A Method for Adjusting PSS Constants of Cross Compound Generator Based on Torque Coefficient Matrix

The Concordia-Demello model is well known method for adjusting PSS constants of tandem type of generators and widely used. However, this method is not able to analyze a cross compound generator correctly which consists of primary and secondary generators and has a local and an interarea modes. Therefore, in order to adjust PSS constants of cross compound generator, a more detail model is required. Such researches are few and an efficient methodology that grasps characteristic of cross compound PSS with sufficient accuracy is strongly desired. In this paper, the authors propose a method using the Park's model considering the damper effects, which can be obtained by linearizing a 2 generator to infinite bus system. The proposed method uses a torque coefficient matrix obtained from the linear state equation and calculates an electric torque by using it. Firstly, this paper reveals the difference of electric torque characteristics between a tandem and a cross compound generator. Next, it points out that conventional methods that adjust PSS constant by evaluating a primary and a secondary generator separately may give wrong results. Finally, the effectiveness of the proposed method is confirmed by using a test model.