The practical criterion of generator self excitation and its field example analysis

The power station in a large power system (especially a hydroelectric power station) is usually located far from the load center. Therefore, extra high voltage long range power transmission is inevitable. The generator will normally be self excited due to the long transmission line charging current under the no load state. This paper introduces four self excitation criteria for generators in power system carrying a no-load long transmission line. They are: the fast estimation method; the impedance comparison method; the circle diagram method; and the charging characteristic method. Each method is checked by the actual power system self excitation contingency and field self excitation tests with calculations and analysis. It is proved that the four methods are accurate, fast, and reliable as well as practical