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

Power stations in a large power system (especially hydroelectric power stations) are usually located far from the load center. Therefore EHV long range power transmission is inevitable. The generator will likely to be self excited due to the long transmission line charging current under the no-load state. This paper introduces four self-excitation criteria for a generator in a power system possessing 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 actual power system self-excitation contingency and field self-excitation tests together with calculations and analyses. It is proved that these four methods of self-excitation criterion are accurate, fast and reliable as well as practical.<>