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