Abstract

The rapid increase in electrical demand and the growing integration of renewable energy sources have introduced significant challenges to the stability and reliability of modern power systems globally. Among these challenges, voltage stability has emerged as a critical concern, particularly with the deployment of large-scale photovoltaic (PV) power plants whose output is dependent on solar irradiation. This study aims to enhance the voltage stability in Nepal's INPS Eastern transmission system by optimally integrating large-scale PV power plants. Load-flow studies and voltage stability analyses were conducted using the DigSILENT PowerFactory. The research methodology comprises three primary stages: (i) base case analysis without PV penetration, (ii) assessment of system performance with PV integration at various bus locations, and (iii) improvement of voltage profiles through the addition of reactive power support using capacitor banks. Optimal PV placement and capacity were identified based on their effectiveness in improving bus voltages, enhancing reactive power balance, and increasing the voltage stability margin of the system. The simulation results indicate that strategically integrating PV plants at selected buses significantly improves the voltage profile and stability margin of the power system. These findings demonstrate that large-scale PV integration, when optimally located and sized, can contribute to cleaner energy generation and a more stable and reliable power grid.