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JEET, Vol. 10, No. 2, March 2015
A New Approach for Constant DC Link Voltage in a Direct Drive Variable Speed Wind Energy Conversion System
R. Jeevajothi
Area B - Electric Machinery and Power Electronics
Abstract Due to the high efficiency and compact mechanical structure, direct drive variable speed generators are used for power conversion in wind turbines. The wind energy conversion system (WECS) considered in this paper consists of a permanent magnet synchronous generator (PMSG), uncontrolled rectifier, dc-dc boost converter controlled with maximum power point tracking (MPPT) and adaptive hysteresis controlled voltage source inverter (VSI). For high utilization of the converters power capability and stabilizing voltage and power flow, constant DC-link voltage is essential. Step and search MPPT algorithm which senses the rectified voltage (VDC) alone and controls the same is used to effectively maximize the output power. The adaptive hysteresis band current control is characterized by fast dynamic response and constant switching frequency. With MPPT and adaptive hysteresis band current control in VSI, the DC link voltage is maintained constant under variable wind speeds and transient grid currents respectively.
Keyword Constant DC-link voltage,PMSG,MPPT,Step and search algorithm,Adaptive hysteresis control.
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