If a GDM is predicted to occur tomorrow, which parts of the system are most at risk?

The most at-risk parts of the system during a predicted Grid Disturbance Management (GDM) event are typically Wye connected transformers. This is due to their design and operational characteristics, which make them more susceptible to certain types of disturbances, especially those that cause significant fluctuations in voltage.

Wye connections provide a neutral point, which can become critical in handling unbalanced loads and stabilizing the system during disturbances. However, if a GDM is expected, it signifies that there may be significant imbalances or voltage issues that could strain the Wye connected transformers. These transformers are also commonly used for step-down applications and can be more affected by sudden load changes or voltage spikes that might accompany a GDM.

In contrast, radial connections and Delta connected transformers generally offer more resilience to GDM scenarios, as they often can better manage impacts due to their configuration and how they handle load variances. Line reactors, while important in managing system stability, do not carry the same level of risk as Wye connected transformers in the context of accommodating sudden disturbances. Therefore, focusing on Wye connected transformers highlights a crucial aspect of system vulnerability during expected GDM events.