LCC-MMC混合直流输电系统单阀投入过程定有功MMC站电压平衡策略  

Voltage balance strategy for constant active power MMC station in the process of valve deblock in LCC-MMC hybrid DC transmission system

作　　者：陆书豪 贾秀芳[1] Lu Shuhao;Jia Xiufang(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学新能源电力系统国家重点实验室,北京102206

出　　处：《电测与仪表》2023年第2期111-116,共6页Electrical Measurement & Instrumentation

基　　金：国家自然科学基金资助项目(51777072)。

摘　　要：送端采用常规直流(LCC)受端采用柔性直流(MMC)的混合特高压直流输电系统,在单阀在线投入过程中,定有功功率MMC站两串联阀组间电压可能出现失衡现象。分析了该不平衡现象的产生机理,随后提出一种基于调整阀间电压偏差值的电压平衡策略。该策略通过设定一个与预升压速率相同的函数分别对阀间电压的偏差值进行调整,并将其转化为有功功率偏差量。进而将该值与初始有功参考量相加后作为有功外环的参考值,最终实现阀组的在线平稳投入并过渡至稳态。基于PSCAD/EMTDC仿真平台搭建了相关模型,通过对比三种不同阀间电压平衡策略对系统动态特性的影响验证了文章所提策略的有效性。In the LCC-MMC hybrid multi-terminal UHVDC system, the feed end adopts conventional DC, and the receiver end adopts flexible DC. The voltage imbalance will appear between two series valve groups in the constant active power MMC station during valve deblock. The mechanism of this imbalance phenomenon is analyzed, and then, a voltage balancing strategy based on correcting the voltage deviation between the valves is proposed in this paper. This strategy adjusts the deviation value of the high and low valves by introducing a function whose decreasing rate is the same as the boost rate of the voltage, and converts it into the active power deviation value. Moreover, the value is then added to the initial active reference value as the reference value of the active outer ring, and finally, the on-line steady input of the valve group is realized and the transition to steady state is achieved. Based on the PSCAD/EMTDC simulation platform, a model of the three-terminal hybrid UHVDC transmission system is built, and the effectiveness of the proposed strategy is verified by comparing the impact of three different voltage balancing strategies on the dynamic characteristics of the system.

关 键 词：特高压混合多端直流输电 电压平衡控制 单阀组在线投入 调整电压偏差量 

分 类 号：TM721.1[电气工程—电力系统及自动化]