In this study, by using two variables of the angle between voltage and current (θsg) and terminal voltage (Vsg) in a precise combinational logic, a new protection method is presented to detect the excitation loss of a synchronous generator. In this structure, the changes in θsg of the machine are continuously monitored and if it becomes positive, the changes in the Vsg parameter are examined. In this situation, if the amplitude of Vsg is greater than 0.95 per unit, it indicates the response of the machine control system and the normal operation of the machine will continue. However, if the magnitude of Vsg decreases and reaches a value less than 0.95 per unit, excitation loss occurs and the generator trip command is issued. The combined method proposed in this study has been evaluated in the MATLAB/Simulink (2017b) software environment during different scenarios of excitation loss and power system transients on the IEEE standard 39-bus system. The results of the simulations confirm the effectiveness of the proposed protection model. It should be noted that the superiority of the proposed method in terms of accuracy, speed, simplicity and implementation cost has also been compared with the impedance method.
fatholahi M S, moradi J, rostami A. A simple optimization logic based on the parameters of the angle between voltage and current and the size of the terminal voltage to protect loss of excitation of synchronous generator. تحقیقات نوین در سیستمهای قدرت هوشمند 2025; 13 (4) :13-22 URL: http://jeps.dezful.iau.ir/article-1-523-en.html