混合级联直流输电系统主动谐波补偿控制

为提升混合级联直流输电系统接入点的电能质量,减少工程占地与造价,提出了一种基于模块化多电平换流器的主动谐波补偿方法.首先,介绍了混合级联直流输电系统的拓扑结构和谐波特征,其中高压阀组采用电网换相换流器,低压阀组则采用模块化多电平换流器.然后,介绍了系统的谐波等值电路与主动谐波补偿控制策略,通过模块化多电平换流器对电网换相换流器的谐波进行补偿,并分析了主动谐波补偿对模块化多电平换流器稳态运行的影响.最后,在PSCAD/EMTDC仿真软件中搭建了混合级联直流输电系统的仿真模型,验证了主动谐波补偿控制策略在系统稳态运行、功率变化和计及延时工况下的有效性.

Active Harmonic Compensation Control for Hybrid Cascaded HVDC Transmission System

To improve the power quality of the integration point of hybrid cascaded high voltage direct current (HVDC) transmission system and reduce the project occupied area and cost, this paper proposes an active harmonic compensation method based on modular multilevel converter (MMC). Firstly, the topology and harmonic characteristics of hybrid cascaded HVDC transmission system are introduced. The high-voltage valve adopts the line commutation converter (LCC), and the low-voltage valve adopts multiple MMCs. Then, the harmonic equivalent circuit of the system and the active harmonic compensation control strategy are described. In the strategy, the harmonics of LCC will be compensated by MMCs. Furthermore, the influence of active harmonic compensation on the steady-state operation of MMC are analyzed. Finally, a simulation model of hybrid cascaded HVDC transmission system is built in PSCAD/EMTDC simulation software, which verifies the availability of the active harmonic compensation control strategy in the steady-state operation, power change and time delay conditions of the system.