Open AccessLeast error squared phasor estimation with identification of a decaying DC component
Author(s) -
Hwang Jin Kwon
Publication year - 2018
Publication title -
iet generation, transmission and distribution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 110
eISSN - 1751-8695
pISSN - 1751-8687
DOI - 10.1049/iet-gtd.2017.0446
Subject(s) - phasor , dc bias , harmonics , control theory (sociology) , noise (video) , fault (geology) , electric power system , computer science , frequency deviation , component (thermodynamics) , power (physics) , electronic engineering , algorithm , engineering , voltage , telecommunications , automatic frequency control , physics , control (management) , quantum mechanics , artificial intelligence , electrical engineering , thermodynamics , seismology , geology , image (mathematics)
A fault current in a power system contains both harmonics and a decaying DC component, which can produce a severe error in phasor estimation of fundamental frequency. Currently, full‐cycle discrete Fourier transform phasor estimation is widely used in numerical relays owing to harmonics immunity, which produces easy identification of the decaying DC component. It is desirable to promptly estimate the phasor for a fast protection of the power system. Such promptness is dependent on the data window length of the phasor estimation. The least error squares (LESs) method is effective to achieve this promptness as it can estimate the phasor with a data window length of less than one cycle. This study proposes a phasor estimation method using LES with the data window length less than one cycle. The time constant of the decaying DC is identified through Prony analysis, while the noise effect on the phasor estimation is investigated according to the data window length. The performances of the proposed method are investigated through simulations on time constants of the decaying DC, frequency deviations of the power system, and signal‐to‐noise ratio. The feasibility of the proposed method is verified to estimate the phasor of a fault transmission line in a MATLAB/Simulink.