A Computational Study Of The Transition Process Of ADK Hydropower Station

The transition process of a hydropower station refers to the dynamic process of a hydraulic unit changing from one steady state working condition to another steady state working condition.The severe transition process will cause damage to the diversion pipeline and mechanical equipment.This paper is in the background of expansion project of 4 # units in ADK hydropower station and the transition process is calculated in this paper.The main research purpose of this article is to ensure the success of the project.This article first introduces the pipeline characteristic line method in detail,uses Matlab software to program the power station pipeline system and each boundary condition,and conducts the transition process calculation research.The first part is the optimized design of the guide vane closing law.Based on the actual situation of the power station,this paper introduces a method to analyze the inflection point of the guide vanes with water pressure as the first limiting condition.In this paper,several optimization designs are carried out with different upper limit of water pressure and closed way of guide vane.The second part is the calculation of the large fluctuation transition process.In this paper,considering the hydraulic disturbance between units,12 different load rejection modes are designed and calculated.The feasibility of the guide vane closing rule designed above is verified.The third part is the calculation of the small fluctuation transition process.In this paper,6 operating conditions are designed,which prove that the power station can meet the stability requirements.Based on the calculation of the transition process of the hydropower station,the fluctuation pattern of the water pressure is further discussed.starting from the equations of valve end pressure increase in the classic theory of water hammer,a general form of the value of the water hammer pressure increase of each phase is derived,and a simplified calculation formula of the water pressure at the end of the pipeline is obtained.Taking the classic pipeline water hammer characteristic line method as the verification method,the calculation presented in this paper are verified by simulation.The results show that the simplified calculation method for the hydraulic pressure at the end of the pipe given in this paper has a high similarity with the pressure change curve obtained from the characteristic line method,and the method is simple and practical.In this paper,some achievements have been made in the optimization design of guide vane closing law,the calculation of transition process and the calculation and the pressure at the ends of pipe.However,some difficulties were found during the research.The sectional closing of guide vane can solve the problem of rising water pressure and rotating speed in the process of transition.But,the influence of hydraulic disturbance between different units in a tubular multi-machine system has not been fully considered.It is necessary to further study the optimization of closure rules in complex pipeline system.The study of the water pressure fluctuation pattern at the end of the pipeline is of great significance to engineering calculations and protection against water hammer,which requires more systematic and in-depth research.