适用于大规模风电场的MMC-HVDC控制策略研究

Research on MMC-HVDC system control strategy for large-scale wind farms

风电场柔性直流并网是大规模风力发电的关键问题之一,而模块化多电平换流器(MMC)是风电场柔性直流并网的发展趋势。本文提出一种适用于大型风电场的MMC-HVDC控制策略,通过建立MMC数学模型,将分层控制思想引入到MMC-HVDC控制中,具体划分为系统级控制、换流器控制及模块电压控制3个层次;此外,为了进一步增强系统侧MMC的动态性能,采用反馈线性化方法设计内环电流控制器,提出一种改进的分组式电容电压排序方法,以平衡直流电容电压。基于实际系统的仿真研究验证了本文提出的MMC-HVDC控制策略的正确性与可行性。

Flexible HVDC （ high-voltage direct current） is the key issues of large-scale windfarms, with the modular multilevel converter （MMC） being the development trend of flexibleHVDC technology. In this paper, the mathematical model of MMC is set up and a novel MMCHVDCsystem control strategy is proposed for large-scale wind farms. With hierarchical control,based on the novel strategy, the whole MMC-HVDC system control strategy is divided into systemlevel control, inverter control and valve control module voltage control. Moreover, feedbacklinearization controller is introduced into the inner current ring of system side MMC control in orderto enhance the dynamic performance of control strategy. The MMC converter controllerstructures at the system side and the wind field side are provided for the realization of the reliableaccess to the power grid of the large-scale wind power. Simulation results based on actual systemare to verify the correctness and effectiveness of the proposed method.