LRTP Informal Feedback: Reliability Dispatch Methodology and Scenarios (20230310)

• GRE supports the MISO recommended scenarios including wind max, wind drought, high transfers and further suggest extreme transfers from ND/SD to the east, an east to west (Buffalo ridge/ND), and even a MH (water drought) being served from the east and south (beyond the Buffalo ridge/NW Iowa).
• MISO will have to consider dispatch assumptions for high curtailment situations.  Preliminary PROMOD results showed ~100 GW of curtailment for an hour equivalent to a high wind shoulder PSSE model where wind significantly exceeds load. From a benefit to cost standpoint, transmission outlet capability shouldn’t be over built for wind that will be curtailed anyway for gen-load imbalance.

ITC would like to provide the following feedback to MISO on LRTP Tranche 2 Reliability Dispatch Methodology and Scenarios:

ITC believes that a scenario or scenarios with high exports to IESO on the Michigan interface, as well as to PJM should be evaluated.  With the models assuming a west to east transfer, it would be good to be able to evaluate what happens when transfers from MISO to IESO and from PJM West to PJM East are looked at in conjunction with the MISO West to East transfers.  With the existing other planned scenarios in tranche 2/F2A, imports into MISO on the same interface should not be required to be evaluated.

In addition, ITC believes that a high load, high wind, high solar (i.e. high load – high renewable) case should be evaluated.  Historically in the ITC Midwest footprint a high wind high load scenario has been observed and is viewed as a credible dispatch, and it seems like this is an additional credible dispatch that will occur as more solar is added to the system.

Lastly, ITC requests that MISO provide the capacity factors used for renewable dispatches in each model/scenario built, possibly as a model guide or similar.  This would be especially helpful for the scenarios/models where the renewable dispatch is not uniform across all MISO LRZ’s.

Feedback of the Mississippi Public Service Commission re: LRTP Tranche 2 Reliability Dispatch Methodology & Scenarios

In the March 10, 2023, Long Range Transmission Planning (LRTP) Workshop, MISO presented an overview of Dispatch Methodology of Core Reliability Models and a first set of additional scenarios.  MISO asked Stakeholders to submit informal feedback on the theme of additional scenarios by March 24, which was extended to March 31.  

While the subject of this feedback request is limited to LRTP Tranche 2 and thus to the N/C MISO subregion, based on the limited information presented at the meeting, and subject to the North/South constraint (RDT), MISO’s proposed methodology may omit some of the value of the MISO N/C and MISO South subregions’ diversity in wind and solar available during critical hours of the analysis.

The Mississippi Public Service Commission (Commission) recommends additional scenarios involving dispatch adjustments necessary to address regional and local solar and wind resource variability and transmission constraints. 

Stakeholders have an interest in better understanding the benefits (and risks) of renewable energy resource geographic diversity. If MISO has the tools to evaluate the diversity of wind and solar resources across the MISO footprint, it should propose methods to benefit from that diversity. If not, we encourage MISO to secure the necessary meteorological knowledge and tools to delve deeper into this topic.  Conversely, the Commission is particularly interested in how MISO will address extended MISO-wide wind droughts such as the ones experienced in Europe in 2021 and 2022 from Summer into Fall.[1] 

The Commission has identified several concerns with MISO’s proposed LRTP Tranche 2 dispatch scenario analysis:

First, the dispatch analysis methodology identifies certain “hours of interest” for the whole MISO footprint and then fixes the Area Interchange (including imports/exports with MISO North-South) prior to “stressing” the system for various dispatch scenarios for MISO N/C (LRZs 1-7). This approach ignores the solar and wind availability in areas contiguous to MISO N/C. The values initially used to establish Area Interchange may be correlated to the wind/solar changes MISO assumed in its dispatch scenarios.  

Second, MISO’s solar/wind resource mix assumed in its most recent resource expansion plan and preliminary siting, is incorrect as it assumes too much wind in MISO South.[2]  Southern seasonal patterns of wind speed and solar irradiance support solar generation coupled with storage and/or clean thermal generation (to better match daily load patterns), not wind generation.  Recognizing prevalence of southern solar could offset MISO N/C Winter Wind Drought conditions in MISO N/C.

Fixing the Area Interchange may overestimate the need to dispatch resources other than wind and solar in MISO N/C (LRZs 1-7).  MISO should gain a better understanding of how weather changes drive wind and solar resource availability simultaneously across its footprint and then dynamically model Area Interchange to identify more realistic dispatch scenarios.

WPPI appreciates MISO’s initial steps in defining dispatch scenarios, both the core models and the additional scenarios.  This appears to be a good start.  We would suggest consideration of the following as well:

• Ensure that MISO’s Summer Night Scenario captures conditions with demand net of solar at near-peak levels, as in hot summer days near sunset
• As a complement to the High Wind in West scenario, consider conditions with low renewable output in the west but high renewable output in other MISO regions
• Consider high-demand/lower-renewable scenarios in which significant depletion of 4-hour battery storage could be expected, to shed light on the question of the appropriate battery-MWh-to-converter-MW ratio for energy storage
• Consider cases that facilitate an understanding of ramping constraints we may encounter with rapid changes in renewable output

We recognize that adequate analyses of these latter two sets of circumstances may require going beyond power-flow analysis to engage in sequential hourly simulation, via production-cost modeling, for example, and we encourage MISO to include such modeling in the Tranche 2 analysis.

The Transmission Owners (TOs) appreciate MISO’s presentation at the 3/10/23 Long Range Transmission Planning (LRTP) Workshop about the reliability dispatch methodology and scenarios that will be used in the Tranche 2 study and the opportunity to provide feedback. The set of dispatch scenarios are important because they will help ensure the portfolio identified in Tranche 2 will address the type of issues experienced currently and anticipated in the future.

The TOs offer these comments.

• Slide 9 from the presentation at the 3/10/23 workshop describes a summer night scenario, which the TOs support using. However, the TOs think this scenario or an additional one should reflect a lower wind and no solar summer twilight scenario.  This 100% peak load scenario would test both higher MW and MVAR demand.
• The TOs suggest MISO consider a scenario that reflects what occurred in the MISO footprint during Winter Storm Elliot on December 23, 2022. This would include:
• Winter peak loads
• No/low solar due to overcast/snow coverage
• No/low wind due to icing or speed cutout
• No/low natural gas dispatch due to gas curtailments and failed starts
  • Could be systemwide, but on 12/23/2022 the South was most impacted so it created a high North to South bias. This pushed MISO to their Regional Directional Transfer limit.
• The TOs also suggest that MISO consider additional scenarios that reflect the tight margin hours that were identified in the 2022 Regional Resource Assessment report.
• Given the amount of storage being added to the LRTP models, both stand alone and hybrid (paired with solar), RRF and Committed, the TOs suggest that MISO further address with stakeholders how storage is to be dispatched in LRTP models and what technologies are assumed. The current 4-hour Lithium-ion battery assumption does not capture the state of energy storage technology capabilities nor development of them. 

Cleco does not join the TOs in these comments.

Alliant Energy provides the following comments as initial feedback on MISO’s proposed LRTP tranche 2 reliability dispatch methodology and scenarios.  The initial set of scenarios provided by MISO appear to be a reasonable starting point.  In addition, MISO should consider a scenario where wind and solar production is low but demand is high.  In addition, MISO should look at the impact of having higher levels of dispatchable resources available as well as the potential impact of longer duration storage (e.g., 8, 12, 24 hour).  This type of analysis would require additional efforts to complete but would be very helpful in understanding the impact of various resource mixes on overall system needs.

MEC recommends MISO to choose summer peak case to be in above the 95^th percentile of Summer load (close to 130GW of MISO load) . A higher loading level with possibly less renewable mix should better test the robustness of the system

MISO should consider additional cases in each season that model tight margin hours as identified in the 2022 Regional Resource Assessment report.

Please see attached for informal feedback from the Environmental Sector regarding LRTP reliability dispatch methodology and scenarios.

Thank you

The Environmental Sector

The LRTP analysis needs to include the possibility of a winter wind drought similar to one which occurred on January 28-30 across the entire MISO footprint.  See  Markets Committee of the Board of Directors - March 24, 2020 (misoenergy.org)  Item 5 Operations Report Slide 7.

Even a less severe wind drought in the future could result in massive transfers and severe capacity shortages due to higher future levels of wind penetration.

Winter wind droughts are particularly detrimental to MISO as solar output is also decreased due to shorter days, poor sun angles and snow-covered solar panels.

Also, battery storage due to wind droughts lasting more than four hours could also be exhausted.