What would be the best indicator for voltage collapse prone conditions?

The best indicator for voltage collapse prone conditions is low reactive power reserves. In an electrical system, reactive power is essential for maintaining voltage levels across the network. When reactive power reserves are low, there may not be enough reactive power available to support voltage levels during periods of high demand or disturbances. This can lead to a situation where the system is unable to maintain stable voltages, thus making it prone to voltage collapse.

During voltage disturbances, if reactive power reserves are inadequate, voltages can drop rapidly, leading to potential cascading failures or blackouts. A strong reactive power support system helps to stabilize voltages and prevent such events, emphasizing the critical role of having sufficient reactive power reserves in maintaining healthy voltage levels in the power system.

In contrast, high reactive power reserves, stable voltage levels, and increased generation typically indicate a robust system with the capability to manage voltage effectively, and therefore would not signify a vulnerability to voltage collapse.