Power filters for power factor correction and harmonics suppression employed with non-linear loads under non-sinusoidal conditions

Abstract

The thesis is about power filters for power factor correction and harmonic suppression applied to non-linear loads under non-sinusoidal conditions. A non-linear load made up of a variable DC load connected via some power electronic converter connected to a three-phase non-sinusoidal supply is chosen as a typical load. The thesis presents two major methods of compensation. This first method does not involve any modification of either the converter or the load. Several power filters are considered and are connected in an external way to the load. Such filters include Passive Power Filters, Active Power Filters and Hybrid and Combination Power Filters. Two different algorithms are considered for the operation of the Active Power Filter; mainly that of the Instantaneous Power Values Algorithm and the Integral Power Values Algorithm. The global approach is considered for this type of compensation. Maximizing the filter's compensation capabilities is done by matching the characteristic impedance of the load with that of the supply at the point of common coupling. The second method is about modifying the converter in order to incorporate active power filtering techniques. In this case two AC to DC converters are considered, that is the Boost and the Buck-Boost Converter. The single-phase converter is modified to a three-phase system in order to include load balancing, while all the design considerations are taken into account. The thesis is complemented by simulated and practical results.