Patent ID: 6938584
Filing Date: 2005-09-06
Classification: G21D,Y02E

Abstract:
1. A feedwater control system considering a pressure drop of feedwater control valves in a nuclear power plant, the feedwater control system for controlling a water level of a steam generator by adjusting a feedwater flow introduced into the steam generator through a control of one or more main feedwater pumps, main feedwater control valves and downcorner feedwater control valves, the feedwater control system comprising: a first detection unit including: a flow error signal generator for generating a flow error signal corresponding to a difference between a steam flow signal and a feedwater flow signal, wherein the steam flow signal corresponds to a steam flow discharged from the steam generator and the feedwater flow signal corresponds to a feedwater flow introduced into the steam generator; and a water level correction error signal generator for generating a water level correction error signal corresponding to a sum of a water level measurement signal and the flow error signal, wherein the water level measurement signal corresponds to a difference between a water level measurement signal and a water level setup signal, the water level measurement signal corresponding to a measured water level of the steam generator, the water level setup signal corresponding to a previously set water level of the steam generator; a second detection unit including: a pressure drop sensor unit for detecting a pressure difference between front and rear portions of at least one feedwater control valve among the main feedwater control valves and the downcorner feedwater control valves and generating a pressure drop signal corresponding to the detected pressure difference; a pressure drop setup value signal generator for generating a pressure drop setup value signal corresponding to a previously set pressure drop setup value of the feedwater control valves; and a pressure drop error signal generator for comparing the pressure drop signal with the pressure drop setup value signal and generating a pressure drop error signal; and a control unit including: a first proportional integrator through which the water level correction error signal passes; a main feedwater pump speed signal converter through which a flow request signal processed through the first proportional integrator passes; a second proportional integrator through which the pressure drop error signal passes; a feedwater pump speed bias signal converter through which a bias signal processed through the second proportional integrator passes; and a correction control signal generator in which an auxiliary control signal output from the feedwater pump speed bias signal converter is operated on a main control signal output from the main feedwater pump speed signal converter, wherein the control unit controls the main feedwater pump based on a correction control signal output from the correction control signal generator.