基于导纳判据的双母线直流微电网稳定性分析OA

With the gradual transformation of low-carbon energy system,the access of a large number of renewable energy and power electronic equipment makes the dynamic behavior of double-bus DC microgrid change and generate new stability problems.At present,there is little research on the stability analysis method of double-bus DC microgrid.Therefore,from the perspective of admittance,a stability criterion which is simple in calculation and suitable for the analysis of double-bus DC microgrid is proposed.Firstly,according to the port characteristics of each converter in the microgrid,the typical structure of the double-bus DC microgrid is obtained,and the double-bus DC microgrid is equivalent with the DC bus on the low-voltage side and the high-voltage side as the source load dividing point,and its equivalent models on the low-voltage bus side and the high-voltage bus side are obtained.On this basis,combined with the closed-loop two port small signal model of the interconnection converter(IC)under different control modes,the admittance sum of the double bus-DC microgrid on the low-voltage side bus and the high-voltage side bus is derived.If and only if the admittance sum of the low-voltage side bus or the high-voltage side bus meets the proposed stability conditions,the double bus-DC microgrid can operate stably;Finally,the simulation model of double-bus DC microgrid is built in PSCAD/EMTDC platform,and the influence of constant power load change on the stability of the system is analyzed according to the proposed admittance criterion.Simulation results show that the proposed stability analysis method can accurately determine the stability of double bus DC microgrid.