Abstract:
his article proposes a novel technique for
fundamental and selective harmonic phasor estimation of
a single-phase voltage signal based on open-loop voltage signal processing approach, under adverse distorted
conditions. At heart, a modified fast discrete Stockwell
transform (FDST) is used for the phasor estimation. The
performance of the FDST is improved by incorporating a
new frequency-dependent Gaussian window for capturing
the time-localized variations of individual frequency component. The modified window has four parameters, which
are selected based on the statistical properties of the given
input voltage signal. Furthermore, under off-nominal frequency conditions the spectral leakage problem, faced by
the S-transform, is avoided by proposing a modified sample value adjustment based preprocessing stage. Various
static and dynamic tests were considered according to the
IEEE Standard 1159, IEEE Standard C37.118.1a-2014, and
EN-50160 standards under harmonics and interharmonics
scenarios. The performance of the proposed method is
validated using synthetic voltage signals, simulated voltage
signals on 6-bus microgrid model developed in power system computer aided design (PSCAD), and hardware implementation on dSPACE 1103. The rigorous test cases reveal
that the proposed phasor measurement unit has a good
adaptability to grid frequency drifts, a good harmonic and
dc-offset rejection capability, and a very good steady state
as well as dynamic response.
