模块化多电平变换器(modulemultilevelconverter,MMC)由于其模块化、灵活性的特点,与传统的两电平、三电平变流器拓扑相比具有功率等级高、谐波畸变小、开关损耗低等显著优点,因此在拥有高功率密度的超导磁储能(superconducting magneti...模块化多电平变换器(modulemultilevelconverter,MMC)由于其模块化、灵活性的特点,与传统的两电平、三电平变流器拓扑相比具有功率等级高、谐波畸变小、开关损耗低等显著优点,因此在拥有高功率密度的超导磁储能(superconducting magnetic energy storage,SMES)系统中拥有广阔的应用前景。提出了基于MMC的SMES新型拓扑结构及其无源控制策略,可有效提高受控系统的输出电能质量和动态特性。首先,建立了MMC-SMES的数学模型及其端口受控耗散哈密尔顿模型;其次,针对其运行过程中的非线性特性,通过考虑受控系统的内外部互联结构,设计了MMCSMES的无源控制策略;然后,针对MMC运行中存在的均压和环流问题,分别采用了子模块电容电压的分级式均压控制和负序二倍频坐标变换下的相间解耦控制;最后,仿真结果验证了所提出的MMC-SMES新型拓扑及其无源控制策略的有效性。展开更多
Software engineering＇s lifecycle models havc proven to be very important for traditional software development. However, can these models be applied to the development of Web-based applications as well？ In recent yea...Software engineering＇s lifecycle models havc proven to be very important for traditional software development. However, can these models be applied to the development of Web-based applications as well？ In recent years, Web-based applications have become more and more complicated and a lot of efforts have been placed on introducing new technologies such as J2EE, PhP, and .NET, etc., which have been universally accepted as the development technologies for Web-based applications. However, there is no universally accepted process model for the development of Web-based applications. Moreover, shaping the process model for small medium-sized enterprises （SMEs）, which have limited resources, has been relatively neglected. Based on our previous work, this paper presents an expanded lifecycle process model for the development of Web-based applications in SMEs. It consists of three sets of processes, i.e., requirement processes, development processes, and evolution processes. Particularly, the post-delivery evolution processes are important to SMEs to develop and maintain quality web applications with limited resources and time.展开更多
文摘模块化多电平变换器(modulemultilevelconverter,MMC)由于其模块化、灵活性的特点,与传统的两电平、三电平变流器拓扑相比具有功率等级高、谐波畸变小、开关损耗低等显著优点,因此在拥有高功率密度的超导磁储能(superconducting magnetic energy storage,SMES)系统中拥有广阔的应用前景。提出了基于MMC的SMES新型拓扑结构及其无源控制策略,可有效提高受控系统的输出电能质量和动态特性。首先,建立了MMC-SMES的数学模型及其端口受控耗散哈密尔顿模型;其次,针对其运行过程中的非线性特性,通过考虑受控系统的内外部互联结构,设计了MMCSMES的无源控制策略;然后,针对MMC运行中存在的均压和环流问题,分别采用了子模块电容电压的分级式均压控制和负序二倍频坐标变换下的相间解耦控制;最后,仿真结果验证了所提出的MMC-SMES新型拓扑及其无源控制策略的有效性。
文摘Software engineering＇s lifecycle models havc proven to be very important for traditional software development. However, can these models be applied to the development of Web-based applications as well？ In recent years, Web-based applications have become more and more complicated and a lot of efforts have been placed on introducing new technologies such as J2EE, PhP, and .NET, etc., which have been universally accepted as the development technologies for Web-based applications. However, there is no universally accepted process model for the development of Web-based applications. Moreover, shaping the process model for small medium-sized enterprises （SMEs）, which have limited resources, has been relatively neglected. Based on our previous work, this paper presents an expanded lifecycle process model for the development of Web-based applications in SMEs. It consists of three sets of processes, i.e., requirement processes, development processes, and evolution processes. Particularly, the post-delivery evolution processes are important to SMEs to develop and maintain quality web applications with limited resources and time.
