Researches On CCPP Gas System Modeling And Anti-surge Strategy Of Compressor

For the advantage of efficiency and environmental protection, the new power technology CCPP (Combined Cycle Power Plant) is paid more and more attention and widely used. Appling CCPP to generate electricity with surplus gas in the spare power plant is good for energy recycle and environmental pollutants reduction. However, the requirements of CCPP to gas compressor system are very high, gas flow rate and pressure changes will bring great influence to the safety and efficiency of the system. Therefore the study of CCPP gas system is of great significance.Based on the CCPP gas system of a steelworks, this thesis is concerned with gas flow and pressure fluctuations and compressor surge problems. Employing the idea of modular modeling, the first principle models of multi-stage centrifugal compressor, cooler, separator and control valves are developed through mechanism analysis. The models are verified by simulations. Then the mathematical models for the high and low pressure gas subsystem are established by the way of connecting the models of each of the sets. Analysis of the performance of gas system is also carried out by simulations. In addition, a feasible anti-surge control strategy is proposed. Finally, simulations based on the gas compressor system model and the strategy above is carried out.Simulation results show that the mechanism model of gas system developed in this thesis is accurate and reliable, which can correctly reflect the characteristics of gas system and its components. The results also show that the control strategy proposed for compressor surge problems can provide effective control in inhibiting the occurrence of compressor surge and achieve good control effect.