Distance Protection

Abstract

With the increasing demand for electricity and expansion of power networks, transferring large capacities of electrical energy over long‐distance transmission lines became necessary. Since these lines pass through different geographical environments, they are exposed to a variety of hazards. Among them, electrical faults are the most common ones that can disturb network performance and cause system outages. If these faults are detected in the early stages and the faulty part is rapidly separated from the entire network, further damages to the network will be prevented. Distance protection is the main protection principle for transmission lines and interconnected sub‐transmission networks. In addition, it can be used as the backup protection for the adjacent lines, busbars, and transformers. Since this protection proves its reliable performance, it has been used for many years in the industry. As the hardware technology progressed from original electromechanical to static and now up to digital microprocessor‐based types, the implemented algorithms were also improved. In modern distance protection devices, in addition to fault detection, there are other functions for phase selection, fault location, power swing detection, communication schemes, and so on. In this chapter, an overview of this protection algorithm is presented, and its different aspects are investigated.