On-Line Identification of an Equivalent Reactance for Stability Applications

This paper describes a procedure for identifying the reactance of a predominantly radial network. Measurements are taken at one location in the network, from which the equivalent reactance to a fictitious high inertia bus is identified. The method makes use of a phase angle related quantity, obtained by integrating the local frequency, and the unknown parameter is identified as soon as power swings occur in the system. The procedure is implemented on a digital processor, and the design is elaborated for real time applications. As such, it is well suited for the decentralized control of power system dynamics. The identification method is verified in a real life field test.