Abstract: On the background of the Ximeng-Taizhou UHV weak delivery end AC system， this paper proposes an optimized voltage-dependent current order limitation control link （OVDCOL）. This paper firstly analyzes the working principle and limitations of the traditional VDCOL， and proposes to use the short-circuit ratio of the transmitting end and the voltage of the converter busbar at the receiving end as the input value to change the VDCOL cut-off voltage， so as to optimize the VDCOL effect. The cut-off voltage is a value that varies with the voltage of the converter busbar on the inverter side， and the control strategy of the system and DC fast recovery can be considered. The process of constructing the transient energy function considering the dynamic characteristics of the DC system is analyzed in detail， and the real-time digital simulation software RTDS is used to build a single-machine infinite DC simulation example. The time domain simulation and the transient energy function margin method are used to verify the optimized DC control. The voltage-dependent current order limitation control link in the system improves the stability of the delivery system.

Key words: weak delivery system, optimized voltage-dependent current order limitation, cut-off voltage, transient energy function, transient energy function stability margin