| This paper studies the coordinated control strategy of multi-send HVDC systems. The PSCAD simulation model of multi-send HVDC systems in Southwest of China is established based on studies about layers of HVDC control system and modeling of each module. Studies are conducted on the frequency stability of the delivering side drawing on the DC frequency control and PSS. A novel emergency DC power support (EDCPS) strategy is proposed based on the discussion of emergency power support of DC system and its overload capabilities. The author also analyzed the effects of transformer tap control and control modes of rectifier by simulation. Further more, aimed at overcoming the voltage drop problems caused by emergency DC power support, the author put forward a coordinated control strategy of reactive power among dc converters and dynamic adjustment strategy of generator voltage. The simulation result depicts that the emergency power support and reactive power/voltage control strategy can significantly improve the frequency and voltage stability of the studied multi-send DC system. |
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