Numerical analysis of the harmonics influence on linear interpolation for Power Quality assessment

This paper presents a numerical analysis to determine the minimum sampling frequency for which a linear interpolation of AC Power signals can be reliably used in the digital domain, regarding the harmonics influence for Power Quality (PQ) assessment. The proposed approach of this paper is based on exhaustive simulations which take into account a large combination of distinct values for module and phase of the third and fifth harmonic components at a given range of sampling frequencies. Our results show that the linear interpolation produces spectrum module errors up to 33.38% for a sampling frequency of 250/32 kHz, while the module percentage error is up to 2.08% at 250/4 kHz. The main contribution of this work is to best determine the minimum sampling frequency that can be used, considering the presence of harmonics components, which makes the linear interpolation an efficient technique for PQ assessment. A minimum sampling frequency turns out to be advantageous for the digital signal processing performance and cost.