CAJ | 학술논문

研究了MMC的电路拓扑结构、运行特性以及充电原理，在PSCAD仿真平台上搭建了MMC在三端柔性直流输电系统中的模型。该三端系统由两个送端一个受端组成。两个送端均采用定有功功率和定交流电压的控制方式，受端采用定直流电压和定交流电压的控制方式。系统级控制器采用直流电压偏差控制。每个换流站都采用最近电平逼近调制方法控制模块投入与切除，采用排序的平衡控制原理均衡各子模块电容电压。对直流侧单极母线进行了接地故障仿真，并分析了对系统运行的影响。仿真结果同时验证了该模型的正确性，MMC能在三端柔性直流输电系统中稳定运行，各子模块电压波动较小，有功、无功控制量均能跟随控制目标，该模型所采用的控制策略的性能良好。
연구료MMC적전로탁복결구、운행특성이급충전원리，재PSCAD방진평태상탑건료MMC재삼단유성직류수전계통중적모형。해삼단계통유량개송단일개수단조성。량개송단균채용정유공공솔화정교류전압적공제방식，수단채용정직류전압화정교류전압적공제방식。계통급공제기채용직류전압편차공제。매개환류참도채용최근전평핍근조제방법공제모괴투입여절제，채용배서적평형공제원리균형각자모괴전용전압。대직류측단겁모선진행료접지고장방진，병분석료대계통운행적영향。방진결과동시험증료해모형적정학성，MMC능재삼단유성직류수전계통중은정운행，각자모괴전압파동교소，유공、무공공제량균능근수공제목표，해모형소채용적공제책략적성능량호。
This paper analyzes the circuit Topological stru-cture,operating characteristics and charging principle of MMC and realizes modeling of three-terminal MMC-HVDC with 20 sub modules(SM)by PSCAD. The three-terminal system con-sists of two power transmitting terminals and one power receiving terminal. The two power transmitting terminals adopt the fixed active power and fixed AC voltage control mode while the power receiving terminal adopts fixed DC voltage and fixed AC voltage control mode. The system controller adopts the DC voltage margin control. Each convertor adopts the principle of NLM to control the SM’s input or removal,and uses the sorting results of the SM capacitor voltages to balance the capacitor voltages. The grounding fault of the positive bus is simulated, and the effect to the system is analyzed. The simulation result demonstrates that MMC can run stably in the three-terminal flexible HVDC transmission system with little fluctuating of the capacitor voltages of the SM and the control strategy adopted by the model has good performance, with both the active and reactive power controllers following their target quantities.