Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable b...Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable barriers to potential users,undoubtedly hindering their penetration in mediumvoltage(MV)power conversion.Key novel technologies such as enhanced gatedriver,auxiliary power supply network,PCB planar dcbus,and highdensity inductor are presented,enabling the SiCbased designs in modular MV converters,overcoming aforementioned challenges.However,purely substituting SiC design instead of Sibased ones in modular MV converters,would expectedly yield only limited gains.Therefore,to further elevate SiCbased designs,novel highbandwidth control strategies such as switchingcycle control(SCC)and integrated capacitorblocked transistor(ICBT),as well as highperformance/highbandwidth communication network are developed.All these technologies combined,overcome barriers posed by stateoftheart Si designs and unlock system level benefits such as very high power density,highefficiency,fast dynamic response,unrestricted line frequency operation,and improved power quality,all demonstrated throughout this paper.展开更多
China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai I...China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai Institute of Space Power-sources.The 42 V medium-voltage fully-regulated high-power EPS has been adopted for the first time in medium Earth orbit,with an output power reaching about 3 kW.Compared with the 42 V medium-voltage semi-regulated bus power system used in the Regional Navigation BDS-2 satellite,the EPS of the BDS-3 MEO satellites has increased power by about 80%,adopting many newly developed products such as high-efficient triple junction GaAs solar cells,high-energy-density lithium ion batteries and a high-efficient autonomous power control unit(PCU).Based on the studies on the medium-voltage fully-regulated and high-power EPS technical principles,and the adaptability and reliability of various working modes,the test verifications for the EPS were conducted both on the ground and in orbit.Compared with other global navigation satellite systems such as GPS,Galileo and GLONASS,the EPS of the BDS-3 MEO satellite has a long design life time which is equivalent to that of the GPS and Galileo,but with a larger power supply capability and power ratio,distinguishing its advancement in the field of satellite power technology.展开更多
This paper discusses a preferable solution to mitigate the CT （current transformer） saturation problem, and at same time, reduce the accuracy errors when considering the selection of CTs for installation on the medi...This paper discusses a preferable solution to mitigate the CT （current transformer） saturation problem, and at same time, reduce the accuracy errors when considering the selection of CTs for installation on the medium voltage switchgear of a nuclear power plant. This consideration is important for both measurement and protection functions of the digital protective relays. This is a study to ascertain the best options for a suitable solution to prevent CT saturation in relations to its protective capabilities during short circuit fault without compromising the CT accuracy class during normal operation of the system, while ensuring its conformity to the design requirement is within limit. The advantages of current transformers have proven not only to be reliable and safe, but also are of easy handling, reduction of the cost and components on the MV （medium voltage） switchgear. The purpose of this research is to identify best approach to resolve the existing problems in the current protection system. With the view of LPCT （low power current transformer） which has been newly constructed by few manufacturers to provide good protection and a wide range of measuring function without errors, some other solutions will be considered in this research.展开更多
Accurately determining when and what to remanufacture is essential for maximizing the lifecycle value of industrial equipment.However,existing approaches face three significant limitations:(1)reliance on predefined ma...Accurately determining when and what to remanufacture is essential for maximizing the lifecycle value of industrial equipment.However,existing approaches face three significant limitations:(1)reliance on predefined mathematical models that often fail to capture equipment-specific degradation,(2)offline optimization methods that assume access to future data,and(3)the absence of component-level guidance.To address these challenges,we propose a data-driven framework for component-level decision-making.The framework leverages streaming sensor data to predict the remaining useful life(RUL)without relying on mathematical models,employs an online optimization algorithm suitable for practical settings,and,through remanufacturing simulations,provides guidance on which components should be replaced.In a case study on gas-insulated switchgear,the proposed framework achieved RUL prediction performance comparable to an oracle model in an online setting without relying on predefined mathematical models.Furthermore,by employing online optimization,it determined a remanufacturing timing close to the global optimum using only past and current data.In addition,unlike previous studies,the framework enables component-level decision-making,allowing for more detailed and actionable remanufacturing guidance in practical applications.展开更多
When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This p...When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This paper proposes to combine ZnO cluster with MoS_(2) to improve the gassensitive properties of the monolayer.Based on the Density Functional Theory(DFT),the effect of(ZnO)n size on the behavior of MoS_(2 )is considered.Key parameters such as adsorption energy and band gap of(ZnO)n-MoS_(2)/NO_(2) system were calculated.The ZnO-MoS_(2) heterojunction was successfully synthesized by a hydrothermal method.The gas sensor exhibits a remarkable response and a fast response-recovery time to 100 ppm NO_(2).In addition,it demonstrates excellent selectivity,long-term stability and a low detection limit.This work confirms the potential of the ZnO-MoS_(2) composite structure as a highly effective gas sensor for NO_(2) detection,which provides valuable theoretical and experimental insights for fault detection in dry air switchgear.展开更多
开关柜上的一些关键部位,比如断路器触头,不能直接安装温度传感器,为了获取合适的温度传感监测点,以实现对开关柜的监测和保护;文中以KYN28A-12型10 k V开关柜为研究对象,建立开关柜三维物理模型,通过Ansys仿真,得到开关柜在额定工况下...开关柜上的一些关键部位,比如断路器触头,不能直接安装温度传感器,为了获取合适的温度传感监测点,以实现对开关柜的监测和保护;文中以KYN28A-12型10 k V开关柜为研究对象,建立开关柜三维物理模型,通过Ansys仿真,得到开关柜在额定工况下的温度场分布规律,初步为后续的监测点选取提供仿真理论基础。为应对开关柜复杂的运行条件,笔者对开关柜在环境温度、载流量等不同工况下进行温度场仿真,基于仿真结果和理论分析,最终综合选取了一些温度变化差异较大的母排节点作为温度监测点,并具体分析了这些监测点在不同工况条件下的温升影响差异,验证了文中选取的温度监测点的合理性。展开更多
基金conducted under ARPA-e from DOE with the award number DE-AR0000892.
文摘Simultaneously imposed challenges of highvoltage insulation,high dv/dt,highswitching frequency,fast protection,and thermal management associated with the adoption of 10 kV SiC MOSFET,often pose nearly insurmountable barriers to potential users,undoubtedly hindering their penetration in mediumvoltage(MV)power conversion.Key novel technologies such as enhanced gatedriver,auxiliary power supply network,PCB planar dcbus,and highdensity inductor are presented,enabling the SiCbased designs in modular MV converters,overcoming aforementioned challenges.However,purely substituting SiC design instead of Sibased ones in modular MV converters,would expectedly yield only limited gains.Therefore,to further elevate SiCbased designs,novel highbandwidth control strategies such as switchingcycle control(SCC)and integrated capacitorblocked transistor(ICBT),as well as highperformance/highbandwidth communication network are developed.All these technologies combined,overcome barriers posed by stateoftheart Si designs and unlock system level benefits such as very high power density,highefficiency,fast dynamic response,unrestricted line frequency operation,and improved power quality,all demonstrated throughout this paper.
文摘China’s BeiDou Navigation Satellite System(BDS)construction has been completed and the system has been formally commissioned.Most of the Electric Power Systems(EPSs)for MEO satellites were developed by the Shanghai Institute of Space Power-sources.The 42 V medium-voltage fully-regulated high-power EPS has been adopted for the first time in medium Earth orbit,with an output power reaching about 3 kW.Compared with the 42 V medium-voltage semi-regulated bus power system used in the Regional Navigation BDS-2 satellite,the EPS of the BDS-3 MEO satellites has increased power by about 80%,adopting many newly developed products such as high-efficient triple junction GaAs solar cells,high-energy-density lithium ion batteries and a high-efficient autonomous power control unit(PCU).Based on the studies on the medium-voltage fully-regulated and high-power EPS technical principles,and the adaptability and reliability of various working modes,the test verifications for the EPS were conducted both on the ground and in orbit.Compared with other global navigation satellite systems such as GPS,Galileo and GLONASS,the EPS of the BDS-3 MEO satellite has a long design life time which is equivalent to that of the GPS and Galileo,but with a larger power supply capability and power ratio,distinguishing its advancement in the field of satellite power technology.
文摘This paper discusses a preferable solution to mitigate the CT （current transformer） saturation problem, and at same time, reduce the accuracy errors when considering the selection of CTs for installation on the medium voltage switchgear of a nuclear power plant. This consideration is important for both measurement and protection functions of the digital protective relays. This is a study to ascertain the best options for a suitable solution to prevent CT saturation in relations to its protective capabilities during short circuit fault without compromising the CT accuracy class during normal operation of the system, while ensuring its conformity to the design requirement is within limit. The advantages of current transformers have proven not only to be reliable and safe, but also are of easy handling, reduction of the cost and components on the MV （medium voltage） switchgear. The purpose of this research is to identify best approach to resolve the existing problems in the current protection system. With the view of LPCT （low power current transformer） which has been newly constructed by few manufacturers to provide good protection and a wide range of measuring function without errors, some other solutions will be considered in this research.
基金supported by the Human Resources Development of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korea government Ministry of Knowledge Economy(No.RS-2023-00244330)the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.NRF RS-2023-00219052RS-2024-00352587)。
文摘Accurately determining when and what to remanufacture is essential for maximizing the lifecycle value of industrial equipment.However,existing approaches face three significant limitations:(1)reliance on predefined mathematical models that often fail to capture equipment-specific degradation,(2)offline optimization methods that assume access to future data,and(3)the absence of component-level guidance.To address these challenges,we propose a data-driven framework for component-level decision-making.The framework leverages streaming sensor data to predict the remaining useful life(RUL)without relying on mathematical models,employs an online optimization algorithm suitable for practical settings,and,through remanufacturing simulations,provides guidance on which components should be replaced.In a case study on gas-insulated switchgear,the proposed framework achieved RUL prediction performance comparable to an oracle model in an online setting without relying on predefined mathematical models.Furthermore,by employing online optimization,it determined a remanufacturing timing close to the global optimum using only past and current data.In addition,unlike previous studies,the framework enables component-level decision-making,allowing for more detailed and actionable remanufacturing guidance in practical applications.
基金the financial support of National Natural Science Foundation of China(Nos.52207175 and 52407178)。
文摘When discharge faults occur in dry air switchgear,the air decomposes to produce diverse gases,with NO_(2) reaching the highest levels.Detecting the NO_(2) level can reflect the operation status of the equipment.This paper proposes to combine ZnO cluster with MoS_(2) to improve the gassensitive properties of the monolayer.Based on the Density Functional Theory(DFT),the effect of(ZnO)n size on the behavior of MoS_(2 )is considered.Key parameters such as adsorption energy and band gap of(ZnO)n-MoS_(2)/NO_(2) system were calculated.The ZnO-MoS_(2) heterojunction was successfully synthesized by a hydrothermal method.The gas sensor exhibits a remarkable response and a fast response-recovery time to 100 ppm NO_(2).In addition,it demonstrates excellent selectivity,long-term stability and a low detection limit.This work confirms the potential of the ZnO-MoS_(2) composite structure as a highly effective gas sensor for NO_(2) detection,which provides valuable theoretical and experimental insights for fault detection in dry air switchgear.
文摘开关柜上的一些关键部位,比如断路器触头,不能直接安装温度传感器,为了获取合适的温度传感监测点,以实现对开关柜的监测和保护;文中以KYN28A-12型10 k V开关柜为研究对象,建立开关柜三维物理模型,通过Ansys仿真,得到开关柜在额定工况下的温度场分布规律,初步为后续的监测点选取提供仿真理论基础。为应对开关柜复杂的运行条件,笔者对开关柜在环境温度、载流量等不同工况下进行温度场仿真,基于仿真结果和理论分析,最终综合选取了一些温度变化差异较大的母排节点作为温度监测点,并具体分析了这些监测点在不同工况条件下的温升影响差异,验证了文中选取的温度监测点的合理性。
