Modeling, simulation and real-time control of active filters

Historically, production and distribution of electricity were carried out taking into account that the voltage and current were perfectly sinusoidal and their frequency was fixed (50 or 60 Hz). In fact, prior to the early eighties, these assumptions were quite verified. Only few types of equipment generate deformed and non-sinusoidal currents: the magnetization current of transformers and motors, fluorescent ballasts and AC/DC rectifiers. Actually, these equipments constituted a negligible portion of charges connected to the networks and generally did not introduce significant distortion. Fantastic progress in electronics has changed the situation. Color televisions, dimmers for lighting, audio equipments, microwave ovens and personal computers, all require the use of electronic converters to operate.The role of active filters is to compensate harmonics in the power system and improve the efficiency of the electrical power system without any active power consumption. Compensation of non-active power substantially improves the power factor and reduces the total harmonic distortion index (THD) and also the total losses. This means that the system can transfer more active power with the same capacity. Another effect of harmonic compensation is the elimination of associated problems on electrical equipment such as transformers and electrical machines.This master dissertation is dedicated to simulation and real-time control of an active filter to compensate current harmonics in a typical electric system. First, a control model appropriate for the active filter based on a literature review is proposed. Then, the control model is simulated using the Simulink toolbox of MATLAB. The model is then interfaced with the real world by using Opal-RT software to achieve an interconnection with the physical hardware for a real-time control. The final system constitutes a Hardware in the loop (HIL) application.Finally, the model is implanted in laboratory with RT-Lab real-time Simulators to interact with a three phase 120/240 V system and a three phase rectifier as a non-linear load. Experimental results are also compared with simulation results. Moreover, the provided real-time structure makes it feasible to apply and compare different control designs and their transient state responses.In addition to these devices, variable speed drives for industrial electric motors, which are made of electronic devices, are also other sources of harmonic pollution. Although, individually, their power is low, together they constitute a considerable source of harmonic pollutions which have serious consequences in the low or medium voltage power networks. In just a few years, issues of the harmonic pollution regarding the quality of electric power had become one of the most important problems that engineers should have confronted.This report proposes two recommendations for future works in this area.