Reliability comparison of different power electronic converters for grid-connected PMSG wind turbines

Reliability is becoming more important as the size and number of worldwide installed wind turbines (WTs) increase. In offshore WTs, reliability evaluation is vital due to their hard and expensive repair and maintenance. Wind turbine producers, if consider reliability, can warrant that their productions will ensure high availability. Power electronic converters play an important role in reliability evaluation of grid connected variable speed WTs. This paper presents a reliability comparison between 3 types of power electronic converters that are conventionally used in the gridconnected permanent magnet synchronous generator-based wind turbines. Type 1 is back to back converter, type 2 is a pulse width modulation inverter with a conventional boost DC/DC converter and a simple diode rectifier, and type 3 is a pulse width modulation inverter with an interleaved boost DC/DC converter and a simple diode rectifier. The failure rate is calculated for each type of the converters, and then, reliability is calculated and compared. Results show that the type 3 is the most reliable and has the lowest failure rate between the above mentioned types of converters.