Representing the risk imposed by different strategies of distribution system operation

Given the increasing use of risk based methodologies for evaluating the suitability of different system operation conditions, it is important to understand the limits on information provided by the different representations of risk. This paper compares the effectiveness of different methods for representing the risk accepted when operating a small distribution test system in different modes and configurations. Using the RTBS test system, the risk posed to continued satisfactory network operation by the use of lines with differing line parameters and/or different levels of protection for the network was calculated and presented using both the notion of risk as an expected value of the impact of the component failures and as a consequence spectrum or consequence plot. It is shown that while the results are complementary, the manner in which risk is represented may constrain the type of decision that the operator can make