Research On Battery Energy Storage Participating In Integrated Adaptive Control Strategy Of Frequency Regulation In Power System

At present,the development of new energy sources such as scenery to replace fossil energy has become a trend of development in various countries.Due to the random fluctuation of wind speed and illumination,the power of wind power and photovoltaic grid-connected has become more unbalanced when large-scale grid-connected,which aggravates the pressure of grid frequency regulation.The traditional thermal power frequency regulation unit has some shortcomings such as low power climbing speed,slow response speed and inaccurate power response due to the huge inertia of the rotor,which has been difficult to meet the frequency regulation requirements of high permeability wind-solar grid-connected system.At the same time,battery energy storage technology has the advantages of fast response,precise tracking instructions and no power climb rate limitation.In the application scenario of power grid frequency regulation,it has developed rapidly with the participation of conventional thermal power units in power grid frequency regulation.This paper studies the integrated adaptive control strategy of energy storage participating in frequency regulation.Firstly,the large-scale grid-connected status of new energy and its impact on system frequency are introduced,as well as the application status of energy storage as a high-quality frequency regulation resource in demonstration projects.The research status of battery energy storage system participating in grid frequency regulation at home and abroad is analyzed,and its problems are summarized.Secondly,based on the principle of power grid frequency regulation,the power fluctuation affecting primary frequency regulation and secondary frequency regulation is extracted by wavelet analysis method,and the fluctuation index is defined to analyze and evaluate the power fluctuation of wi nd power.The frequency response model of regional power grid with battery energy storage system is established,and the frequency characteristics of energy storage participating in primary frequency regulation control mode in high wind power permeability grid are analyzed.Then,by studying the control characteristics in time domain of the two control strategies of energy storage participating in primary frequency regulation of power grid,according to the control characteristics and effects of the two con trol modes,the time period of the frequency change curve of primary frequency regulation is divided,and considering the smoothness of the two control modes,an adaptive primary frequency regulation control strategy is proposed.In order to maintain the c harging state of energy storage in a reasonable range,a self-recovery control strategy of energy storage is proposed.Considering the conflict between frequency regulation strategy and recovery strategy,penalty coefficient is introduced to restrict the recovery power of energy storage.Combined with the two-part control strategy,a comprehensive adaptive control strategy is proposed,which is mainly frequency regulation and supplemented by recovery.The results of multi-condition simulation show that the integrated adaptive frequency regulation control strategy is reasonable and effective.Finally,considering that energy storage participation in primary frequency regulation belongs to free frequency regulation,and energy storage participation in secondary frequency regulation belongs to paid frequency regulation,combined with energy storage charging state and energy storage participation in power grid frequency regulation,the regional demand signal allocation strategy for dynamic adjustment of energy storage reference power is designed.The strategy of adjusting the reference power value of energy storage according to the charging state of energy storage is put forward,which can make the energy storage have different regulating capacity under different charging state,thus slowing down the change of the charging state of energy storage.At the same time,the priority-based regional demand signal allocation strategy is adopted,with energy storage as the first priority,to improve the participation of energy storage in power grid frequency regulation to achieve greater benefits,and to use the fast responsiveness of energy storage to speed up the frequency recovery of the system.The simulation results show that it is reasonable and effective.