Influence Analysis of Photovoltaic Output on Harmonics and Flicker under Extreme Weather Conditions

Abstract

To solve the influence of photovoltaic connected to the station on the power quality of the low-voltage distribution network under extreme weather conditions, the two key points of harmonic and flicker are researched, and the analysis model of harmonic and flicker of the low-voltage distribution network is established according to the characteristics of the low-voltage distribution network in the station area. The characteristics of harmonics and flicker in low-voltage distribution networks with photovoltaic grid-connected inverters as grid-connected interfaces are studied in this paper. Through simulation, it can be concluded that the meteorological factors in the operating environment of distributed grid-connected photovoltaic power supply will have a certain impact on the harmonics and flicker of the low-voltage distribution network in the station area. The main reason is that extreme weather affects the output of the photovoltaic power supply, and the reduction of the PWM duty cycle under low output conditions leads to a significant increase in the number of odd harmonics. At the same time, the low output operation condition also leads to the occurrence of flicker. Finally, a method of controlling the generation of harmonics and flicker by using BP artificial neural network to predict the photovoltaic output and optimize the operation of photovoltaic is proposed. This method has certain practicability for improving the power quality of distributed photovoltaic power supply after connecting to the low-voltage distribution network in the station area.