Delay-dependent Stability of generator-excitation control system using root-locus approach

In this paper, a simplified analysis procedure is presented to ascertain delay-dependent stability of a closed-loop generator-excitation control system operated in a networked environment. In the networked control system framework, it is inferred that the use of smart grid technology like the de-ployment of complex sensor/measurement circuits, signal conditioning systems and data transfer through open communication links to effect closed-loop control of dynamic systems introduces time-delays in the feedback path. The feedback delays exert a destabilizing effect on to the overall performance of the closed-loop system. Using a modified root-locus approach combined with Padé approximation, a graphical analysis is presented in this paper to assess delay-dependent stability of a closed-loop generator-excitation control system with and without damping compensation. Using standard bench mark systems, the proposed analysis procedure is illustrated with appropriate simulation results.