The generators with static excitation systems in the Tong-Shiao Generation Station had been tripped when the adjacent electric arc furnaces were in operation. After re-tuning the parameters of excitation systems, these generators have been in normal operation. This thesis describes the test and assessment of stability for generators under voltage fluctuation. First, the output responses of generators are measured under long duration voltage fluctuation, and then the variations of active power and reactive power are checked to be inside the rating curve or not, which is designed by manufactures. Secondly, the methods of frequency response and time response are used to assess the dynamic stability of two generators with different excitation systems. The procedure of frequency response needs to calculate the transfer function from the system model, and then the performance index is obtained by the Bode diagram. In the time response test, a unit step signal is added into the excitation system, and then the dynamic responses of generators are measured and analyzed under off-load and on-load conditions. The dynamic stability conditions are obtained from output waveforms. Finally, the equivalent power system network with the Tong-Shiao Generation Station and adjacent 161kV buses are built. Several fault events, such as tripping of transmission lines and generators, are applied in computer simulations to assess the influences of these events.
