Abstract

Subject of the present work is the study, design and construction of a pico-hydroelectric system of 350W that has an axial flux coreless generator with permanent magnets for grid connected applications.

An introduction is made on the principles of appropriate technology and hydro-electric systems, while the characteristics of pico-hydroelectric systems are also presented, their structure and the process of their techno-economic design.

Each part of the micro-hydro scheme (like the intake, the channel, the forebay tank, the penstock and the powerhouse) is studied, as well as its design and special characteristics. The different kinds of hydro-turbines are presented along with their characteristics, design, sizing process and means of control. Description of different drive systems is included. Most frequently used generators (induction machines, synchronous generators with permanent magnets or wound field) along with their main topologies, basic equations and the simplest means of their control are mentioned. There is also a brief description of the required switchgear and protection equipment.

The different ways of connecting the pico-hydro generator are divided into three categories and studied (connection to an AC bus of the utility grid or of an autonomous microgrid and connection to a DC bus of an autonomous system with batteries). The ways of establishing these connections are presented depending on the kind of the used generator.

After some bibliographic research, the author tries to establish some criteria, which may later lead to a simple method of choosing the appropriate equipment (like penstock, hydro-turbine, generator ) and kind of connection for a special micro hydro-scheme.

A case study of electrifying a rural health clinic is presented. The clinic is supposed to be at a rural region of the developing world and its electricity needs are satisfied by a microgrid, which includes the pico-hydroelectric system of 350W, a photovoltaic generator, batteries and a diesel generator.

The penstock, hydro-turbine and permanent magnet generator are designed, the generator is constructed and tested in the NTUA laboratory. Also, after the assembly of the generator with the hydro-turbine, the hydroelectric system is tested and measured in the NTUA laboratory in order to observe and measure its operation.

Finally, conclusions are drawn and proposals for improvement and further work are presented.

Keywords: appropriate technology, low cost, rural electrification, micro-hydroelectric system, hydro-turbines, axial flux permanent magnet generators, microgrids

Author: Stamatia Gkiala-Fikari

Responsible PhD: Kostas Latoufis / latoufis@power.ece.ntua.gr

Supervising Professor: Nikos Hatziargyriou / nh@power.ece.ntua.gr

PDF: Full version (Greek) and Short version (English)