Descoberta de causa-raiz em ocorrências de sistemas elétricos.

Abstract

This paper presents a root cause analysis technique for electric power systems. The root cause analysis is a way to assist the operator in understanding the occurrence of failure, interpreting the events cascade occurrences. The proposed technique uses a rule based reasoning, where parameterized rules construct a propagation model with diagnosis of an occurrence of failure. The technique allows to point out the element that causes the occurrence, and detailing its propagation to other elements in a cause and effect model. The use of parameterized rules brings major benefits to the process, allowing the technique to be adaptable to changes in system topology, and contributing to its scalability A case study was prepared for evaluation in the context of the Companhia Hidro Elétrica do São Francisco (CHESF). We developed a prototype that implements the technique, and raised a set of parameterized rules and a set of failure scenarios using a tool to simulate a real environment, the Simulop. We also used in the evaluation process, a set of regressions, which are historical data stored by CHESF. The regressions were important in the first phase of the technique, but they have problems such as lack of data, and unexpected behavior of the system, where the accuracy of the technique was 74%. For the set of scenarios created with Simulop, the proposed technique has achieved success in the root cause analysis process, identifying the root cause of the occurrence in 100% of failure scenarios, and detailing their propagation to all other equipments involved in 89% of scenarios, where the margin of error is composed of scenarios whose propagation has been identified only in part due to the lack of rules that contemplate these scenarios. Thus, the proposed technique proved to be a viable approach to root cause analysis in electrical systems. The reduced margin of success in the regressions , indicates that, to be applied to an operational environment, it is necessary to elaborate a comprehensive set of rules that can deal these problems.