTATION (LOLE)
How is the LOLE modeling performed?
Resource Adequacy calculations in MISO’s LOLE studies use a probabilistic model. This model considers how system uncertainties may affect the ability of the system to reliably serve load and quantifies and characterizes the events in which load is unserved. Uncertainties considered include demand and energy forecast, timing and magnitude of load, resource maintenance and forced outages, dispatch limits, weather effects on renewable generation, and reliance on external imports, among others. An overview of the model is available here.
How is load modeled in the LOLE simulation?
The resource adequacy probabilistic model uses 30 years of historical hourly data to capture load uncertainty. These load profiles are modified to account for load growth for the target year. Economic load uncertainty is also considered along with the 50/50 load forecast. More information can be found here.
How can I get more information about the LOLE model that was not covered in the whitepaper?
The DLOL Design paper is intended to describe conceptual design of MISO’s proposed accreditation methodology. A workshop is being planned in September for detailed discussion on LOLE modeling and the determination of the PRMR.
Will there be any improvements to the LOLE model?
MISO plans to work with stakeholders on future improvements to LOLE modeling.
Where will MISO be sharing LOLE modeling improvements/changes?
Stakeholder can follow LOLE modeling improvements through the LOLE Working Group (LOLEWG).
How will LOL hours be determined for each season?
Loss of Load Hours (LOLH) are any hour where the demand for energy exceeds the resources available in a given hour within the model. The resulting system risk from the probabilistic simulations of 30 years of correlated weather load shapes in the LOLE model can be represented as cumulative LOLH in each season.
Will MISO be expanding the class-level constraint of load>generation to the top 3% of tight margin hours within 25% reserve margin or less per season?
MISO is still evaluating if and how to expand the threshold for DLOL hours for class level accreditation. MISO will share its analysis with stakeholders when they are available.
How do seasons with significantly fewer LOL hours impact the accreditation of resources in those seasons?
The minimum reliability level for all seasons (0.01 days/season) determines the number of hours considered in the DLOL calculations. MISO has confirmed that all seasons have at least 200 hours being used in the determination of DLOL values. Seeking a larger or smaller number of loss of load hours would require modifying the minimum established reliability level for those seasons, which is out of scope for this project.
If the PRM was lower than what is needed to meet peak load wouldn’t this lead to potential loss of capacity to retirement and/or other markets?
The resulting PRM will ensure that all hours of the year (including peak load) will be reliably served. MISO’s proposal to directly align the PRMR with LOLE modeling will ensure that sufficient capacity is available to meet load during the most critical hours by using a Monte Carlo simulation to anticipate a variety of load and generation outcomes and will continue to be informed by peak load forecasts.
What does MISO mean by “translation to PRA,” from “percentage based” to “Megawatt (MW) based”?
Currently, MISO provides the PRMR from the LOLE study as a percentage in the PRA. In the future, the LOLE study PRMR MW will directly inform the PRA.