What type of reserve is required to return an area to a pre-contingency state?

The required type of reserve to return an area to a pre-contingency state is the synchronous reserve. Synchronous reserves are necessary for maintaining system stability and ensuring that generation can match load almost instantaneously, particularly in response to sudden disturbances or outages of generation sources.

These reserves consist of online generation that can be quickly ramped up to respond to frequency deviations and maintain the balance of the power system. This capability is essential during contingency events, where the loss of a generator or a significant change in load could create frequency instability. By having sufficient synchronous reserves in place, the system operator can effectively manage such disturbances, quickly restoring the system to its pre-contingency condition.

Other types of reserve, while crucial to power system operation, serve different purposes. Dynamic reserve refers to reserves that can respond to changing conditions over time, while static reserve indicates a certain amount of generation that is always available and ready to be used. Contingency reserve is a broader category that includes several kinds of generation resources prepared to address unexpected events, but synchronous reserve specifically relates to stabilizing the system immediately after such events.