The stability study and simulation analysis on multi-infeed AC-DC hybrid power system

It is planned that several ultra-large-scale multi-infeed AC-DC hybrid power systems would be built in China by 2018. In multi-infeed AC-DC hybrid power systems, since AC-DC transmission lines are in parallel operation and the electrical distances between many DC converters are very short, there will be interactions between AC-DC hybrid power systems. And this will bring new challenges to the operating characteristics analysis and stability control strategy of multi-infeed AC-DC hybrid power systems. This paper begins with discussing complicated the interactions between AC-DC systems and the interactions between DC systems in the multi-infeed DC transmission system, and outlining the studies on researches of commutation failure of multi-infeed AC-DC hybrid power system, DC system failure recovery, the power angle / voltage stability problems, and etc. This paper sets up two indicators, namely Multi-infeed Short Circuit Ratio and Multi-infeed Interaction Factor, to measure the interaction extent between the AC power systems and its connected DC power systems. Then, the paper introduces the principle of emergency DC power support and the support strategy of DC power increase and fallback. Next, the paper takes the Jibei Power Grid, which is planned for 2018, as an example, using PSD simulation program to simulate and calculate the stability conditions of Jibei Multi-infeed AC-DC hybrid power system. In the end, the paper proposes the technical solutions for the structure enhancement of AC systems and the additional stability control strategy of DC systems, and etc., according to the simulation results.