New self-excited variable speed constant frequency generator for wind power systems

In this work, the possibility of using a new single-phase commutator machine as a stand alone self-excited generator is investigated. The performance of this generator is tested under variable speed operation to simulate the practical case of variable wind turbine speed. The generator is self-excited through a resonance capacitor. The effect of varying the capacitance of this capacitor on the generated voltage and its frequency is studied. Load tests under a wide range of operating conditions are conducted to explore the capability of this type of generator. It has been found that this machine can operate as a variable speed constant frequency generator simply by varying the capacitance of the excitation capacitor. This important property makes this type of generator suitable for use in wind driven power systems. Finally, a mathematical model for the generator is obtained and a simulation program is developed to predict the performance of the generator. Close agreement between the simulation and the experimental results is obtained. (C) 2000 Elsevier Science Ltd. All rights reserved.