Study On Control Strategy Of Wind Power Compensating For Water Hammer Effect Of Hydropower System And Frequency Characteristics Of Power Grids

With the in-depth implementation of the 13 th Five-Year Plan,hydropower in China has developed rapidly.In a power grid with a relatively high turbine capacity,the water hammer effect seriously threatens the safe and stable operation of the grid when a large load disturbance occurs in the system.Therefore,this paper studies the effect of water hammer effect on grid frequency and a wind power compensation control strategy for hydraulic turbine water hammer.The main work is as follows:(1)For large-scale interconnected power grids,it is difficult to meet the requirements of online applications using full-time domain simulations that take into account the detailed model of the system.In order to quickly analyze the influence of the water hammer effect on the grid frequency,In order to quickly analyze the impact of the water hammer effect on the grid frequency,this paper rationally simplifies the turbine-governor system and equates the turbine governor to a ramp model(approximate model)based on the theory of the traditional turbine governor delay model.In addition,the analytical solution of the frequency response of the power grid considering the spin-standby and water hammer effects were deduced.Then the simulation software ADPSS was used to simulate the EPRI36 node system,and the impact of the water hammer effect on the power system frequency was further analyzed.(2)This paper studies a wind power compensation control strategy for hydraulic turbine water hammer.The variable-speed fan has the characteristics of fast active power response and the ability to output any active power within a certain range.Therefore,based on the traditional virtual inertia control,the control link is added,so that the variable speed fan can not only respond to the grid frequency change in real time,It can also respond to changes in the opening of the turbine guide vanes,thus increasing the output power by releasing the kinetic energy stored in the rotor when the load disturbance occurs,making up for the power shortage caused by the water hammer effect,effectively preventing the grid frequency from falling seriously,and protecting the grid Safe and stable operation.(3)For the simulation and verification of the control strategy for the water hammer effect of the wind turbine compensation turbine,this paper carries out the simulation verification on the single-machine system and the multi-machine system.The single-machine system simulation is mainly based on the simplified wind power grid-connected model and uses Matlab/Simulink as the simulation method to perform simulation verification.The multimachine system is based on ADPSS for electromechanical-hybrid simulation,in which the wind farm part is used as the electromagnetic transient simulation part to access the EPRI36 node.The rest of the system is used for electromechanical transient simulation.This simulation method can not only add its own design of the controller in the fan,and is not limited by the size of the simulation system,the simulation speed is fast,and provides a new idea for multi-machine system simulation on the fan control.