Robust hierarchized controllers using wide area measurements in power systems

• We propose a methodology for robust hierarchized pole placement in power systems.
• The power system model used is the small signal stability model.
• This technique guarantees stability for the system at various operating points.
• It also guarantees adequate damping for oscillations at various operating points.
• Decentralized and PSS structured controllers are used in a first layer; centralized controllers are used in a second layer.

In this paper, we present a new method for robust centralized controller design using LMI’s with applications to power systems. This method makes possible to increase the damping rate of the decentralized system (that is, power system with PSS’s). It considers delays added to the signals that travel from the generators to the central controller. The robust hierarchized controller is composed by two control layers: the first one consists on decentralized controllers, that are applied independently to each machine of the system, what guarantees the stability and a minimum damping rate; the second one is composed by a centralized controller, that receives delayed information from all machines of the system, and it sends control signals to all generators. The centralized controller algorithm is robust, once it considers various operative conditions for the power system, and it also permits the choice of the communication delays.