Emilio Figueres Amorós

Average Current Mode Control of Three-Phase Boost Rectifiers with Low Harmonic Distortion Applied to Small Wind Turbines

This paper presents the application of averagecurrent mode control to reduce the THDi and increasethe PF in a Three-Phase Boost Rectifier driving asmall wind turbine. It is used as the input stage ofsmall wind turbines with permanent magnetsynchronous generators operating at variable speed.The Boost Rectifier output is connected to an inverterwhich injects the energy to a distribution power grid.The operation in discontinuous conduction modeallows significantly reducing the Total HarmonicDistortion of the current in the small wind turbine.However, it is necessary to add an input filter so thatthe switching ripple doesn´t affect the small windturbine. It is evaluated the convenience of the currentsensors placement in the DC side of the rectifier or atthe output of the generator. The results demonstratethat it is better to place the sensors at the output of thegenerator, because it is achieved a smaller THDi and ahigher PF.

Low power wind energy conversion system based on variable speed permanent magnet synchronous generators

This paper presents a Low Power Wind Energy Conversion System based on a permanent magnet synchronous generator and a High Power Factor rectifier. To achieve a high power factor at the generator side, it is proposed a power processing scheme based on a diode rectifier and a boost DC-DC converter working in discontinuous conduction mode. 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 have been carried out taking into consideration the electrical and mechanical characteristics of the wind energy conversion system, as well as the turbine aerodynamics. 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. Simulation and experimental results on a 2 kW prototype are shown to validate the concept.

Output Impedance Analysis In A Closed Loop Of Inverters Connected In Parallel Operating In Island Mode.

In this paper the island mode condition is analysed. The island mode refers to a microgrid that is not connected to the electrical grid and the inverters have to operate as a voltage source in parallel with others equipments of similar characteristics. This study focuses on how to interconnect the inverters without using any type of communication, by using droop schemes. First, an analisys is performed on how to obtain a certain value of output impedance by using an impedance loop. Then, we propose to use physical characteristics of the inverter and the type of controller to achieve results similar to those obtained by the impedance loop. In order to validate this analysis, simulations on parallel connection of several inverters supplying power to load are performed. Lastly some conclusions are presented.