Abstract:In order to make the relay setting calculation precision, avoid “setting calculation error”, the author using two-dimensional coordinates of the quadrilateral vector elements characteristic impedance characteristic value are analyzed. Through the analysis of " relevance vector impedance " and quadrilateral characteristic diagram of relations, reveals the “modular” algorithm to get the results, cover the quadrilateral characteristic impedance protection secret mechanism for measuring distortion of the actual grid impedance. This mechanism will cause the original resistance component reliability coefficient variation, impedance sensitivity calibration value false results.Through mathematical analysis and logical judgement, is derived for quadrilateral impedance value for a calculated item setting calculation and verification, to reflect the reliability coefficient variation and sensitivity results from decomposition of screen out false sensitivity.