What is the primary voltage control concern when re-energizing the transmission system after a blackout?

The primary voltage control concern when re-energizing the transmission system after a blackout is high voltage caused by closed capacitor banks and Under Load Tap Change Transformers being in the full raised position.

During the re-energization process, there is typically a concern that circuit conditions can lead to excessive voltage levels. Closed capacitor banks can contribute to this situation because they are designed to provide reactive power support and can overly increase voltage if not properly managed. Under Load Tap Change Transformers help in maintaining voltage levels; however, if they are in a full raised position right from the beginning, it can exacerbate the voltage rise as systems come back online without a corresponding load to stabilize it.

The dynamics of re-energizing a system can lead to rapid voltage increases if there are not enough loads present to absorb the reactive power being introduced by the capacitors and transformers. Therefore, effective management of these devices is crucial for voltage stability during this critical phase of system recovery.