CAJ | 학술논문

现有三极直流输电系统基于晶闸管换流器，存在一些与传统直流输电系统相似的固有缺陷。文中提出了一种改进系统：极3采用基于全桥子模块的模块化多电平换流器，极1和极2采用基于钳位双子模块的模块化多电平换流器。同时，提出了三极直流协调控制策略，并且为了抑制过渡阶段的暂态过电压，减小接地电流和功率波动，还提出了电压反向控制、电流维零控制和功率协调控制。采用PSCAD/EMTDC进行仿真验证，结果表明利用所提控制策略，三极直流输电系统能够获得较好的响应特性，在维持电容电压平衡的同时，能够抑制交直流间功率扰动和接地极电流波动。
현유삼겁직류수전계통기우정갑관환류기，존재일사여전통직류수전계통상사적고유결함。문중제출료일충개진계통：겁3채용기우전교자모괴적모괴화다전평환류기，겁1화겁2채용기우겸위쌍자모괴적모괴화다전평환류기。동시，제출료삼겁직류협조공제책략，병차위료억제과도계단적잠태과전압，감소접지전류화공솔파동，환제출료전압반향공제、전류유령공제화공솔협조공제。채용PSCAD/EMTDC진행방진험증，결과표명이용소제공제책략，삼겁직류수전계통능구획득교호적향응특성，재유지전용전압평형적동시，능구억제교직류간공솔우동화접지겁전류파동。
The use of thyristor converters in existing tripole high voltage direct current (HVDC) transmission system suffers some inherent defects similar to those of the traditional HVDC transmission system.For this reason,this paper proposes an improved scheme which uses the modular multilevel converters(MMCs)based on full bridge sub-modules(FBSMs)to replace the thyristor converters in pole 3,and the converters in pole 1 and pole 2 are also replaced by the MMCs based on clamp double sub-modules (CDSMs).Meanwhile,the coordination control between the three poles is proposed.In order to suppress the transient overvoltage and minimize the grounding current and power fluctuation in the transition process,the voltage inverse control,power coordinated control and the control strategy of keeping current zero in pole 3 are also proposed. The performance of the proposed tripole HVDC transmission system is validated through time-domain simulation study in PSCAD/EMTDC.The results show that the tripole HVDC transmission system based on the proposed control strategy can achieve a satisfactory response characteristic,while maintaining the balance of capacitor voltage and minimizing the grounding current and power fluctuation.