Multivariable design of a multiple-functional unified power flow controller

One of the most important features of a unified power flow controller (UPFC) is its multiple control functions. These control functions have been suggested to be implemented by multiple controllers. However, examples presented in the paper demonstrate the existence of the dynamic interactions among different UPFC controllers and it is suggested that the multiple functional UPFC is designed to be a multi-input multi-output (MIMO) controller. It is demonstrated in the paper that a single multivariable controller can be designed successfully for the UPFC to perform the multiple control functions which takes full account of the control interactions in the MIMO UPFC system and guarantees the closed-loop system stability