Enhanced sensorless predictive direct power control for PWM rectifier with constant switching frequency under grid disturbances

Abstract

This work presents a voltage sensorless predictive direct power control strategy for PWM-rectifier. Firstly, the line-voltages are estimated using Second-Order Generalized Integrators (SOGI) coupled with Frequency Locked Loop (FLL). SOGI are inherent noise rejectors and FLL provides instantaneous tracking of the grid frequency. Their combination offers high robustness against grid disturbances, distinctively: harmonics distortion and frequency fluctuations. Secondly, Model Predictive Control (MPC) with Finite Control Set (FCS) attributes conceptual simplicity and higher accuracy than conventional controllers but suffers from variable switching frequency. In this paper, we propose MPC approach that solves the switching frequency problem while maintaining the accu- racy of FCS. Last, the decoupled control between active and reactive powers of Direct Power Control (DPC) offers flexibility of operation over variable power factors. The effectiveness and reliability of the proposed approach are investigated through simulation using MATLAB/SIMULINK software