Improving distance protection performance at zone1 using new adaptive tripping time scheme

This paper presents a new adaptive tripping time scheme which provides high speed distance relay operation under fault conditions near the relay point and provides high secured detection for the faults occurred at the end of the protected transmission line with tripping time less than one power cycle. The proposed scheme automatically controls the data window length to adaptively speed up its response under various fault conditions. The advanced feature of this scheme provides capability for fast tripping decisions with secure operation. The proposed scheme possesses the advantage of removing decaying DC offset component in the current signals according to the length of data window, and compensates the capacitive current during the calculation of the fault impedance. Extensive simulations show that the proposed scheme provides better protection performance compared with the conventional schemes of the fixed data window.