부산대학교 도서관

Recent advancements in renewable energy technologies have brought focus on microgrids that have resulted in many predicaments for safe and reliable operation. Two of the major protection concerns are varying fault level and island handling. Integration of various types of sources at different levels of power system alters the existing power system studies and jeopardizes the passive and radial nature of conventional systems. Connection and disconnection of utility grid and other power sources varies the fault levels of the system. Moreover, disconnection of main utility grid results in islanded mode operation where frequency and voltage can be unregulated. The concept of unified protection scheme for microgrid is proposed to meet the protection requirements, which comprises of a unified protection controller (UPC) that supervises the connection and disconnection of existing power sources and updates the relay settings accordingly. The proposed unified protection methodology has been analyzed in MATLAB Simulink. Faults are introduced in the system to check the capabilities of UPC in allowing correct tripping, preventing nuisance tripping.