Frequency Regulation Control Strategy Of Wind Farm Based On Flywheel Energy Storage

In recent years,with the connection of large-capacity and high-proportion wind power systems to the power grid,the thermal power space has been crowded out,which has seriously weakened the ability of the power system to support the moment of inertia,and the power system has lost its buffer against low-frequency shocks.Causes frequency fluctuations in the grid system.The flywheel energy storage technology is very suitable for primary frequency modulation control of wind power system due to its advantages of fast response speed,high conversion efficiency and basically unlimited number of charge and discharge times.Therefore,in this thesis,aiming at the frequency fluctuation of the grid system caused by the large-scale integration of wind power into the grid,the flywheel energy storage device is connected at the AC outlet of the wind farm to improve the power quality of wind power and reduce the occurrence of wind power abandonment.Firstly,this thesis analyzes the output characteristics of the wind power system,and points out the influence of the wind power system on the system frequency caused by the operation of the large-scale power grid.Through the comparative analysis of the existing energy storage technologies,it is concluded that the flywheel energy storage has the characteristics of shock power and the ability to support instantaneous large inertia,which can provide instantaneous power support for wind power generation,and can help the power grid system to avoid the instantaneous low frequency shock and maintain the power grid.normal power supply to the system.In this regard,a frequency modulation control strategy for wind farms based on flywheel energy storage is proposed.Secondly,the working mechanism of the flywheel energy storage device is analyzed,and the physical and mathematical models are established.The flywheel energy storage system based on permanent magnet synchronous motor is obtained by analyzing the operation mode and working characteristics of flywheel energy storage.The permanent magnet synchronous motor is analyzed from both electrical and mechanical aspects,and the voltage vector control method of the permanent magnet synchronous motor is proposed,so as to realize the precise control of the motor torque,so that the energy storage system can keep up with the power grid frequency change to realize the charging / discharge operation.Thirdly,through the key analysis of the grid-side converter and the machine-side converter of the flywheel energy storage system,it is proposed that the grid-side converter of the energy storage system adopts the voltage directional vector control to keep the DC bus voltage constant,so that the energy can be Normal circulation between the machine side and the network side.The machine-side converter adopts current vector control,which makes the system have better flexibility.The rotational speed of the flywheel motor is limited through a logical relationship to ensure the service life and safety performance of the energy storage device.Finally,the two connection methods of wind energy storage are analyzed from the aspects of economy and wind power operation safety,and the scheme of connecting the flywheel energy storage at the AC outlet of the wind farm is obtained.The system model of wind power and flywheel energy storage is built through the Matlab/Simulink simulation platform,and the experimental analysis of wind energy storage and grid-connected operation is carried out to verify the effectiveness and correctness of the control strategy proposed in this thesis.