2030 ADS _ Transmission Nomograms

Jamie Austin, PCDS Chair

Peter Mackin, StS Chair

September

RAC Meeting

2030 ADS Transmission Nomograms

Introduction ...... 3

Confidentiality ...... 4

COI Utilization Report by BPA, May 04, 2011 ...... 4

Quantification of Relationship of Path Flows to Market Drivers ...... 6

Additional Resource Information ...... 6 Conclusion ...... 6

Version History ...... 7

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Introduction

The Production Cost Data Subcommittee (PCDS) is responsible for building the ADS dataset constituting two cases:

1. Production Cost dataset, used in production cost modeling (PCM), and 2. One hour exported from the PCM, solved in power flow (PF)

The reason for creating these two cases, PCM and PF, with the same loads, resources and transmission topology, is to allow for complete power system analysis, both reliability and economics, as stipulated by the Federal Energy Regulatory Commission under FERC Order 1000.

For the 2030 ADS dataset, PCDS has found that collecting nomogram data from “nomogram” owners \operators has been challenging. This is particularly true for data that have been developed to identify simultaneous operating constraints between multiple paths (the definition of nomograms), especially nomograms that impact the operation of the Western Interconnect as a whole (e.g. COI in the NW and in , IPP DC, etc.). PCDS is requesting updates to the nomogram data modeled in the 2028 ADS PCM; these nomograms have been modeled in the WECC PCM since its inception but a number of entities are now declining to provide updated information. This requested update consists of the following steps:

1. Verify if the nomogram modeled in the PCM is still required; 2. If the nomogram is still required, then submit data for new nomograms; 3. Update nomograms modeled in the 2028 ADS PCM using the newly submitted data.

The ADS PCM is developed through a combination of tasks collaboratively performed by the PCDS, PMDS, SRS, StS and WECC staff. PCDS has called on the StS, the committee that oversees Path Rating studies, for help establishing the need for modeling nomograms in the 2030 ADS PCM case. In a meeting held August 20, 2020, participating StS Members generally supported the inclusion of nomograms in the PCM for the following reasons:

1. PCM models the 8760 hour dispatch that requires modeling operating limits that reflect hourly \ seasonal changes to path’s capacity 2. The Locational Market Pricing (LMP) is directly dependent on price differential between two areas, which can be affected by the capacity available on transmission between two areas. 3. Just modeling a few limiting contingencies as was suggested by CAISO instead the full definition of the nomogram is not the best solution because: a. It is inefficient to model contingencies in PCM as the simulation covers hourly dispatch for a year, unlike PF that runs a single dispatch simulating only one hour. b. Unlike many other WECC Paths, the System Operating Limit (SOL) for COI is variable and is stability limited. Even though the COI has a 4800 MW rating, it

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seldom has its full capability available for use. Modeling contingencies in PCM (which uses a decoupled network solution) will not show voltage violations.

Confidentiality

CAISO and BPA representatives, participating in PCDS have expressed concerns about data confidentiality. The ADS PCM loads and generation data is developed in committee, by members, stakeholder and WECC staff, starting with data in public domain, hence it is posted publically. This data includes loads and resources data that comes from the WECC L&R report, submitted by “Data Submitters” however, for the year 10 horizon; only L&R data for years 4 through 10 are public information. PF data in the PCM is confidential as it is CEII data and is shared in accordance with the WECC Information Sharing Policy as discussed below.

On June 17, 2020 the WECC Board of Directors approved a revised WECC Information Sharing Policy. This revised policy classifies base-case data (power flow and dynamics data), Geomagnetic Induced Current (GIC) data, and Remedial Action Scheme (RAS) models as information that can be shared by demonstrating legitimate need and agreeing to abide by the terms outlined in the WECC Confidentiality Agreement. The WECC Path Rating Catalog is also considered CEII and is treated the same as the base case data mentioned above. The WECC Path Rating Catalog contains nomograms describing the simultaneous interaction between various Rated Paths. Given that nomograms are already available from WECC through the WECC Information Sharing Policy, there is no justification for imposing a higher level of confidentiality on other nomograms that may not currently be in the Path Rating Catalog, but that are needed to accurately simulate the operation of the system in the PCM.

COI Utilization Report by BPA, May 04, 2011

Following is an excerpt from a COI utilization report by BPA, posted on the BPA website. The study demonstrates the need for modeling the COI nomogram in both the Northwest and in California:

The nominal COI rating is 4,800 MW from north-to-south, and 3,675 MW from south to north. However, in addition to limitations due to outages, nomograms have been developed to identify simultaneous operating constraints between this path and other paths including:

3. The Pacific DC Intertie (Path 65), 4. The North of John Day (Path 73), 5. Hemingway-Summer Lake (Path 75), and 6. Borah West (Path 17).

Other factors that affect operating conditions are:

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7. Northern California hydro generation, 8. Other northern California generation, 9. Northern California load, 10. Northwest hydro and thermal generation dispatch, 11. Northwest load levels, and 12. Reno-Alturas (Path 76 or NW-Sierra) flow.

Unlike many other WECC Paths, the System Operating Limit (SOL) for COI is variable and is voltage stability limited. Even though the COI has a 4800 MW rating, it seldom has its full capability available for use.

The 4800 MW rating is highly dependent on interactions with other WECC Paths, Northern California Hydro (NCH) output, Northern California load, and also relies on a multifaceted and complex Remedial Action Scheme (RAS) to support reliable power transfers.

Impacts of Northern California Hydro Generation on the COI Rating

N. Cal Hydro COI / NW - Sierra 60% 4800 MW 70% 4725 MW 80% 4575 MW 90% 4200 MW 100% 3950 MW

If Northern California Area Load (PG&E, BANC and TID Balancing Authorities) is greater than 28,604 MW the COI/NW-Sierra limit is curtailed by 15 MW for every 100 MW that the Northern California Area Load is expected to exceed this level.

Utilization categories for COI have been established, with the amount of COI utilization based on the ratio of the hourly COI N-S Usage to hourly COI N-S Limit. The utilization categories are:

• High (90% or above), • Medium (between 50% to 90%), and • Low (50% or below).

Finally, seasonal groupings have been created and are defined as:

• Summer (California summer from July to September) • Hydro Run-Off (Northwest hydro run-off from April to June) • Other (from October to March)

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Quantification of Relationship of Path Flows to Market Drivers

The BPA study demonstrates the strongest correlation of COI utilization to market prices is with daily average NP15 to Mid C price spread. The strong relationship to usage suggests that prices are the most significant driver of COI utilization. This is most likely a result of the frequent COI derates below 4,800 MWs and the practice of some entities using their transmission rights for reserves and emergencies as opposed to using these rights to schedule capacity.

Additional Resource Information

• CAISO 2018-19 Study Plan, section 3.9 Major Path Flow and Interchange, page 32,

Footnote 51, cites COI () will be stressed during Summer Peak; The Path 66 flows will be modeled to the applicable seasonal nomogram for the base case relative to the northern California hydro dispatch.

o Footnote 52, cites (N-S) stressed during Spring Off Peak. Path 15 flow is adjusted to a level close to its rated limit of 5400 MW (S-N). This is typically done by increasing the import on (S-N) into the PG&E service territory. The Path 26 flow is adjusted between 1800 MW south-to north and 1800 MW north-to-south to maintain the stress on Path 15 as well as to balance the loads and resources in northern California. Some light load cases may model Path 26 flow close to 3000 MW in the south-to-north direction which is south-to-north limit for Path 26.

The Bonneville Power Administration (BPA) is responsible for monitoring system conditions in the Northwest. The California Independent System Operator (CAISO) is responsible for monitoring system conditions in California.

Conclusion

It is evident that the COI nomogram and any other nomograms impacting the Western Interconnection system operations are necessary for inclusion in the production cost model. We strive to improve data modeling in the PCM. We are concerned that data that is significant to local areas such as behind the meter resources and additional progress to achievable energy efficiencies are being provided; however, some data owners are reluctant to provide nomogram data that impacts the entire Western Interconnection’s dispatch.

PCM data is used by WECC and WECC members, the Western Planning Regions, and the National Labs in system reliability analysis. Not all users have access to nomogram data; however, all users have access to the ADS dataset, including nomogram owners. Therefore, it is vitally important to

6 2030 ADS Transmission Nomograms model nomograms that impact the flows on various transmission paths in WECC so that we can produce the most accurate results possible through our PCM simulations.

Version History

Modified Date Modified By Description

7