A Novel Loss-of-Excitation Protection Strategy Based on Reactive Power Increment of Synchronous Generators
Ali Rostami, Navid Rezaei
Abstract
This paper outlines a novel loss of excitation (LOE) protection scheme for synchronous generators (SGs) based on reactive power increment (RPI) strategy and tracking the variation of SG output voltage (<i>V<sub>SG</sub></i>). When variation of the <i>V<sub>SG</sub></i> exceeds lesser than a specified threshold value, the proposed RPI strategy is triggered and <i>V<sub>SG</sub></i> deviation is analyzed. For RPI execution, generated reactive power by SG (<i>Q<sub>SG</sub></i>) is shifted in increment direction. Following the applying RPI strategy, the <i>V<sub>SG</sub></i> does not have any increasing changes during LOE events due to lack of excitation system to provide the required field current; while for Non-LOE (NLOE) events, <i>V<sub>SG</sub></i> will be increased. Therefore, this provided feature by RPI strategy can properly and immediately cluster all LOE/NLOE events even under worst-scenarios. Due to power quality issues, the value of the shifted reactive power (<i>ΔQ<sub>SG</sub></i>) is considered small as much as possible. Meanwhile, it does not require any extra devices for execution. The exhaustive simulation studies on the power system prove that, the proposed scheme is quite reliable for clustering all LOE/NLOE events, and is much faster than other available methods.