Multifunctional Digital Current Protection of 6–35 kV Distribution Networks

In Russia, modernization of both 6-35 kV distribution networks and their automatic control and relay protection devices is underway. The most widely used types of protections in these networks are current protections. Although having certain shortcomings, they will nevertheless be used also in advanced active-adaptive electric networks owing to their low cost and high efficiency. The existing algorithms implemented on microprocessor devices still repeat in many respects the principles of electromechanical protections, a circumstance that limits the potential of their technical capabilities. Matters of improving current protection effectiveness by using digital information processing methods and simulation modeling are of relevance. In doing so, the most important task is to preserve their main advantages over other types of protections, such as simplicity and low cost. A current protection implementation version is proposed, which is based on statistical principles. The proposed method implies the use of not only the effective phase currents values, as a conventional current protection, but also other network operating parameters. The results of comparing the efficiency of the proposed algorithm with classical current protection are presented.