Application of HVDC emergency control to mitigate the first swing peak of UHV tie-line power flow

It was observed that the long-distance 1000kV UHV AC tie-line, which connects the Central and North China power grids, is quite vulnerable to disturbances like a single unit trip at the receiving end, exhibiting high first swing peak which threatens the synchronous operation of the interconnected power system seriously. This paper proposed an emergency control scheme by use of existing HVDC line as well as the control strategy for first swing peak suppression of UHV tie-line power flow to improve the transient stability of the interconnected power system. The controller design and its algorithm implementation, aimed at the purpose of practical engineering application, are modelled with both offline and real time simulation software for effectiveness and feasibility validation. Satisfactory results have been obtained from the simulations announcing a big progress toward field test of the proposed control scheme.