Self-tuning controller for generator excitation control

The design of an excitation self-tuning controller for a generator connected to an infinite bus through a long transmission line is presented in this paper. The control strategy is to minimize a cost function which incorporates fluctuations of input, output, and set point with the system parameters identified in real time by a recursive-least-squares algorithm. The penalty factor used in the cost function to penalize excessive control action is selected by analysis to enhance the system stability. The salient points of the controller are its adaptive nature and application of a least squares formulation as a parameter estimator. The proposed excitation controller enables the power system to be stable over a wide range of operating conditions from no load operation up to the transmission power limit determined by the transmission network itself. For the situation that the system is subjected to random disturbances, or a change occurs in the operating terminal voltage by resetting the set point, the excitation controller also exhibits excellent performance. These results are demonstrated by computer simulation studies. These examples are for long transmission lines and large systems. The system dynamics are represented by voltage fluctuation at the bus at which the transmission line terminates.