Fixed-order controller for reduced-order model for damping of power oscillation in wide area network

The use of wide area monitoring system (WAMS) offers an integrated measurement-based and model-based control, which suits to the operation of large electric power system (EPS), along with online analysis. This paper presents a study on fixed-order controller design for reduced-order model of coherent generators in the system. Firstly, the coherent generators in each area of large EPS are determined by mutual information theory, which represents the dynamic equivalence. Then state-space model of each area is reduced to lower size by square-root variant of balanced truncation algorithms. The two-input three-output models are identified for a single generator in each coherent area. Finally, controller is designed at WAMS level, i.e. centralized reducing the H^∞ norm of its closed loop transfer function as much as possible. The centralized controller uses difference of power flow/speed between the coherent generators of different area as input signal. The simulation results reveal effective damping of power/speed oscillations achieved by designed controller with respect to conventional PSS implemented.