When reactive resources are insufficient, what corrective action is required by the Transmission Operator (TOP) to prevent voltage collapse?

When reactive resources are insufficient, it is crucial for the Transmission Operator (TOP) to take measures to maintain system stability and prevent voltage collapse. One effective corrective action is to shed firm load. This process involves intentionally reducing the demand on the system by disconnecting certain customers or reducing their consumption.

By shedding load, the TOP can alleviate the stress on the electrical network and help stabilize voltages. When reactive power resources are lacking, the system may become unable to support the existing load, leading to a rise in voltage instability and a risk of voltage collapse. To counteract this, reducing the overall demand helps balance the load with the available reactive power capacity.

While other options may seem viable, they do not address the immediacy of the voltage stability issue as effectively as shedding load does. For instance, increasing load would exacerbate the problem, and emergency generation may not provide the necessary reactive support needed in this situation. Likewise, decreasing transmission line flows might not be feasible or effective in quickly addressing the shortage of reactive resources. Thus, shedding firm load is a direct and necessary action to protect system reliability under conditions of reactive power insufficiency.