A Novel Mechanical Hardware in the Loop Platform for Distributed Generation Systems

Abstract

The growing number of distributed generation (DG) plants has em-phasized the need to perform tests before the plants begin to operate. DGsystems are complex enough that setting up of an experimental phaserequires high costs and efforts. Moreover, renewable energy sources areintrinsically intermittent as they vary randomly with the time of day, theseason and the weather. Consequently, the possibility of emulating thebehavior of the whole renewable generation system in a real time envi-ronment, where a part of the real system, the natural energy source, isreplaced by a real time computer simulation allows one to test the actualsystem in all the operating conditions, optimizing the control strategy be-fore its service entrance, overcoming the randomness of renewable en-ergy sources. This article proposes a mechanical hardware in the loop ap-proach applied to a renewable energy generating system, where the wholedrive (control, power electronics and electric machine) is tested and themechanical part is simulated in real time environment. The problem ofemulating the inertial torque, which can have a significant high value, issolved through an approach that relaxes the high dynamic requirementsof the electrical drive that emulates the mechanical part. The hardware inthe loop test bench emulates two energy sources (hydro and wind). In ad-dition, a control strategy that emulates the inertial torque is implemented.An experimental phase in which different energy sources are modeledand emulated in a real time environment is presented as well. The under-lying hardware-in-the-loop energy source emulation and experimentationscheme is shown to accurately represent real systems performance, undervarious control strategies and varying operating conditions