Reference estimation technique for active power filters using a digital Kalman algorithm

This paper presents a new technique for the control of shunt active power filters for current harmonic compensation in power systems. A real-time digital Kalman filter is used to obtain the reference estimation of the control current. This algorithm provides the best estimate of the electrical magnitudes from their sampled values in a response time of less than one sampling interval. This adaptive algorithm allows the response to be obtained for sudden changes in current consumption in less than three sampling intervals, which means that it is possible to perform the attenuation of harmonics which vary rapidly with time. Its capacity for prediction avoids the delay in obtaining the control signal resulting from digital processing and thus minimizes cancellation errors. This technique is capable of performing the selective fading of harmonics, optimizing the use of the available power of the active filter. Experimental results for the proposed technique using a DSP based board are presented for different loads and supply voltage conditions.