可靠性是过程控制系统的第一要求。 冗余技术是计算机系统可靠性设计中常采用的一种技术， 是提高计算机系统可靠性的最有效方法之一。为了达到可靠性和低失效率相统-的目的，我们通常会在控制系统的设计和应用中采用冗余技术。合理的冗余设计将大大提高系统的可靠性，但是同时也增加了系统的复杂度和设计的难度，应用冗余配置的系统还增加了用户投资。因此，如何合理而有效的进行控制系统冗余设计，是值得研究的课题。冗余技术冗余技术概要:冗余技术就是增加多余的设备,以保证系统更加可靠、安全地工作。冗余的分类方法多种多样，按照在系统中所处的位置，冗余可分元件级、部件级和系统级;按照冗余的程度可分为1:1冗余、1:2冗余、 1:n冗余等多种。 在当前元器件可靠性不断提高的情况下，和其它形式的冗方式相比，1:1 的部件级热冗余是一种有效而又相对简单、配置灵活的冗余技术实现方式，如/O卡件冗余、电源冗余、主控制器冗余等。因此，目前国内外主流的过程控制系统中大多采用了这种方式。当然，在某些局部设计中也有采用元件级或多种冗余方式组合的成功范例。
TK-CCR014
控制系统冗余设计的目的:系统运行不受局部故障的影响，而且故障部件的维护对整个系统的功能实现没有影响，可以实现在线维护，使故障部件得到及时的修复。冗余设计会增加系统设计的难度，冗余配置会增加用户系统的投资，但这种投资换来了系统的可靠性，它提高了整个用户系统的平均无故障时间(MTBF)，缩短了平均故障修复时间(MTTR) ，因此，应用在重要场合的控制系统，冗余是非常必要的。二个部件组成的并联系统(互为冗余)与单部件相比，平均无故障时间是原来的1.5倍。系统的可用性指标可以用两个参数进行简单的描述，- -个是平均无故障时间(MTBF) , 另一个是平均修复时间(MTBR)。系统的可用性可用下式表示:系统可用性= MTBF/(MTBF + MTBR)当可用性达到9.999%时，系统每年停止服务的时间只有6分钟。
TK-CCR014
Reliability is the first requirement of process control systems. Redundancy technology is a commonly used technique in computer system reliability design and is one of the most effective methods to improve the reliability of computer systems. In order to achieve the goal of integrating reliability and low failure efficiency, we usually use redundancy technology in the design and application of control systems. A reasonable redundancy design will greatly improve the reliability of the system, but it also increases the complexity and difficulty of the design. The application of redundancy configuration in the system also increases user investment. Therefore, how to design control system redundancy reasonably and effectively is a topic worth studying. Summary of Redundancy Technology: Redundancy technology refers to adding redundant equipment to ensure that the system operates more reliably and safely. There are various classification methods for redundancy, and redundancy can be divided into component level, component level, and system level according to its location in the system; According to the degree of redundancy, it can be divided into various types, such as 1:1 redundancy, 1:2 redundancy, and 1: n redundancy. In the current situation where the reliability of components is constantly improving, compared to other forms of redundancy, 1:1 component level thermal redundancy is an effective and relatively simple redundancy technology implementation method with flexible configuration, such as/O card redundancy, power redundancy, main controller redundancy, etc. Therefore, most mainstream process control systems both domestically and internationally adopt this approach. Of course, there are also successful examples of using component level or multiple redundancy combinations in certain local designs.
TK-CCR014
The purpose of redundancy design for control systems is to ensure that the system is not affected by local faults, and that the maintenance of faulty components has no impact on the functional implementation of the entire system. Online maintenance can be achieved to ensure timely repair of faulty components. Redundant design increases the difficulty of system design, and redundant configuration increases the investment of user systems. However, this investment in system reliability increases the average time between failures (MTBF) of the entire user system and shortens the average time to repair (MTTR). Therefore, redundancy is necessary for control systems in important situations. The parallel system composed of two components (mutually redundant) has an average time between failures of 1.5 times that of a single component. The availability indicators of the system can be simply described by two parameters, one is the mean time between failures (MTBF), and the other is the mean time to repair (MTBR). The availability of the system can be expressed as follows: System availability=MTBF/(MTBF+MTBR) When the availability reaches 9.999%, the system only stops serving for 6 minutes per year
TK-CCR014
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