NERC Probabilistic Assessments Overview & Future Improvements

Transcription

1 NERC Probabilistic Assessments Overview & Future Improvements Noha Abdel-Karim, PhD. NERC IEEE LOLEWG Meeting July 31, 2015

2 Overview NERC Probabilistic Assessment (ProbA) reports extend the LTRA data with probabilistic reliability measures on all 20 Assessment Areas for two of the 10 years of the LTRA. The ProbA calculates: Expected Unsupplied Energy (EUE) Loss-of-Load Hours (LOLH) These measures add in aspects such as: Load shape Internal transmission constraints Generator forced outage rates Use of Emergency Operating Procedures Supply of operating reserve. 2

3 ProbA Objectives Calculate a complete and non-overlapping set of probabilistic reliability metrics across the NERC footprint. Perform a resource adequacy assessment covering all hours (compared to the peak demand hour observed for each season in the LTRA). Provide probabilistic reliability metrics for each NERC Assessment Area and convey a clear understanding of the reserve margin implications. Compare results over time and between studies. Examine the availability of non-firm capacity transfers between Assessment Areas. Provide a composite generation and transmission assessment (resource adequacy), which considers the ability of load to receive power supplied by aggregate resources. Calculate probabilistic uncertainty measures under a scenario with load interrupted to maintain all operating reserves. 3

4 Background PC Approved GTRPMTF Methodology and Metrics Report in September OBJECTIVE: To provide a common set of probabilistic reliability indices and recommend probabilistic-based work products that could be used to supplement the NERC s long-term reliability assessments. Pilot Assessment Report 2011 ProbA Reports 2012 & 2014 Annual EUE Annual LOLH EUE as a percentage of Net Energy for Load (normalized EUE). ProbA Report 2014 Annual EUE, Annual LOLH, and EUE as a percentage of Net Energy for Load (normalized EUE). Scenario Modeling: calculate the LOLH and EUE if load were interrupted to maintain full operating reserves. 4

5 Background Some significant aspects of power system reliability NERC needs to consider but which are NOT part of the current ProbA does not consider: Operating restrictions causing issues at light load Short-term reliability issues often caused by load or variable generation ramping uncertainties Short-term loss of load caused by resource-forced outages Loss of load from transmission or distribution, especially those caused by adverse weather Common-mode failure due to natural gas pipeline interdependencies External factors such as environmental regulations Monthly reliability indices, including targets and calculated values 5

6 Minimum ProbA Modeling Requirements All Assessment Areas must adhere to the following minimum requirements: Years Studied: LTRA forecast years 3 and 5 (i.e., 2016 & 2018 for the 2014 ProbA) Load Modeling: Use an hourly load model that includes load forecast uncertainty Capacity Modeling: Create a limitation on what generation is included in the modeling. To be included, future generation must have associated transmission. Outages: Model random outages for all units as random variables as opposed to derating the unit s capacity when modeling dispatchable capacity. Transmission Modeling: The Assessment Area may select the transmission modeling method at its discretion. Each Assessment Area must document: o How that approach takes in to account transmission constraints within and outside of the Assessment Area o How it developed the data needed for modeling. Probabilistic Measures: Generate three metric results Annual LOLH Annual EUE EUE as a percentage of Net Energy for Load (normalized EUE). 6

7 2014 ProbA Key findings Scenario analysis: has a significant impact on LOLH and EUE measures in most Assessment Areas Findings encourage further probabilistic development to assess overall BPS reliability, primarily in the context of resource adequacy planning, but also for operations. MISO tight PRM at increasing LOL Statistics Planning Reserve Margin: approaching the Reference Margin Level with increasing LOL statistics. Modeling Approach: MISO relied on prospective instead of anticipated resources in its probabilistic modeling approach. 7

8 Gigawatts 2014 ProbA Key findings The North American BPS is experiencing transformational changes, such as retirements of baseload generating units, rapid integration of Variable Energy Resources, a noticeable use of DR and distributed generation and their effects on load dynamic behavior change. NERC 2014 LTRA: Cumulative Fossil-Fuel and Nuclear Retirements between 2011 and 2024 Total 83 GW LTRA 10-Year Net Change Indicates Ongoing Declines in Coal and Growth in Gas Gas (Year 1) Gas (Year 10) Coal (Year 1) Coal (Year 10)

9 Percent Capacity Mix NERC 2015 CPP Phase 1 Assessment Potential Reliability Impacts of EPA s Proposed Clean Power Plan 9

10 Reserve Margin Scenario NERC 2015 CPP Phase 1 Assessment Impacts of CPP Cases on Regional Reserve Margins Scenario for

11 2014 ProbA Key findings In addition, using large amounts of natural gas triggered by current and proposed environmental regulations increases the displacement of the traditional large rotating generating machines and the operating characteristics those machines provide, which strains essential reliability services. NERC Phase 1 CPP Assessment: Changes to Natural Gas Generation 11

12 Summary of Results FRCC 12 Report LTRA ProbA Base Case ProbA Scenario 2012 Report 2014 Report Anticipated Reserve Margin 26.9% 25.1% 25.7% 22.3% Prospective Reserve Margin 38.2% 34.2% 30.1% 26.7% Reference Margin Level 15.0% 15.0% 15.0% 15.0% ProbA Forecast Planning Reserve Margin 25.0% 23.6% 25.7% 22.3% ProbA Forecast Operable Reserve Margin 18.0% 16.7% 20.4% 17.4% EUE (MWh) EUE (ppm) LOLH (hours/year) Scenario EUE (MWh) Scenario LOLH (hours/year)

13 Summary of Results - MISO Scenario Analysis: Interrupting Firm load while maintaining non-spinning and spinning reserves of 2,010 MW is equivalent to tightening the reserve margin by 1.6 percent. This gets MISO very close to the target reserve margin in

14 2014 ProbA Recommendation to PC Reassess the ProbA Study Effort NERC identified several considerations and lessons learned that should be evaluated before proceeding with additional probabilistic assessments. The Planning Committee should consider: Reviving the Generation and Transmission Reliability Planning Models Task Force (GTRPMTF). Centralizing the approach for probabilistic assessment to gain consistency in modeling and modeling assumptions. Increasing value of the transmission parameters required for the probabilistic assessment. Aligning an approach for scenario development with high-risk emerging reliability issues. 14

15 ProbA Next Phase Probabilistic Assessment Improvement Plan NERC PAIG Working Group Objectives Apply more rigorous treatment of the uncertainties impacting the reliability of the operation and planning of the BPS. Determine the impact of the transformational shift in BPS resource adequacy on reserve margins by assessing Short term uncertainties inside timeframes of one year Seasonal Resource Adequacy Assessment Long term uncertainties over a multi-year period Annual Probabilistic Resource Adequacy Assessment 15

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17 Discussion with LOLE WG Short term reliability metrics: Characteristics to EOE, LOLH on a monthly basis. Introducing additional metrics (i.e., LOLE, ALLR Annual Load Loss Risk) Short term data needs: Off-peak probabilistic assessment. Variable Generation: Modeling Variable Energy Resources (Wind & Solar) rather than using the current (conservative) approach: Annual Existing Certain Capacity Software tools: For NERC interconnections What other important probabilistic aspects does NERC need to focus on in the future? 17