模块化多电平换流器(Modular Multilevel Converter,MMC)作为一种新型多电平拓扑结构的电压源换流器,具有扩展性强、输出电压质量高、谐波含量少等优点,已经展现出极其重要的工程应用前景。首先介绍了模块化多电平高压直流输电(Modular ...模块化多电平换流器(Modular Multilevel Converter,MMC)作为一种新型多电平拓扑结构的电压源换流器,具有扩展性强、输出电压质量高、谐波含量少等优点,已经展现出极其重要的工程应用前景。首先介绍了模块化多电平高压直流输电(Modular Multilevel Converter based High Voltage Direct Current,MMC-HVDC)的拓扑结构及运行原理,然后通过故障附加状态网络分别对区内和区外故障进行了分析,并利用二阶微分法提取了故障时电压、电流的故障分量,得出了保护策略。根据故障网络分析可知,当直流线路发生区内故障时,电流故障分量极性相同;当直流线路发生区外故障时,电流故障分量极性相反。因此,可以根据电流故障分量的极性是否相同来识别区内、外故障,利用二阶微分法来提取故障时电流的故障分量,用以识别区内、外故障。另外,根据故障网络分析还发现,当直流线路发生区内故障时,单极故障时电压故障分量极性相同,双极故障时电压故障分量极性相反。因此,可以根据电压故障分量的极性是否相同来识别故障极。利用二阶微分法来提取故障时电压的故障分量,根据电压故障分量的极性,识别故障所在的极。最后利用PSCAD电磁暂态仿真软件建立了MMC-HVDC的仿真模型。仿真结果验证了故障分析以及保护方法的正确性。展开更多
The identification of fractures is of great importance in gravity and magnetic data processing and interpretation.In this study,four fracture identification methods are applied,and widely used in processing and analys...The identification of fractures is of great importance in gravity and magnetic data processing and interpretation.In this study,four fracture identification methods are applied,and widely used in processing and analysis of the gravity anomaly,including vertical second derivative method,tilt derivative method,theta map method and normalized differential method,for gravity data acquired in a given area in Heilongjiang.By comparing the distribution of the zero contour or maximum contour,we summarize the application effects,and both advantages and disadvantages of each method.It is found that tilt derivative method and normalized differential method provide better effects than other two methods:the narrower anomaly gradient belt and higher identification precision of fracture or geological boundary.The inferred fractures and geological boundaries have a great match with the results obtained from geologic map and remote sensing data interpretation.Those study results have definitely provided the theoretical foundation for identifying faults and the geological boundaries.展开更多
文摘模块化多电平换流器(Modular Multilevel Converter,MMC)作为一种新型多电平拓扑结构的电压源换流器,具有扩展性强、输出电压质量高、谐波含量少等优点,已经展现出极其重要的工程应用前景。首先介绍了模块化多电平高压直流输电(Modular Multilevel Converter based High Voltage Direct Current,MMC-HVDC)的拓扑结构及运行原理,然后通过故障附加状态网络分别对区内和区外故障进行了分析,并利用二阶微分法提取了故障时电压、电流的故障分量,得出了保护策略。根据故障网络分析可知,当直流线路发生区内故障时,电流故障分量极性相同;当直流线路发生区外故障时,电流故障分量极性相反。因此,可以根据电流故障分量的极性是否相同来识别区内、外故障,利用二阶微分法来提取故障时电流的故障分量,用以识别区内、外故障。另外,根据故障网络分析还发现,当直流线路发生区内故障时,单极故障时电压故障分量极性相同,双极故障时电压故障分量极性相反。因此,可以根据电压故障分量的极性是否相同来识别故障极。利用二阶微分法来提取故障时电压的故障分量,根据电压故障分量的极性,识别故障所在的极。最后利用PSCAD电磁暂态仿真软件建立了MMC-HVDC的仿真模型。仿真结果验证了故障分析以及保护方法的正确性。
文摘The identification of fractures is of great importance in gravity and magnetic data processing and interpretation.In this study,four fracture identification methods are applied,and widely used in processing and analysis of the gravity anomaly,including vertical second derivative method,tilt derivative method,theta map method and normalized differential method,for gravity data acquired in a given area in Heilongjiang.By comparing the distribution of the zero contour or maximum contour,we summarize the application effects,and both advantages and disadvantages of each method.It is found that tilt derivative method and normalized differential method provide better effects than other two methods:the narrower anomaly gradient belt and higher identification precision of fracture or geological boundary.The inferred fractures and geological boundaries have a great match with the results obtained from geologic map and remote sensing data interpretation.Those study results have definitely provided the theoretical foundation for identifying faults and the geological boundaries.
