Orthogonal reference frame based methods in three-wire active power line conditioners: Practical evaluation under unbalanced load and nonideal voltage conditions

This paper is concerned with the practical implementation of some orthogonal reference frame based methods in the control of a shunt three-phase three wire active power line conditioner in order to compensate unbalanced nonlinear loads under nonideal voltage conditions. The first two developments are based on the components of voltage and current space vectors in the orthogonal stationary reference frame associated with the p-q theory of the instantaneous reactive power. They allow obtaining either unity power factor or perfect harmonic cancellation after compensation. Other two developments are based on the current components in the orthogonal rotating reference frame d-q with axis d in the direction of the voltage vector, which is specific of the id-iq method. This time, the compensation target is the total compensation through the perfect harmonic cancellation. The control algorithms were first modelized and tested by simulation under Matlab/Simulink. Then, experimental tests were conducted on a dSPACE platform based on DS1103 controller board for modern rapid prototyping. The compensating performance, in terms of harmonic distortion factor, unbalance factor, global power factor and displacement power factor, are analyzed for each situation. All the results prove that the desired compensation goals can be achieved through the conceived algorithms and the proposed practical implementation.