1994 Volume 114 Issue 11 Pages 1142-1149
As the capacity of the generator increases, a cross-compound turbine-generator consisting of two axes is generally adopted at thermal power stations in our country that are connected to a 50 Hz power system. If oscillation occurs to this cross-compound turbine-generator because of a power system disturbance, a local mode is formed between a primary machine and a secondary machine. This mode coex-ists with the intertie mode that is formed between the cross-compound turbine-generator and the power system to which it is connected. When the PSS is applied to the design of the cross-compound turbine-generator, a full understanding of these two oscillation modes is therefore required to optimize the design and to improve the effect of damping. The abstract of this paper can be summarized as follows:
(1) With a power system using cross-compound turbine-generators, a local mode of 2 Hz to 3.5 Hz is formed across operating machines along with the intertie mode that has an oscillation of about 1 Hz.
(2) We could build a two-machine infinite-bus power system model consisting of primary and secondary machine, which can tune the PSS design for the cross-compound turbine-generator with a high level of accuracy.
(3) To improve efficiency of the PSS design, we proposed that the equivalent one-machine infinite-bus power system model be established for the intertie mode and the local mode. In conclusion, we presented the PSS design procedures that can be used in actual power systems.