Development Of Advanced Control & Optimization Software System And The Application In Predictive Control Of Superheated Temperature

Industrial enterprise reform and the deepening of the internationalization let the domestic enterprises facing unprecedented competition and challenges. At the same time, energy reduction become the "11th Five-Year Plan". These all requires enterprises to adopt advanced control and optimization method, in an effort to improve production efficiency and reduce the energy consumption so as to improve overall economic efficiency.Thermal power takes more than three-quarters of the total electricity capacity in China. So, the applications of advanced control and optimization in this field have a very important significance. It is because of the application rate of advanced control and optimization in thermal power units remains low, which is multifaceted: (l)Advanced algorithms are generally too complicated and are difficult for computer applications. And the parameters are also too complicated for normal engineers to adjust; (2)There are a large number of early built large scale thermal power units, which lack of the necessary means of control ability because of the outdated design and obsolescence; (3)The lack of advanced control and optimization software system based on independent intellectual property rights. This paper will focus on two aspects: The development and implementation of advanced control and optimization software system. And the application of advanced methods for the control of the super-heat steam temperature of large scale power plants.1. Super-heat steam loop is one of the most important loops of power plant boiler system. The stability of super-heat steam temperature directly affects the boiler efficiency and also the safety. And the unit's efficiency increases l%o when super-heat steam temperature increases 1°C. At the same time, steam temperature must be very stable, because overheating will directly affect the boiler safety, and frequently overheating will lower pipes' life, and even produce pipe explosion and forces boiler to be shutdown for maintenance; On the other side, over-low-temperature will significantly drop the boiler's efficiency. However, many power plant boilers, especially the early built ones, their super-heat steam temperature control were not optimal, or even unable to be automatic controlled. It is because the super-heat loop is of a typically large inertia, and the model varies much with the boiler load. At the same time, many of them lack controllable instruments, which has substantially increased the difficulty of the control. Because Pingwei #1 and Shiheng #2 Unit are of the most problematic boilers, we specifically proposed a Model-switching Stair-like Generalized Predictive Control method, and taking air volume, main steam pressure, feeds of the upper coal, steam flow, and other factors into consideration. And then we designed cascaded controller based on the model-switching method and the controller showed very good control quality. The controller design successfully solved the automatic super-heat steam temperature control problem since the two plants' foundation, and showed exclusive performance and portability of the new method.2. Existing control software system generally has problems such as lack of stability and functionality, weak of portability and scalability, unable to tightly integrate with large scale DCS system and perform stabile and high-speed data exchange with DCS, etc. To solve these problems, we proposed several efficient data exchange methods for different application occasions, and designed a highly efficient module-scheduling strategy. And we also designed many advanced features such as bi-directional data pool, unified data preprocessing interface, unified module template, multi-threaded dynamic loaded and scheduled modules, unified configuration file and configuration database support, standardized formatted logging system, and heartbeat signals support. Finally, based on the Solaris operating system, we produced DCS-embedded advanced control and optimization software system. The system features high stability, versatile modularity, fast&stable data processing, and is highly expansible and portable. The software's application in the super-heat steam temperature control and combustion optimization project in Shiheng Power Plant showed significant performance and stability advantages.