LAUSR

This paper describes a new steady-state model to represent the synchronous machines, generators or motors, in unbalanced power flow studies. Also some power and voltage controls, which can be applied in the machines, are modeled. The groundings of the synchronous machines can be represented. Most power flow studies represents the synchronous machines in a very simplified way, such as conventional fixed power injections in a bus (PQ bus) or as a voltage controlled bus (PV bus). This representation can present good results for power flow studies in balanced electrical systems, but in unbalanced electrical systems can lead to considerable errors due to particularities of the electromechanical behavior of the machine. In the proposed model, it is possible to represent the internal losses of the machines, an internal voltage source in phase-domain, defining the internal voltage module and a fixed angular difference between phases. The controls developed allow to specify the three-phase active and reactive power demanded or consumed by the machine and to control the voltage in a bus in different ways, dependent on how the control systems are in practice. The model was applied to the IEEE13, IEEE34, IEEE123, and IEEE8500 test feeders, and proved to be robust and more accurate than conventional models in situations of imbalance.