Modeling Of CCPP Units Multistage Gas Compressor System

Centrifugal compressor is the key equipment in industry departments. It has the character of high discharge pressure and low inlet flow. But there are also some disadvantages, such as stable operation area is narrow and it is easy to surge. Surge is harmful to compressor, so it must be equipped with control system to avoid surge. Therefore, establishing the accurate mathematical model, for centrifugal compressor anti-surge control, plays an important role.This thesis set CCPP(Combined Cycle Power Plant) gas system of LuoJing power plant in Shanghai baosteel group as the research object, for due to current gas system flow and pressure fluctuations larger, leading to the compressor surge frequently problems, established the mathematical model of the centrifugal compressor. Thesis specifically includes the following several parts content:(1)Though the Euler equation and Bernoulli equation, this article analyzed the compressor levels of energy transfer, and established by energy transfer process of centrifugal compressor one-stage model, then constructed by superposition method of multistage centrifugal compressor model, including stress model, temperature model and the efficiency model. Because of hard to get some key parameters of the mechanism equation, using DCS process data to the mechanism model parameter identification. The model provides estimates of performance of the centrifugal compressor under different conditions. Its effectiveness has been proved through model validation and simulation studies.(2)With the process data, this dissertation used particle swarm optimization algorithm to optimize the BP neural network so as to establish compensation model. Compensation model and mechanism model output addition as centrifugal compressor mixture model output. Finally, using the local controller of the algorithm, hybrid model is validated. Verification results proved the accuracy of the models.Finally, the summary and perspectives of centrifugal compressor modeling approach are addressed.