What is the principal cause of voltage collapse?

The principal cause of voltage collapse is heavily loaded transmission lines exhausting reactive resources. When transmission lines carry large amounts of electrical load, especially near their capacity limits, they may struggle to maintain adequate voltage levels. This is particularly true if the system lacks sufficient reactive power support, which is necessary to manage voltage levels effectively.

As the reactive power resources are depleted due to overloading on the transmission lines, the voltage drops can escalate quickly, leading to voltage instability. This condition can ultimately result in a voltage collapse, where the system is unable to sustain the voltage levels required for reliable operation. Proper management of reactive power and the load on transmission lines is crucial to preventing such scenarios.

In contrast, factors like excessive wind power generation or high residential demand may influence the overall load on the system, but they are not the direct causes of voltage collapse in the same way that overloading and depletion of reactive resources are. Frequent switching of transmission lines can cause momentary disturbances but is not a primary cause of sustained voltage collapse.