Analytical formation of the state matrix of a regulated power system accounting for UPFC action

An approach for determining the state matrix of a regulated system, including the action of the most versatile FACTS device, namely the UPFC (Unified Power Flow Controller), is presented in this paper. A way to model a UPFC is shown, which results in a representation particularly suitable when the linearisation of the system is of interest. The procedure for the formation of the state matrix is then presented, including generator inertia, asynchronous effect of damping windings and speed governor action. I. INTRODUCTION In the wide range of large power electronics based transmission controllers (FACTS), the latest generation is the UPFC (Unified Power Flow Controller) which can control simultaneously the various parameters governing the power flowing into a transmission line, both under normal and transient operating conditions. A revision of the analytical method for the formation of the state matrix of a dynamic and regulated power system is considered in the paper, introducing the UPFC action on the basis of a control function already suggested by the authors [1]. The approach appears to be attractive for software implementation on mathematical commercial packages, because of both its educational conciseness and its analytical evidence.