Threshold decision for instrument control system and its application in nuclear power plant

Threshold decision is an important function of nuclear instrument control system based on physical parameters threshold decision. Because the conventional decision methods lack correlation with time and conditions, by analyzing the existing methods, some optimized methods are adopted. Considering safety, those methods are improved in data processing algorithms, floating threshold with multiple values, association with specific working condition, etc. These measures im- prove the nuclear instrument control system in fault tolerance and fault diagnosis, especially, the shutdown number of nucle- ar power plant decreases.

Acceleration feedback control (AFC) enhanced by disturbance observation and compensation (DOC) for high precision tracking in telescope systems

Abstract In this paper, a cascade acceleration feedback control （AFC） enhanced by a disturbance observa- tion and compensation （DOC） method is proposed to improve the tracking precision of telescope systems. Telescope systems usually suffer some uncertain disturbances, such as wind load, nonlinear friction and other unknown disturbances. To ensure tracking precision, an acceleration feedback loop which can in- crease the stiffness of such a system is introduced. Moreover, to further improve the tracking precision, we introduce the DOC method which can accurately estimate the disturbance and compensate it. Furthermore, the analysis of tracking accuracy used by this method is proposed. Finally, a few comparative experimental results show that the proposed control method has excellent performance for reducing the tracking error of a telescope system.

Acceleration feedback of a current-following synchronized control algorithm for telescope elevation axis

This paper proposes a dual-motor configuration to enhance closed-loop performance of a telescope control system. Two identical motors are mounted on each side of a U-type frame to drive the telescope elevation axis instead of a single motor drive, which is usually used in a classical design. This new configuration and mechanism can reduce the motor to half the size used in the former design, and it also provides some other advantages. A master-slave current control mode is employed to synchronize the two motors. Acceleration feedback control is utilized to further enhance the servo performance. Extensive experiments are used to validate the effectiveness of the proposed control algorithm in synchronization, disturbance attenuation and low-velocity tracking.

Network Reliability Analysis of Digital Instrument and Control System with GO-FLOW Methodology

In this paper,the network reliability of an actual digital instrument and control system (DICS) network is analyzed by using GO-FLOW methodology (GFM).The evaluations of common-cause failure (CCF) and uncertainty are incorporated.Three significant CCF groups (real time servers,gateways,reactor protection system) and three typical time intervals (10 min,1 h,and 24 h) are selected in the analysis.It is concluded that the network contribution of CCF accounts for over 68% of the system failure probability.The result indicates that GFM is suitable for the network reliability analysis.

A general observatory control software framework design for existing small and mid-size telescopes

A general framework for observatory control software would help to improve the efficiency of observation and operation of telescopes, and would also be advantageous for remote and joint observations. We describe a general framework for observatory control software, which considers principles of flexibility and inheritance to meet the expectations from observers and technical personnel. This framework includes observation scheduling, device control and data storage. The design is based on a finite state machine that controls the whole process.

The Information Security of Digital Control Systems for Nuclear Power Plants

The NPP （nuclear power plant） being vital objects of an energy infrastructure must be protected against malicious actions affecting their safety, and cyber security plays a key part in attaining this goal. The paper considers, implemented by the authors within the project of advanced digital control system for NPP with the reactor VVER-1000, a system of unauthorized access protection, partially built up on the technology of AA （active audit） and expert system. The AA technology is based on response of the system on deviation of current signature of the automated process control system from stable state rather than on a certain signature of attack and relies on the estimation of the behavioral models of the particular digital control system. The advent of active audit reflects the current situation in the digital control systems where complex distributed platforms are used to construct automated process control system. The active audit allows one to make the digital control system functionally closed, provided that it is determinate. The methodology of the active audit does not give u external （barrier） and traditional （password, antivirus） methods of unauthorized access protection. These methods can be used when it is appropriate to achieve a required protection level.

Review on Thermal Power Automation Development in China

A review on thermal power plant automation development in China over 50 years is presented. The level of thermal power automation is introduced, especially for 200 MW and above units which are clarified into three categories by grade. The conditions, existing problems, relevant solutions and policies are summarized chronologically in aspects of centralized control, automatic regulation and controllability of main and auxiliary units, turbine control system, furnace security protection, and computer application in thermal power plants. This paper also points out the development tendency of thermal power plant automation and concepts of some vocabularies.