What could indicate that interconnection system loads are higher than on-line generation?

When analyzing the relationship between interconnection system loads and on-line generation, monitoring the system's frequency is paramount. A frequency of 59.15 Hz suggests that the system is experiencing strain; in this case, it is operating below the standard nominal frequency of 60 Hz.

When loads exceed the generation capability, the frequency tends to drop, indicating that the demand for electricity is greater than what is being produced. This drop brings about a frequency lower than the nominal level, and sustaining operation at this frequency may lead to further instabilities unless corrective actions are taken. A well-functioning system should maintain frequency close to 60 Hz, and any significant deviation, such as 59.15 Hz, is a clear signal of imbalance, pointing towards higher loads relative to generation capacity.

Understanding frequency behavior is crucial, as it reflects the system's overall health and balance between generation and consumption. Conversely, conditions such as stable voltage levels or generation exceeding demand would not suggest a scenario of surplus load, as they indicate operational normalcy or excess generation, respectively.