Quad Variable Relay for Protection of AC Microgrids | Chapter 01 | Advances in Applied Science and Technology Vol. 6
The two major technical challenges facing widespread deployment of microgrids are the impacts of microsources and active loads on control instruments and protective devices. Classical protective devices operate through detection and response. Detection is performed by measuring parameters of the system and comparing with set values. Response is performed through isolation of faulted segment if the result of comparison dictates isolation. These classical protective devices as well as modified classical devices reported in literature malfunction under complex operating conditions of microgrids that have multiple controls regimes and are capable of grid interconnection and islanding. In this book chapter, a quad-variable rule-based relay is described. The relay meets both plug-and-play and peer-to-peer requirements of microgrids. The interaction of four critical parameters of complex microgrids is modeled using fuzzy rule. Using the rules, sub-controllers are designed for microsource a...