Loss-of-mains detection by frequency protection functions

摘要

In the paper performance of Under/Over-frequency protections and Rate of Change of Frequency (ROCOF) relay are discussed. In the first part, working principle of these methods are presented with special consideration to various approaches to numerical realization of frequency and df/dt calculation. To illustrate the problem of nuisance trippings, simulation results of performance of the considered frequency protection functions under various system disturbances (faults, switching conditions, power swing, islanding) are presented. For this purpose different power system models with embedded distributed generators (both synchronous and inverter based) were prepared in ATP-EMTP and MATLAB environment. In the final sections, reliability of considered methods is discussed and compromise between operation sensitivity, security and operation speed is analyzed.