Abstract: A plurality of buses of an electrical power system are grouped into agents, family lines of agents and families of agents based on the reactive reserves depleted when the buses are loaded. Contingencies are applied and the reactive reserves are monitored to determine an exhaustion factor for one or more family lines in one or more families. A boundary case solution exists for each outage that has no solution when the outage is removed in small steps and an additional step has no solution and is used to assess where, why, and how the contingency causes voltage instability, voltage collapse and local blackout. Based on this information, the voltage rescheduling, active rescheduling, unit commitment and load shedding is determined that can be used as preventive, corrective or emergency controls in system design and planning, operation planning, reactive and voltage management, real time control, and Special Protection System Control.