Impacts of On-Grid Solar PV on Distribution Networks and Potential Solutions: A Case Study in the Region of Zahle

Abstract

Recent years have witnessed an increase in the installation of solar photovoltaic-based distributed generators or PV DGs mainly in countries with high solar potential such as Lebanon. In this country among others, the outgrowing trend towards installing on-grid PV-DGs is gradually impacting the safe and reliable operation of distribution networks. This research investigates the impacts of on-grid PV DGs on the power factor, active and reactive power flows, voltage and current profiles in the region of Zahle, Lebanon, and examines solutions to mitigate these impacts using available and affordable resources, infrastructures, and policies. For this purpose, the research develops a model for heavily PV DG-loaded distribution lines in Zahle. Then, power flow simulations are conducted in OpenDSS on these modeled lines with and without the presence of PV DGs to quantify their impacts on voltage, power factor, and power flows. Afterward, the optimal siting and sizing of capacitor banks (CBs) are performed on the modeled network to alleviate the impacts of the PV DGs using both MATLAB and OpenDSS. The siting and sizing methodology is conducted by considering five different optimization algorithms, namely the single-objective genetic algorithm (SOGA), the combined SOGA and loss sensitivity factor algorithm (SOGA-LSF), the multi-objective genetic algorithm (MOGA), the combined MOGA-LSF and the CAPADD algorithm of OpenDSS. The CB allocation solutions obtained from these algorithms are then compared from a technical and economic perspective. The effects of the addition of the CBs on the operation of the distribution network of Zahle are further studied by examining different types of CB control available in OpenDSS (voltage and time control). The results of the impact assessment showed severe problems mainly at the end of Feeder 2. Both the size and location of the PV DGs were concluded to have the most influence on the results. The optimal siting and sizing of the CBs succeeded in reducing the power losses and improving the voltage profile. The MOGA allocation solution achieved the highest power loss reductions and the combined allocation solutions, MOGA-LSF and SOGA-LSF, resulted in the best improvements in the voltage profiles of the endmost buses of Feeder 2. The MOGA and MOGA-LSF were deemed superior in terms of technical performance and cost. The novelty of the research lies in the realistic portrayal of the impacts that PV energy has on distribution networks that are generally forsaken, and on the practicality of the CB allocation methodology and network model proposed. It is expected that the results and conclusions drawn from this research will help distribution utilities deal with the rising issues emanating from PV DGs and predict the impacts they may have before their integration into distribution networks.