What is the frequency control range during restoration?

During the restoration phase of power system operation, the frequency control range is critical for ensuring system stability and reliability. The correct range of 59.75 - 61.0 Hz reflects the operational limits set to safely manage frequency fluctuations while restoring service after a disturbance or outage.

The lower limit of 59.75 Hz allows for some variability below the nominal frequency of 60 Hz, accommodating slightly lower system frequencies that can occur during restoration efforts without leading to instability. The upper limit of 61.0 Hz provides a cap to prevent frequency from rising excessively, which can also pose risks to system reliability and equipment.

This range is established based on operational protocols and the need to maintain a balance between generation and load during restoration, ensuring that frequency remains within a safe threshold. Such parameters help prevent system overloads and maintain the overall integrity of the grid during recovery periods, underscoring the importance of carefully managing frequency in the electricity supply system.