2003 Volume 123 Issue 9 Pages 1064-1072
This paper presents a new digital type protection relay based on matrix operations. The basic principle of the matrix operation type protection scheme has been already discussed and investigated. However, further studies have been required especially to confirm the real time capability of the proposed scheme, in addition to evaluate the accuracy of fault detection and the identification of fault location. The off-line pre-calculation has been proposed for solving the time-consuming problem. Furthermore, the interpolation technique based non-iterative solution has been developed, which replaces the traditionally iterative Newton-Raphson's method for saving required calculation time. Combining both of the off-line pre-calculation and the interpolation method enables to ensure the activation time of the proposed protection relay within two cycles after a fault occurrence. Moreover, a high accuracy of fault detection can be achieved. In order to demonstrate the reliability of the proposed scheme, numerical simulations have been performed through using the actual data measured on real power systems with different voltage levels. The compared results indicate the highly precise estimation of the fault locations compared with the inspected fault locations on transmission lines. The required computation time is also estimated with considering types of numerical calculations included in the proposed algorithm. The estimated computation time is short enough for the real time implementation of the proposed scheme.