Individual and Collective Recognition Capability of the Measuring Elements of Relay Protection

Abstract

The existing method is to estimate the recognition capability of relay protection on the plane of fault parameters of a power facility simulation model is described. Adevelopment and generalization of this approach is to transfer the estimation procedure to the multidimensional domain of modes controlled by relay protection (a-modes). The task is to select the part of the domain where one or several measuring elements are capable of discriminating a-modes from alternative â-modes in which the action of relay protection is prohibited. Failure to recognize an a-mode can be attributed to its physical indistinguishability from some â-mode (absolute unrecognizability) or the incapability of the measuring elements to ensure sufficient recognition capability (relative unrecognizability). The recognition capability of the measuring elements of remote backup protection in the situation where the a-mode is a three-phase short circuit in a branch, and the â-modes are the connection of the line to the grid is evaluated as an example.