Direct Predictive Power Control of Grid Tied Distributed Generator Systems

This paper explains the direct power predictive control of three phase VSI interfaced DG. The controller aims are three-fold: a) Maintain the nominal voltage and frequency, b) Supply the required load power, c) Match the reference setpoint for power. The traditional direct power control utilizes complex optimal sequence calculations for the implementation and in this paper a methodology aimed at incorporating the discrete switching nature of power electronic switches. The switch can be either ON or OFF at a given instance and for any converter, the number of possible switching vectors is limited. By limiting the search space for the solution of switching vectors the optimization problem is reduced to an evaluation problem and by utilizing the direct power control, it is possible to quickly control the converter and support the active and the reactive power demands. The proposed control is simulated in MATLAB-Simulink and is compared against traditional control for performance of tracking.