What should an Operator do first if a transmission line is overloaded above its SOL?

• A. Shed load at the downstream bus
• B. Open the line
• C. Re-Dispatch Generation
• D. Initiate the restoration of the parallel line

Answer: (D)

When a transmission line's loading exceeds its System Operating Limit (SOL), the priority is to take actions that ensure system reliability and prevent further stress on the compromised line. The first step that an operator should take is to mitigate the overload effectively while maintaining system stability.

Initiating the restoration of the parallel line is a logical first action because it can help alleviate the load on the overloaded transmission line. By bringing a parallel line back online, the operator creates an additional path for electricity flow, which can effectively distribute the load more evenly across the network. This reduces the stress on the overloaded line and helps to restore balance to the system.

In contrast, shedding load at the downstream bus may be essential but is often considered a more drastic step. Opening the line is typically only done as a last resort because it can disrupt service and impact reliability. Re-dispatching generation may also be necessary, but it often takes more time to assess and implement than restoring a parallel line. Therefore, the best response in this situation is to prioritize actions that directly address the overload while maintaining system integrity.