A Human-Machine Interface applied for a Low-Voltage-Ride-Through Test System for Grid-Connected Wind Turbines

This paper describes the implementation of a symmetrical cascaded multilevel converter used as a fault generator for low-voltage-ride-through tests of grid-connected wind turbines. The converter is able to emulate the main faults that can occur in real power systems, with no significant impact on the grid during tests. The proposed system is comprised of three control levels: a human-machine interface (HMI), a central unit and local controllers in each power cell. The cells are composed of a back-to-back single-phase full-bridge converter, measurement circuits and a Digital Signal Processor (DSP) that controls the DC bus voltage through the grid-side converter and performs the modulation of the output-side converter. The central controller is also a DSP, that generates the voltage references for the cells and synchronizes them to the central DSP. The HMI is comprised of a Raspberry Pi and its peripherals, being the main focus of this paper. Finally, experimental results are shown to demonstrate the proposed system.