风场并网的MMC-HVDC故障穿越控制策略研究

Research on Control Strategy of MMC-HVDC Fault Ride-through Connected to Wind Farm

针对海上风电场并网的模块化多电平变换器(MMC)-高压直流(HVDC)系统在故障穿越过程中,由于卸荷电路是在直流电压达到一定值一段时间后才开始起作用,导致陆上侧子模块电压有很大的冲击,会有损坏元器件的风险,此处根据故障期间的系统特性对控制策略进行改进,在保证系统故障穿越性能的前提下对子模块电压进行抑制。最后,基于RTDS仿真系统搭建了两端伪双极柔性HVDC输电系统半实物仿真模型,并在控保装置中对改进的控制策略进行了实物验证。

During the fault ride-through process of the modular multilevel converter(MMC)-high voltage direct current(HVDC)system for the grid-connected offshore wind farm,the unloading circuit does not start to function until the DC voltage reaches a certain value for a period of time,which results in a great impact on the sub-module voltage on the land side,there is a risk of damaging the electronic components,the control strategy is improved according to the sys-tem characteristics during the fault,and the sub-module voltage is suppressed under the premise of ensuring the sys-tem fault ride-through performance.Finally,a semi-physical simulation model of the pseudo-bipolar flexible HVDC transmission system at both ends is built based on the RTDS simulation system,and the improved control strategy is verified in the control and protection device.