Optimized Design of LCL Filter for Grid Tied Inverters With Deployment of Large-Scale Grid Connected PV System for Harmonics Compensation and Stable Operation Under Sudden Changes in Weather Conditions

With the growing concerns about climate change and energy security, solar energy has been recognised as a green and reliable source of electrical energy. However, considering the variations of solar irradiance, particularly in Grid Connected Photovoltaic (GCPV) systems, the operating point of the PV panel is shifted, which ultimately cause several power quality issues in the power systems. When the operating conditions change, two major concerns arose regarding the power quality in GCPV systems (i) voltage instability at the point of common coupling (PCC) (ii) harmonic distortion for voltage and current waveforms at the PCC. Therefore, it is essential to maintain the power quality at varied operating points caused by variations of solar irradiance and weather conditions. In this paper, a Voltage Source Converter (VSC) based control strategy is developed for the voltage regulation, with a LCL filter design as the key component for harmonics elimination. Though, with the changes in the operating conditions, conventionally designed filters can deteriorate the control performance and risk the stability of the system. To overcome such issues, an optimized design method of LCL filter is also presented to incorporate changes in solar irradiance and to maintain the Total Harmonic Distortion (THD), in accordance with the IEEE standards 519. A MATLAB/Simulink based model was developed and analysed to exhibit the effectiveness of the proposed control and design method. Experimental work on an industrial scale was also caried out to validate the developed control scheme and the associate LCL filter.