Study On The Problem Of Hydraulic Disturbance In The Case Of The Load Mutation Occurring In One Diversion Penstock For Two Hydro-generators System

With the development of hydropower development conditions in China, the number of multi-machine common hydraulic piping units is increasing. At this time, there is "water mechanical and electrical" coupling between hydropower units. The increase and decrease of load during operation of the unit will cause the problem of hydraulic disturbance between multi-machine When the load of a unit changes rapidly, the stability of other units will be greatly affected. Anti at this problem, this paper studies the mutual influence of hydraulic disturbance on the sudden change of load in the unit.Firstly, a schematic model of hydraulic system is given, and the mechanism of hydraulic disturbance and the adverse effect on the operation of the unit are analyzed. The mathematical model of the hydraulic system of the bifurcated pipeline with the surge chamber is established.The calculation process of the unsteady flow of the pressurized pipe is introduced in detail;Secondly, the structural block diagram of control system of hydropower unit is given, and the mathematical model of hydroelectric generating set and load, governor and excitation system is established; Then, the general steps and flow chart of the calculation of the hydraulic disturbance are given, and the simulation model of the control system of the hydropower unit control system is established by using Matlab/Simulink as the numerical calculation platform. Finally, based on the data of the actual power station, a whole simulation system of a two-machine system is constructed. The problem of hydraulic disturbance in the two-machine system is studied under the two kinds of operating conditions of isolated power grid and large power grid; When a unit load changes, its pipeline flow pressure changes on the impact of another unit operation.The simulation results show that the change of the unit frequency caused by the hydraulic disturbance is obvious with the load change when the isolated grid is running; When combined into the operation of the large power grid, the unit caused by hydraulic interference caused by the unit power changes with the load is more obvious; When the surge chamber area is reduced or the length of the main pipe increases, the hydraulic disturbance increases and the unit power influence changes; The change of the closing time of the guide vane of the load shedding unit has little effect on the result of hydraulic disturbance.