在海上风电直流汇集-直流送出系统中,基于单相模块化多电平换流器的面对面型(modular multilevel converter based front-to-front,MMC-FTF)高压大功率DC/DC变换器是连接中压汇聚线与高压直流输电(high voltage direct current,HVDC)线...在海上风电直流汇集-直流送出系统中,基于单相模块化多电平换流器的面对面型(modular multilevel converter based front-to-front,MMC-FTF)高压大功率DC/DC变换器是连接中压汇聚线与高压直流输电(high voltage direct current,HVDC)线路的关键接口设备。然而,针对MMC-FTF变换器的阻抗建模鲜有报道,且含MMC-FTF变换器的HVDC系统的小信号稳定性问题尚不明确。针对此问题,该文首先根据频率耦合效应提出共差模提取矩阵,实现了多谐波线性化方法下单相及三相MMC交直流侧阻抗模型的统一,并建立了MMC-FTF变换器的直流侧阻抗模型。其次,利用阻抗稳定性判据揭示了MMC-FTF变换器与岸上三相MMC换流站互联时存在的振荡风险。接着,根据相角灵敏度指标定量评估了不同控制器参数对系统稳定性的影响,并提出用于提升系统稳定性的调参准则。最后,基于MATLAB/Simulink仿真和硬件在环实验验证了结果的正确性。展开更多
Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the sta...Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment.展开更多
针对现有污水样本快速检测技术存在的不足,以及传统实验室质谱技术无法应用于现场快速检测、检测耗时较长等问题,本文提出了一种基于脉冲直流电喷雾电离质谱(pulsed-DC-ESI-MS)测定生活污水中11种常见毒品(吗啡、甲基苯丙胺、去甲氯胺...针对现有污水样本快速检测技术存在的不足,以及传统实验室质谱技术无法应用于现场快速检测、检测耗时较长等问题,本文提出了一种基于脉冲直流电喷雾电离质谱(pulsed-DC-ESI-MS)测定生活污水中11种常见毒品(吗啡、甲基苯丙胺、去甲氯胺酮、苯丙胺、3,4-亚甲基双氧甲基苯丙胺、可卡因、6-单乙酰吗啡、3,4-亚甲基双氧苯丙胺、苯甲酰爱康宁、氯胺酮、可待因)的快速检测方法。污水样品经浓盐酸调节pH至2,用Oasis PRiME MCX固相萃取柱进行萃取,萃取液经氮吹至近干后用200μL甲醇复溶,涡旋0.5 min;复溶后的样品溶液经0.22μm有机相滤膜过滤后采用pulsed-DC-ESI-MS进行分析。方法学验证结果表明,11种毒品在各自的线性范围内具有良好的线性关系,相关系数(r2)均≥0.9986,检出限(LOD)为0.01~0.5μg/L,定量限(LOQ)为0.05~5μg/L。在低、中、高3个加标水平下,11种毒品的回收率为88.0%~107.6%,日内和日间精密度均≤8.5%。该方法检测速度快,大大提高了检测效率,适用于生活污水中常见毒品的快速检测分析。展开更多
建立模块化多电平变流器(modular multilevelconverters,MMC)的电磁暂态数学模型以及采用MMC为变流器的高压直流输电系统(high voltage direct current,HVDC)直流侧电压的动态数学模型。在此基础上,分析HVDC系统的直流侧电压动态特性,给...建立模块化多电平变流器(modular multilevelconverters,MMC)的电磁暂态数学模型以及采用MMC为变流器的高压直流输电系统(high voltage direct current,HVDC)直流侧电压的动态数学模型。在此基础上,分析HVDC系统的直流侧电压动态特性,给出HVDC控制器参数协调设计原则和算法。最后,基于PSCAD/EMTDC的数字仿真结果证明了所提出的HVDC控制系统参数协调设计原则和算法的正确性。展开更多
文摘在海上风电直流汇集-直流送出系统中,基于单相模块化多电平换流器的面对面型(modular multilevel converter based front-to-front,MMC-FTF)高压大功率DC/DC变换器是连接中压汇聚线与高压直流输电(high voltage direct current,HVDC)线路的关键接口设备。然而,针对MMC-FTF变换器的阻抗建模鲜有报道,且含MMC-FTF变换器的HVDC系统的小信号稳定性问题尚不明确。针对此问题,该文首先根据频率耦合效应提出共差模提取矩阵,实现了多谐波线性化方法下单相及三相MMC交直流侧阻抗模型的统一,并建立了MMC-FTF变换器的直流侧阻抗模型。其次,利用阻抗稳定性判据揭示了MMC-FTF变换器与岸上三相MMC换流站互联时存在的振荡风险。接着,根据相角灵敏度指标定量评估了不同控制器参数对系统稳定性的影响,并提出用于提升系统稳定性的调参准则。最后,基于MATLAB/Simulink仿真和硬件在环实验验证了结果的正确性。
基金Project supported by National Basic Research Program of China (973 Program) (2011CB 209400)State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments (SKLD10M09)Program for ±1 100 kV UHVDC Technology
文摘Direct current (DC) partial discharge (PD) test has drawn extensive attention from world-wide electric power research institutes in recent years. However, presently, no DC PD detection device on the market has the statistical function. Thus, we developed a test system for PD detection under DC voltage, which is characterized by strong anti-jamming capability, continuous high-speed real-time data acquisi- tion and effective, complete detection of DC PD signals. The DC PD mechanism, as well as the measuring principles, software system, and hardware design of the test equipment were introduced. Adopting typical electrode pairs, we tested the statistical spectrum of PD under DC voltage. The main difference in statistical spectrums between parallel plate electrodes and needle-plate electrodes was that the time interval between two consecutive discharges for needle-plate electrodes has obviously larger variation range than that for parallel plate electrodes, which could be the convincing proof for distinguishing the type of electrodes under DC PD. Practical results indicate that the proposed sys- tem can measure time domain signals of DC PD of oil-paper insulation effectively and promptly, and it can be used to determine and detect defects in DC power transmission equipment.
文摘针对现有污水样本快速检测技术存在的不足,以及传统实验室质谱技术无法应用于现场快速检测、检测耗时较长等问题,本文提出了一种基于脉冲直流电喷雾电离质谱(pulsed-DC-ESI-MS)测定生活污水中11种常见毒品(吗啡、甲基苯丙胺、去甲氯胺酮、苯丙胺、3,4-亚甲基双氧甲基苯丙胺、可卡因、6-单乙酰吗啡、3,4-亚甲基双氧苯丙胺、苯甲酰爱康宁、氯胺酮、可待因)的快速检测方法。污水样品经浓盐酸调节pH至2,用Oasis PRiME MCX固相萃取柱进行萃取,萃取液经氮吹至近干后用200μL甲醇复溶,涡旋0.5 min;复溶后的样品溶液经0.22μm有机相滤膜过滤后采用pulsed-DC-ESI-MS进行分析。方法学验证结果表明,11种毒品在各自的线性范围内具有良好的线性关系,相关系数(r2)均≥0.9986,检出限(LOD)为0.01~0.5μg/L,定量限(LOQ)为0.05~5μg/L。在低、中、高3个加标水平下,11种毒品的回收率为88.0%~107.6%,日内和日间精密度均≤8.5%。该方法检测速度快,大大提高了检测效率,适用于生活污水中常见毒品的快速检测分析。
文摘建立模块化多电平变流器(modular multilevelconverters,MMC)的电磁暂态数学模型以及采用MMC为变流器的高压直流输电系统(high voltage direct current,HVDC)直流侧电压的动态数学模型。在此基础上,分析HVDC系统的直流侧电压动态特性,给出HVDC控制器参数协调设计原则和算法。最后,基于PSCAD/EMTDC的数字仿真结果证明了所提出的HVDC控制系统参数协调设计原则和算法的正确性。
