Mechanical power-hardware-in-the-loop: Emulation of an aeroderivative twin-shaft turbine engine

This paper presents a method for driving an AC electric motor so that it emulates, at its drive shaft, the steady-state and transient loading and unloading dynamics of an aeroderivative twin-shaft gas turbine engine. This approach allows safe and robust testing of connected equipment, for example an electric generator, without having to install (or risk damage to) an actual gas turbine engine and all of its support systems. The lower inertia constant of an aeroderivative twin-shaft gas turbine relative to a comparably powerful AC motor introduces power, accuracy, and stability limitations in the emulation system. We have studied the performance of the emulation method at reduced scale using two identical 15 kW induction machines on a common shaft in which one machine acts as gas turbine emulation motor and the other one as a generator under test. The speed controller of the vector controlled emulation motor tracks the speed of a real time reference model of an aeroderivative twin-shaft gas turbine engine. Experimental results demonstrate the power and stability limitations that apply to the emulation system.