Noise mitigation in voltage and current waveforms in harmonic distortion estimation

Power quality deals with waveform of sine voltage. Good power quality is supplied by utilities when a perfect sine waveform is delivered. However, several adverse phenomena negatively affect the power quality, e.g. harmonic currents injected to the network. Hence, voltage and current waveforms are distorted. In order to obtain the harmonic content in voltage and current waveforms, they are captured using data acquisition systems. Unfortunately, data can be contaminated by noise. This paper analyzes how affects this noise to determine the harmonic content by an algorithm designed for this purpose such as the Fast Fourier Transform, among others, and proposes an algorithm based on moving average filter to mitigate these adverse effects. The proposed method has been tested using the modified IEEE 14 bus test system. The results show that the harmonic content obtained from low noisy voltage and current waveforms present a considerable error in harmonics of low magnitude; hence, a procedure is necessary to mitigate the noise in contaminated measurements, before they are used to obtain the harmonic content or to assess the time domain state estimation. The results suggest that by using the proposed method, the noise in measurements can be mitigated to low values, thus improving the accuracy of the harmonic content estimation.