This work defines a systematic approach, using synergetic control theory, to develop a high-performance control for a high-speed turbo-generator unit that is interfaced to a compliant 60 Hz power system through a power converter. The design procedure is illustrated and validated using a specific example a high-speed turbo-generator unit rated at 4 MW, a back-to-back converter, and a finite-inertia 60Hz line-connected synchronous generator. A hierarchical control structure yields a modular design which is more easily implemented by the control engineer at the component-level.

The control design procedure was first applied to a stand-alone 4MW high-speed turbo-generator. The resulting synergetic control provides superior performance when compared to a traditional PI control. While simulation results show that the traditional PI control results in the high-speed turbine stalling when a 3MW step-load increase is applied, the synergetic control safely follows the load increase without stall or over-speed.

This work next develops a full set of synergetic controls for an AC power system consisting of a 4MW high-speed turbo-generator unit and a 36MW 60Hz conventional generator unit. A power-sharing study using this system answers the previously unanswered questions of whether a high-speed generator unit can supply power to a large transient load and how it shares this load within a limited-inertia 60Hz system. Simulation results reveal that the system’s ability to accommodate abrupt load increases or decreases depends largely on the response of the 60Hz generator. When step-load disturbances with infinite rate increase are added to the system AC bus, the simulation results reveal that the severe AC-bus voltage drop is the critical requirement. When a rapid load increase with a finite increase rate is required, the study shows that the 36MW turbine stall is the most important factor that limits the load increase speed as well as the final power stage of the load. When a fast load decrease is imposed onto the system AC bus, the 36MW generator frequency stability confines the maximum decrease rate.