What is used to help balance a system after it separates from the interconnection during a disturbance?

The selection of automatic under-frequency load shedding (UFLS) as the correct answer is appropriate because this system is specifically designed to help restore balance to the electrical grid when it has become separated from the interconnection due to a disturbance.

During a disturbance, such as a sudden loss of generation or a fault, the frequency of the power system can drop. To protect the grid and prevent larger-scale blackouts, automatic UFLS systems quickly disconnect pre-defined amounts of load from the system to reduce the demand and help restore the frequency to a stable level. This is done without the need for operator intervention, allowing for rapid response to immediate issues.

The importance of automatic UFLS lies in its ability to act swiftly and efficiently, which is critical in mitigating the impact of disturbances. This proactive measure stabilizes the system, allowing operators to manage the situation and restore normal conditions.

In contrast, while manual load control, load shedding protocols, and frequency regulation equipment all play important roles in grid management, they do not provide the same immediate, automated response that UFLS does in the context of system separation from the interconnection. Manual load control relies on human intervention and may take longer to implement, and load shedding protocols may not specifically address under-frequency conditions as proactively as