An Improvement Design Of High Reliability Alarm System On Nuclear Power Plant

The alarm system can provide and monitor all the information needed the power plant's deviation from normal operating conditions,which is one of the important systems of the nuclear power station.It transmits the alarm information to the nuclear electronic instrument control system,and the system self-diagnosis function detects the main failure of system hardware and software,and corresponding action is adopted automatically,which is very important for ensuring safe and reliable operation of nuclear power plant.The current alarm window has the problems like high failure rate caused by spare suspend production and the equipment aging.In addition,plenty of hard wiring of the original equipment also lead to the difficulty of maintaining constantly improving.In order to solve the above problems and meet the continuation requirements of operation license of subsequent power plant,it is necessary to upgrade the conventional alarm system,especially the improvement of communication mode.This paper proposes the solution of simple structure,high reliability,high stability and simplified wiring,aiming to the refonn design of conventional alarm for a nuclear power plant.It analyzes the advantages and disadvantages of several TTCAN protocol redundant architectures,using two relatively independent channels to build a redundant system.The field wiring is simplified while ensuring high stability and high reliability.SOE function is also added in the alarm window,which eventually finishes the improvement and optimized design of high reliability nuclear power plant alarm system.At first,through the investigation of the conventional alarm system and the high reliability communication network,the requirements of the improvement and optimized design of the conventional alarm system of this paper.According to the equipment field requirement,operation interface and function configuration are confirmed.Then redesign from the main defect of the original equipment,integrating field situation,determining the field bus with high real-time and good predictability.Redundant architecture is used to improve security.On the basis of analyzing the previous TTCAN redundant architecture,more reliable redundant architecture is designed.The field wiring is simplified while ensuring high stability and high reliability.SOE function based on GNSS clock is also added in the alarm window.The delay parameter is introduced for the delay of the field bus in information transmission,increasing the system overall clock precision.After that,on the basis of preliminary work,the overall hardware and software design to the system is conducted,adopting the hardware design based on STM32 interconnected chip,mainly including GPS timing and punctuality circuit,TTCAN communication circuit,alarm data acquisition circuit,etc.Building block design to each hardware is conducted so that the future maintenance may be convenient,which can effectively solve the problem of field equipment maintenance and replacement.The functions of each hardware circuit and the selection of components are also be discussed.The key points are introduced in aspects of software design,including lower computer software and upper computer software,in TTCAN bus configuration,message sending and receiving process and redundant management.Finally,with the existing experimental conditions,the system was tested and each functions and reliability were verified.