  This paper investigates the potential of wind turbine generators (WTGs) and
load aggregators (LAs) to provide supplementary damping control services for
low frequency inter-area oscillations (LFOs) through the additional distributed
damping control units (DCUs) proposed in their controllers. In order to provide
a scalable methodology for the increasing number of WTGs and LAs, a novel
distributed control framework is proposed to coordinate damping controllers.
Firstly, a distributed algorithm is designed to reconstruct the system Jacobian
matrix for each damping bus (buses with damping controllers). Thus, the
critical LFO can be identified locally at each damping bus by applying
eigen-analysis to the obtained system Jacobian matrix. Then, if the damping
ratio of the critical LFO is less than a preset threshold, the control
parameters of DCUs will be tuned in a distributed and coordinated manner to
improve the damping ratio and minimize the total control cost at the same time.
The proposed control framework is tested in a modified IEEE 39-bus test system.
The simulation results with and without the proposed control framework are
compared to demonstrate the effectiveness of the proposed framework.
