DESCRIPTION

The Sierra Area covers the southern portion of Sierra County, and most of El Dorado, Yuba, Sutter, Nevada, and Placer Counties. This area is located east and northeast of Sacramento and includes the cities of Yuba, Marysville, Auburn, El Dorado Hills, Lincoln, and Grass Valley. The major transmission sources are: (1) two 230/115kV transformers at Rio Oso; (2) three 230/115kV transformers at Goldhill; (3) two 230/60kV transformers (one at Colgate and the other at Atlantic); and (4) two 115kV and one 60kV lines that connect this area to the Sierra Pacific Power Company.

This area has about 1015MW of internal generation, from hydro generators and gas turbines. QFs can provide about another 170MW. The summer peak load is about 1020MW. Projected load growth in the area for the next few years is about 20MW per year on average.

PROBLEMS

The most critical problems identified in this area are four facilities projected to be overloaded under normal conditions: (1) Drum-Grass Valley-Weimer 60kV circuit by 2001; (2) Atlantic 230/60kV transformer bank by 2003; (3) Palermo-Nicolaus 115kV circuit by 2005; and (4) Table Mountain-Rio Oso 230kV circuit by 2001. If left unaddressed, these problems could cause emergency overloads which may eventually result in load dropping or low voltages in the 60kV portion of the system.

There are also about a dozen emergency concerns, or contingencies (at the 230kV, 115kV, and 60kV voltage levels) causing criteria violations in the Sierra Area. However, these are not as critical as the facilities that are overloaded under normal conditions.

POSSIBLE SOLUTIONS

The Palermo-Nicolaus 115kV line reconfiguration completed in May 2000, and the new Gold Hill-Clarksville 115kV line, expected to be completed in December 2000, helps mitigate some of the major problems identified above. Other examples of solutions that would mitigate the major problems described above include: (1) a new Atlantic-Del Mar 60kV line; (2) a new Atlantic-Pleasant Grove #2 60kV line; and (3) re-rating the Table Mountain-Rio Oso 230kV circuit.

1.7 North Bay

TYPE OF CONSTRAINTS

_ Economic (Bulk)

¬ None in this area

_ Reliability Must Run (RMR)

¬ None in this area

_ Stability:

¬ None in this area

_ Normal Overload

¬ Solution

_ Reconductor lines.

· Projects:

· Fulton #1 60 kV line reinforcement (T490)

_ Contingency (Outage)

¬ Problem 1:

· Loss of Cortina 230/115/60 kV transformer in the Eagle Rock pocket area would cause low voltage at the Clear Lake area.

¬ Solution:

· Need 224 MW RMR contract to solve this contingency problem. Only 218 MW of RMR candidates (total nameplate is 327 MW) is available in year 2001.

¬ What happens if problem is not fixed:

· If this contingency problem is not corrected, it will cause low voltage and possible voltage collapse in the Clear Lake area.

¬ Problem 2:

· Loss of Fulton-Ignacio 230 kV line with the overlapping outage of a large Geysers unit connected to Fulton (e.g., Geysers 11 or Geysers 16) in the Fulton pocket area would cause the Lakeville-Corona and Sonoma-Napa 115 kV lines to exceed their emergency ratings.

¬ Solution:

· Need 206 MW RMR contract to solve this contingency problem. A total 271 MW of RMR candidates (total nameplate is 571 MW) is available in year 2001.

¬ What happens if problem is not fixed:

· If the emergency overloading problem for Lakeville-Corona and Sonoma-Napa 115 kV lines is not corrected, load dropping must be done in order to protect those two 115 kV lines.

RECOMMENDATION

· Solicit more QF facilities in the Eagle Rock area.

DESCRIPTION

The North Bay Area covers most of Mendocino County as well as portions of Lake, Sonoma, and Napa Counties. It includes the cities of Ukiah, Mendocino, Clear Lake, and Willits.

The major transmission lines serving this area are two 115 kV lines from Cortina (fed from one 230/115/60kV transformer) in the east, one 115 kV line from Fulton in the south, and one 60kV line from Humboldt in the north.

This area has about 795 MW of internal generation in 2001, from geothermal and hydro generators. QFs can provide about another 203 MW. The summer peak load is about 1100MW. Projected load growth in the area for the next few years is in the neighborhood of 25MW per year on average, mostly from the Napa County and areas of Sonoma County.