Component-Level Reliability Assessment of a Direct-Drive PMSG Wind Power Converter Considering Two Terms of Thermal Cycles and the Parameter Sensitivity Analysis

The availability and efficiency of a wind power system are highly affected by the failure or the unreliable operation of its power converter. This article investigates the failure rate and annual consumed lifetime for a 2-MW direct-drive permanent magnet synchronous generator based full-scale converter in a wind power generation system. The reliability assessment mainly focuses on the component level, namely, diodes and IGBTs, in both of the machine-side converter and the grid-side converter. Annual damages and power cycles for semiconductors are calculated separately under long-term thermal cycles (several seconds to hours) and short-term thermal cycles (dozens to hundreds of milliseconds). Experiments regarding thermal stress measuring for different semiconductors under short-term thermal cycles are affiliated. A comparison between different thermal cycles is given and discussed in detail. To ensure a visualized time-to-failure evaluation, a Monte Carlo method is used to generate the lifetime distributions and entire unreliability functions for power semiconductors. Final B 10 and B 1 lifetimes can easily be observed from the cumulative distribution functions. Moreover, different standard deviations are assumed for parameters in the Bayerer's lifetime model, and by using several parallel Monte Carlo algorithms, parameter sensitivity to the final lifetime evaluation is analyzed.