Abstract
SUb-transmission Network Probabilistic Reliability Analysis System (SUNPRAS) has been developed to support more rational planning of the sub-transmission network. In the developed system, many fault events are assumed at first and the effects of these faults on the loss of load are analyzed. Then based on both the result of the fault analysis and the occurrence probability of these faults, the several reliability indices are calculated by using the probabilistic method. The fault restoration procedure should be considered in analyzing the fault, and is formulated in the radial network as the combinatorial optimization problem which is very difficult to solve in large system. In this research, a quite efficient algorithm composed of gradual maximum flow method and branch exchange method was newly developed as the fault restoration logic to minimize the loss of load. The gradual maximum flow method efficiently finds the initial system configuration close to the global optimum solution by attaining the flow condition as balanced as possible in the margin of the line capacity. The reliability indices given by the developed system are expected power not supplied, expected energy not supplied, expected duration not supplied and so on. These are given as load point indices at each distribution substation.
The developed system was applied to the model system to confirm the effectiveness of the method. Furthermore, the quantitative evaluation of alternative reinforcement plans from the improvement of reliability point of view was demonstrated as a typical example of its useful applications. The possibility of the new planning criterion taking probabilistic factors into consideration was also discussed.
