Double Stator Winding Induction Generator for Wind and Hydro Applications: 2D-FEM Analysis and Optimal Design Lucian Nicolae Tutelea, Sorin Ioan Deaconu, Nicolae Budisan, Ion Boldea POLITEHNICA UNIVERSITY OF TIMISOARA Revolutiei str., no. 5 Hunedoara, Romania Tel.: +40 / (254) – 207529 Fax: +40 / (254) – 207501 E-Mail: sorin.deaconu@fih.upt.ro URL: http://www.fih.upt.ro Acknowledgements This paper was supported by the project "Microgrid integrated small power renewable energy hybrid systems" PCCA 36/2012, PN-II-PT-PCCA-2011-3.2-1519, Funding Application for Joint Applied Research Projects. Keywords «Induction generator», «Double stator winding», «Wind and hydro applications», «FEM analysis», «Optimal design». Abstract In an effort to introduce a low cost (PM less), low power electric wind or hydro generators, this paper reports on preliminary optimal design aspects and FEM analysis of a 3kW, 250 rpm, dual stator winding asynchronous (DSWA) generator. At the first stage the single winding, three phase asynchronous rotor is optimally designed for low speed and low frequency considering the influence of the poles pairs on the main dimensions, weight, active material cost and efficiency. Than, the rated power and cost reduction of the inverter is analyzed considering dual stator winding asynchronous generators in two topologies: with the inverter placed on the excitation windings and with the inverter placed on the main winding. The analytical model used for optimal design and the model of the double stator winding is validated trough finite element method. Finally the proposed solutions are compared with the single winding induction generators. Introduction Cage rotor induction generators have been employed to operate as wind turbine generators and small hydroelectric generators in isolated power systems [1], [2], due to the practical advantages related to low maintenance cost, better transient performance, ability to operate without dc power supply for field excitation, and brushless construction. A direct connection between the prime mover and the generator has many advantages, such as low noise, high efficiency, and high power density. In a split- wound machine, the stator winding consists of two similar but separate three-phase windings wound for the same number of poles. Both stators are fed with the same frequency and the rotor is a standard squirrel cage. The two stator windings are mutually coupled and small unbalances in the supplied voltages generate circulating currents. Furthermore, because of the low impedance to harmonic currents there is a high level of circulating currents when a non sinusoidal voltage source supply is used, adding losses and demanding larger semiconductor device ratings [3]-[7]. The induction machine is very suitable for high speed electric power generation, although there are many problems to be solved, such as the terminal voltage of a self-excited induction generator being highly dependent on rotor speed, terminal capacitance, and load [1], [2], [8]-[15]. These disadvantages of the performance of self-excited induction generators limit their widespread application. With the