The Lewis River Hydroelectric Projects - PacifiCorp

Lewis River Interpretive & Education Plan
Via a shaft, the spinning turbine turns a rotor, containing an enormous mass of
magnets, inside a stator that contains a stationary ring of tightly-packed copper
coils. Because of the nature of magnetic fields and electrical conductors, the
motion of the magnets creates a changing magnetic field that induces electrons
to move within the copper coils. The motion of the electrons (switching back
and forth from positive to negative) creates a moving electric field within the
copper. This moving field is electrical energy.
Hydraulic turbine generator units are uniquely designed to take maximize
advantage of the specific site where they will be installed. Considerations in
their design include the volume of water available, the height of the dam (head
produced) and the variability of both of these as they typically change from
season to season throughout the year.
Hydroelectric
Transmission
The amount of electricity generated in the copper wire of the generator stator
can be quite large—enough to power hundreds of homes or businesses. To
deliver that power efficiently, the hydroelectric plant first passes it through stepup
transformers: systems of wound wires with central magnetic cores that allow
the voltage, or electric potential, of the electric energy to be increased so that
it can pass efficiently via conductive wires from where it’s generated to where
it’s needed. These high-voltage lines are familiar features of many American
landscapes, suspended from extremely tall steel towers, zig-zagging their way
across mountainsides and plains.
At points where the electric power is needed, step-down transformers at
electrical substations reduce the voltage of the electricity to levels suitable for
everyday use. These smaller transformers sre mounted on power poles.
The “Grid”
The Lewis River hydroelectric plants feed power into the “grid”—a system
of interconnected power transmission and distribution lines and associated
facilities throughout the American West (there is a similar grid in the East, but
although the two grids are connected, they operate independently, with slightly
different frequencies). Within the larger western grid there are smaller regional
grids, and within these are smaller company grids.
Power is fed into the grid by generation facilities (such as the North Fork Lewis
River Hydroelectic Project), and power is pulled from the grid by consumers.
Many different power providers feed into the grid—including private companies
(such as PacifiCorp) and public utilities (such as Cowlitz PUD). Many different
methods of power generation are represented, including coal-fired and nuclear
plants, and solar- and wind-driven facilities, and geothermal plants.
Sea Reach Ltd • 146 NE yamhill Street • Sheridan, OR draft 3 • November 2008 • page 73