Desenvolvimento de um sistema de controle e supervisão de inversor para turbinas eólicas

Abstract

The worldwide interest in renewable energy has increased, with a large emphasis on wind energy. In this sense, this work presents the supervision and control of an inverter for wind turbines. It uses a three-phase PWM converter with LCL filter for connecting the primary source to the grid. The state-space model of the system in discrete time is shown, as well as the design of the controllers for the grid current and DC bus voltage. The control loop of grid current uses the response of the DC bus voltage as reference. Furthermore, considering the development of wind turbines, a modulation strategy for converters with magnetically coupled parallel legs is proposed, as this makes possible to increase the processing of current by static converters. The modulation properly distributes the pulses between the switches and produces equivalent multilevel line-to-line voltage with reduced harmonic content. The circulating currents, which arise among the parallel legs, are limited through the use of a proportional controller and the addition of a double switching. On the other hand, some protections for connection of the primary source to the power grid are required by grid codes and must be respected. As a result, implementation methods of the necessary relays are also presented, which will be integrated into the inverter. Finally, simulation and experimental results are presented in all chapters to validate the proposed methods.