Dynamic Properties of Remote Sensing Algorithm in Digital Resistance Elements

In microprocessor-based distance protection of lines, digital resistance elements are used as measuring instruments for determining the components of the input resistance vector and their subsequent mathematical comparison with the boundaries of the selected response characteristics. The values of the resistance vector components are calculated from the voltages and currents measured at the installation site of the protection. The most common are algorithms for remote measurements of input resistance based on: two samples of instantaneous values of line voltage and current; line models; using orthogonal voltage components and current. In the resistance elements of modern microprocessor line protections for remote measurements, the last of the above algorithms is most widely used. Its dynamic properties are determined mainly by the implemented method of generating the orthogonal components of the input signals. In distance protection measuring device, non-recursive digital Fourier filters are predominantly used for this purpose. To improve the dynamic properties of the remote measurement algorithm based on them, it is proposed to correct additionally dynamic errors in transient modes. In the dynamic modeling environment MATLAB-Simulink-SimPowerSystems, digital model is implemented that allows for a comparative assessment of the dynamic properties of the proposed algorithm for remote measurements of input resistance based on the results of a computational experiment. The research results have shown that the proposed algorithm for remote measurements of input resistance has higher dynamic properties compared to the known ones.