Synchronising and damping torques in synchronous machines

The paper investigates synchronous-machine damping and synchronising torques analytically and experimentally, in two distinct reference frames. The first is that of Park and the second is a freely rotating frame used by Kron, Ku and others. it is found that the uniformly rotating free frame presents a clear picture of the nature of the torque components and the sources of these during hunting conditions. The analysis has been confirmed by tests on a laboratory machine.