What should a System Operator do first to improve the voltage when it is decreasing due to high load demand?

Placing capacitor banks in service is a fundamental step to improve voltage levels in response to decreasing voltage due to high load demand. Capacitor banks provide reactive power support, which helps in counteracting the effects of increased load on the system. When the load demand is high, the power factor can drop, causing voltage levels to fall. By placing capacitor banks into service, the system operator can supply the necessary reactive power (VARs) to stabilize the voltage. This is essential because stable voltage levels help in ensuring the reliability and efficiency of the power system.

Using generators to absorb VARs, while useful in certain scenarios, does not directly address the immediate need for reactive power support to counteract voltage drops, making it less effective as an initial response. De-energizing lightly loaded lines could exacerbate the situation by further increasing load on remaining lines. Increasing voltage to increase load is counterintuitive because it does not resolve the underlying issue of voltage drop but rather risks adding more stress to the system. Therefore, placing capacitor banks in service is the most appropriate and effective first action to improve voltage during high load conditions.