 Protective relays work in concert with sensing and control devices to accomplish their function. Under normal power system operation, a protective relay remains idle and serves no active function. But when fault or undesirable condition arrives Relay must be operated and function correctly.  A Power System consists of various electrical components like Generator, transformers, transmission l...

In modern protection system the key challenge is the trade-off between the security demand (no false tripping), the speed of operations and the dependability requirements. To meet this challenge properly, the application of a novel Artificial Intelligence (AI) method, using fuzzy logic, in power system protection has been proposed in this paper along with the simulated data. The examined techni...

All algorithms for impedance calculation use an analog-to-digital converter. The high accuracy of the impedance seen by a distance relay is an important factor in the correct isolation of the faulty part of power systems. To achieve this, a novel technique based on third order interpolation is used in this paper. According to this technique, the times and the values of the obtained samples are...

Power industry deregulation trend and proliferation of digital electronic devices are deeply affecting operations of power utility companies. Engineering departments, in particular, must deal with increasing complexity of existing applications as well as with emergence of new applications. Such an environment, creates many new challenges for protection system engineers. Use of new business mode...

This paper will outline the features required for a multifunction protective relay or intelligent electrical device (IED) that meets the special requirements of the distributed generation environment.

Distributed generators (DGs) are defined as generators that are connected to a distribution network. The direction of the power flow and short-circuit current in a network could be changed compared with one without DGs. The conventional protective relay scheme does not meet the requirement in this emerging situation. As the number and capacity of DGs in the distribution network increase, the pr...

We consider relay channels in which the source-destination and relay-destination signals are assumed to be orthogonal and thus have to be recombined at the destination. Assuming memoryless signals at the destination and relay, we propose a low-complexity quantize-and-forward (QF) relaying scheme, which exploits the knowledge of the SNRs of the source-relay and relay-destination channels. Both i...

This paper presents the proper underfrequency relay settings to enhance the operation of industrial power systems with cogeneration facilities. A cogeneration unit was installed in the plant in 1996 to supply the power demand of the plant. The cogeneration unit always faces the shutdown problem when a severe fault occurs on the nearby Taipower network. It is, therefore, necessary to investigate...

rotection schemes employing the differential relaying principle exhibit certain limitations in applications with power transformers. This is because the detection of a differential current does not clearly distinquish between internal faults and other possible conditions. Among the phenomena most likely to upset the current balance and cause the relay to malfunction are inrush magnetizing curre...