Hydro Modeling Improvement for TAS Approval May 4, 2017 Kevin Harris, ColumbiaGrid TEPPC\Model Work Group - Chair

Overview Clean up Item Convert Select Fixed Hourly Shape to PLF Correct HTC p Factor for use in Triangle Method Castaic PS Thermalito Duplicate units Convert Select Fixed Hourly Shape to PLF Modeling of the Core Columbia River Consolidate Assumption on the Core Columbia River Eliminate Multi Region for Core Columbia River Lowering HTC on the Columbia River

For TAS Approval

HTC p Factor Review of the 2026CC results show an input error GridView support two methods for evaluating HTC: Rectangle and Triangle method Rectangle Method divides by 4 Triangle Method divides by 2 Aggregate Hydro by Plant Issue: P factor in the 2026CC are divided by 4. This reduces the HTC dispatch range by 50% Propose WECC: Correction all “p” factors to correspond to ‘Triangle Method’ by multiplying by 2

Castaic PS Current PS efficiency 85%, 75% and 65% Notes from CEC the average operational PS efficiency is 70% Proposed WECC lowering PS efficiency of Castaic to 71%, 66% and 61% (and adj the benefit cost ratio to 1.0)

Thermalito Duplicate Units Duplicate units exist for Thermalito 2-4. It is modeled as a hourly shape and PLF Propose WECC consolidate modeling as Thermalito as PLF only

Aggregate Hydro Units by Plant Aggregates Hydro units by plant simplifies the process of maintaining and processing Hydro data ABB is no issues with this aggregation in the PCM or the round-trip process For the Core Columbia River and lower Snake this eliminates 197 units from the dataset Propose WECC apply scenario that aggregate Hydro by plant when they become available or when WECC staff has time to create them ColumbiaGrid will provide a scenario to aggregate the Core Columbia and Lower Snake River

Hourly Shape Hydro Dispatch Converting Hydro unit that support daily peak from fixed hourly shape to Proportional Load Following (PLF) will allows them to support a changing load curve The primary advantage is when Hydro is dispatching against “Load – Solar” the daily peak generation shifts in response to the net load This feature will be evaluated in a WECC scenario

Hourly Shape Hydro Dispatch Propose the following: Convert the listed units in “Convert Fixed to PLF 2026CC1.7 v02.xlsx” from fixed hourly shapes to PLF For any plant the owner/operator disagrees with will not be converted

Modeling Changes for Columbia River

Consolidate Assumption on Core Columbia River Mismatch assumption are currently used in the 2026CC Consolidate modeling assumption on the Core Columbia River Propose WECC completing the modeling change on the Core Columbia by changing the fixed hourly shapes to PLF

Hydro Dispatch to Multi Regions Hydro dispatch to multi regions scales the Hydro unit and dispatched it against the region load This makes it difficult to calc an appropriate K when load factor of the regions are not similar A clean relationship exist of historic Hydro operation to BPA load. See posted file ‘ Columbia Riv Gen HTC PLF Compare v01’ posted DWG 4/11/17 Propose WECC eliminate multi regions assignment for NW entities with regions outside of the NW

Core Columbia with 50/50 PLF/HTC From posted spreadsheet ‘ Columbia Riv Gen HTC PLF Compare v01’ DWG 4/11/17 50% HTC shifts morning ramp energy to afternoon ramp in most months PLF only misses the afternoon ramp in when NW peaks in the morning (Mar) 20% HTC is a reasonable compromise that balances 50% HTC with 0% HTC (100% PLF)

Core Columbia with 50/50 PLF/HTC Posted spreadsheet (DWG 4/11/17) ‘ Columbia Riv Gen HTC PLF Compare v01’ compares average weekday Hydro generation shape vs. historic Hydro operation and load For both absolute and unitized values Overall the 50/50 PLF/HTC results in a significate shift from historic avg hourly generation shape Propose WECC lowers PLF/HTC modeling assumption on the Core Columbia River from 50/50 to 80/20 Long term: Work with BPA to determine what an appropriate Hydro flexibility exist and provide to the HMTF with updates when new information becomes available

Other Questions harris@columbiagrid.org (503) 943-4932