Reliability Evaluation of a Tidal Power Generation System Considering Tidal Current Speeds

This paper presents a reliability evaluation method for a tidal power generation system (TPGS) with a doubly-fed induction generator (DFIG). The key to the method is the modeling of the tidal current speed-dependent failure rates of the rotor side converter (RSC) and grid side converter (GSC). The models for calculating the rotor currents through the RSC and GSC and the rotor current state related failure rates are presented. Based on the Wakeby distribution of tidal current speed, a multistate discrete probability distribution technique for rotor current is developed. Case studies are described using tidal current speed data from four coastal sites in North America. The results indicate that the failure rates of the RSC, GSC, and the entire TPGS vary with tidal current speeds and the probability distributions of tidal current speed. The TPGS suffers a much higher failure risk in the super-synchronous mode than in the idle and subsynchronous modes. The failure rate of the RSC is much higher than that of the GSC. The change trends in the failure rates of RSC and GSC in the operation modes are different. The probability distributions of tidal current speed have significant impacts on the reliability of the TPGS.