Scheme for synchronous machine stator turn‐to‐turn protection

Abstract

This study presents a new protection scheme for turn-to-turn fault protection in the stator windings of synchronous machines. The main difference with other methods is the calculation of voltage of the winding from the phase to ground and neutral to ground voltages, which can be obtained from the monitoring provided by any commercial generator multifunction protection relay. This new method allows the employment of the protection transformers already installed in the protection scheme, simplifying and reducing the cost of the protection function. To validate this new technique, finite element method simulations and numerous tests have been performed in a specially built synchronous generator with taps in one of the stator windings. In this way, several turn-to-turn faults have been created at different fault severity levels.

An overview of various faults detection methods in synchronous generators

“…To distinguish the internal fault from other disturbances and faults, the difference between the SG phase currents is estimated. In the internal fault, the difference between the phase currents of F I G U R E 4 Proposed protection scheme for TTF detection using zero-sequence voltage [51] F I G U R E 5 Schematic model of a generator with an internal fault in phase A MOSTAFAEI AND FAIZ -397 the two healthy phases is negligible, but the difference between the currents of the faulty phase and two healthy phases is large. If the difference of instantaneous current of phase A and phase B in the faulty case is ΔFAB and in healthy case, just in the previous cycle is ΔHAB, the ratio ΔFAB/ΔHAB can help to distinguish the internal fault from other disturbances and faults.…”

“…In the above‐mentioned detection method, an additional PT is necessary, it may cause some installation problems, and in some cases, it is not economical. To solve this problem (required additional PT), a novel protection scheme shown in Figure 4 has been proposed which calculates zero‐sequence voltage (ZSV) instead of measuring it [51]. In this method, the ZSV is calculated as follows.…”