Improved current control strategy for power conditioners using sinusoidal signal integrators in synchronous reference frame

In this paper, an improved current control scheme for shunt type power conditioners is proposed, with the aim of simplifying current harmonic compensation for industrial implementations where strict limitations on the harmonic distortion of the mains currents are required. To compensate current harmonics, the proposed scheme is based on proportional-integral regulators using sinusoidal signal integrators, implemented to operate both on positive and negative sequence signals. One regulator, for the fundamental current component, is implemented in the stationary reference frame. The other regulators, for the current harmonics, are implemented in a synchronous reference frame rotating at the fundamental frequency. This allows to compensate simultaneously two current harmonics with just one regulator. The whole control algorithm has been implemented on a 16-bit, Fixed-point digital signal processor (DSP) platform controlling a 20 kVA prototype. Experimental results are presented to show the validity of the proposed solutions.