| Diagnosis of a system is the task of identifying failed parts that are responsible for the discrepancies between the observed and correct behavior of the system. The reason to perform diagnosis is to find faulty components and provide support for system repair so the system can be restored to its normal operation. Diagnostics in energy distribution network is a relevant and current field of study. By applying knowledge about the general electrical network domain, the design information and properties of the devices, and past experience with these electrical networks, we can greatly reduce the complexity of the diagnosis task. Specifically, because of the structure of electrical networks, we can formulate the diagnosis algorithm as a hierarchical diagnosis of its sub-networks. The most difficult problem in diagnosis of large networks, scaling in the fault hypothesis space, can be handled by using an advanced graph-based mathematical abstraction called Ordered Binary Decision Diagrams (OBDD) to reduce the search space.; This paper will present a fault management system we have developed for power distribution networks, called the Outage Restoration Management Server (ORMS). The ORMS employs an advanced diagnostics reasoning algorithm to determine the location of faulty components during electrical outages. In the ORMS diagnostic engine, we used an OBDD based technique to generate and prune the fault hypothesis space. OBDDs are symbolic representations of logical relationships, and can be used to symbolically manipulate complex logical expressions. OBDDs have been shown to be very efficient for traversing such large solution spaces with reasonable resources. Using OBDD technique, symbolic manipulation is performed, eliminating the need for enumeration and avoiding the trap of combinatorial explosion in the diagnosis space. The diagnostics results are presented to the user for decision-making support to aid in planning repair actions. We will show how this fault management system (1) provides accurate and relevant diagnostics results, and (2) can easily be integrated with other system components used in utilities. |
