An adaptive PMU based fault detection/location technique for transmission lines. I. Theory and algorithms

TLDR

The study proposes an adaptive PMU‑based fault detection and location technique for EHV/UHV transmission lines, including a novel smart discrete Fourier transform (SDFT) algorithm to suppress noise and measurement errors for precise fundamental frequency extraction. The authors derive a fault detection/location index from Clarke components of synchronized voltage and current phasors, develop a line‑parameter estimation algorithm to counter aging effects, and validate the approach via EMTP simulations with added Gaussian noise. Simulation results show the SDFT method extracts accurate phasors under frequency deviation and harmonics, the parameter estimation algorithm tracks exact line parameters, and the overall fault location accuracy reaches up to 99.9% (with DFT accuracy up to 99.999% and parameter estimation up to 99.99%).

Abstract

An adaptive fault detection/location technique based on a phasor measurement unit (PMU) for an EHV/UHV transmission line is presented. A fault detection/location index in terms of Clarke components of the synchronized voltage and current phasors is derived. The line parameter estimation algorithm is also developed to solve the uncertainty of parameters caused by aging of transmission lines. This paper also proposes a new discrete Fourier transform (DFT) based algorithm (termed the smart discrete Fourier transform, SDFT) to eliminate system noise and measurement errors such that extremely accurate fundamental frequency components can be extracted for calculation of fault detection/location index. The EMTP was used to simulate a high voltage transmission line with faults at various locations. To simulate errors involved in measurements, Gaussian-type noise has been added to the raw output data generated by EMTP. Results have shown that the new DFT based method can extract exact phasors in the presence of frequency deviation and harmonics. The parameter estimation algorithm can also trace exact parameters very well. The accuracy of both new DFT based method and parameter estimation algorithm can achieve even up to 99.999% and 99.99% respectively, and is presented in Part II. The accuracy of fault location estimation by the proposed technique can achieve even up to 99.9% in the performance evaluation, which is also presented in Part II.