ECN publication
A high efficiency electrical conversion system with variable reluctancegenerator for variable speed wind turbines: contract JOU2-CT92-0133: vol. 1: power electronics and control
Published by: Publication date:
ECN 1996
ECN report number: Document type:
ECN-C--95-113 ECN publication
Number of pages: Full text:
173 Download PDF  

The purpose of the project on the title subject was to examine thefeasibility of variable reluctance generators in direct drive variable speed wind turbines. The effort undertaken is reported in two volumes: Part 1, Power Electronics and Control; and Part 2, Direct Drive Generator Design. Activities in the development of the conversion system were: (1) design and construction of the generator side power electronic converter (rectifier); (2) design and implementation of the overall control strategy; (3) operational system tests for assessing the electric efficiency and dynamic behaviour. The constructed phase rectifier is suited for both high-speed and low-speed conversion systems. Each phase is individually controllable; it uses two switching devices (IGBT's) and diodes for power extraction. The IGBT's are protected against switching stress (snubbers) and over-current. The control optimizes the energy capture and electric efficiency and stabilizes the DC-link in the power electronic converter. The control parameters are scheduled over the range of operation for constant dynamic performance whereas the voltage and switching of the IGBT's are scheduled for the efficiency. Empirical models for the dynamic and loss behaviour of the used reluctance machine were derived for control development. The applied control equipment was not commercial. The tracking of electric power to changing conditions is sufficiently fast for realisation of expected variable speed benefits. The overall electric efficiency lies between 80% and 90%. The measured dynamic and loss behaviour of the controlled system agrees well with model predictions. High acoustic noise prohibited operation at very low speed. It is concluded that a variable speed wind turbine with variable reluctance generator has an electric efficiency which is similar to that of systems with synchronous or induction machines and has good controllability. Hence, the simplicity of the reluctance machine makes commercial application attractive if acoustic noise problems are solved and the cost of the control equipment is reduced. 71 figs., 29 tabs., 27 refs.

Back to List