Identification of voltage collapse margins in power systems

Voltage collapse has been associated with a stress condition of power systems. Control actions must provide the desired results, otherwise a system may operate in an unknown condition. It has been shown that this unknown condition is associated with two regions of operation and the boundary between them. The boundary between the two regions is associated with a singular load-flow Jacobian. In order to identify the critical bus, a reduction of the load-flow Jacobian in relation to each load bus is derived. To reduce computational burden associated with large power networks, a network partitioning is proposed based on voltage variation at each load bus in relation to load variation at the other load buses. For calculating the margins, for all load buses of the weak area of the power system identified from network partitioning, the relation between load variation at each load bus and voltage magnitude and angle phase variations at the critical bus are normalized, one by one. The buses strongly connected to the critical bus have smaller load variation in relation to the buses weakly connected to the critical bus. The proposal method has been tested using an IEEE 24-bus system