With the increase of dc based renewable energy generation and dc loads,the medium voltage dc(MVDC)distribution network is becoming a promising option for more efficient system integration.In particular,large-capacity ...With the increase of dc based renewable energy generation and dc loads,the medium voltage dc(MVDC)distribution network is becoming a promising option for more efficient system integration.In particular,large-capacity photovoltaic(PV)-based power generation is growing rapidly,and a corresponding power conversion system is critical to integrate these large PV systems into MVDC power grid.Different from traditional ac grid-connected converters,the converter system for dc grid interfaced PV system requires large-capacity dc conversion over a wide range of ultra-high voltage step-up ratios.This is an important issue,yet received limited research so far.In this paper,a thorough study of dc-dc conversion system for a medium-voltage dc grid-connected PV system is conducted.The required structural features for such a conversion system are first discussed.Based on these features,the conversion system is classified into four categories by series-parallel connection scheme of power modules.Then two existing conversion system configurations as well as a proposed solution are compared in terms of input/output performance,conversion efficiency,modulation method,control complexity,power density,reliability,and hardware cost.In-depth analysis is carried out to select the most suitable conversion systems in various application scenarios.展开更多
The over modulation strategy of matrix converter(MC) is put forward on the basis of conventional AC/DC/AC MC control theory. Firstly,imaginary AC/DC converter is over modulated to get the greatest fictitious DC voltag...The over modulation strategy of matrix converter(MC) is put forward on the basis of conventional AC/DC/AC MC control theory. Firstly,imaginary AC/DC converter is over modulated to get the greatest fictitious DC voltage,secondly,imaginary DC/AC converter is over modulated,which effectively improve the voltage transfer ratio. Two voltage transfer ratio is emphatically analyzed with Fourier transform. At last,different modulation method is simulated with MATLAB,the simulation results verified the theoretical analysis and validity of the over modulation strategy,which provide a theoretical basis for the further research.展开更多
基金Supported by the National Natural Science Foundation of China(51811540405,52007096)National Key R&D Program of China(2016YFB0900205).
文摘With the increase of dc based renewable energy generation and dc loads,the medium voltage dc(MVDC)distribution network is becoming a promising option for more efficient system integration.In particular,large-capacity photovoltaic(PV)-based power generation is growing rapidly,and a corresponding power conversion system is critical to integrate these large PV systems into MVDC power grid.Different from traditional ac grid-connected converters,the converter system for dc grid interfaced PV system requires large-capacity dc conversion over a wide range of ultra-high voltage step-up ratios.This is an important issue,yet received limited research so far.In this paper,a thorough study of dc-dc conversion system for a medium-voltage dc grid-connected PV system is conducted.The required structural features for such a conversion system are first discussed.Based on these features,the conversion system is classified into four categories by series-parallel connection scheme of power modules.Then two existing conversion system configurations as well as a proposed solution are compared in terms of input/output performance,conversion efficiency,modulation method,control complexity,power density,reliability,and hardware cost.In-depth analysis is carried out to select the most suitable conversion systems in various application scenarios.
基金Supported by education department of Hunan Province(No.03C462)
文摘The over modulation strategy of matrix converter(MC) is put forward on the basis of conventional AC/DC/AC MC control theory. Firstly,imaginary AC/DC converter is over modulated to get the greatest fictitious DC voltage,secondly,imaginary DC/AC converter is over modulated,which effectively improve the voltage transfer ratio. Two voltage transfer ratio is emphatically analyzed with Fourier transform. At last,different modulation method is simulated with MATLAB,the simulation results verified the theoretical analysis and validity of the over modulation strategy,which provide a theoretical basis for the further research.
