Block Diagrams and Torque-Angle Loop Analysis of Synchronous Machines

Block diagrams of synchronous machines supplying an infinite bus or lumped parameter load are develQped for large and small-signals. This representation includes the effects of saliency, the amortisseurs, variable speed operation, positive and negative sequence components of the infinite bus voltage and an approximate treatment of the saturation. The paper illustrates the application of the block diagram technique. First, the electrical torques proportional to the load angle and their contribution to the overall transfer function of the torque-angle loop are investigated by the elementary theory of servomechanisms. Second, transfer functions are derived for excitation system analysis. Finally self-excitation of the machine connected to a capacitive load is described.