Damping of electro-mechanical oscillations in a multimachine system by direct load control

Utility controlled customer loads as actuators present new possibilities for power system control. The use of active loads controlled by local bus frequency is proposed for damping of electro-mechanical oscillations. The viability of the idea is studied for one load in a three machine system with a meshed network. Active power mode controllability and phase angle mode observability are determined from the eigenvectors of a differential algebraic description of the uncontrolled system. The geographical variations in the entire network of controllability and observability are shown to be identical. It is presented graphically on a 3D-view of the network topology and is used as a generalization of the term mass scaled electrical distance. System zeroes limit the maximum damping. An electro-mechanical mode pendulum analog is introduced that explains this. Time simulations verify the final controller design.