Design of inter-stations H∞ decoupling controller in VSC-HVDC system

Abstract

The purpose of this work is to reduce the mutual interference between converter stations when the AC power or DC voltage fluctuates in VSC-HVDC system. The global small signal mathematical model of VSC-HVDC system is established firstly. Then, according to the principle of mixed sensitivity H∞ robust control, the appropriate weight function is selected and the decoupling controller between stations is deduced. In addition, the high-order controller deduced is reduced to an appropriate order which is beneficial to engineering application by using the balanced truncation method of coprime factors. Finally, the electromagnetic transient simulation is carried out to verify that the H∞ decoupling controller between stations can be effectively weakened the interaction between two converter stations and improves the dynamic performance and robust stability of the system.