Abstract

This thesis presents a study on the wind energy conversion systems (WECS) for small and medium power variable speed operation, this work studies the state of the art in terms of the different existing topologies, in addition to modeling each elements and its effect on the integration between the power converter, electric generator and wind turbine. Also, it is studied the main techniques for estimating rotor speed and position applied to permanent magnet synchronous generators (PMSG), showing that the simplified Kalman estimator technique  presents the best performance in this application. Also is studied the vector control techniques applied to permanent magnet synchronous generators, concluding that the technique Id=0 is the one with better performance. Similarly, we study the control strategies for back-to-back power converters, where the current control loops, speed and power are designed taking into account the dynamic characteristics of the wind turbine in order to tune control loops with best dynamic response possible. Another important aspect addressed in this thesis is the variable control structure adopted, which is modified depending on the region in which the turbine operates. The structure uses a maximum power point tracking algorithm (MPPT) and a linear loop power control, moving from one to another depending on the point of operation. Another major contribution of this thesis is to propose a new algorithm (MPPT), obtained from the known Perturb and observe technique (P&O), with which it is possible to reduce the mechanical stress of all turbine-generator system, which is reflected in an expected increase in the life of the PMSG. On the other hand, an experimental study on static behavior of the whole power converter electric generator has been studied, which has identified the system performance based on operating point effectively. It has also conducted an analytical study of the current of DC-link capacitor inverter, which has allowed for an optimization by synchronizing carrying signals PWM modulators for the rectifier and inverter stage, respectively. The practical consequence is that it can reduce capacitors losses, or what can be more interesting for the design, it can be implemented power stages with a reduced number of capacitors. All aspects discussed in this work have been experimentally validated by testing simulated environmental conditions with a wind experimental emulador built for these tests. The control stage of the back-to-back converter prototype has been implemented using a fixed-point DSP TMS320F2812.