Track 1 Session 11

10:20 to 11:20 a.m. Friday March 25, 2011

Reliability of Voltage-Source Converters: Reliability Standards, Aging Components and Load-Sharing Redundancy

Reliability of electrical equipment used for wind power or photovoltaic installations is extremely important because maintenance and service may be challenging and costly. In order to estimate risks and costs of system failure, the mean time between failures (MTBF) needs to be known. Reliability prediction standards are often used for estimating system failure rates. However, classical reliability prediction does not realistically address components that experience wearout failures and also cannot consider redundancy. In this presentation, the reliability of a voltage-source converter is assessed. The converter electronics (consisting of hundreds of parts) is treated using classical methods based on the following reliability prediction standards: 1) IEC 62380 (2004). 2) Telcordia SR-322(2) (2006). 3) MIL-HDBK-217F(2) (1995) with and without the rules and recommendations of VITA 51.1 (2008). Correlations between the standards are discussed. Lifetime critical components that experience wearout failures are treated separately using non-constant failure rates and, consequently, the resulting converter failure rate is also not constant. Finally the impact of load-sharing redundancy is discussed.

Key Words: Reliability Prediction, Reliability Standards, Aging Components, Load-sharing Redundancy

Gernot J. Riedel

ABB Switzerland