Steam generator level control system and method of preventing oscillation of steam generator level

Patent metadata

Field	Value
Publication number	US-2016189807-A1
Application number	US-201514981407-A
Country	US
Kind code	A1
Filing date	Dec 28, 2015
Priority date	Dec 29, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

Provided are a method and system for improving control of a steam generator level for preventing oscillation of the steam generator level in a nuclear power plant. In order to prevent oscillation of a steam generator level and resultant shutdown of a nuclear reactor, which may be caused when a high-level priority control function is frequently and repeatedly turned on/off as the steam generator level is excessively increased, by improving a feedwater control system in the nuclear power plant, a proportional integral control value may be controlled to be reduced, and thus, output while a certain condition is met after a high-level priority mode is deactivated or a signal instructing to enter the high-level priority control mode may be controlled not to be output.

First claim

What is claimed is:

1 . A steam generator level control system configured to prevent oscillation of a steam generator level at a nuclear power plant, the steam generator level control system comprising:
a comparator configured to compare a steam generator level with a predetermined level-set value; a proportional integral control output unit configured to generate a proportional integral control value by using an output from the comparator; a high-level priority control signal generator configured to output a signal instructing to enter a high-level priority control mode if the steam generator level is equal to or greater than first criteria, and output a signal deactivating the high-level priority control mode if the steam generator level is equal to or less than second criteria; and a high-level priority control signal receiver configured to control a control signal using a value of the proportional integral control output unit to be transmitted to a main feedwater pump and a feedwater control valve in a normal mode, obstruct a control signal using a value of the proportional integral control output unit in the high-level priority control mode, and control a predetermined output value to be transmitted to the main feedwater pump and the feedwater control valve, wherein the proportional integral control output unit controls to output a value obtained when the proportional integral control value is reduced for a certain time period after the high-level priority control mode is deactivated.

2 . The steam generator level control system of claim 1 , wherein the proportional integral control output unit comprises:
a proportional integral controller configured to generate a proportional integral control value by using an output from the comparator; and an output reducer configured to control the proportional integral controller to reduce the proportional integral control value for a certain time period if a high-level priority control mode is deactivated according to a signal from the high-level priority control signal generator.

3 . The steam generator level control system of claim 1 , wherein the proportional integral control output unit comprises:
a proportional integral controller configured to generate a proportional integral control value by using an output from the comparator; and an output reducer configured to receive the proportional integral control value, and reduce the proportional integral control value for a certain time period after a high-level priority control mode is deactivated according to a signal from the high-level priority control signal generator and output the reduced proportional integral control value to the high-level priority control signal receiver.

4 . The steam generator level control system of claim 2 , wherein the output reducer reduces the proportional integral control value at a certain rate.

5 . The steam generator level control system of claim 3 , wherein the output reducer reduces the proportional integral control value at a certain rate.

6 . The steam generator level control system of claim 4 , wherein the output reducer reduces the proportional integral control value in correspondence with a rate equal to or greater than 50%.

7 . The steam generator level control system of claim 5 , wherein the output reducer reduces the proportional integral control value in correspondence with a rate equal to or greater than 50%.

8 . The steam generator level control system of claim 2 , wherein the output reducer reduces the proportional integral control value in correspondence with a predetermined value.

9 . The steam generator level control system of claim 3 , wherein the output reducer reduces the proportional integral control value in correspondence with a predetermined value.

10 . The steam generator level control system of claim 2 , wherein the output reducer reduces the proportional integral control value for a predetermined time period.

11 . The steam generator level control system of claim 3 , wherein the output reducer reduces the proportional integral control value for a predetermined time period.

12 . The steam generator level control system of claim 2 , wherein the output reducer reduces the proportional integral control value until the steam generator level is reduced to a value equal to or less than a predetermined value after the high-level priority control mode is deactivated.

13 . The steam generator level control system of claim 3 , wherein the output reducer reduces the proportional integral control value until the steam generator level is reduced to a value equal to or less than a predetermined value after the high-level priority control mode is deactivated.

14 . The steam generator level control system of claim 2 , wherein the output reducer reduces the proportional integral control value until the proportional integral control value is reduced to a value equal to or less than a predetermined value after the high-level priority control mode is deactivated.

15 . The steam generator level control system of claim 3 , wherein the output reducer reduces the proportional integral control value until the proportional integral control value is reduced to a value equal to or less than a predetermined value after the high-level priority control mode is deactivated.

16 . The steam generator level control system of claim 1 , further comprising:
a main feedwater pump speed controller configured to receive an output from the high-level priority control signal receiver and control a speed of the main feedwater pump; and a feedwater control valve opening controller configured to receive an output from the high-level priority control signal receiver and control a degree of opening the feedwater control pump.

17 . A steam generator level control system configured to prevent oscillation of a steam generator level at a nuclear power plant, the steam generator level control system comprising:
a comparator configured to compare a steam generator level with a predetermined level-set value; a proportional integral control output unit configured to generate a proportional integral control value by using an output from the comparator; a high-level priority control signal generator configured to output a signal instructing to enter a high-level priority control mode if the steam generator level is equal to or greater than first criteria, and output a signal deactivating the high-level priority control mode if the steam generator level is equal to or less than second criteria; and a high-level priority control signal receiver configured to control a control signal using a value of the proportional integral control output unit to be transmitted to a main feedwater pump and a feedwater control valve in a normal mode, obstruct a control signal using a value of the proportional integral control output unit in the high-level priority control mode, and control a predetermined output value to be transmitted to the main feedwater pump and the feedwater control valve, wherein the high-level priority control signal generator receives a proportional integral control value from the proportional integral control output unit, and controls a signal instructing to enter the high-level priority control mode not to be output until the proportional integral control value is reduced to a value equal to or less than a predetermined value after the high-level priority control mode is deactivated.

Assignees

• Kepco Eng & Constr Co Inc

Inventors

• Song In Ho
• Song Myung Jun
• Jeong See Chae
• Lee Ju Han
• Kim Shin Whan
• Kim Eung Seo

Classifications

• F22D5/30

  responsive to both water level and amount of steam withdrawn or steam pressure · CPC title

• G21D3/001 Primary

  Computer implemented control · CPC title

• G21D5/12 Primary

  Liquid working medium vaporised by reactor coolant · CPC title

• F22D5/32

  influencing the speed or delivery pressure of the feed pumps · CPC title

• G21D3/04

  Safety arrangements (emergency protection of reactor G21C9/00) · CPC title