Abstract:
This article proposes a novel, fast discrete orthonormal Stockwell transform (FDOST)-based protection-class
microphasor measurement unit (P-µPMU) algorithm. The proposed algorithm provides very fast and high-resolution measurements of the system state, which are then expected to
serve various active distribution networks (ADNs) protection
applications, e.g., islanding detection and fault detection. The
phasors are estimated from FDOST, utilizing the half-cycle
discrete Fourier transform (DFT). The two major concerns
of the half-cycle FDOST with respect to the response in the
presence of even harmonics and off-nominal frequency are
handled using the even harmonics filtration (EHF) and half-cycle
sample value adjustment (HC-SVA), respectively. Since both of
these techniques, namely, EHF and HC-SVA, require system
frequency as the input, a new peak and zero-crossing-based
hybrid frequency estimator (PZC-HFE) is also proposed in
this article. The performance of the proposed methodology is
evaluated for various simulated scenarios as per the IEEE Std.
C37.118.1a-2014, as well as in the hardware setup. The results
of the proposed P-µPMU algorithm are also compared with two
other methodologies, i.e., the Hilbert transform and convolution
based PMU (HTC-PMU) and two-cycle interpolated discrete
Fourier transform-based PMU (IpDFT-PMU) using the hardware
setup. The test results reveal the superiority of the proposed
P-µPMU algorithm over the compared methods in terms of
response time and the estimation accuracy.
