THE ANNALS OF “DUNAREA DE JOS” UNIVERSITY OF GALATI FASCICLE III, VOL.34, NO.2, 2011, ISSN 1221-454X ELECTROTECHNICS, ELECTRONICS, AUTOMATIC CONTROL, INFORMATICS AN ANALYSIS OF DYNAMICS REGIMES OF PARALLEL GENERATORS OPERATION IN WIND TURBINE SYSTEMS Elena Voncila*, Madalin Costin*, IonVoncila*, Cristian Nichita**, Grigore Fetecau* *Faculty of Automatic Control, Computer Science, Electrical and Electronics Engineering, „Dunărea de Jos ” University of Galati, Romania, ** GREAH – Groupe de Recherche en Electrotechnique, ET Automatique du Havre, University of Le Havre, France e-mail: Elena.Voncila@ugal.ro Abstract: The parallel connection of different types of AC generators, used as example in isolated sites, represents a difficult problem due to the different particularities of the that generators involved. This paper analyses the specific dynamic processes that may occur with the development of such systems. Although some dynamic processes that not affect the magnetic and/ or electric symmetry of the system can be excellent modelled through  models, most of them cannot take into account such symmetry, reason to resort the models in phase coordinates, often implemented with professional Software (Psim). The dynamical particularities obtained by simulations revealed different dynamics in most of the regimes, prefigured by the different nature of the generators: asynchronous and synchronous. Further development using automatic control techniques will allow uniform integration of such systems with different dynamics.  q d , Keywords: dynamical regimes, permanent magnet synchronous generator, induction generator, wind turbine systems, numerical simulation 1. INTRODUCTION Continuous development of wind systems is claimed by the potential expansion of the consumers at isolated grids also by the progress of the technologies that created manifold equipments that are becoming much cheaper. For three decades, the technical solution of generator used in the conversion of wind energy in electricity is the induction one (Burton et al, 2001). Therefore, nowadays the induction generator is the most popular generator used in renewable systems, at wind farms and also at isolated sites. However, the problem that cannot be overcome is related to the exclusion of gear box (Blaabjerg Chen, 2006), the device cannot be physically designed at these requirements. It has been observed that the presence of the mechanic reducer incur a multitudinous of disadvantages that significantly increase the maintenance costs and reducing the lifecycle of the turbine (Burton et al, 2001). For this purpose, the multi-polar generators with permanent magnet excitation have been developed. The permanent magnet generators represent a great opportunity (Boldea, 2005) in the conversion systems of wind energy, because of the gearbox elimination, the insulated operation without additional excitation devices (as in the case of induction generator with short-circuit rotor). The wind energy systems development by connecting in parallel of different types of AC generators can be determined by the seasonal growth/ expansion of important loads and the extension of wind farms, where often removing the turbines equipped with asynchronous generators it is not justified due to the high amortization period of initial investment. 15