Small Hydroelectric Systems

Abstract

In present days, most government policies plan to increase their national electricity grid. The reality is that several villages, farmers, and settlers will not have access to electricity because of infrastructural and economic constraints. Although high technological solutions can be necessary to expand the main grid, small stand-alone projects may sometimes require very simple solutions. Even so, there is a lack of knowledge and understanding of how to implement them without major social or environmental impacts. This chapter shows the basic principles of hydropower resources, how to plan sites in rivers where the water flow and height differences are large enough so that new small hydropower plants can be built. Usually these plants will have a capacity of 10–20 ${\text{kW}}$, for runoff the river applications, or from 20 to 100 ${\text{kW}}$ for water flows above 0.3 m³/s during the dry season, and a height difference of at least a few meters. Even during the dry season, the electricity is often sufficient for powering light at night, computers or television sets and a refrigerator, which will already have major impacts on such places. In this chapter, the following hydro turbine systems are discussed: fixed-speed with an induction generator; variable-speed with a cage-bar induction generator; variable-speed with a multiple-pole synchronous generator or multiple-pole permanent magnet synchronous generator; and variable-speed with a doubly-fed induction generator.