Explain the term “Transmission Congestion”.

Transmission congestion refers to a scenario where the demand for electricity surpasses the available capacity of the transmission infrastructure to deliver that electricity. Essentially, this situation occurs when the existing transmission lines are unable to accommodate all the electricity being produced or requested by consumers, leading to a bottleneck.

In such circumstances, the excess demand can result in increased costs for electricity as market operators may need to rely on more expensive generation sources closer to the demand load or construct temporary solutions. Transmission congestion can also lead to reliability concerns, as network operators must manage flow limits and ensure that power deliveries do not exceed the safe operational thresholds of the lines.

Understanding transmission congestion is vital for effective electricity market planning and ensuring that both supply and demand can be met without overloading the system. This situation does not relate to low demand, planned decreases in demand, or maintenance activities, which are caused by distinct factors.