Research On The Frequency Modulation Control Strategy Of Speed Governing System In A Pumped-storage Power Station

With the development of new energy sources a large number of intermittent electricity inflow has a higher demand for the regulation of dynamic quality of power grid.As one of the most important means of dynamic frequency modulation in power network,pumped storage unit plays an important role in ensuring the power quality of power network.In order to keep the power grid running steadily,it is necessary for the pumped storage units to take effective measures to improve the primary frequency modulation capability of the power network on the basis of the established control strategy at the present stage.Nowadays,the installed capacity of hydropower is increasing and the complexity of the control mechanism is improving day by day.The control strategy under the disturbance of the unit has also been studied more deeply.However,at present,most of the pumped storage units that have been put into production in our country are imported as the whole machine,and the traditional PID control strategy is still used in the control mode.With the increasing requirements of the grid for the operation of the storage units,the frequent switching of the units during the transition process has exposed the deficiencies of the control strategy and control structure gradually.For example,when the power network frequency falls sharply,the response speed of the unit has a great effect on the recovery time of the power network frequency,and the overshoot of the control signal is also the key to the success of the gridconnected phase in the process of changing the operating conditions.In this paper,the primary frequency modulation effect of the storage unit is improved through the optimization of the control strategy of the speed regulation system,which provides some reference for the localization of the speed regulation control system of the energy storage unit and the optimization of the control strategy of the existing units in the future.The selection and optimization of control strategy requires accurate control system model establishment and accurate response to the nonlinear transition process under different operating conditions.In this paper,the transfer function used in each simulation module is analyzed deeply in Matlab-Simulink,and the model of frequency response and opening response is established for the outstanding problems in the actual operation of the unit.In general,it is difficult to achieve a good balance between the real-time requirement of the system and the simulation accuracy of the model in the simulation process.So before the simulation is carried out,the parameters of each system module in the model are accurately adjusted according to the field primary frequency modulation experiment data.The accuracy and effectiveness of the proposed model can be further improved by introducing model validation analysis for different response types.As for the selection of intelligent control strategy,fuzzy PID control and BP neural network,which is mature at present,are adopted.The weight optimization of fuzzy rules under single fuzzy control makes the control system possess certain learning ability and predictive ability.At the same time,taking a pumped storage unit as an example,the intelligent algorithm is embedded in the mixed flow storage unit simulation model based on the elastic water hammer model in the form of Simulink identifiable characteristic function,and the intelligent control method is verified.Through the analysis and comparison of the simulation results and the practical problems in the field,it is shown that the embedding of the intelligent algorithm has a good optimization effect on all kinds of response curves under the traditional control mode.