Diseño de un acondicionador activo de potencia basado en la combinación de filtro activo serie y filtro activo paralelo para la compensación de cargas trifásicas no lineales

Zusammenfassung

This thesis presents the design of a combined series – parallel active power filter for a complete conditioning of the load, both in the voltages with which it works and in the currents that it requires from the supply network, with a dedicated compensation strategy. The equipment, called Load Compensation Active Conditioner, LCAC, consists of two active power filters, one in series with the supply network and another in parallel with the load side, with a common DC bus. The series active filter balances and regulates the applied voltages, isolating the load from mains voltage distortions. On the other hand, the parallel active filter compensates the harmonics of the load current, as well as the reactive and unbalance components. The selected compensation strategy allows the converters to act in a coordinated manner, with a robust and fast dynamic behavior, with a reduced dependence of the precise values of the components used, as well as a high stability response to the different operating conditions. It makes it suitable for application to a wide range of load types and the control implementation, expressed in time domain variables, allows an intuitive and flexible design with a fast dynamic response. On the other side, chapter II studies the criteria used for the evaluation of the improvement of the power quality achieved with active compensation equipment. The determination of quality indices based on the IEEE Std. 1459 approach is analyzed, as well as the interpretation of the diverse indicators. The study of the contribution of the harmonic components to the unbalance has led to the definition of an improved method, both in calculation requirements and in the interpretation of the corresponding indices. This new procedure has been systematically applied to all the cases analyzed for the evaluation of its results. Chapter III describes the design stage of the active conditioner. After the review of the existing proposals, the most appropriate compensation strategy for the LCAC is established according to the proposed objectives. Subsequently, the procedure for obtaining the voltage and intensity reference signals is determined. The behavior of the auxiliary passive elements is then analyzed with their state space model to evaluate their dynamic response and their high frequency filtering capacity, as well as for tuning the control parameters. The dimensioning of the components of the equipment is also calculated based on the voltages and currents that it has to supply according to the general objectives. This theoretical analysis is particularized in the selection of the elements for a reference prototype, for the purpose of verification with a simulation platform and its subsequent validation with an experimental laboratory prototype Chapter IV presents the simulation and laboratory platforms developed, as well as the different practical cases selected. The simulation platform has been developed in the MATLAB-Simulink environment and incorporates a considerable level of detail in its modeling, in order that its results are representative of those obtained with the laboratory prototype. Next, the simulation case studies that allow a first validation of the behavior of the proposed design are presented and analyzed, as well as the method of characterization and interpretation of the results. Finally, the laboratory platform and the corresponding case studies are described, for the experimental validation of the proposed design and the evaluation procedure.