Unified power flow controller: a critical comparison of Newton-Raphson UPFC algorithms in power flow studies

A new and comprehensive load flow model for the unified power flow controller (UPFC) is presented. The UPFC model is incorporated into an existing FACTS Newton-Raphson load flow algorithm. Critical comparisons are made against existing UPFC models, which show the newly developed model to be far more flexible and efficient. It can be set to control active and reactive powers and voltage magnitude simultaneously. Unlike existing UPFC models, it can be set to control one or more of these parameters in any combination or to control none of them. Limits checking and an effective control co-ordination between controlling devices are incorporated in the enhanced load flow program. The algorithm exhibits quadratic or near-quadratic convergence characteristics, regardless of the size of the network and the number of FACTS devices.