A comparison of active power filter control methods in unbalanced and non-sinusoidal conditions

Active power filters are used to eliminate current harmonics near nonlinear loads. This paper evaluates four different methods of determining the compensating current for a shunt active filter that is working under nonsymmetrical conditions. The methods compared are the instantaneous reactive power theory, the modified instantaneous reactive power theory, the synchronous reference frame theory and the modified synchronous reference frame theory. The comparison is based on simulation results. In balanced sinusoidal source voltages, the difference between the results obtained by the four methods are of minimum importance. For unbalanced and nonsinusoidal source voltage conditions, the results obtained by the methods referenced are quite different. The synchronous reference frame method had shown the best choice for all situations studied in this paper.