Slide 9 of 33
Notes:
Hydro generation uses the 1929 to 1978 PNW streamflow record.
Hourly demand model for PNW loads uses the daily historical NW temperature record over the same time period.
Full flexibility of hydro system is used to meet demand if required
Flex hydro, which could cause draft of reservoirs below non-power constraints (F&W targets), is used as a resource of last resort, and restored as soon as possible.
The relationship between daily average hydro energy generation and sustained peaking capability for each of 2, 4, and 10 hour duration limits is modeled. Relationships are estimated through the trapezoidal approximation linear program.
The California-Oregon Intertie (COI) south to north transfer limit is an inverse function of net PNW west side demand, per Bonneville transmission group nomogram (During severe NW cold snaps, transfer capability typically drops)
Supply availability out of Northern California is a function of daily average temperatures in Northern California due to increased native demand and gas supply constraints. Below 50 degrees, surplus for export begins to decline and reaches zero at 40 degrees. The NC daily temperature record over the same historical record is used.
Reserve requirements are tracked and are equal to the larger of 5% of hydro generation plus 7% of thermal, or the single largest contingency (frequently the intertie in cold snaps).
