Constraints Violation Handling of GUPFC in Newton-Raphson Power Flow

Generalized Unified Power Flow Controller (GUPFC) is one of the newest Flexible AC transmission system (FACTS) devices based on voltage source converters. This paper presents a developed model of GUPFC based on power injection approach. The series converters of GUPFC is represented by injected complex loads as function of the specified powers flow, while the shunt converter is represented as a synchronous condenser that provides the reactive power compensation to control the bus voltage magnitude. The main advantage of the developed model is that the original structure and symmetry of the admittance and Jacobian matrices can still be kept avoiding the changes of the original Jacobian matrix. Consequently, the complexities of the load flow are reduced. This model includes simple strategies for handling the operating constraints of GUPFC, including the injected series and shunt voltages magnitude, currents of the series and shunt converters, and the real powers exchanged in the converters. The strategies are based on decreasing one or more values of specified values or by modifying the specified values as a function of the required constraint limits. The developed model and proposed strategies for handling violation of GUPFC operating constraints are tested on IEEE test systems such as 57-bus and 118-bus systems.