Robust Digital Redesign of Continuous PID Controller for Power system Using Plant-Input-Mapping

the digital redesign technique is one of the most popular approaches to the design of digital controllers in industries. Which converting a good-designed continuous time controller to a digital controller suitable for digital implementation. In this paper, the Plant-Input-Mapping algorithm (PIM) is used for converting the S-domain model of the PID controller to a Z-domain model counterpart. The proposed digital PID controller is used to enhance the damping of a single machine power system. The proposed method is based on a transfer function from the reference input to the plant input, which called continuous time plant input transfer function CT-PITF. All the poles of the transfer function that need to be controlled must appear in the CT-PITF. The results obtained from the proposed digital PID controller more convergence to the CT-PID controller especially for longer sampling period where Tustin's method is violated. The proposed algorithm is stable for any sampling rate, as well as it takes the closed loop characteristic into consideration. The computation algorithm is simple and can be implemented easily. The proposed digital PID controller is successfully applied to the linearized model of a single machine infinite bus system and the performances of the analog PID controller, Tustin's controller and the proposed digital PID controller are compared and their results are presented. Key-Words:Dynamic stability, Digital redesign, Discretization, Plant-Input-Mapping, Discrete systems.