What indicates the hourly output of generating units?

The generation schedule is the document or plan that outlines the expected hourly output of generating units in a power system. It provides essential information regarding how much power each generating unit is expected to produce at different times throughout the day. This schedule is vital for balancing supply and demand and for ensuring that the grid operates efficiently and reliably.

In contrast, frequency variation refers to changes in the electrical frequency of the grid, which can occur due to imbalances between generation and consumption. While frequency is a critical aspect of power system stability, it does not specifically indicate the hourly output of generating units.

The grid code refers to the set of rules and standards that govern the operation of the electrical grid, including requirements on how generating units should operate. While important for overall operations, it doesn’t directly specify the hourly output of each unit.

Frequency regulating reserve pertains to the additional capacity that can be deployed to maintain frequency stability. While this reserve plays a crucial role in responding to unexpected changes in load or generation, it does not directly provide information about the planned output of generating units.

Thus, the generation schedule is the appropriate answer, as it directly correlates to the expected and managed hourly output of power generation resources.