Generator and power system performance with the GENERREX excitation system

Increasing pressures to limit transmission facilities while increasing the utilization of remote coal reserves and generating station sites is proving a challenge to the nation´s utilities. Delays in obtaining construction permits, intervener actions, and difficulties in obtaining the required capital for financing have added to the challenge. The generator excitation controls can play an important role in achieving the goal of high service reliability under conditions which tend to reduce stability margins. High initial response excitation systems with high ceiling voltage capabilities can produce significant performance improvements, particularly in conjunction with power system stabilizer controls. A new concept featuring a high initial response excitation system has been developed which combines the excitation system power supply as an integral part of the generator design, utilizing common parts and cooling systems. Analytical prediction of the on-line performance of this new excitation concept is a vital requirement for both detailed design of the equipment and confirmation of power system design. Correlation of analytical results with factory test data on the prototype unit, The Montana Power Company Colstrip No. 1, establishes a measure of confidence in the ability to predict performance of this new equipment.