Application of the Min-Projection and the Model Predictive Strategies for Current Control of Three-Phase Grid-Connected Converters: a Comparative Study

This paper provides a detailed comparative study concerning the performance of min-projection strategy (MPS) and model predictive control (MPC) systems to control the three-phase grid connected converters. To do so, first, the converter is modeled as a switched linear system. Then, the feasibility of the MPS technique is investigated and its stability criterion is derived as a lower limit on the DC link voltage. Next, the fundamental equations of the MPS to control a VSC are obtained in the stationary reference frame. The mathematical analysis reveals that the MPS is independent of the load, grid, filter and converter parameters. This feature is a great advantage of MPS over the MPC approach. However, the latter is a well-known model-based control technique, has already developed for controlling the VSC in the stationary reference frame. To control the grid connected VSC, both MPS and MPC approaches are simulated in the PSCAD/EMTDC environment. Simulation results illustrate that the MPS is functioning well and is less sensitive to grid and filter inductances as well as the DC link voltage level. However, the MPC approach renders slightly a better performance in the steady state conditions.