With the rapid development of power generation by renewable energy and the grid-connection technology,the microgrid dominated by power electronic converters has attracted more and more attention in recent years. Owing to the low inertia and high nonlinearity of power electronic converters,an islanded microgrid under large disturbances is more likely to lose its transient stability. Considering the interactions between grid-forming and grid-following converters in the microgrid,a transient stability criterion based on the equal area criterion(EAC) and an improved control strategy for transient stability are proposed. First,the simplified second-order dynamic model of the islanded microgrid is estab-lished,which contains a nonlinear damping term relying on the power angle. Then,the impact of the nonlinear damping term on the acceleration and deceleration areas is revealed from the energy perspective. Considering the distribution characteristics of nonlinear damping,a transient stability criterion is formulated for the positive damping region. In addi-tion,according to the stable boundary conditions,an improved control strategy for transient stability based on voltage feedforward is also put forward. Finally,simulations are carried out with MATLAB/Simulink to verify the effectiveness of the proposed stability criteria and the improved control strategy. The results show that the microgrid transient stability criterion and the improved control strategy proposed can provide a theo-retical basis for the parameter optimization design of power electronic converters and the improvement of the stable opera-tion capability of microgrid.
关键词
孤岛微电网/构网变流器/跟网变流器/等面积法则/暂态稳定性
Key words
Islanded microgrid/grid-forming converter/grid-following converter/equal area criterion(EAC)/transient stability
维普
万方数据