新能源、基于模块化多电平换流器的多端柔性直流(modular multilevel converter-based multi-terminal high voltage direct current,MMC-MTDC)以及交流电网之间宽频振荡风险凸出,严重制约MMC-MTDC安全稳定运行和新能源高效消纳。MMC-M...新能源、基于模块化多电平换流器的多端柔性直流(modular multilevel converter-based multi-terminal high voltage direct current,MMC-MTDC)以及交流电网之间宽频振荡风险凸出,严重制约MMC-MTDC安全稳定运行和新能源高效消纳。MMC-MTDC各换流站呈现定交流电压、定直流电压、定功率等异构化控制方式,多端换流站之间又存在强非线性耦合,给系统振荡建模与分析带来挑战。为此,首先提出计及正负序控制的MMC-MTDC控制系统模块化建模方法。然后,针对复杂交直流网架结构,建立计及多端非线性耦合的MMC-MTDC不同断面通用化阻抗模型。最后,以三端MMC-MTDC环网为例,仿真验证通用化阻抗建模的准确性和有效性,并分析多端互联系统及正负序控制对阻抗特性的耦合影响,为新能源基地经MMC-MTDC互联系统振荡分析提供基础。展开更多
A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous...A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.展开更多
当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence cur...当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence current control,BPSC)和瞬时有功功率控制(instantaneous active power control,IAPC)。采用BPSC策略能够扩展PWM整流器最大运行功率,但有功功率波动较大,而IAPC策略能够抑制有功功率波动,但运行功率较小。在此基础上文中提出了一种平衡正序电流和瞬时有功功率的协调控制策略(hybrid balanced positive sequence and instantaneous active power control,HBPSIAPC),从而实现PWM整流器功率扩展和有功功率波动最小。通过采用标幺值,简化了理论推导和分析过程。最后,在实验室搭建了PWM整流器的实验平台,验证了所提出控制策略的可行性。展开更多
模块化多电平技术(modular multilevel converter,MMC)因其电磁兼容性好、谐波含量低、开关损耗较小等优势已经在高压直流输电(high voltage direct current,HVDC)中得到了广泛的运用。在MMC-HVDC向无源网络供电的情况下,为了抑制不对...模块化多电平技术(modular multilevel converter,MMC)因其电磁兼容性好、谐波含量低、开关损耗较小等优势已经在高压直流输电(high voltage direct current,HVDC)中得到了广泛的运用。在MMC-HVDC向无源网络供电的情况下,为了抑制不对称故障对向无源网络供电的电能质量的影响,采用了将微分平坦理论应用于向无源网络供电的MMC-HVDC系统的方法,以提高发生不对称故障时MMC换流器的动态性能。首先分析了向无源网络供电的MMC-HVDC的系统结构和工作原理,针对MMC-HVDC整流级的MMC换流器建立了在不平衡电网电压时基于正负序系统的数学模型;其次针对不同输出变量,分别进行了平坦性分析;接着,对MMC系统进行稳定性分析,并根据微分平坦理论设计了MMC-HVDC换流站的内外环正负序控制器;最后,在Matlab/Simulink中建立一个对无源网络供电的MMC-HVDC系统,结果表明:在发生不对称故障的运行条件下,MMC-HVDC系统的控制策略具有较好的动态性能。展开更多
文摘新能源、基于模块化多电平换流器的多端柔性直流(modular multilevel converter-based multi-terminal high voltage direct current,MMC-MTDC)以及交流电网之间宽频振荡风险凸出,严重制约MMC-MTDC安全稳定运行和新能源高效消纳。MMC-MTDC各换流站呈现定交流电压、定直流电压、定功率等异构化控制方式,多端换流站之间又存在强非线性耦合,给系统振荡建模与分析带来挑战。为此,首先提出计及正负序控制的MMC-MTDC控制系统模块化建模方法。然后,针对复杂交直流网架结构,建立计及多端非线性耦合的MMC-MTDC不同断面通用化阻抗模型。最后,以三端MMC-MTDC环网为例,仿真验证通用化阻抗建模的准确性和有效性,并分析多端互联系统及正负序控制对阻抗特性的耦合影响,为新能源基地经MMC-MTDC互联系统振荡分析提供基础。
基金Project(JC200903180555A) supported by Shenzhen City Science and Technology Plan, China
文摘A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.
文摘当电网不对称时,PWM整流器最大运行功率会受到功率器件容量的限制而降低。该文基于瞬时功率理论分析了PWM整流器在电网不对称时的数学模型。介绍了电网不对称时两种整流器的控制策略:平衡的正序电流控制(balanced positive sequence current control,BPSC)和瞬时有功功率控制(instantaneous active power control,IAPC)。采用BPSC策略能够扩展PWM整流器最大运行功率,但有功功率波动较大,而IAPC策略能够抑制有功功率波动,但运行功率较小。在此基础上文中提出了一种平衡正序电流和瞬时有功功率的协调控制策略(hybrid balanced positive sequence and instantaneous active power control,HBPSIAPC),从而实现PWM整流器功率扩展和有功功率波动最小。通过采用标幺值,简化了理论推导和分析过程。最后,在实验室搭建了PWM整流器的实验平台,验证了所提出控制策略的可行性。
文摘模块化多电平技术(modular multilevel converter,MMC)因其电磁兼容性好、谐波含量低、开关损耗较小等优势已经在高压直流输电(high voltage direct current,HVDC)中得到了广泛的运用。在MMC-HVDC向无源网络供电的情况下,为了抑制不对称故障对向无源网络供电的电能质量的影响,采用了将微分平坦理论应用于向无源网络供电的MMC-HVDC系统的方法,以提高发生不对称故障时MMC换流器的动态性能。首先分析了向无源网络供电的MMC-HVDC的系统结构和工作原理,针对MMC-HVDC整流级的MMC换流器建立了在不平衡电网电压时基于正负序系统的数学模型;其次针对不同输出变量,分别进行了平坦性分析;接着,对MMC系统进行稳定性分析,并根据微分平坦理论设计了MMC-HVDC换流站的内外环正负序控制器;最后,在Matlab/Simulink中建立一个对无源网络供电的MMC-HVDC系统,结果表明:在发生不对称故障的运行条件下,MMC-HVDC系统的控制策略具有较好的动态性能。
