Online Non-iterative Estimation of Transmission Line and Transformer Parameters by SCADA Data

Utilization of various measurements provided by supervisory control and data acquisition (SCADA) system has recently attracted increasing attention. Real-time estimation of transmission line parameters, utilizing voltage and power flow measurements provided by remote terminal units (RTUs) located at line terminals, has been investigated. This paper significantly improves the existing approaches by introducing a novel linear formulation of the problem, which can be solved in a closed form. The distributed-parameter model of long transmission lines is considered and its parameters are estimated in a noniterative manner using traditional SCADA measurements. The new method is further extended to estimate transformer series impedance and tap position using SCADA measurements, linearly. As such, the shortcomings associated with the previously proposed iterative approach, e.g. concern over convergence, for transmission line parameters are avoided. Moreover, the novel technique for estimating transformer parameters allows to determine the tap position as well as updated transformer series impedance. Furthermore, a thorough analysis is presented to take the measurement accuracy into account. Simulation results for different transmission lines and transformers in the IEEE 118-bus test system are reported. The results obtained indicate successful performance of the proposed algorithms.