Coordinated System Protection Scheme against Voltage Collapse Using Heuristic Search and Predictive Control

A coordinated system protection scheme (SPS) against voltage collapse based on model predictive control and tree search is presented. It optimally coordinates dissimilar and discrete controls, such as generator, tap changer, and load shedding controls, in presence of soft and hard constraints on controls as well as voltages and currents in the network. The response with the coordinated SPS is compared to an SPS based on local measurements using simulation of the Nordic 32 test system. In terms of the amount of load shedding required to restore voltage stability, the simulations indicate that load shedding based on local criteria is near optimal in the system studied. However, when generator controls are considered also as emergency controls, the coordinated scheme reduces the amount of required load shedding by 35% compared to the local scheme.