TURBINE GENERATOR OVERSPEED PREVENTIVE DEVICE

摘要

PURPOSE:To accurate prevent the overspeed of a turbine generator by precisely detecting load cut-off and preventing the overspeed of the turbine generator without malfunctioning even when unbalanced current is applied to the generator main circuit. CONSTITUTION:The positive phase filter arithmetic circuit 21 in a turbine overspeed preventive device 11 inputs the load current signal from a current transformer 6 and outputs a positive phase component current signal 12. A wave form processing circuit 22 processes the positive phase component current signal 12 and a mean value signal 13. A variation rate detection circuit 25 outputs a signal 14 when the variation rate of the mean value signal 13 exceeds the fixed value and a large change detection circuit 24 outputs a signal 16 when the differential signal 15 between the mean value signal 13 and the turbine mechnical input signal 8 exceeds the fixed value. A match circuit 26 operates when the signals 14 and 16 are matched and a turbine steam valve 3 is controlled by the output 30.