Abstract：Voltage source converter（VSC）working as the interface of new energy stations connects to urban

main network with long-distance AC line，which results a weak grid connected condition and has a risk of DC

voltage instability. To analyze the mechanism of DC voltage instability of weak grid connected VSC，a DC voltage

stability analysis model for VSC grid connected systems applicable to various control strategies was established.

The impact mechanism of the interaction between weak grid connected VSC operating points and control loops

interaction on DC voltage stability was revealed. Then a DC voltage stability improvement control strategy was

designed with the characteristic of compensation frequency range flexible and variable. The simulation model in

Matlab/Simulink environment verified the correctness of the proposed research content.

      Key words：weak grid connected voltage source converter（VSC）；DC voltage stability；general model；

control loops interaction；compensation control