Model Predictive Direct Power Control for a Grid-Connected Converter with an LCL-Filter

This paper presents a Model Predictive Direct Power Control (MPDPC) scheme for the control of a three-phase grid-connected Neutral Point Clamped (NPC) converter with an LCL-filter. MPDPC is a variant of Model Predictive Control (MPC) which regulates the output power of the converter within a set of hysteresis bounds, whilst minimising switching frequency and/or losses. By incorporating an Active Damping (AD) strategy which suppresses spectral content around the main resonant frequency of the LCL-filter, MPDPC achieves low levels of grid current distortion at low switching frequencies. Through simulation, it is shown that the proposed MPDPC strategy is capable of offering a significant improvement over the performance of Carrier-Based Pulse Width Modulation (CB-PWM) at the chosen steady-state operating points.