review of power converter topologies for wind generators

Wind energy conversion systems have become a focal point in the research of renewable energy
sources. This is in no small part due to the rapid advances in the size of wind generators as well as the
development of power electronics and their applicability in wind energy extraction. This paper
provides a comprehensive review of past and present converter topologies applicable to permanent
magnet generators, induction generators, synchronous generators and doubly fed induction
generators. The many different generator–converter combinations are compared on the basis of
topology, cost, efficiency, power consumption and control complexity. The features of each
generator–converter configuration are considered in the context of wind turbine systems.

Power extracted from wind energy contributes a significant proportion of consumers’ electrical power demands. For example, 20% of the entire electricity consumption in Denmark is provided by wind energy [1]. In recent years, many power converter techniques have been developed for integrating with the electrical grid. The use of power electronic converters allows for variable speed operation of the wind turbine, and enhanced power extraction. In variable speed operation, a control method designed to extract maximum power from the turbine and provide constant grid voltage and frequency is required. A wide range of control schemes, varying in cost and complexity, have been investigated for all the previously considered conversion systems. All control schemes integrated with the power electronic converter are designed to maximize power output at all possible wind speeds. The wind speeds range from the cut-in speed to the rated wind speed, both of which are specific to the size and type of generator used in the wind energy conversion system (WECS). In this paper, the possible combinations of converter and generator topologies for permanent magnet generators, caged rotor induction generators, synchronous generators and doubly fed induction generators including more specifically wound rotor induction machines are discussed and some of the possible control strategies are touched upon. This paper serves as a concise summary and comparison of the state of art regarding power electronic topologies and wind energy conversion systems.

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