Enhancement of static excitation system performance for generators near electric arc furnace loads

The tuning of static excitation systems (SESs) to enhance the performance of six gas turbine (GT) generators near an electric arc furnace (EAF) feeder has been successfully accomplished. The operation of these EAFs causes severe and long duration voltage fluctuations at the generator bus. Frequent generator tripping was reported when the adjacent EAFs were in operation. Preliminary field measurements and computer simulations indicated that the SESs did not have sufficient damping under this type of voltage fluctuation. By the adjustment of the SES gains and time constants according to the guideline set by the IEEE Standard 421.2, the SES damping can be greatly improved. This has been verified by additional field tests on six GT generation units. Now these generators can be operated very well although the EAFs still cause voltage fluctuation.