IMPROVING THE EFFICIENCY OF DIFFERENTIAL PROTECTION OF OVERHEAD TRANSMISSION LINES

When applied to protecting over head transmission lines, the differential protection may mal-operate due to unbalanced currents caused by electromagnetic saturation of the current transformers under transient conditions. Restrain methods are the most common used to mitigate the effect of these currents. The disadvantage of such methods is that the restrain signal for external fault is significantly reduced by increasing the magnetizing current of the current transformers, whereas the differential signal increases. This leads to a reduction of the sensitivity of protection or increase tripping time to prevent mal-operation. This paper proposes an additional algorithm based on control (calculation) of capacitive currents mathematical models by using MATLAB/Simulink. to improve the sensitivity of transmission lines differential protection. Simulation results on MATLAB/Simulink. Simulation Results show that the new algorithm that using capacitive compensation current signal has better sensitivity than other methods.