Abstract: Focus on the instability of the reactive power output precision caused by the voltage drop and loss of DG lines being switched to grid and the low output frequency and voltage caused by power deficiency of DG islanding, an improved droop control strategy is proposed to ensure the running stability of Active Distribution Network during DG connecting to network. The DG model applies the feedback regulation of f-U droop output power and voltage drop compensator. The control system is applied to the quasi-synchronization grid-connected model, island mode and the modes switching process of an active distribution network's domain transient response. The simulation results show the feasibility of the improved droop control strategy and verify the effective control method to achieve the voltage and frequency stability of the active and reactive power, and can provide a theoretical basis of the active protection and control of the distribution network.

Key words: low voltage distribution network, the switch to grid and island mode, droop control, transient