Control Strategy Research On The Large-scale Battery Energy Storage System Involved In Frequency And Voltage Regulation

In a high percentage of new energy power system,the fluctuating characteristics of new energy output will increase the frequency regulation burden of conventional power sources,the use of energy storage and thermal power units to form a joint frequency regulation system can play the advantages of rapid regulation of energy storage and reduce the regulation of thermal power units.At the same time,the DC-fed grid at the receiving end has voltage stability problems under the condition that the local conventional unit is under-run and the proportion of external power receiving is large,and the reactive voltage support capability of large-scale battery energy storage can play a significant role.This paper focuses on the coordinated secondary frequency control of fire storage and the storage layout method to cope with voltage instability and reactive voltage control to carry out research.The characteristics and simulation modeling requirements of primary and secondary frequency regulation of the interconnection system are analyzed,and a typical two-area frequency simulation model is established using MATLAB/Simulink software,and the meanings and effects of important parameters in the model are analyzed.Based on this,a secondary frequency regulation simulation model of thermal storage coordination is established,which contains the parts of thermal secondary reheat unit frequency regulation,control performance standard(CPS)control and storage coordination control,creating conditions for the simulation study of control strategy.The proposed CPS-controlled battery storage secondary frequency optimization control strategy with secondary reheat unit,zoning the regional control requirement(ARR)for different operating conditions,and dynamically adjusting the energy storage output according to the change of battery state of charge(SOC),which has the advantages of no secondary disturbance compared with the traditional fixed proportional allocation method,better SOC maintenance of battery storage,effective reduction of the impact on other regional frequencies,and reduction of the FM demand of thermal power.This method has the advantages of no secondary disturbance compared with the traditional fixed ratio allocation method,better SOC retention of battery energy storage,effective reduction of the impact on the frequency of other regions,and reduction of the frequency regulation demand of thermal power.The effectiveness of the established simulation model and the optimized control strategy is verified based on a typical two-area example.In view of the voltage stability problem of the DC-fed receiving grid,a battery storage plant optimal site selection method is proposed,defining the node voltage support strength index of the severely voltage unstable bus,the voltage support strength index of the 220kV subdivision where the severely voltage unstable bus is located and the degree of power supply level in the subdivision where the severely voltage unstable node is located as the site selection basis,based on the voltage instability characteristics and site selection Based on the calculation of voltage instability characteristics and site selection index,the substation with large voltage support range and high power supply load level is quantitatively selected as the preferred access location for energy storage.The validity and feasibility of the site selection method is verified by a provincial planning grid example.In addition,the effects of the reactive power control mode,reactive power adjustment coefficient and active power recovery speed of the energy storage plant on the voltage stability support effect are studied.