20220204PAC to Sierra Club OR LC-77 Sierra Club 8.5.pdf

LC 77 / PacifiCorp February 3, 2022 Sierra Club Data Request 8.5

Despite PacifiCorp's diligent efforts, certain information protected from disclosure by the attorney-client privilege or other applicable privileges or law may have been included in its responses to these data requests. PacifiCorp did not intend to waive any applicable privileges or rights by the inadvertent disclosure of protected information, and PacifiCorp reserves its right to request the return or destruction of any privileged or protected materials that may have been inadvertently disclosed. Please inform PacifiCorp immediately if you become aware of any inadvertently disclosed information.
Sierra Club Data Request 8.5 Please refer to PacifiCorp’s Reply Comments at page 73 which state:
“By applying an hourly planning reserve margin to individual load areas, PLEXOS is
adding proxy resources into these locations on an east and west control area basis. The location of these added proxy resources creates geographic diversity to the system but also considers imports from adjacent areas. Applying a reserve margin requirement at the
system level creates flexibility but may not ensure load growth is being met due to
transmission limitations or resource retirements”. (a) Please confirm that PacifiCorp’s IRP calculates reserve margins (and any shortfall of the 13 percent requirement) individually for each of the load areas shown on Figure 8.3. If denied, please explain what geographic area the 13 percent reserve margin
applies to.
(b) Please explain whether resources imported from neighboring load areas within PacifiCorp’s system are able to contribute to the 13 percent reserve margin of each of
the individual load areas.
(c) If the answer to (b) above is yes, please provide the specific transmission limits assumed (i.e., in MW) between each of PacifiCorp’s load areas. (d) If the answer to (b) above is yes, please identify the year and hours in which each of
these transmission limits are binding for P02 base case and each of the P02 variant
cases. Response to Sierra Club Data Request 8.5

(a) Yes, the PLEXOS model enforces a 13 percent capacity planning reserve margin (PRM) as a floor in each individual load area in the topology. If the 13 percent capacity PRM is not met, the PLEXOS long-term (LT) study would be infeasible. PLEXOS reports energy not served (ENS) and unserved reserves.
(b) Yes, the PLEXOS model allows transmission between bubbles to transfer energy to
meet 13 percent capacity PRM in each of the load areas in the topology. (c) Please refer to the Company’s response to Sierra Club Data Request 8.1.
(d) The Company has not assessed each hour of each year in each study for evidence of binding transmission constraints. Transmission constraint binding can be inferred for any hour in which a transmission line’s transfers equal the transmission line capacity.