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Thermal Stress Analysis of IGBT Modules in VSCs for PMSG in Large Offshore Wind Energy Conversion Systems
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| Author(s) |
Riccardo PITTINI, Salvatore D'ARCO, Magnar HERNES, Astrid PETTERTEIG |
| Abstract |
Components for offshore wind farms are required to be highly reliable due to harshenvironmental conditions and poor accessibility for maintenance. Direct-Drive Permanent MagnetSynchronous Generator (PMSG) connected with back to back converters represents an attractivesolution for large offshore Wind Energy Conversion Systems (WECSs). Large direct driven WindTurbine Generators (WTGs) operate at lower speed compared to conventional geared WTs withoperating frequencies that can be as low as 6-13 Hz (e.g. Enercon). The low operating frequenciesintroduce a continuous power cycling of the semiconductor devices and can lead to a reduced lifetimeof the generator side converter. Accurate thermal models integrated with circuital simulations canassist in predicting these stresses and in analyzing countermeasures.This paper describes a method for thermal analysis of power converters based on a customdeveloped module in PSCAD/ETMDC that implements a thermal model running in parallel to theelectrical simulations. The custom module calculates the power dissipation and the temperature of thedevices based on their physical characteristics and on their operating conditions derived from theelectrical simulation. The method is applied for the analysis of a Voltage Source Converter (VSC)connected to the PMSG in a Direct Drive WECS. The simulations prove that the worst operatingcondition for the generator side converter in the sample system examined is represented by the turbinegenerating at its rated power. The temperature swings over the power semiconductors at lower powerand lower generator frequency induce a minor stress. However, the worst operating condition may notcorrespond to the rated power in other cases especially for Direct Drive PMSG-WTs with a relativelylow number of poles. |
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| Filename: | 0190-epe2011-full-16295684.pdf |
| Filesize: | 611.8 KB |
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| Type |
Members Only |
| Date |
Last modified 2012-01-26 by System |
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