Application of distributed control to mitigate disturbance propagations in large power networks

During the past decades the electric power infrastructure has evolved into one of the largest and most complex systems due to its extreme dimension, geographic reach and high reliability requirements. Maintaining sufficient security margins requires major enhancement of the existing control. Particular emphasis should be placed on improving the ability of the system to survive extreme contingencies, triggered by very unlikely chains of events, but capable of propagating into widespread outages. In this paper, a distributed control scheme is proposed to mitigate disturbance propagations in large power networks. We find a linear state feedback that simultaneously optimizes a standard Linear Quadratic Regulator (LQR) cost criterion and induces a pre-defined communication structure. The proposed controller provides supplementary damping through the excitation of the generators. The main advantage of this approach lies in the limited communication and limited model information required for the design which makes it practically applicable for large scale systems. We use a large two-dimensional mesh structure test system with homogenous parameters, to demonstrate that the proposed controller performs almost as well as the optimal centralized control with far less amount of communication and computation. The choice of test system is due to the fact that electromechanical wave propagation behavior observed in actual power systems can be readily recognized in that structure.