Study On Unit Variable Speed And Additional Control Cooperative Suppressing Tail Wave For Hydraulic Turbine Governing System With Surge Tank

The power system requires higher dynamic characteristics of the hydropower units undertaking the peak regulation task,but the hydropower plant with long pressure diversion channel,the tail wave decay caused by the water level fluctuation of the surge tank in the transition process is slow,deteriorating the adjustment quality of the regulation system,and the problem of having a serious impact on the frequency regulation has not been solved.This paper proposes the strategy of variable speed and additional control,using the rotor energy storage suppress the power fluctuation of the generator,and improve the regulation quality of the turbine regulation system with the additional control.(1)Analyze the characteristics of pressure pipeline,surge tank,pressure diversion channel,hydro turbine,speed regulator,follower system,optimal speed generator,doubly-fed induction generator,frequency converter and control system,write the mathematical model of each part respectively,and establish the overall simulation model of the variable speed hydro turbine generator set containing the surge tank.(2)Presents the tail wave fluctuation of generator output power,based on reasonable assumptions,simplifies the generator and control part of regulation system and obtains the simplified model of doubly-fed induction generator active control.Then realize active power response through rotor vector control to suppress the power tail wave fluctuation of turbine generator caused by surge tank.Finally,through model simulation and adjusting the quality index proved that the generator power tail wave is improved after the unit variable speed operation.(3)The tail wave fluctuation of turbine output,speed,head,flow and other parameters,the low frequency oscillation control ability of the water level fluctuation in the conventional speed regulator is limited,and the adjustment quality of the transition process of unit operation cannot meet the requirements.According to this problem,firstly simplified the model,derived the transfer function between the opening and power of the turbine system,analyzed the reason of the regulation quality in the turbine speed regulation system,to obtain the additional control signal and introduced the speed regulator to suppress the tail wave fluctuation.Finally,the model simulation can adjust the quality index and verify the control effect of the correction signal introduced.The results show that with a certain range of parameters,through the collaborative suppression of the unit variable speed and the additional control,the system tail wave oscillation amplitude decreases and the adjustment time decreases.The study proves that this method is an effective way to improve the adjustment quality of the unit.