Simplified Setting Method of Distance Backup Protection Based on Random Matrix Theory

The setting of traditional distance zone-II protection is very complicated, which is due to the difficulty in determining the operating mode and its branch coefficient under the cooperation of multiple lines. So this paper proposes a novel simplified setting method of distance backup protection. This method simplifies the calculation of setting value and accelerates the action time of protection device, which makes the distance zone-II protection only cooperate with the protection of zone-I of local line and only consider the sensitivity coefficient. To further ensure the selectivity of relay protection, the paper develops a fault line detection to match the above method based on random matrix spectral analysis, whose matrix formed by the measured lines current. Then the paper designs a feasible simplified setting process of distance zone-II backup protection by integrating the above methods. Finally, the example analysis shows the simplified setting method of distance backup protection can ensure the selectivity of relay protection, correctly identify the faulty line and speed up the action time.