Effects of Varying Operating Conditions of Different Renewable Energy Sources on Steady State, Fault Performance, and Transient Stability of Power Systems

Performance issues may arise with the increased integration of renewable energy sources (RESs). In this paper, ETAP analysis tools are used to examine IEEE 9-bus system by integrating various RESs, including photovoltaic (PV) panels, two types of wind turbines (WTs), and hybrid configurations. To assess steady-state performance, the operating conditions are varied including changes in RES types, penetration levels, power factors, and topology. Improved voltage stability and reduced power losses can be attained by implementing optimal operation techniques and utilizing RESs with controllable volt/var capabilities to adjust the power factor. Further, fault analysis at different buses reveals that the presence of RESs can significantly alter fault currents, potentially causing maloperation of protective devices. When RESs are distributed among multiple buses, fault currents in the lines close to RESs increase while those in distant lines decrease by 50% in certain cases. Additionally, the behavior of the system under transient events-including faults, loss of generation units, and sudden load changes-is examined. The findings indicate that while RES integration improves the overall stability, notable differences exist between PV- and wind-based sources. Specifically, the power system may overcompensate for the lack of inertia-support in PV-based sources, leading to a speed drop below the nominal value of the swing bus. Therefore, adaptive protection schemes and inertia-support capabilities are required when RESs are integrated into existing grids to provide accurate protection operations and stability support particularly during major disturbances.