采用小电流接地方式的模块化多电平多端柔性直流输电系统(MMC based multi-terminal HVDC,MMC-MTDC)发生直流线路单极接地后,所有非故障极线路电压升高为额定值的2倍,威胁线路和设备安全,因此,需要快速识别并切除故障线路,以恢复MMC-MTD...采用小电流接地方式的模块化多电平多端柔性直流输电系统(MMC based multi-terminal HVDC,MMC-MTDC)发生直流线路单极接地后,所有非故障极线路电压升高为额定值的2倍,威胁线路和设备安全,因此,需要快速识别并切除故障线路,以恢复MMC-MTDC系统的正常运行。而小电流接地方式的MMC-MTDC系统单极接地后,无稳态故障电流,且各直流线路稳态电压基本相同,无法依靠稳态电压、电流量来识别故障线路。分析了MMC-MTDC单极接地时线路对地电容电流暂态变化特性,提出采用线路两端的暂态差流作为区分故障线路和非故障线路的依据;进一步通过计算线路两端差流的短时能量来扩大故障线路和非故障线路的差异,减少暂态过程对故障线路识别的影响,达到可靠识别故障线路的目的。在PSCAD中搭建四端MMCMTDC系统进行仿真,结果表明故障线路两端差流短时能量远大于非故障线路两端差流短时能量,并且该故障线路差动电流短时能量波动较小,能可靠识别接地线路。展开更多
We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance...We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.展开更多
文摘采用小电流接地方式的模块化多电平多端柔性直流输电系统(MMC based multi-terminal HVDC,MMC-MTDC)发生直流线路单极接地后,所有非故障极线路电压升高为额定值的2倍,威胁线路和设备安全,因此,需要快速识别并切除故障线路,以恢复MMC-MTDC系统的正常运行。而小电流接地方式的MMC-MTDC系统单极接地后,无稳态故障电流,且各直流线路稳态电压基本相同,无法依靠稳态电压、电流量来识别故障线路。分析了MMC-MTDC单极接地时线路对地电容电流暂态变化特性,提出采用线路两端的暂态差流作为区分故障线路和非故障线路的依据;进一步通过计算线路两端差流的短时能量来扩大故障线路和非故障线路的差异,减少暂态过程对故障线路识别的影响,达到可靠识别故障线路的目的。在PSCAD中搭建四端MMCMTDC系统进行仿真,结果表明故障线路两端差流短时能量远大于非故障线路两端差流短时能量,并且该故障线路差动电流短时能量波动较小,能可靠识别接地线路。
基金Project supported by the National High-Tech R&D Program of China(No.2013AA09A414)the National Natural Science Foundation of China(No.51221004)the Interdisciplinary Research Foundation of Zhejiang University(No.2012HY003A)
文摘We develop a new kind of underwater inductive coupling power transfer(ICPT)system to evaluate wireless power transfer in autonomous underwater vehicle(AUV)docking applications.Parameters that determine the performance of the system are systematically analyzed through mathematical methods.A circuit simulation model and a finite element analysis(FEA)simulation model are developed to study the power losses of the system,including copper loss in coils,semiconductor loss in circuits,and eddy current loss in transmission media.The characteristics of the power losses can provide guidelines to improve the efficiency of ICPT systems.Calculation results and simulation results are validated by relevant experiments of the prototype system.The output power of the prototype system is up to 45 W and the efficiency is up to 0.84.The preliminary results indicate that the efficiency will increase as the transmission power is raised by increasing the input voltage.When the output power reaches 500 W,the efficiency is expected to exceed 0.94.The efficiency can be further improved by choosing proper semiconductors and coils.The analysis methods prove effective in predicting the performance of similar ICPT systems and should be useful in designing new systems.
