Research And Application Of The Safety Related System Design Based On IEC 61508 Functional Safety Standard

Safety has always been one of the vital considerations in electric power industry, As industrial control plays an important role in electric power industry,'safety'has definitely become the key of it. Conventional industrial safety measures focus on protecting the staff working in dangerous areas from getting injured or losing life. While today, in order to unify safety and efficiency, safety measures include not only life-protection but also equipment functional enhancement. For the realization of'Safe Industry', more and more safety-related systems (including Automatic Control System and Automatic Protection System) are used in different areas. They protect the staff from harm, ensure that the machinery, equipment set and even the entire plant operate automatically, normally and safely. While the industrialization of safety-related systems encounters a biggest obstacle, that is, the systems'own functional safety- uncertainness. Therefore, functional insurance and functional reliability of safety systems have become the main direction for safety system research in industries.This paper begins from a discussion on definition of safety, and leads to the research on safety systems. It is a systematical introduction of the main function, application and trend of safety system. It summarizes current safety system researches, carries on a study of common design methods based on E/E/PE (electrical/electronic/programmable) safety-related system, including measures of risk analysis, risk allocation, safety grading and rules of system structural arrangement, safety logic design and control loop design. It studies the main problems of safety system design, develops models for functional safety communication and MooN redundant reliability analysis, deduces formula of safety communication integrity grading and redundant structure reliability, puts forward safety system design of power plant. In the conclusion of the paper, there is a summarization of the series researches mentioned above, and also anticipation for the future.Work as following are completed:1. Technical specification of safety system is introduced, as well as top fresh technology of it up to now. With the publish of standard IEC61508, importance of safety and reliability of safety system is pushed out. Requirements on safety system and research progress are introduced.2. Concept and content of Safety Function Standard IEC 61508 is introduced, Regard with the methods of increasing Reliability and Availability, plenty of redundant structure are applied in safety system design, including Woring Redundancy, Backup Redundancy, Vote System, Retreat Redundancy and Multi-level Operating Redundant. These measures ensure the Safety Integrity Levels up to SIL3 and Availability up to 99.9% of the whole system. By description of application of FSSS system, design of Safety system is completed and perfect.3. Consider the practical engineering requirements of project and safety system performance, safety system design is completed, the detail configuration is described, including the strategy to realize the functional reliability.4. Deeply dig the problem met in the safety system design, modeling for redundancy reliability analysis, figure out the formula to calculate safety integrity level and redundancy structure reliability and finally complete the calculation for the practical safety system.