Investigation of symmetrical optimum PI controller based on plant and feedback linearization in Grid-Tie inverter systems

Up to now, conventional proportional-integral (PI) controllers are the most common DC-bus voltage regulation strategy used in grid-tie inverter systems. The popularity of PI controllers are mainly due to the simplicity of its control structure and the feasibility of its control performance. The main aim of this work is to investigate and to compare the performance of two linearization techniques in which PI controller implemented to handle the nonlinear problem of the DC-bus voltage regulation, namely: plant linearization and feedback linearization technique. To get optimum responses, in this paper, the PI controller parameters were chosen by the popular symmetrical optimum tuning method. By using simulation study under Matlab/Simulink software environment, it is shown that both the linearization techniques based PI controller have almost the same performance in response to relatively small power disturbances. Whereas for the relatively large power disturbances, the performance of the plant linearization based-PI controller, although not too significant, is more superior than that based on the feedback linearization technique.