| Due to the variability of its operation mode,the combined power plant ensures the effective compatibility of efficiency and economy,and its application in ship propulsion system has been paid more and more attention.In order to adapt to its changeable working conditions,the structure design of the transmission system of the combined power plant is complex,and the frequent switching operation poses a great challenge to the reliability of the transmission system.In this paper,the semi physical simulation test-bench of a type of combined power plant is taken as the research object.From the perspective of electromechanical coupling,the dynamic characteristics of the transmission system in the bench are analyzed,and the boundary conditions of the control parameters for the stability of the coupling system are studied,which provides reference for the adjustment of the control parameters and the low vibration design of the transmission system.Based on the idea of modular modeling,a fast calculation model of the overall characteristics of a three-axis gas turbine is established.Considering the operation characteristics of the driving source and the structural characteristics of the actual bench,a parallel power feedback governor is selected as the joint control algorithm of the two engines.The feasibility of the algorithm is verified by simulation and experiment.The overall design scheme of a semi physical simulation system is built,which defines the operation logic for simulation and experiment,and ensures the rationality of simulation and experiment.The finite element method is used to model the multi rotor structure of gear transmission in the test-bench.Considering the coupling of multi degrees of freedom of the transmission system,a general dynamic model assembly method is designed to improve the modeling efficiency of the complex rotor system.Through the combination of simulation and experiment,the brace stiffness parameters in the rotor system are identified to ensure the accuracy of the rotor model parameters.The mode of the rotor system is calculated and the characteristics of the coupling vibration in the rotor system are analyzed.Combining the control system and mechanical system model established above,according to the coupling logic relationship among driving source,transmission system and joint control method,the electromechanical coupling system model of the combined power plant is built.Based on the gear dynamics theory,the gear meshing dynamic excitation is constructed and embedded in the electromechanical coupling system model,which is the main excitation source in the experiment bench system.The research on the steady-state operation characteristics of the combined power plant is carried out from three aspects: the influence of the driving source regulation on the transmission system,the influence of the driving system on the synchronous characteristics of the driving source,and the influence of the load sharing characteristics of the driving source on the transmission system.The interaction relationship between the control system and the transmission mechanism is obtained.In the transient operation of parallel operation and disconnection,the impact of the load adjustment time on the rotor system is greater than that of the load adjustment amplitude,so the rapid completion of load transfer process can avoid large vibration of rotor system.Further,the system identification method is used to identify the working process of the driving source and the rotor system in the electromechanical coupling system,then the transfer function relationship between them is obtained,and a simplified closed-loop coupling model is built.The frequency domain analysis method is used to evaluate the stability of the current system,and the system is stable with sufficient margin.The root locus method is used to further exploring the influence boundary of the system stability of the proportional coefficient in the controller.Through the impact simulation of the splitting process,the accuracy of the system boundary is verified,which provides a reference for the adjustment of the control parameters of the coupling system. |
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