Analysis of a DC collector-based power converter topology for an offshore wind farm

Abstract

The conventional collection grids for offshore wind farm consist of internal AC link comprising of series-parallel connections of identical wind energy conversion units (WECUs). Each WECU includes a 60- or 50-Hz power transformer. The power transformers are replaced by the power converters in this article. The weight of a power converter is much lower compared to that of a power transformer of similar characteristics, thus reducing the weight of the offshore wind farm. Most of the studies being done to design DC collection grids use the conventional full-bridge voltage source converter as the topology of power converter. The efficiency of the wind farm is low due to the switching losses. In this article a cascade connection of a diode rectifier and an interleaved DC-DC boost converter is used for the converter topology. The switches duty cycle is reduced, thus improving the efficiency of the wind farm. The dynamic model of the proposed power converter is derived, including its control schemes. Power Simulator (The Powersim, Rockville, USA) and MATLAB Software (The MathWorks, Natick, Massachusetts, USA) are used to test the performances of the proposed converter model.