Small scale hydropower: generator analysis and optimization for water supply systems Guilherme A. Caxaria 1,* , Duarte de Mesquita e Sousa 2,** , Helena M. Ramos 3,*** 1 Electrical and Computer Engineering Department, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal. 2 Electrical and Computer Engineering Department and CIE 3 , Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal. 3 Civil Engineering Department and CEHIDRO, Instituto Superior Técnico, Technical University of Lisbon, Lisbon, Portugal. * Av. Rovisco Pais, 1049-001, Lisbon, Portugal , E-mail: gui.caxaria@gmail.com ** Av. Rovisco Pais, 1049-001, Lisbon, Portugal , E-mail: duarte.sousa@ist.utl.pt *** Av. Rovisco Pais, 1049-001, Lisbon, Portugal , E-mail: helena.ramos@civil.ist.utl.pt Abstract: This work focuses on the analysis of the power generation feasibility of both a pump as turbine (PAT) and an experimental propeller turbine, when applied to water supply systems. This is done through an analysis of the electrical generation aspects of the PAT’s induction motor and of a permanent magnet DC motor, which was connected to the propeller turbine. The collected data allows for parameter optimization, adequate generator choice and computational modeling. These tests constitute a good sample of the range of applicability of small scale turbines as valid solutions for micro-hydro. It is also possible to consider multiple scenarios, such as rescaling/resizing, for larger turbines and systems, and the use of power electronics for further efficiency enhancing. Keywords: Small-scale hydropower, water supply systems, low power turbines, behavioral analysis 1. Introduction Starting from a scientific research base in the field of hydraulics, the objective of this work is to study the applicability and performance of electrical generators when connected to low power hydro turbines, for use in water supply systems (and others with similar characteristics). The generated power has a broad range of application, namely in the field of decentralized production (either on or off-grid) for use in rural or isolated areas, as well as in urban areas. It is possible to use the generated power to supply devices related with the small- scale industry (e.g. hydro-mechanical systems in pumping stations), communication stations, data acquirement, control or telemetry systems, or even observation posts in isolated areas. Through the use of computer models, laboratorial tests and prototype analysis, a solution for a certain micro-hydro scheme is chosen. Behavioral analysis is then undertaken, allowing for further generator parameter optimization. 1.1. Water supply systems Water supply systems aren’t built with a power generation purpose. However, due to the type of infrastructure which is used for their normal operation (pressure reducing and flow control valves, reservoirs, pumps, and piping), they offer a multitude of power generation scenarios while assuring an almost constant flow rate 24h/day. It is then possible to generate power in the following manners: replacing (or assembling a joint installation with) pressure reducing valves; taking advantage of the hours where there’s an increased demand for water (hours which coincide with an increase in demand for electrical power); piping water between 1386