Dynamic Behaviour of AGC Systems Including the Effects of Nonlinearities

A general mathematical model capable of representing multi-area, multi-unit systems has been used to study the dynamic behaviour of AGC systems. The eigenvalues of the system are obtained and classified. The modes which play the most Important role in the system dynamics are identified and related to the system control loops. The effects of the nonlinearities are assessed by their position in the control loops. It is shown that the adverse effects of the nonlinearities are pronounced when the linear model at operating point, has lightly damped critical modes. The effects of the nonlinearities can be minimized by increasing the damping of these modes using methods outlined in the paper.