A practical method for calculation of over-excited region in the synchronous generator capability curves

The capability curves are used for loading the synchronous generators as a useful and essential tool. Moreover, one of the important applications of the capability curves is setting the relays. The main purpose of the proper loading and accurate setting of the relays is stable operating of the synchronous generators in desired margins. Therefore, the accurate calculation of the curves is significant. Although in the papers some methods and formula for calculating and drawing the capability curves have been presented, the obtained results do not coincide with the original capability curves provided by the manufacturers. It could be potentially because of disregarding the real conditions of synchronous generators such as saturation, temperature, mechanical considerations, altitude and etc. Also, there is no complete source about the capability curves which cover all parts of the curve.