Research Of DCS Safety Design In 600MW Power Unit

With the development of electricity power industry in the state, electricity power generate unit has grow from mini capacity to mass capacity and even super-critical pressure unit. It is also decided by power policy of the nation to develop mass capacity coal fired generate unit with more efficiency, less energy consuming and more protection to environment. However, mass capacity unit requires much more reliability and safety in performance than mini ones. There is huge impact on net grid of power system when mass capacity unit tripps, which may cause extensive failure to the grid. When mass capacity unit shuts down, generating schedule has to be adjusted, which will take great loss both to power plant and customers. Mass capacity unit operates with high pressure and high temperature steam, which will brings more risk to equipment as well as humen when accident happens. And disaster caused by mass capacity unit results in tremendous tragedy to environment. Anyhow, regard with mass capacity unit, reliability and safety means benefit and profit.By now, DCS system has been widely used in whole plant control in power generate unit. As neural center of process control including supervisory, control and protection in whole plant, the topology structure, hardware constitution and software designing of the system play a key role in reliability and safety in DCS.In this dissertation, a integrate DCS system is designed according to 2*600MW unit project in Pannan Power Plant. According to Safety Integrety Levels of IEC61508 standard, high safety level control system and software configuration are structured to improve reliability and safety of DCS in 600MW unit. Homemade DCS system– XDPS is applied in Pannan Power Plant. High praise is won from customers on excellent operation of the Unit.Work as following are completed: 1. Technic specification of DCS is introduced, as well as top fresh technology of DCS up to now. With the publish of standard IEC61508, importance of safety and reliability of DCS is pushed out. And based on actual condition of development of coal fired power plant in our nation, requirement on DCS system is introduced.2. Consider the practical engineering requirement of 2*600MW unit in Pannan Power Plant, as well as basic performance demand of DCS in mass capacity generate unit and result of SAT test, an integrated DCS system is designed, including functions as DAS, MCS, SCS, FSSS, BPC and ECS. Method of implementation of all functions are described.3. A detailed hardware configuration is described, including DPU, I/O modules, MMI and network structure to present a whole design of DCS system.4. Concept and content of Safety Function Standard IEC 61508 is introduced, as well as safety target, including Reliability, Invalidation, MTBF, MTTR, Availability. Regard with the methods of increasing Reliability and Availability, plenty of redundant structure are applied in DCS in Pannan Power Plant, including Working 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, especially MFT trip panel, design of Safety and Reliability of DCS in Pannan Power Plant is completed and perfect. By all these means, reliability and safety are increased.5. Site operation conditions of #3 unit DCS in Pannan Power Plant are introduced. MMI pictures are presented. Experience is summed up, defects are found and solutions are brought forward to make Safety and Reliability of XDPS more better.System design of PANNAN #3 DCS was finished in Feb.2006, site commissioning started in Dec.2006, and 168 hours test running finished in Jun.2007. DCS system runs steadily at site with convenient maintainance, and got high praises from customers.