Estimação dos parâmetros de linhas de transmissão: uma abordagem utilizando medições fasoriais e representação em quadripolos

Abstract

The estimation of transmission line parameters represents a critical issue for the operation and planning studies of electric power systems. This topic explores methodological approaches aimed at obtaining the impedance parameters of transmission lines through the continuous monitoring of electrical variables. With the advent of synchrophasor technology, new methodologies have been developed based on measurements collected at the terminals of a transmission line using Phasor Measurement Units (PMUs). This dissertation presents a novel approach based on the formulation of an optimization problem for estimating the impedance parameters of transmission lines, where the least squares equation is used as an objective function to be minimized, subject to a set of constraints associated with the impedance parameters of a transmission line. The line is initially modeled using quadrupoles (two-port network) with series-connected PI sections, and subsequently, an intermediate high-impedance fault model is included to analyze faults in transmission systems that do not result in circuit breaker operation but still affect the line’s performance during its operation. As a solution to the proposed optimization problem, the impedance parameters of a given high-voltage line can be calculated with reduced estimation errors (smaller than the accuracy of the measuring devices themselves), as well as the fault location and its corresponding impedance. The main contribution of this work is the representation of an explicit transmission line model in an optimization problem formulated in rectangular coordinates to determine overhead line parameters in real time with the assistance of PMUs. To demonstrate the applicability of the proposed method, computational tests and hardware-in-the-loop (HIL) simulations are conducted using the RTDS (Real-Time Digital Simulator), which validate the results and the applicability of the proposed method.