STABILITY ANALYSIS OF AN ISLANDED GENERATOR

The authors investigate the stability of an islanded generator. They examine the effect of a predominantly resistive load on small-signal (frequency) stability of an islanded generator. The authors derive a new linear generator model for the islanded power station, and perform small-signal analyses using this model. The analyses are also performed using two industrial–grade software packages, and the results are compared. The authors show that predominantly resistive loads lead to poor damping of the speed response, and that an increase in the L/R ratio further decreases the damping. The use of a power system stabilizer is proposed to increase the damping of the speed response by varying the generator terminal voltage in response to speed changes. In this sense the PSS is also contributing to frequency control. Finally, the authors study the effect of the turbine and its control system on stability.