分析了多端直流系统的接线方式对暂态稳定性的影响。研究结果表明，与并联型接线方式相比，串联型接线方式的多端直流系统无功需求大、有功损耗多，使暂态过程中交流功率和直流功率的传输比较困难，不利于维持交直流系统的暂态稳定性。以并联型接线方式为例，研究了多端直流系统的控制方式对暂态稳定性的影响，指出了定电流控制和定电压控制可以在暂态期间减缓换流器交流母线电压的下降，有利于防止直流功率的降低，所以其保持暂态稳定性的能力要好于定功率控制和定熄弧角控制。

The impacts of the connection mode of multi-terminal DC (MTDC) power transmission system on transient stability are analyzed. Research results show that different from parallel connection mode the MTDC system adopting in-series connection mode needs more reactive power and its active power loss is greater, thus the transmission of active and reactive power is more difficult during transient process, so such a connection mode is unfavorable for keeping transient stability of AC/MTDC power system. Taking in-series connection mode for example, the impacts of control modes of MTDC system on transient stability are researched and it is pointed out that constant voltage control and constant current control can slow down the voltage decrease of AC busbar of converter during transient process and it is favorable to prevent the decrease of DC power, therefore the ability of constant voltage control and constant current control in keeping transient stability is better that those of constant power control and constant extinction angle control.

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