When the grid voltage drops due to grid fault, the voltage source converter (VSC) under the weak grid will enter the stage of low voltage ride through (LVRT). Many countries have formulated corresponding standards, i.e. reactive power compensation is performed according to the grid voltage to support the grid. However, there are stability issues when using the LVRT strategy. This paper first reveals the conditions for the existence of equilibrium points and their distribution under the typical LVRT strategy. Besides, the setting of the current order is investigated for avoiding instability. Furthermore, the influence of bandwidths on stability range is analyzed and the selection of bandwidth to maintain stability is studied. Finally, the correctness of the theoretical analysis is verified by simulation.

Voltage source converter,LVRT,nonlinear modeling,equilibrium point,transient stability