Optimal Control Implementation of Three Phase-Four Wire Active Power Filter on dSPACE 1103 DSP Board

The aim of this paper is the implementation of the optimal control of four-wire, shunt active power filters, designed for industrial use. The experimental setup consists of the active power filter controlled by means of a dSPACE DS1103 prototyping board, tested in a real industrial environment. The latter is characterized by high load variation both regarding the harmonic content of the currents on the three phases as well as the phase load balance. This leads to a difficult imbalance current compensation for the three-wire active filters, difficulty which is overcome by the four-wire active filters. At the same time, high harmonic (and reactive) current imposes high compensating capacitor working voltage. The variable harmonic content of the load current, makes unpractical to maintain a high capacitor voltage, so the adaptive control reduces the switching power loss without affecting the compensation performance. The performance of the control algorithm was quantitatively proved by analyzing the data sampled by the prototyping board analog to digital converters in the Matlab Simulink environment. The compensation results were also qualitatively confirmed by a Metrix 7042 oscilloscope.