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