Power transformers are protected by different relays that operate independently. Malfunction of each relay has a major role in reducing the reliability of the protection system. In order to mitigate the main drawbacks of the power transformer relays, an overall protection scheme is presented in this paper. This scheme proposes a novel multi criterion algorithm using decision-making based on fuz...

This paper contains the application criteria and coordination process for a proposed overcurrent relay in a radial power system with feed from one or multiple sources. This relay uses independent functions to detect faults and to calculate the operation time. Also this relay uses a time element function that allows it to reduce the time relay operation, enhancing the backup protection. Some of ...

the design and application of a fuzzy logic based controller to a leakage current relay waspresented in this paper. a novel approach based on fuzzy logic to form the tripping action of leakagecurrent relay was investigated. in addition to the theoretical aspect of fuzzy logic, detection of a leakagecurrent, measurement of the leakage current, determination of its duration, trip opening of fault...

This paper presents a distance protection test procedure by applying the Real-Time Digital Simulator (RTDS) of a power system. RTDS is a tool to design, develop, and test power-system protection. The RTDS enables real-time computation of electromagnetic phenomena with a calculation time step of even 50μs. The hardware allows the import and export of many signals from the simulator to an ext...

Malfunction of relay protection is one of the main causes of the serious failures that periodically occur in power systems all over the world. According to the North American Electric Reliability Council [1] in 74 % cases the reason for heavy failures in power systems was the incorrect actions of relay protection in trying to avoid the failure. Thus the reliability of a power system depends on ...

A major concern in the application of multifunction digital relays for the protection of generators is that almost all the electrical protection, including both primary and the backup relay functions, are embodied in one digital package. The failure of that package results in the loss of virtually all generator electrical protection. This paper discusses how multifunction relays can be designed...

In this paper, a novel approach based on the Thévenin tracing is presented to modified conventional impedance-based out-of-step (OOS) protection. In conventional approach, the OOS detection is done by measuring positive sequence impedance. However, the measured impedance may be change due to different factors such as capacitor bank switching and reactive power compensators that it can cause the...

Distance relay plays an important role in the protection of transmission lines. The application of flexible AC transmission systems (FACTS) devices, such as the static synchronous compensator (STATCOM), could affect the performance of the distance relay because of compensation effect. This paper analyzes the application of distance relay on the protection of a transmission line containing STATC...