Performance, reliability and economy of DFIGs for micro-hydropower applications. A case study

Today, the Doubly Fed Induction Generator (DFIG) is widely used in wind power systems, thanks to its great versatility in regulation. In the last two decades, DFIGs diffused also in large hydropower applications, and more recently there is an increasing interest in micro-hydroelectric applications. To evaluate technical, economical and reliability aspects of the latter, a tool has been developed on purpose. An accurate mathematical model, including the losses of the real machine in operating conditions, has been developed and validated with experimental data. The proposed model, integrated with the calculation of reliability and cost parameters, has been applied to a paradigmatic real case study of a micro-hydroelectric power generator. With a DFIG, the reliability is increased with respect to other conventional solutions. Indeed, the Mean Time Between Failure (MTBF) of the whole system results 38% higher. As to the economy, the system allows savings between 20% and 35% over the whole lifecycle, with respect to the conventional solution. The obtained results show the economic feasibility and reduced maintenance needs of a DFIG for micro-hydroelectric applications.