Real-time determination of the best interval of calculation for moving averages used for DC value extraction in active power filter control methods

In many cases, active power filters based on the i/sub d/-i/sub q/ and p-q control methods can have their dynamic response improved and their computational effort reduced by using moving averages instead of filters for the DC value extraction. An optimal dynamic performance, however, can not be achieved without the knowledge of the shortest calculation interval for the moving averages. The best interval depends on the harmonic content of the load currents and/or supply voltages that will be compensated. This paper presents a method for the instantaneous determination of the shortest calculation interval of the moving averages. The paper describes the strategy and presents the simulations.