Performance of a shunt reactor controller with non-identical parallel turbogenerators

The damping of torsional oscillations in two parallel generating units using a single common controlled shunt reactor is investigated. The shunt reactance is regulated using either a speed signal from one of the generating units or a combined speed signal from both units. The effect of load differences and torsional mode frequency differences between the units on the performance of a controller designed assuming truly identical units is investigated. Results indicate that for the controller using only a single generator speed signal as input, it is better for the damping of a particular mode to take the input signal from the generator with the higher mode frequency for that mode. When the generator speed signals are combined to form the controller input, then mode frequency differences do not detract from the controller´s performance but load differences do