Modified walsh transform for harmonic assessment

Abstract

Harmonic assessment at end users through energy meter is a part of power quality monitoring to determine harmonics contamination level in distribution network. Integration of harmonics extraction technique with energy meter requires two considerations which are measurement accuracy of the technique and its computational complexity to extract harmonics. These two aspects are main requirements for meter to support the execution of harmonics extraction since it is operated under low-cost microcontroller. In harmonic extraction of Fast Fourier Transform (FFT), the computation burden is quite high and requires additional hardware installation to support the algorithm’s operation. Therefore, this thesis presents a Modified Walsh Transform algorithm as an alternative harmonic extraction. The proposed algorithm consumes less arithmetic operations than FFT and suitable to be integrated into energy meter. This study involves with extracting distorted current signal into harmonic components, measuring the harmonics magnitude and calculating Root-Mean-Square (RMS), Total Harmonic Distortion (THD) and Distortion Power Factor (DPF) as well as computational analysis between FFT and Modified Walsh Transform algorithms. The result from simulation indicates that the proposed algorithm has 99% of accuracy percentage with more consistent result than FFT. Moreover, the arithmetic operation in Modified Walsh Transform is less than FFT to show that less computation burden consumed by the proposed algorithm. Meanwhile, a laboratory experiment has been conducted to demonstrate consideration of DPF in harmonics assessment and power factor measurement as complied in IEEE Std.1459-2010.