An Adaptive Distance Protection Scheme Based on the Voltage Drop Equation

In order to improve the performance of the conventional distance protection scheme under high-resistance fault, an adaptive distance protection scheme is proposed in this paper. First, according to the geometric distribution characteristics of voltage and current in the system, the equation of voltage drop from the relaying point to the fault point is established. Second, the fault point is determined by the measured current and the measured negative-sequence current. And then, the new adaptive distance protection criterion is formed according to the relationship between the fault point and the protection zone. Simulation tests on the Real Time Digital Simulator verify that the proposed scheme is able to modify the protection setting value adaptively online, and is immune to the impact of transition resistance and load current. Besides, it has the potential to be applied in a real power system because of small computation amount and high accuracy.