Hydroelectric Power Generation - Renewable Energy: Technology, Economics and Environment - page 352

The current state of technological development is the basis for this description
(i.e. /8-2/, /8-3/, /8-4/).

8.2.1 Schematic layout

The components described in Fig. 8.2 are required for the technical conversion of
energy in flowing water to electricity in a run-of-river power station. These com-
ponents are the water intake at the headwater, the weir, the inlet and outlet of wa-
ter to and from the turbine, the outlet at the tailwater, and the powerhouse with
machinery and electrical equipment. These system elements are usually combined
in the dam that enables the use of the head and the powerhouse.

Power house

Headwater

Electric energy

p 1

v 1

Dam

h

1

Tailwater

Turbine

p

h 5

v

5

5

Fig. 8.2 Schematic layout of a hydroelectric power station (p pressure, h height, v velocity,
indices according Fig. 8.1; see /8-5/)

Two system components are the main elements of the actual energy conversion
within a typical hydroelectric power station. Together with the turbine that draws
the energy from the water and converts it into mechanical energy, the second
component is the generator for further conversion into electrical energy, and thus
into the final product. Depending on the plant configuration, a transmission is ad-
ditionally required if turbine and generator rotational speeds are different or if
both components are not on the same axis. In smaller plants the transmission is
often replaced by a simple belt drive.

8.2.2 Categorisation and construction types

Hydroelectric power stations can be divided into low, medium and high head
power stations (Fig. 8.3); additionally run-of-river power stations and hydroelec-
tric power stations with reservoirs can be distinguished. The differences between
the various types are not clear-cut; in practice, there are a number of combinations