Virtual Flux based Enhanced Predictive DPC Technique for Grid Connected Converter with Improved Power Quality Performance

Abstract

In this paper a line voltage sensorless predictive Direct Power Control (DPC) technique for three-phase Active Front End (AFE) rectifiers without inner loop PI controllers and Phase locked loop (PLL) is presented. The proposed predictive power control technique is based on the Virtual Flux (VF) concept and direct power control philosophy. The introduced technique has combined features of predictive technique for better response as well as a virtual flux concept as an inherent filtering. Therefore, it improves reference voltage generation which is further utilized by Space Vector PWM (SVPWM) technique for generation of the pulses. In this manner, the estimation of reference voltages from the proposed approach reduces the power errors, power ripples and Total Harmonic Distortion (THD) in line current. SVPWM provides the constant switching frequency therefore EMI filter designed is easier. In the proposed approach no PI controllers in inner control loop is required, therefore it does not need any tuning effort. Also, the sampling frequency requirement for the proposed technique is lesser to follow the IEEE standard-519. The experimental laboratory results demonstrate that the introduced technique provides independent control of real and reactive powers with better power quality performance than the existing VF table based DPC.