Aiming at the system stability problems existing in large-scale grid connection of new energy

this paper analyzes the reactive power compensation capacity of DFIG units

introduces battery energy storage static synchronous compensator（STATCOM/BESS） into DFIG grid connection system

and puts forward a method to maintain the power and voltage stability of DFIG wind power grid connection system by using STATCOM/BESS. Based on the traditional STATCOM reactive power compensation

the battery energy storage is connected in parallel on its DC side

which can quickly and smoothly adjust the active power of the wind farm input and network point

support the system voltage stability

and achieve the function of peak shaving and valley leveling. By comparing the reactive power compensation capability of DFIG

STATCOM and STATCOM/Bess in case of three-phase grounding fault

the results show that the system with STATCOM/Bess has the smallest voltage drop

the fastest recovery speed and the best compensation effect.