Coordinated Strategy to Improve Post-Fault Characteristics of Hybrid Multi-Infeed HVDC Transmission System

The characteristics of the dynamic reactive power demand of a hybrid multi-infeed HVDC transmission system during the post-fault recovery period are analyzed and a coordinated control strategy to improve the fault recovery characteristics of the hybrid multi-infeed HVDC transmission system is proposed in this paper. During the process of fault recovery, the LCC-HVDC adopts a progressive staggering recovery strategy. At the same time, according to the reactive power shortage of LCC-HVDC, the dynamic power limiter is used to adjust the upper and lower limit values of the outer loop power controller of VSC-HVDC, and the reactive power generated by the VSC-HVDC can be rapidly adjusted. Therefore, the problem of excessive reactive power demand during the recovery process can be solved and the reactive power demand can be satisfied with the proposed strategy. Moreover, the ability of VSC-HVDC to provide reactive power support can be fully utilized. Finally, a simulation model of a hybrid tri-infeed HVDC system is built using PSCAD/EMTDC (Version 4.6.2) software to verify the effectiveness of the proposed control strategy.