Daniel von den Hoff participates in the conference IEEE Energy Conversion Congress and Expo in Baltimore, USA.

Daniel von den Hoff presents his papers with the titles “Simple Empiric Root-Mean-Square Electric-Drivetrain Model for Wind Turbines with Full-Size Converter“ and “Instantaneous Start-Up and Shutdown Method for Three-Phase Dual-Active Bridge DC-DC Converters“ at the conference IEEE Energy Conversion Congress and Expo in Baltimore, USA. The abstracts of the papers can be found below.

Simple Empiric Root-Mean-Square Electric-Drivetrain Model for Wind Turbines with Full-Size Converter

Due to the growing share of wind power, the demands placed on the grid compatibility of wind turbines (WT) have increased significantly. Simulation models are therefore important to avoid a large number of expensive and time consuming field tests. In this paper, we present an empiric root-mean-square electric-drivetrain model of a 2.75 MW type-4 wind turbine (WT). Unlike the standardized generic WT models, it is especially intended for the simulation of long-time test scenarios with reduced requirements on the model dynamics, e.g. to determine the voltage-flicker strength of a WT. The proposed model is derived from an existing detailed electro-magnetic transient model of the considered WT. As shown in the paper, both models match for an exemplary simulated test scenario. To validate the model, voltage-flicker coefficients obtained in simulations of the derived model are compared with measurements.

Instantaneous Start-Up and Shutdown Method for Three-Phase Dual-Active Bridge DC-DC Converters

The three-phase Dual-Active Bridge (DAB3) dc-dc converter benefits from inherent soft-switching operation over a wide power and voltage range using the conventional Single Phase-Shift modulation (SPS). However, it is hard-switched at light load and considerably deviating input and output voltages. Several modulation schemes have been proposed to overcome this disadvantage and to extend the soft-switching range of the converter. An immediate start-up and shutdown method for the DAB3 in SPS operation can be used to switch between different modulation schemes. Those methods must be fully soft-switched to maintain the advantages of the mentioned modulation strategies. In this paper, we propose a soft-switched control scheme to start up and shut down the three-phase Dual-Active Bridge converter from or to zero transformer currents with energized input and output capacitors. Both, start-up and shutdown happen in less than one switching period without causing imbalances or oscillations of transformer phase and magnetizing currents. The soft-switching behavior of the proposed methods is analyzed in detail. Their effectiveness is proven mathematically and demonstrated with the aid of simulation results.