Appling improvement of the inverse time overload protection of large generating units

Inverse time protection is widely used in overload protection scheme of large generating units, but the operation curve adopted by inverse-time overload protection is different from the practical overload curve of generating units. Hence, there are many inconveniences for application of inverse-time overload protection. Problems about constitution of inverse-time characteristic curve, realization of micro-computer and curve-fitting are analyzed in this paper. Setting principles for inverse-time overload protection of large generating units are described, based on its application in protection scheme of large-scaled generating units installed in Three Gorges Right Bank Power Station.