Study On The Control Models And Strategy Of Battery Energy Storage Participating In Primary Frequency Regulation

Wind,solar and other new energy power generations develop rapidly,and their output power is fluctant and uncertain.Large-scale grid-connected is bound to increase the pressure of frequency regulation in the power grid.Conventional generation partincipating in frequency regulation can no longer meet the increasing demand of power grid.Battery energy storage systems have advantages of quick action and flexible adjustment,and they can assist traditional units to participate in the grid frequency regulation.Then the problem of increasing need of frequency regulation.For energy storage systems,reasonable and optimal control models and strategies can not only achieve the better frequency regulation effect,but also effectively reduce the capacity of energy storage systems.Based on the response characteristics of the traditional units participating in the primary frequency regulation in the grid,this paper studies the response mechanism of the virtual inertial control mode and virtual droop control mode of battry energy storage systems.Based on the frequency regulation characteristics of the two control modes and considering the frequency characteristics of the grid,an adaptive control model is proposed,which can make the two controls dynamic combination.In addition,a model is also proposed to calculate parameters of the adaptive model.Considering the frequency regulation characteristics of the two control modes as well as the characteristics of the battery energy storage systems,an adaptive control model and a calculation model of model parameters for the battery energy storage systems are proposed,which can be automatically adjusted with the change of the state of charge of battery energy storage systems.Finally,based on the two adaptive models,a comprehensive adaptive control strategy is proposed,with considering the disturbance type of the power grid.Firstly,the response mechanism and frequency regulation characteristics of the virtual inertia control and the virtual droop control of the battery energy storage systems are analyzed.In the inertial response stage,the virtual inertial control mode promotes the restoration of frequency,and the greater coefficients of the virtual inertial is,the better effect will be.However,in the stage of primary frequency regulation,the virtual inertial control mode impedes the restoration of frequency in grid,and the larger the virtual inertial control coefficient is,the more obvious the obstruction effect will be.At the same time,it is pointed out that the virtual droop control mode always promotes the restoration of frequency in the primary frequency regulation,and the greater the virtual droop control coefficient is,the better the effect of power network frequency restoration will be.Secondly,considering the frequency characteristics of the power grid,an adaptive control model is proposed,which can combine advantages of the two control modes of battery energy storage systems.By analyzing the characteristics of the two control models in primary frequency regulation,this paper proprosed a novel model,which can automatically adjust parameters with change of frequency deviation.This model can realize the complementary advantages of the two control modes,and it can realize smooth switching of the two control modes,which can effectively avoid secondary disturbance,when the two control modes switch directly.Thirdly,considering the state of charge of the battery energy storage systems and considering the frequency regulation characteristics of the two basic control modes,an adaptive control model is proposed,which can automatically adjuste parameters with the change of state of charge.In addition,by considering characteristics of the energy storage systems,a model is presented,which can calculate the parameters of the adaptive control model.This model can make full use to abilities of the charging/discharging capacity of the energy storage systmes,optimize the charging state of the energy storage systems,and ensure the frequency regulation effect.Finally,analyzing the characteristics of the two adaptive control models to different load types and considering the frequency characteristics of the grid under different disturbance types,a comprehensive adaptive strategy is proposed,which can not only achieve the optimal frequency regulation effect,but also optimize the state of charge of battery energy starage systems.