Methodology for Flicker Estimation and Its Correlation to Environmental Factors in Photovoltaic Generation

Abstract

Flicker is a very common power quality disturbance due to the inclusion of photovoltaic generation on the electric grid. This paper presents a methodology for flicker estimation in a photovoltaic generation that fuses multiple signal classification (MUSIC) and discrete wavelet transform (DWT) to provide high-resolution frequency estimation with an accurate amplitude measurement. This tool considers that flicker is not stationary over time and that more than one frequency component can exist on a voltage signal. Additionally, this work finds that sun irradiance, temperature and the action of the solar inverter are the sources of flicker in photovoltaic generation. The methodology is applied to real signals from three days with different weather conditions. Additionally, two different solar inverters are evaluated to see their influence on the parameters of flicker. Results show that flicker can contain more than one frequency component that can change over time. Finally, this work shows that around 70 to 80 percent of flicker is linked to irradiance and cell temperature whereas the 20 to 30 percent can be attributed to the operation of solar inverters.