Study on Multi-infeed AC and DC Hybrid Power System Security and Stability

摘要

By 2015, several ultra-large-scale multi-infeed AC and DC hybrid power systems will be formed inrnChina. Comparing with pure AC transmission system and Single-infeed HVDC system, multi-infeedrnDC power system will increase the complexity of system structure while increase flexibility of systemrnoperation mode and power sources arrangement as well as expand transmission capacity. In the multiinfeedrnAC and DC hybrid power systems, since AC and DC transmission lines are in parallelrnoperation and the electrical distances between many DC converters are very short, there will berninteractions between AC and DC systems and between DC subsystems, which will put forward newrnchallenges to the operating characteristics analysis and stability control strategy of multi-infeed ACrnand DC hybrid systems. This paper starts from discussing complicated interactions between AC andrnDC systems and interactions between DC systems in the multi-infeed DC transmission system,rnoutlining the studies on researches of commutation failure of multi-infeed AC and DC power system,rnDC system failure recovery, the power angle/voltage stability problems, and etc. Then, it proposes twornindicators, namely Multi-infeed Short Circuit Ratio and Multi-infeed Interaction Factor, to measurernthe interaction extent between the AC systems and its connected DC systems. In the end, the paperrntakes the grid structure of North China power grid planned for 2015 as an example, using PSD-BPArnsimulation program, to conduct simulation and analysis for following failure situations respectively,rnsuch as DC system commutation failures caused by other unipolar/bipolar DC block, major ACrnchannel failure, and AC receiving system failure.