O. Carranza

Design and application of a two degrees of freedom control with a repetitive controller in a single phase inverter

This paper presents the design, analysis and implementation of two degrees of freedom control combined with a repetitive controller in the context of inverters working in microgrids. The goal of control under study is to reduce the harmonic distortion of the inverter output voltage. The inverter is designed to operate in island mode as a voltage source. Simulations where performed with both linear and nonlinear loads.

Low Power Wind Generation System based on variable speed permanent magnet synchronous generators

This paper presents a Low Power Wind Generation System based on a permanent magnet synchronous generator and a High Power Factor rectifier. To achieve a high power factor in the generator side, it is proposed a power processing scheme that uses a passive rectifier and a DC-DC converter working in discontinuous conduction mode. This circuit is known as a boost rectifier. The proposed generator control structure is based on three cascaded control loops that regulate the generator current, the turbine speed and the amount of power that it is extracted from the wind, respectively, following the turbine aerodynamics and the actual wind speed. The analysis and design of both the current and the speed loop has been carried out, taking into consideration the electrical and mechanical characteristics, as well as the turbine aerodynamics, of the wind generation system. The power loop is not a linear one, but a Maximum Power Point Tracking algorithm, based on the Perturb and Observe technique, from which it is obtained the reference signal for the speed loop. Finally, to avoid the need of mechanical sensors, a linear Kalman Filter has been chosen to estimate the generator speed.

Comparison of speed estimators applied to wind generation systems with noisy measurement signals

This paper presents a comparative study of several speed estimators to implement a torque control loop, in a wind generation system with a three-phase boost rectifier operating in discontinuous conduction mode. The electrical variables measured for speed estimation contain low frequency harmonics of the fundamental frequency of the wind generator, as well as switching frequency components due to the boost rectifier. In this noisy environment the linear Kalman filter estimator is the best among the options under study, because of its faster response time and lower estimation error.