Application of WAMS and SCADA Data to Online Modeling of Series-Compensated Transmission Lines

Transmission line parameters are indispensable prerequisites for power system studies such as power flow analysis, state estimation, congestion management, protective relaying, etc. Since the line parameters vary in time due to various reasons such as environmental condition changes, online estimation of line parameters is thus crucial to assure reliable outcome of system studies. Phasor measurement units (PMUs), as the basis of measurement infrastructure in a smart transmission grid, turn out the online estimation of transmission line parameters feasible. In this paper, a practical method for online estimation of series-compensated transmission lines parameters is devised in which PMU and supervisory control and data acquisition data are jointly used. To do so, the nonlinear weighted least square error algorithm is employed. Additionally, the proposed method is extended to set forth the parameter estimation of three-phase model of a transmission line needed for unbalanced system studies. Unlike the existing methods, which necessitate PMU installation at both sides of the lines, the proposed method works with few PMUs and has admirable practical merits in nowadays power systems. Case studies through software and hardware simulation efforts demonstrate validity of the modeling approach.