Unavailability analysis of an underwater cable system

Generating capacity reliability studies in interconnected systems normally consider the interconnecting facilities simply in terms of their transmission capabilities and only in certain cases include the associated probability of transmission unavailability. The unavailability parameter when included is usually a single steady state probability value. This paper illustrates the development of a relatively simple methodology to evaluate the unavailability associated with an underwater cable facility subject to repair restrictions due to climatic conditions. The probability of system unavailability is a periodic function which varies over the annual period and repeats each year. The techniques presented in this paper are not restricted to cable installations and can be utilized to include a wide range of physical conditions.