Influence Of Voltage Stability Of The Weak Receiving AC System From Forced Commutation Technique

Firstly, this paper introduced the interaction between ac system and dc system based on a ac-dc system, emphasized the importance of stability when dc system linked to a weak ac system, and leaded the capacitor commutation converter(CCC)-a effective measure to improve the stability. Secondly, the development situation of the capacitance commutation inverter and its application in HVDC are listed. And then, based on a certain dc net project planning to construct in china, the CCC-HVDC simulation model is built using the electro-magnetic transient simulation software PSCAD/EMTDC. Research on the dynamic performance influence and stability analysis of CCC when connecting to the weak AC system. This paper emphatically discussed the size selection of the commutation capacitor, the characteristics of normal start and stop of CCC-HVDC, the harmonic characteristic analysis of CCC-HVDC and compared with the LCC-HVDC. And the different responses between LCC-HVDC and the CCC-HVDC under the different faults are studied. The comparison shows that the CCC-HVDC have a better normal start characteristics than LCC-HVDC, and a higher operational stability during AC system disturbances, but the harmonic characteristic of CCC-HVDC should combine with the project operation condition.