串联电容换相换流器中主要设备电压特性的研究

Research on Voltage Characteristics of the Main Equipments on CCC-HVDC

相对于常规高压直流输电(LCC-HVDC),基于CCC换流器的高压直流输电(CCC-HVDC)在减少换相失败,减少无功补偿等方面有明显优势,但过电压问题直接限制了其应用。为了掌握CCC-HVDC的主要设备电压特性,针对不同一次设备,分别进行了数学建模,理论推导换相电容、换流变压器和换流阀的稳态电压特性,同LCC-HVDC进行比较,分析各个电气设备稳态电压随着串联电容值的减小而增加的程度。基于PSCAD/EMTDC研究了CCC-HVDC不同运行状态、不同故障情况时上述设备的暂态电压特性及其恢复特性,得出不同故障点和故障形式对CCC-HVDC运行的影响程度。该结论可为以后的改造和应用提供理论依据。

Compared with LCC-HVDC, HVDC based on the CCC converter （CCC-HVDC） has obvious advantages in reducing commutation failure and compensation of reactive power, but the problem on over-voltage directly limits its ap- plication. In order to grasp the voltage characteristics of the main equipment in CCC-HVDC, mathematical modeling is carried out for different devices and theoretical derivation is made on the steady-state voltage characteristics, compared with that of LCC-HVDC, to analyze the increasing degree of the voltage with the decreasing of the series capacitor. In addition, based on PSCAD / EMTDC, transient voltage characteristics after the fault are analyzed to obtain the transi- ent voltage characteristics. And fault recovery of the devices with different faults and different operation condition is studied. Finally, the influence of the place and the mode of short-circuit fault on the CCC-HVDC is expounded, which may provide a theoretical basis for future reconstruction and applications.