Advantages of Transforming the Relay Protection Operating Characteristics into Characteristics in Multidimensional Space

In the classical theory of relay protection, the recognition of emergency modes is carried out based on operating characteristics. Proper selection of the operating characteristics ensures the selectivity of relay protection. Traditionally, the operating characteristics of relay protection devices are defined on a plane. However, this approach does not always provide unambiguous recognition of emergency modes. The classical approach to the formation of the operating characteristics sometimes leads to the display in the same area of the operating characteristics of various electrical system modes, turning the recognition of emergency modes into an unsolvable task. The report describes one of the approaches to the analysis of the operating characteristics of relay protection. In the example of the phase selection and fault classification, it is shown that the classical approach to the formation of the operating characteristics has limitations and introduces uncertainties in the tasks of mode recognition. This complicates the implementation of relay protection functions, requiring the implementation of additional blocking and backing. To overcome this imperfection, the report’s authors propose a new strategy for improving the operating characteristics of relay protection. It is demonstrated that the transformation of classical operating characteristics into characteristics in multidimensional space through the possible expansion of the information base and the presentation of operating characteristics provides recognition of various short-circuit modes in the electrical network.