Reliability and availability model of offshore and onshore VSC-HVDC transmission systems

Environmental concerns, system security and energy efficiency requirements are posing special demands on power transmission options. Particularly, increased bulk power transmission, as well as large-scale integration of renewable energy sources act as main drivers for the development of HVDC technology. This paper deals with the development of a reliability/availability model for Voltage-Source Converter HVDC (VSC-HVDC) transmission systems for offshore and onshore applications, such as offshore wind farms connection or DC interconnectors. The goal of the present work is to develop vendor independent model for system reliability studies and sensitivity analysis of system availability. The proposed method overcomes the constraints that the currently dominating reliability and availability analysis methods introduce. A novel modelling tool - based on Bayesian Network theory - will be capable of serving as valuable asset towards design optimization and operational strategy of VSCHVDC systems. Two component-based modelling approaches are demonstrated within this study. The first is based on the Boolean logic of “operating” or “not operating” element, promising identical results with Fault Tree Analysis, but enabling identification of the weakest point in the system and sensitivity analysis as well. The second approach takes into consideration the distributive character of real components availability data, integrating in such a way uncertainty in the estimated output system availability.