A Half-Cycle Fast Discrete Orthonormal S Transform based Protection-class μPMU

This paper proposes a novel Fast Discrete Orthonormal Stockwell Transform (FDOST) based Protection-class Micro Phasor 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, fault detection, etc. The phasors are estimated from FDOST, utilizing the Half Cycle Discrete Fourier Transform. 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 Filteration (EHF) and Half Cycle Sample Value Adjustment (HC-SVA), respectively. Since both of these techniques, viz., 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 work. 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., Hilbert transform-convolution based PMU (HTC-PMU) and 2-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.