Application of Hilbert-Huang transform to protect synchronous generator against loss of excitation

The loss of excitation (LOE) fault is known as one of the most frequent electric generators' internal faults. Conventional methods based on impedance measurements slow down the protection system and cause mal-operation during power swing. This study proposes a new approach for LOE detection in synchronous generators where changes in generator armature current after LOE fault are used for this purpose. By applying EMD and Hilbert-Transform methods to the generator armature current signal, the proposed Index is calculated. Based on this Index, the loss of generator excitation can be distinguished from power swing and various types of short circuits. To evaluate the performance of the mentioned Index, simulations have been performed in electromagnetic transient program (EMTP) on a test power system in different operating conditions, and the results confirm the outstanding performance of the proposed approach in comparison with other methods.