Test results of three excitation systems for generators suffering continuous voltage flicker disturbance

This paper uses field test methods to compare the dynamic stability of three types of excitation systems, static excitation systems, brushless rotating excitation systems, and digital excitation control system, at the Tong-Shiao Generation Station of the Taiwan Power System. Three electric arc furnaces in this area produce continuous disturbance of voltage flicker (voltage fluctuation). The dynamic performances of generators and effects of voltage flicker will be evaluated by a series of field tests and measurements. At first, the field measurement is taken by injecting a small step signal into the reference input of the excitation systems for the generators at no-load. The system responses are examined and compared with the IEEE standard 421.2 recommendation to check the stability conditions. The tests for the generators at on-load are repeated again. Then the outputs of the generators are continuously monitored during the operation of the electric arc furnaces. The dynamic characteristics of the generators with different excitation systems are compared to reveal the effect of voltage flicker.