When the traditional active power versus frequency and reactive power versus voltage magnitude droop control is applied

if the droop coefficients are irrational

the output power of the inverter will keep oscillating. When the microgrid operates in the islanding mode

the microgrid frequency will fluctuate because of the output power oscillation of the energy storage inverter. When serious

there will be the power angle stability problem. Based on the concept of dynamic frequency-power characteristic

this paper proposes an improved droop control method according to phase condition and magnitude condition of positive damping. The improved droop control can effectively increase system damping to suppress the oscillation of output power of the inverter and improve system stability without affecting the steady state frequency and output power of the inverter. Finally

PSCAD simulation results have validated the feasibility of the proposed method. This work is supported by National High Technology Research and Development Program of China (863 Program) (No. 2012AA050217).