Fault tolerant control for increased safety and security of nuclear power plants

在安全关键型系统中，如核电站，对可靠性、安全性和容错性的要求很高。故障危及工厂安全，导致工业流程操作效率低下，并减少部件寿命。在这种安全关键系统中，设计能够容忍潜在故障的控制系统以提高可靠性和可用性，同时提供理想的性能是有用的。一个能够自动容忍组件故障，同时保持理想性能和稳定性的控制系统被称为容错控制系统。容错控制方法允许控制系统在故障条件下以最小的性能和稳定性退化运行，防止局部，随机，防止故意的故障发展为灾难性的系统故障，导致可能对人类生命、设备、基础设施或环境造成严重后果的事故。当采取补救措施来修复或消除故障时，容错有助于减少故障可能产生的破坏性影响。拟议的工作将为压水堆核电站制定一种分层容错控制方案，该方案将分为三个层次：执行、协调和管理层次。执行层包括反应堆、蒸汽发生器和水轮机，通过执行器实现上级产生的控制动作，感知相关的工厂变量，并将该信息传递给上级。中间层是工厂经理层和执行层之间的协调者。为了最大限度地发挥其能力，协调级别将包括一个由四个不同控制器组成的库，这些控制器将被设计为能够容忍不同严重程度的故障，并且将有一个机制，根据工厂的情况根据管理层的要求选择最合适的控制器。协调层还包含一个诊断和预测系统，该系统将工厂数据和有关组件使用寿命的知识用于检测和表征传感器相关和其他工厂故障。高层管理工厂绩效监测、工厂状况评估，并向协调层传递命令。此外，管理层将操作数据传输到中央指挥、控制和通信系统，并从中央指挥、控制和通信系统接收指令，该系统与人类操作员接口。该项目还将涉及一个核电站模拟器的开发，该模拟器将用于实时测试将要开发和实施的分层容错控制方案，生成关于正常和故障条件下工厂行为的数据，并生成工厂或工厂部分的简化模型，用于控制器设计的目的。实时测试将允许在接近真实工厂的计算环境中评估发展情况，从而确保所开发的控制方法尽可能真实。这项工作将与专门研究核能的印度研究机构Bhabha原子研究中心合作进行，并将受益于专门从事核安全管理和培训的英国组织STS nuclear的参与。

In safety-critical systems, such as nuclear power plants, the demand for reliability, safety and fault tolerance is high. Faults compromise plant safety, cause inefficiencies in the operation of industrial processes and reduce component life. In such safety-critical systems, it is useful to design control systems which are capable of tolerating potential faults to improve the reliability and availability while providing a desirable performance. A control system which can automatically tolerate component malfunctions, while maintaining desirable performance and stability properties is said to be a fault-tolerant control systemFault tolerant control approaches allow control systems to operate under fault conditions with minimal degradation of performance and stability, preventing localised, random, or intentional faults from developing into catastrophic system failures leading to accidents that may have severe consequences to human life, equipment, infrastructure, or the environment. Fault tolerance helps to reduce the damaging effects that faults can have while remedial action is taken to repair or eliminate the fault.The proposed work will develop a hierarchical fault-tolerant control scheme for PWR nuclear power plants which will be defined over three levels: execution, coordination and management levels. The execution level, which includes the reactor, steam generator and turbine, implements the control actions generated by the higher levels through actuators, senses relevant plant variables, and passes this information to the higher levels. The middle level acts as a coordinator between the plant manager level and the execution level. To maximise its capabilities, the coordination level will include a bank of four different controllers that will be designed to tolerate faults of different severity, and there will be a mechanism to select the most appropriate controller given the circumstances of the plant as required by the management level. The coordination level also contains a diagnostic and prognostic system, which will the plant data and knowledge about the useful life of components to detect and characterise sensor related and other plant faults. The top level manages plant performance monitoring, plant condition evaluation, and passes commands to the coordination level. In addition, the management level transmits operational data to and receives instructions from a central command, control, and communication system which interfaces with human operators. The project will also involve the development of a nuclear plant simulator which will be used to test in real-time the hierarchical fault tolerant control scheme to be developed and implemented, to generate data about the behaviour of the plant under normal and fault conditions, and to generate simplified models of the plant, or parts of the plant, to be used for the purposes of controller design. The real-time tests will permit to assess the developments in a computational environment that is close to what would be encountered on a real plant, hence ensuring that the control methods to be developed are as realistic as possible. The work will be carried out in collaboration with Bhabha Atomic Research Centre, an Indian research institution that specialises in nuclear energy, and will benefit from the involvement of STS Nuclear, a UK organisation that specialises in nuclear safety management and training.