Reliability evaluation model of wind power converter system considering variable wind profiles

This paper presents a reliability assessment model for the wind power converter system (WPCS). In this study, the most influential factors of average wind speed and wind turbulence intensity are considered. First, WPCS operation state is partitioned into different phases in terms of different thermal stress levels which are determined by its operation conditions of average wind speed and wind turbulence intensity. Then, based on FIDES reliability guide, thermal factor and thermal cycling factor for each WPCS operation phases are calculated to indicate the contribution of average wind speed and wind turbulence to WPCS reliability. Finally, the randomly changed thermal profile is regulated by rain-flow cycling count algorithm and thus the junction temperature cycling information is extracted to calculate the thermal factor and thermal cycling factor. The reliability assessment on a real full-rated WPCS of a 2.5MW wind turbine with a permanentmagnet synchronous generator (PMSG) is carried out and the influences of cut-in, rated, cut-out wind speed and heat sink design parameters to the WPCS reliability is analyzed.