Study On System Modeling And Control Strategies Optimization Of Turbine Generator Unit With Long Headrace Tunnel

The hydroturbine governing system is a complex nonlinear system which is affected by the hydraulic-mechanical-electrical transient process and their coupled function;its characteristics are directly related to the safe operation of the electrical power system and the quality of the supplied electrical energy.In recent years,with the hydropower projects being carried forward in the southwest district and considering the geography affection,the build of the hydro-power plant with long conduit is necessary.But at the same time,it also brings new problems and challenges to the analysis of the hydraulic transient process of the hydroturbine governing system.Aiming at these problems,some researches were done in this paper and some achievement was made.Firstly,the whole hydroturbine governing system was divided into several parts,.i.e.the conduit,hydroturbine,governor,generator and loads;then these parts were put together and the complete coupled system was established.The improved method of characteristic curves was used in the conduit model,which could not only solve the inconformity of the simulation period between the conduit and unit,but also could make the simulation results more close to the reality.The hydroturbine model was made by using the hydroturbine characteristic curves model based on the BP neural network,and the method of obtaining the boundary conditions by combining the runaway curves was given.The first-order model of the generator and loads was used by taking the dynamical characteristics of the single unit with loads into consideration.Then,combining the factual conduit and the characteristic of the unit of Tianshengqiao hydropower plant,the complete math model of the plant was established and realized in the simulation platform.And the no-load disturbance test at the rated head and load shedding test were done for the whole coupled model;the validity was verified from these tests.In addition,the effect that the parameters of the governing system on the regulating process were also researched,which giving a certain theory guide to the value range of the governor parameters.Following,aimed at the slow regulating problems of the load-increasing and load-reducing caused by the long conduit of the Tianshengqiao hydropower plant,based on the sufficient hypothesis and the model test,for the different conditions of the load-increasing and load-reducing problems in the plant,a scheme was put forward by adjusting the load distribution in different units and utilizing the fluctuation period of the surge bank.With the changing period for the load-up and load-down,the fluctuation caused by the load-up and load-down would be offset and the water level was well controlled.On the basis,a load-up and load-down scheme was given,by analyzing the data of the water level of surge tank and the frequency of the unit and the pressure of the spiral case,the rationality and advantages of the new scheme was illustrated when compared with the original one.In the end,the power oscillation problem appeared in the No.4 unit of the Tianshengqiao hydropower plant was analyzed and the preliminary conclusion was made.