AI Xin, LE Kim Anh, DANG Ngoc Huy

 

(State Key Laboratory of Alternate Electrical Power System With Renewable Energy Sources, North

 

China Electric Power University, Beijing 102206, China)

 

 

Abstract: Aiming at solving the voltage instability of microgrid caused by the instability of the distribution generation in the microgrid, a typical system of AC/DC hybrid structure microgrid was provided. The bidirectional AC/DC converter (rectifier and inverter models) and the mathematical model of distribution generation inverter and its control system were also established. From that, a newtype of bidirectional AC/DC converter control method was proposed. According to the micro grid voltage and power relationships, a feedback controller was designed  based on voltage outer loop, current inner loop and power loop etc, and the corresponding droop control strategy was provided as well. The power and voltage characteristic of distribution generations (DGs) and their effects on voltage stability of the microgrid were analyzed theoretically to propose the effective control strategy of controlling the power fluctuation of DGs, improving the power quality of the microgrid. The results indicate that the bidirectional AC/DC converter can stably control the microgrid voltage, which has a fine steady state.

 

Key words: distributed generation(DG); microgrid; voltage stability; AC/DC bidirectional converter; control strategy