Investigation of Frequency Response of a Power Network Under Varying Penetration Levels of Renewable Energy Sources

Numerous countries worldwide have prioritized the expansion of renewable energy sources (namely wind and solar photovoltaic) in their energy generation portfolio in order to maintain a healthier environment. Therefore, when the use of renewable energy sources grows, the traditional synchronous-based power generation decreases, leading to a reduction in power system inertia. This is because renewable energy sources do not naturally supply inertia, unless certain reserves are maintained. This study examines the characteristics of the system's frequency behaviors considering varying degrees of renewable energy integration. The study utilized power system software (DIgSILENT Power Factory) to model the IEEE 39-bus test system. The simulation results indicated that when the wind penetration reached 50%, the sudden failure of the largest machine caused a significant increase in rate of change of frequency (ROCOF) of -0.5579 Hz/s. This was in contrast to the ROCOF of -0.3707 Hz/s observed at 0% wind penetration. As a result, the minimum frequency dropped to 59.15Hz, which is below the acceptable threshold of 59.5Hz.