Linear and nonlinear optimisation of power system performance

A review and comparative study of the various optimisation methods applied to electrical power systems is made in this paper. The linear optimal control derived by solving the matrix Riccati equation requires feedback of all the state variables. It is shown that the suboptimal control using feedback of a selected number of variables derived by Liapunov method can be equally effective. Under certain conditions optimal control derived from lineamised system equations can give improved system perfommance following large disturbances. However to achieve maximum improvement it is necessary to retain all the system nonlinearities in the optimisation procedure. A method of optimising a system for a nonlinear mode of operation retaining the advantages of closed loop control is described. Finally, the feasibility of practical implementation is investigated by incorporating the various optimal controls derived in a laboratory micromachine system.