Incorporating aging failure mode and multiple capacity state model of HVDC system in power system reliability assessment

The paper presents an approach to incorporating the aging failure mode and multiple capacity states of a HVDC system in power system reliability assessment. Subcomponents in HVDC converter stations have a much shorter mean life compared to an ac line or cable. When their age approaches the mean life, the failure rate due to aging increases greatly and it is necessary to include their aging failure mode in the assessment. The modeling method presented for multiple capacity states includes three reliability block networks. Probabilities of a HVDC system being at the full, derated and zero capacities can be easily calculated using the three reliability networks. Once the state probabilities are obtained, the HVDC system can be represented using a three-state model in overall power system reliability evaluation. An actual example in a utility is given to demonstrate the application of the presented approach in a power supply system with an aged HVDC link.