Reducing DC-Link Capacitance Requirements in Large Wind Turbines

Abstract

The thesis aims to determine a practical method to reduce the DC-Link voltage ripple in large wind turbines. Various wind energy conversion system configurations have been discussed and analysed in the literature review. One of the key issues found are the requirement for devices to be connected in series in order to attain the high voltages of large wind turbines. Amulti-levelmodulartopologyhasbeenpresentedandanalysedindetail,simulation results showing the topology operating as part of a wind energy conversion system for a large wind turbine have been presented and discussed. Experimental results have also been produced in a lab enviroment using scaled down voltages and currents. The control system was developed digitally and implemented using a DSP and CPLD board. The topology is able to overcome the issues of connecting devices in series by providing a modular structure which is inherently fault tolerant, and able to reach the high voltages required without connecting devices in series (for a single power switch). Further work has been carried out in order to simplify the control complexity of the system, by reducing the number of active switching components. Simulation results have been presented for this, both as a standalone converter and in the wind energy conversion system in order to validate its feasibility.

Date of Award	7 May 2019
Original language	English
Awarding Institution	The University of Bristol
Supervisor	Xibo Yuan (Supervisor) & Phil H Mellor (Supervisor)