An Improved Method for Online Fault Location Based on the Phasor Measurement Unit in Transmission Lines Considering the Thermal Limit

In this paper, an improved online method for simultaneous estimation of parameters and fault location in transmission lines based on Phasor Measurement Units (PMUs) installed on both sides of the transmission line is proposed. Unlike offline methods, the proposed method does not depend on the geometric characteristics of the lines, the fault resistance and the impedance of the equivalent Thevenin sources. The most important application of line modeling is to estimate the thermal rating of transmission lines, which limits the power transmission capacity. Offline methods cause part of the power transmission capacity to be unused and create unrealistic congestion in the transmission system. Therefore, the estimation must be determined in a way that is online and has the appropriate accuracy and speed. Calculating the thermal rating is a complex task that requires estimating the parameters of the lines, calculating the temperature of the lines and determining the climatic conditions of the environment around the studied lines. Therefore, a new method based on a combination of direct conductor temperature monitoring method and method based on climatic conditions is proposed in this paper. In this method, first, the parameters of the transmission line are estimated and then using these parameters and the weather conditions of the desired line, the thermal rating is calculated online. In this paper, the Nonlinear Least Squares (NLS) method is used to perform the process of simultaneously estimating the fault location and line parameters. The simulations were performed in the MATLAB software environment on a standard series capacitor-compensated transmission lines. The simulation results show that the proposed method has high accuracy and speed and can play a significant role in increasing the speed of line repairs and system reliability and reducing social and economic losses.