Análise de metodologia para detecção de perda total de excitação em geradores síncronos sob condição de perda parcial de campo

Abstract

A synchronous generator is a constant frequency voltage source that supplies power to a load, whose voltage at its terminals is controlled by the excitation system that provides DC current to the field winding of the generator, which produces a magnetic field. However, it is known that problems can occur due to the generator's underexcitation, such as voltage sags at the generator terminals and loss of active power generation capacity, and the generator starts to consume reactive power. , Heating the machine. Therefore, there is a need for studies aimed at developing synchronous generator protection methodologies that eliminate undesired situations such as those caused by partial and total machine excitation losses. In this context, the presente work presents the problems caused by partial and total loss of excitation insynchronous generators, through simulations of situations where excitation losses occur, using DigSilent® software. In addition, a methodology for the detection of partial and total excitation losses, capable of differentiating these phenomena from a stable power oscillation, was developed based on the analysis of the signals generated in the simulations. This technique is based on the extraction of the current and voltage signal envelopes at the generator terminals, which have specific characteristics in both excitation loss and power oscillation events. The detection of these characteristics allows the classification of the respective event. Thus, the proposed technique was fast, accurate and with good performance in the detection of stable oscillations of power and excitation losses, total or partial, when compared to the traditional methodologies applied for the detection of field losses.