Tuning and real-time evaluation of a four-loop cascaded control scheme for a Combustion Turbogenerator

Development of control systems for power plants must demonstrate satisfactory real-time performance in both, the development and the target platforms, before going into actual operation. This paper presents the tuning procedure of a four-loop cascaded control scheme for a gas-turbine driven electric generator, and the real-time performance evaluation, against a conventional three-loop control scheme, when controlling speed (ω), terminal voltage (V), active power (P) and reactive power (Q). The cascaded-scheme considers parallel-cascaded and series-cascaded configurations using Pω and VQ control couples for the turbine and the generator, respectively. The proposed control scheme, based on discrete-time PID controllers, is compared to a conventional Pω-V control scheme by means of real-time simulation experiments in a PC-based development platform. Simulations are carried out at the start-up, synchronization and generation stages. Results show that the four-loop Pω-VQ parallel-series scheme has better performance than the conventional Pω-V three-loop scheme.