Optimized Design and Analysis of
Integrated Renewable Energy
Resources with the Deployment of
Photovoltaics for Power Quality
Improvement

Abstract

With the growing concerns about climate change and energy security, solar energy has been recognized as a green and reliable source of electrical energy in recent years. However, considering the variations in solar irradiance levels the operating point of the PV panel is shifted. This phenomenon leads to the abrupt changes in operating conditions, particularly in Grid Connected Photovoltaic (GCPV) systems, which ultimately result several power quality issues in the power systems. Another reason for these abrupt changes is abnormalities at grid side. The sudden variations in operating conditions give rise to two major concerns regarding the power quality in GCPV systems (i) voltage instability at the point of common coupling (PCC) (ii) harmonic distortion for voltage and current signals at the PCC. Therefore, it is essential to maintain the power quality at varied operating points caused by sudden changes of solar irradiance and weather conditions as well due to abnormal condition at grid side. In this thesis, extensive literature review was conducted for exploring the causes, effects and recently implemented solutions for various power quality issues in GCPV system. Accurate integration of GCPV system with grid requires a Voltage Source Converter (VSC) based control strategy for voltage regulation and appropriately designed LCL filter 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 presented in this research work to incorporate changes in solar irradiance and to maintain the Total Harmonic Distortion (THD) in accordance with the IEEE standards 519. As any changes in operating conditions at the supply side cause poor quality of the delivered current. Similarly, grid side abnormalities deteriorate the reference signal and ultimately results poor quality of the delivered power by PV system. Accordingly, in the thesis, power quality problem caused by both reasons have been addressed and solved. To ensure the delivery of clean voltage and current signals, a novel approach for optimized filer design has been presented. The respective technique was designed based on the numerical evaluation considering various factors of the PV system and its integration with grid. Considering the other reason of poor power quality caused by measured distorted voltage from grid, a modified DSOGI-PLL SVPWM based VSC control scheme was proposed which incorporates the digital control method of filtering the distorted measured grid voltage, the reference signal provided to the PV system will not be impacted. A MATLAB/Simulink based GCPV model was developed and proposed research methods were analysed to exhibit the effectiveness of the proposed control and design method. Additionally, laboratory-based system was developed to validate and analyse the accuracy of the proposed design method.