Multivariable control design for damping interarea oscillations of bulk power systems using a modal reduction technique

A new technique for multivariable control design in order to raise precision and facilitate design procedures is described. The multivariable control scheme for damping improvement of power swings is based on the optimal feedback control theory, and in the design process, eigenvalues of a 2n x 2n matrix for an n-th dimension state equation must be calculated in order to solve the Riccati equation. Hence, in order to apply to a bulk power system, the matrix size must be reduced. By modal reduction technique which is proposed in this paper, the matrix size can be reduced by about 75%. The multivariable control scheme is applied to a 164-machine system. The result shows that the proposed technique enables the multivariable control design for a bulk power system with simple procedures.