Online Determination of External Network Models Using Synchronized Phasor Data

This paper proposes an online measurement-based method for determining multiport Thevenin equivalent circuit parameters of an external power system. The equivalent circuit is estimated using synchronized voltage and current phasors measured at the boundary nodes and it is intended to work continuously leading to real-time equivalent models of the external system. The measurement errors and noise are taken into account by utilizing extra measurements and applying the least-squares method to find the equivalent model parameters. A method to determine the origin of the disturbances is proposed to detect system changes that can be used for the parameter identification process. The performance of the proposed method has been demonstrated by using the IEEE 118 bus system.