Mission-Profile-Based System-Level Reliability Analysis in DC Microgrids

Mission profiles such as environmental and operational conditions together with the system structure including energy resources, grid and converter topologies induce stress on different converters and thereby play a significant role on power electronic systems reliability. Temperature swing and maximum temperature are two of the critical stressors on the most failure prone components of converters, i.e., capacitors and power semiconductors. Temperature related stressors generate electro-thermal stress on these components ultimately triggering high potential failure mechanisms. Failure of any component may cause converter outage and system shutdown. This paper explores the reliability performance of different converters operating in a power system and indicates the failure prone converters from wear out perspective. It provides a system-level reliability insight for design, control and operation of multi-converter system by extending the mission profile-based reliability estimation approach. The analysis is provided for a dc microgrid due to the increasing interest that dc systems have been gaining in recent years; however, it can be applied for reliability studies in any multi-converter system. The outcomes can be worthwhile for maintenance and risk management as well as security assessment in modern power systems.