Study On Control Method Optimization And Application Of Reciprocating Compressor Capacity Stepless Regulation System

Reciprocating compressor is a key equipment with high power consumption,and is widely installed and operated in petrochemical process,gas pipeline transportation,gas storage and other fields.Due to the constant change of production process load and the influence of energy conservation,the demand for energy conservation regulation of compressor capacity is becoming more and more obvious.Although the regulating methods and the related system based on the active control of intake valve are the effective technical measures to realize the energy-saving regulation of compressor capacity,there are still some shortcomings of key technologies to be solved urgently.The existing regulation method cannot be applied to the unit whose air volume is sensitive to the intake air temperature.The existing multi-cycle regulation method does not consider the influence of compressor running state caused by unbalanced load regulation.The capacity control of multistage compressor is a complex multivariable system with nonlinear,coupling and time-delay characteristics.However,conventional PID controller is still used in the existing capacity control system in the application of multistage compressor,resulting in poor dynamic characteristics and poor robustness of capacity control.The stability and reliability of the existing system are still insufficient.Since the capacity regulation system is a complex system with electromechanical and hydraulic structures coupled to each other,the failure of any system component or the change of performance characteristic parameters in the long-term operation process will cause the system performance to decline or even failure.Therefore,it is of great significance and value to develop the optimization control method of multi-stage compressor capacity regulation and the self-healing control method to optimize the stability and reliability of the system and ensure the safe,efficient and energy-saving operation of reciprocating compressor.In this paper,based on the principle of inlet valve backflow regulation of reciprocating compressor,the coupling mechanism model of multiple subsystems of reciprocating compressor capacity regulation was established,and theoretical and experimental research was carried out.The optimization research of capacity regulation method was carried out.The optimized multi-cycle capacity regulation method can effectively reduce the adverse impact on the compressor.Aiming at the problems of nonlinear and strong coupling in the capacity control of multistage compressor,a control-oriented average flow model and the optimization calculation model of overall energy consumption were established,and the optimization research on the capacity control strategy of multistage compressor was carried out.At the same time,based on the coupling mechanism model,the regulation performance degradation of the capacity regulation system was deeply studied,and the self-healing control method was studied for different faults.The system framework of compressor condition monitoring and capacity energy saving optimization control was designed to form a set of capacity control prototype system with integrated monitoring and control.The results of experimental tests and engineering applications have been provided to verify the theoretical research conclusions.The main work is as follows:Firstly,based on the principle of inlet valve backflow regulation,the coupling mechanism model of multiple subsystems of reciprocating compressor capacity regulation was constructed,and the relationship between capacity load ratio parameters and crankshaft angle and inlet and exhaust pressure were analyzed.The calculation method of capacity load ratio parameters was optimized.The multi-period capacity regulation method was optimized based on the mechanism model and experimental data.The flexible interval was introduced to solve the problem of pressure fluctuation caused by different control cycle switching.The optimal control cycle set of multi-stage compressor was obtained by optimizing the control cycle set with multiple parameters such as pressure,current and temperature rise of inlet valve.To solve the problem of air compressor displacement fluctuation caused by the change of intake air temperature,the capacity control method based on intake air temperature and pressure ratio was proposed.Secondly,aiming at the problem of multi-stage compressor capacity regulation and control,the model of average flow of multi-stage compressor and the model of energy consumption of the whole compressor were constructed,and the pressure parameters between the stages were optimized,so that the energy consumption of the whole compressor was minimized.The multi-stage compressor pressure control is a multivariable system with coupling and nonlinear characteristics.The distributed internal model PID controller and the adaptive predictive PID controller were designed respectively for different control schemes to optimize the system control.Then,by means of simulation,the influences of the failure states of actuator not in place,actuator stuck,partial actuator failure and valve leakage on the regulating performance of capacity control system were revealed.The corresponding self-healing optimization control method was studied for different faults.Aiming at the performance degradation problems caused by actuator performance degradation or gas valve leakage,a performance degradation evaluation model of the system was built by using improved PSO-BP neural network.The self-healing regulation was carried out by compensating the electronic control components of the system based on the results obtained by the evaluation model,which ensured the regulation accuracy of the system.Faced with the problem of capacity regulation failure caused by the failure of some actuators in the capacity regulation system of reciprocating compressor,a self-healing control strategy based on the reconfiguration of the regulation domain and the redistribution of load was proposed.The self-recovery of fault was realized without human intervention and based on load adaptive redistribution.Then,an integrated system architecture design scheme of capacity control and condition monitoring and diagnosis of reciprocating compressor was proposed,and an integrated prototype system experiment and test platform were built.Many verification tests have been carried out on the experimental platform,and the results obtained in the control methods and self-healing regulation methods of the capacity regulation system in this paper have been effectively verified.Finally,the capacity regulating system using the optimized technology in this paper had been applied in the three-stage Hydrogen compressor and four-stage air compressor.The good application results further verified and tested the optimization method of reciprocating compressor capacity control system proposed in this paper.