Y型模块化多电平换流器(modular multilevel converter in Y configuration,Y-MMC)的Y形结构,使其预充电及并网过程更为复杂,基于环流控制的一般启动策略不再适用。针对上述问题,设计基于模型预测控制的渐进预充电方法及无扰动并网方法...Y型模块化多电平换流器(modular multilevel converter in Y configuration,Y-MMC)的Y形结构,使其预充电及并网过程更为复杂,基于环流控制的一般启动策略不再适用。针对上述问题,设计基于模型预测控制的渐进预充电方法及无扰动并网方法,提出一种模型预测渐进启动控制策略。首先,建立桥臂电流和电容电压预测模型,通过模型预测控制改变充电电流回路、幅值和相角,实现可控充电最大有功输入,对各个桥臂渐进充电。其次,根据电流误差灵活投切子模块,逐渐平衡充电回路电势差,辅助模型预测控制抑制冲击电流。然后,协调外环比例积分控制与内环模型预测控制,通过切换外环功率和电压控制模式,实现基于Y-MMC的柔性低频输电系统无扰动并网过程。最后,通过Matlab/Simulink对双端柔性低频输电系统进行仿真分析,所提控制策略保障了启动过程较低的电流冲击和较高的充电速度,使系统平稳快速进入稳定运行状态。展开更多
Three parallel lab-scale expanded granular sludge bed(EGSB) reactors were employed to evaluate the start-up process of bio-hydrogen production from molasses wastewater.With other start-up parameters controlled the sam...Three parallel lab-scale expanded granular sludge bed(EGSB) reactors were employed to evaluate the start-up process of bio-hydrogen production from molasses wastewater.With other start-up parameters controlled the same,the effect of inoculating sludge pre-treatments was studied.Two methods of pre-treatments(pre-heating and pre-aeration) were conducted for the inoculating sludge in two reactors compared with a non-pre-treatment reactor(control reactor).The results showed that the reactors with pre-treatment performed better in the start-up process than the control one.The hydrogen-producing bacteria were efficiently enriched at the start-up period,shortening the start-up process.At the end of the start-up stage,the acidification rate of the pre-treatment reactors was 10%—30% more than the control one,and hydrogen production increased by 1.69—1.82 times.Considering cost and feasibility,the authors suggest applying the pre-aeration method to treat the inoculating sludge to get more efficient start-up in the industrial scale bio-hydrogen production plant.展开更多
为快速平稳的启动基于模块化多电平换流器的多端柔性直流输电系统(modular multilevel converter-multi-terminal direct current,MMC-MTDC),避免各站启动时序配合不当引起大的电气冲击甚至启动失败,提出了MMC-MTDC系统协调启动控制策...为快速平稳的启动基于模块化多电平换流器的多端柔性直流输电系统(modular multilevel converter-multi-terminal direct current,MMC-MTDC),避免各站启动时序配合不当引起大的电气冲击甚至启动失败,提出了MMC-MTDC系统协调启动控制策略。首先,指出MMC存在交流侧、直流侧和交直流侧混合3种预充电方式,基于其充电机理,设计了预充电方式识别方法,提出了可将子模块充电至额定电压的闭环均压充电策略;其次,研究了多端系统启动时序的有效配合方案,提出了基于直流电压斜坡控制方式的并联式MMC-MTDC系统协调启动控制策略;最后,通过Matlab/Simulink构建三端系统进行仿真。结果表明:闭环均压充电方法能自动适应MMC 3种预充电方式,使子模块平稳充电至额定值;协调启动策略则能很好的实现多端系统平稳解锁。展开更多
文摘Y型模块化多电平换流器(modular multilevel converter in Y configuration,Y-MMC)的Y形结构,使其预充电及并网过程更为复杂,基于环流控制的一般启动策略不再适用。针对上述问题,设计基于模型预测控制的渐进预充电方法及无扰动并网方法,提出一种模型预测渐进启动控制策略。首先,建立桥臂电流和电容电压预测模型,通过模型预测控制改变充电电流回路、幅值和相角,实现可控充电最大有功输入,对各个桥臂渐进充电。其次,根据电流误差灵活投切子模块,逐渐平衡充电回路电势差,辅助模型预测控制抑制冲击电流。然后,协调外环比例积分控制与内环模型预测控制,通过切换外环功率和电压控制模式,实现基于Y-MMC的柔性低频输电系统无扰动并网过程。最后,通过Matlab/Simulink对双端柔性低频输电系统进行仿真分析,所提控制策略保障了启动过程较低的电流冲击和较高的充电速度,使系统平稳快速进入稳定运行状态。
文摘Three parallel lab-scale expanded granular sludge bed(EGSB) reactors were employed to evaluate the start-up process of bio-hydrogen production from molasses wastewater.With other start-up parameters controlled the same,the effect of inoculating sludge pre-treatments was studied.Two methods of pre-treatments(pre-heating and pre-aeration) were conducted for the inoculating sludge in two reactors compared with a non-pre-treatment reactor(control reactor).The results showed that the reactors with pre-treatment performed better in the start-up process than the control one.The hydrogen-producing bacteria were efficiently enriched at the start-up period,shortening the start-up process.At the end of the start-up stage,the acidification rate of the pre-treatment reactors was 10%—30% more than the control one,and hydrogen production increased by 1.69—1.82 times.Considering cost and feasibility,the authors suggest applying the pre-aeration method to treat the inoculating sludge to get more efficient start-up in the industrial scale bio-hydrogen production plant.
