Comparison of current control strategies based on FCS-MPC and D-PI-PWM control for actively damped VSCs with LCL-filters

Abstract

This paper presents a comparative study of the proportional-integral-based (PI-based) synchronous current control strategy with derivative-feedback-based active damping and the finite-control-set model-predictive-control-based (FCS-MPC-based) synchronous current control strategy with cost-function-based active damping. For a fair comparison, the sensor requirement and the average switching frequency of FCS-MPC are made equivalent to that of the pulse-width-modulation-based counterpart through internal model estimation and control sampling frequency adjustment. The comparative study considers gain/weighting-factor tuning, delay compensation, switching harmonics, and active damping performance at the critical frequency operating point. The overall performance of both schemes is validated through the same experimental setup and test scenarios. The results conclude that the emerging FCS-MPC has the potential to produce similar results as the classical PI-based counterpart while carrying some practical features. These include being intuitive in active damping design and tuning, guaranteeing fast dynamics, and being sufficiently robust to grid impedance shifting. These findings essentially justify the potential of model predictive control being a viable alternative for this area of application.