特高压级联混合直流输电及其控制策略研究

Study on UHV cascaded hybrid DC transmission and its control strategy

远距离大容量输电常采用直流输电方式,但以晶闸管构成的LCC换流器容易发生换相失败。而以全控器件构成的模块化多电平换流器(MMC),虽然具有控制灵活、不会发生换相失败的优点,但柔性直流输电的成本远远超过常规直流。混合直流可以结合常规直流和柔性直流两者的优点,为远距离、大容量输电提供一种全新的模式。研究了特高压混合直流的拓扑方式,提出了特高压级联混合直流的控制策略及应对直流换相失败的控制策略,并用仿真模型进行了验证。

DC transmission is often used in long distance and large capacity transmission,but LCC converter composed of thyristors is prone to commutation failure.The modular multi-level converter(MMC)composed of full-controlled devices has the advantages of fexible control and no commutation failure,but the cost of fexible HVDC transmission is much higher than that of conventional HVDC.Hybrid DC can combine the advantages of conventional DC and fexible DC,and provide a new mode for long distance and large capacity transmission.The topology of UHV hybrid DC is studied,and the control strategy of UHV cascade hybrid DC and the control strategy to deal with DC commutation failure are proposed.And it is verifed by the simulations.