连接风电系统的柔性直流电网MMC在线投入分析与验证  

Analysis and verification of MMC online entry into a flexible DC gridconnected to wind power system

作　　者：随顺科 任铁强 邹强[1] 李钢[1] 卢宇[1] 汪楠楠[1] SUI Shunke;REN Tieqiang;ZOU Qiang;LI Gang;LU Yu;WANG Nannan(NR Electric Co.,Ltd.,Nanjing 211102,China)

机构地区：[1]南京南瑞继保电气有限公司,江苏南京211102

出　　处：《供用电》2022年第11期26-31,共6页Distribution & Utilization

基　　金：国家电网有限公司总部科技项目“大规模海上风电经柔性直流送出系统继电保护及振荡抑制关键技术研究”(5100-202118029A-0-0-00)。

摘　　要：针对大规模海上风电的送出,组成柔性直流电网,能够极大地提高系统的可靠性,有效避免大规模停机,弃风问题。基于模块化多电平换流器的柔性直流输电(MMC-HVDC)系统组成柔性直流电网后,处于有源运行的换流器的投退不影响柔直电网的稳定运行,进而保证了海上风电的可靠送出。在线投入过程中,换流器和直流电网之间会产生一定的冲击电流,冲击电流的大小和投入策略有较大关系。提出了改进型换流器机电暂态模型,分析了换流器投入冲击电流的影响因素,研究和比较了转控制模式同步并入策略和先并入后转控制模式策略这2种换流器在线投入策略。最后,采用RTDS建立了±500 kV双极四端柔性直流输电系统模型,对2种投入策略进行了仿真和对比,结果表明,策略1具有控制简单可靠、受极母线开关特性影响小、冲击较小等特点,适用于海上风电经柔直电网送出工程应用。Aiming at the large-scale offshore wind power transmission,the flexible DC grid can greatly improve the reliability of the system and effectively avoid the problems of large-scale shutdown and wind abandonment.After the MMC-HVDC system based on modular multilevel converters forms a flexible DC network,the switching-off of a single converter in active operation will not affect the stable operation of the flexible DC network,thu s ensuring the reliable transmission of offshore wind power.During on-line operation,a certain impulse current will be generated between the converter and the DC network,and the magnitude of the impulse current is closely related to the operation strategy.This paper develops an improved MMC electromechanical transient model,analysis the influence factor of impulse current,studiesand compares two MMC entry strategy of control mode and breaker switch simultaneously and control mode switches after breaker.Finally,a detailed±500kV MMC-HVDC model with 4 bipolar MMCs is developed tosimulat and compare this two entry strategy.The results show that first strategy,which is reliable,immune from breaker performance and instrumental in decreasing impulse current,is suitable for the engineering application of offshore wind power transmission through flexible vertical power grid.

关 键 词：MMC 机电暂态模型 在线投入 冲击电流 柔性直流 

分 类 号：TM46[电气工程—电器]