The Stability Of Hydro Power System Under The Framework Of Hamiltonian Theory

Hydro power generation system is mainly composed of penstock,hydro-turbine,generator,servicing facility and power load,its stability is directly related to the dynamic characteristics of each subsystem,but not completely dependent on the behavior of each subsystem.The whole system is a typically complex system of dissipation,and its stability is dependent on imbalance between the energy generated by system and the energy of dissipation,as well as the exchanging energy between the system and the external environment.Therefore,the generalized Hamiltonian theory is introduced to establish the generalized Hamiltonian model of shafting,hydro-turbine and hydro-electromechanical coupling of hydraulic power generation system,respectively,to analyze the stability of the system from the viewpoint of energy.The contents and the conclusions of this paper include:(1)To study the lateral vibration characteristics of the shafting system of a hydro-turbine generating set,a generalized Hamiltonian control model of the shaft system was established by defined the centroids of rotor and runner as generalized coordinates and the external forces were taken as input excitation.The dynamic responses of rotor and runner system with varying damping coefficients were analyzed by numerical analysis method.The results show that the increase of damping can significantly decrease the vibration amplitude of rotor and runner.The system exists periodic motion and periodic-doubling motion when the damping is slight.Therefore,all the results provide the theoretical references for hydro-turbine generating set working well.(2)To better study the transient energy characteristics and stabilization mechanism of the hydroelectric generating set in the sudden load decreasing transient.To make full use of strengths of generalized Hamiltonian system in describing energy flow,the Hamiltonian model of a hydroelectric generating set including the turbine,water diversion system and generator is established by the method of orthogonal decomposition.Firstly,the energy flow of the hydroelectric generating set in the framework of generalized Hamiltonian theory is proved theoretically to be consistent with the real system,and the transient process of sudden load decreasing can be described effectively.Moreover,the variation laws of the flow,the rotating speed and the power angle of the set in the sudden load decreasing transient are studied respectively.The results indicate that the constructed Hamilton function can effectively describe the energy change of the system.It provides theoretical support for the stable operation of the hydroelectric generating set in the sudden load decreasing transient,and a new research idea for the stable operation of the set in other transient processes.(3)This paper focus on the multi-fields coupling which includes hydraulic,mechanic and electric systems of a hydropower station in transient processes.A unified Hamiltonian form of the hydro turbine generation system is proposed,coupled by a first-order differential motion equation of the shafting system and a generalized Hamiltonian model of the hydro turbine.In order to validate the model,the effects of the opening laws on the shafting vibration and the changing characteristics of operating parameters are analyzed.Besides,the conversion of the generalized energy within the HTGS is investigated during the start-up process.The results suggest that the proposed model can investigate coupling dynamic characteristics among the shafting vibration,transient of the hydro-turbine generation units,and generalized energy of the system,which provides new ideas to the research of the stability of the hydropower station.