During a system restoration, load block additions should be limited to what percentage of the online generation availability?

In the context of system restoration in the electric power sector, managing load block additions is critical for maintaining system stability and reliability. The guideline to limit load block additions to a small percentage of online generation availability is designed to prevent overloading the system, which could lead to further disturbances or even cascading failures.

Opting to limit load block additions to 5% of available generation ensures that the system is not pushed beyond its capacity, allowing for sufficient headroom to address any fluctuations or unforeseen issues that may arise during the restoration process. This conservative approach enables operators to safely increase system loads while keeping the system stable and ensuring that there is adequate margin to handle unexpected events, such as the sudden loss of generation or variation in demand.

In contrast, higher percentages, such as 10%, 50%, or even 2%, do not provide the same level of operational safety and flexibility. A limit of 2% might be too restrictive, potentially delaying restoration efforts unnecessarily, while limits of 10% or 50% would significantly increase the risk of instability and would not be considered best practice during system recovery scenarios. Thus, adhering to a 5% limit strikes the right balance between restoration speed and operational safety.