Protection of radial distribution networks is widely based on coordinated inverse time overcurrent relays (OCRs) ensuring both effectiveness and selectivity. However, the integration of distributed generation (DG) int...Protection of radial distribution networks is widely based on coordinated inverse time overcurrent relays (OCRs) ensuring both effectiveness and selectivity. However, the integration of distributed generation (DG) into an existing distribution network not only inevitably increases fault current levels to levels that may exceed the OCR ratings, but it may also disturb the original overcurrent relay coordination adversely effecting protection selectivity. To analyze the potentially adverse impact of DG on distribution system protective devices with respect to circuit breaker ratings and OCR coordination fault current studies are carried out for common reference test system under the influence of additional DG. The possible advantages of Superconducting Fault Current Limiter (SFCL) as a means to limit the adverse effect of DG on distribution system protection and their effectiveness will be demonstrated. Furthermore, minimum SFCL impedances required to avoid miss-operation of the primary and back-up OCRs are determined. The theoretical analysis will be validated using the IEEE 13-bus distribution test system is used. Both theoretical and simulation results indicate that the proposed application of SFCL is a viable option to effectively mitigate the DG impact on protective devices, thus enhancing the reliability of distribution network interfaced with DG.展开更多
In DC micro grids and networks,DC-DC power converters having a large number of semiconductor-based power electronic devices are usually adopted to interconnect the renewable sources and flexible loads.Most of the semi...In DC micro grids and networks,DC-DC power converters having a large number of semiconductor-based power electronic devices are usually adopted to interconnect the renewable sources and flexible loads.Most of the semiconductor-based devices suffer from poor fault withstanding abilities,but conventional power electronic protection schemes have the bottlenecks of the time-delay,self-malfunction and mis-judgement.This paper presents a novel solution using the superconducting fault current limiter(SFCL)to protect a power electronic device and extend the usage to a micro grid.This SFCL is actually a self-triggering,recoverable,and passive current limiter,which does not involve any additional circuit hardware and software.Experimental investigations and simulation analyses clarify the feasibility of using this superconductor-based protection scheme to implement the self-acting fail-safe protection of DC-DC converters.Further system-level simulations explore the SFCL to suppress the over-current and stabilize the bus voltage of a photovoltaic based DC micro grid,particularly facing millisecond-level transients and faults.Our experimental and theoretical investigations lay some technical bases to establish a superconductor-semiconductor-coupled interdisciplinary application from the view from the applied superconductivity,to power electronics,and to micro grids.展开更多
高温超导限流器(SFCL)是一种限制电网短路电流的有效措施,500 k V SFCL设备研制已有较大发展,对500k V SFCL接入电网系统的工程方案进行了研究,首先介绍了SFCL的工作原理,结合220 k V和35 k V SFCL投入电网的运行情况分析了SFCL的故障类...高温超导限流器(SFCL)是一种限制电网短路电流的有效措施,500 k V SFCL设备研制已有较大发展,对500k V SFCL接入电网系统的工程方案进行了研究,首先介绍了SFCL的工作原理,结合220 k V和35 k V SFCL投入电网的运行情况分析了SFCL的故障类型,接着针对500 k V SFCL的设备特点和电网要求,提出了一种主接线方案,该方案具有可靠性高,运行灵活,施工方便等特点,并给出了2个适用于不同工程环境情况下的平面布置方案。展开更多
随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速...随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速转为高阻抗,可作为配合断路器开断的理想选择,提高电力系统的运行安全性。介绍了一种磁偏置型超导故障限流器(magneto-biased superconducting fault current limiter,MBSFCL),提出了考虑短路电流非周期分量影响的MBSFCL设计方法,对于MBSFCL的制造具有一定的指导意义。通过搭建仿真模型,验证了所提出方法的可行性,并对MBSFCL的限流特性进行了深入分析,讨论了不同非周期分量对断路器的开断影响,以及MBSFCL中电感、电阻参数变化对短路电流及其分量的限流效果影响。分析结果表明,在所提出MBSFCL设计方法中必须考虑非周期分量,且MBSFCL的电阻参数变化对短路电流的抑制效果更为显著。展开更多
在建立饱和铁心型高温超导故障限流器(saturated iron-core type high temperature superconductive fault current limiters,SR-SFCL)电磁暂态仿真计算模型基础上,对电网发生短路故障后SR-SFCL一次绕组与励磁绕组的电流、电压过渡过程...在建立饱和铁心型高温超导故障限流器(saturated iron-core type high temperature superconductive fault current limiters,SR-SFCL)电磁暂态仿真计算模型基础上,对电网发生短路故障后SR-SFCL一次绕组与励磁绕组的电流、电压过渡过程进行了定量计算,深入研究了一次绕组与励磁绕组电流、电压的特征和相互关系,分析了限流器对短路电流交流分量初始值、冲击电流和稳态短路电流的限制效果。研究指出:SR-SFCL对稳态短路电流具有很好的限制作用,充分发挥限流效果的关键是缩短励磁回路的灭磁时间,灭磁时间与一次电流、灭磁电阻取值等因素关系密切。展开更多
电阻型超导限流器R-SFCL(resistive superconducting fault current limiter)在柔性直流系统中的优化配置是超导限流器应用的关键技术。通过对电阻型超导限流器在模块化多电平换流器型直流系统中的应用场景分析,得到R-SFCL不同安装位置...电阻型超导限流器R-SFCL(resistive superconducting fault current limiter)在柔性直流系统中的优化配置是超导限流器应用的关键技术。通过对电阻型超导限流器在模块化多电平换流器型直流系统中的应用场景分析,得到R-SFCL不同安装位置对其限流能力的影响,并改进了超导限流器和直流断路器配合下换流站闭锁初期的多端柔性直流系统短路电流迭代计算方法,在此基础上提出了基于人工免疫算法的R-SFCL柔性直流系统中的优化配置计算方法。最后,通过五端柔性直流系统实例研究,给出了该系统中R-SFCL的最佳安装位置、安装数量、限流电阻大小和限流效果。展开更多
文摘Protection of radial distribution networks is widely based on coordinated inverse time overcurrent relays (OCRs) ensuring both effectiveness and selectivity. However, the integration of distributed generation (DG) into an existing distribution network not only inevitably increases fault current levels to levels that may exceed the OCR ratings, but it may also disturb the original overcurrent relay coordination adversely effecting protection selectivity. To analyze the potentially adverse impact of DG on distribution system protective devices with respect to circuit breaker ratings and OCR coordination fault current studies are carried out for common reference test system under the influence of additional DG. The possible advantages of Superconducting Fault Current Limiter (SFCL) as a means to limit the adverse effect of DG on distribution system protection and their effectiveness will be demonstrated. Furthermore, minimum SFCL impedances required to avoid miss-operation of the primary and back-up OCRs are determined. The theoretical analysis will be validated using the IEEE 13-bus distribution test system is used. Both theoretical and simulation results indicate that the proposed application of SFCL is a viable option to effectively mitigate the DG impact on protective devices, thus enhancing the reliability of distribution network interfaced with DG.
基金the National Natural Science Foundation of China[Grant No.51807128].
文摘In DC micro grids and networks,DC-DC power converters having a large number of semiconductor-based power electronic devices are usually adopted to interconnect the renewable sources and flexible loads.Most of the semiconductor-based devices suffer from poor fault withstanding abilities,but conventional power electronic protection schemes have the bottlenecks of the time-delay,self-malfunction and mis-judgement.This paper presents a novel solution using the superconducting fault current limiter(SFCL)to protect a power electronic device and extend the usage to a micro grid.This SFCL is actually a self-triggering,recoverable,and passive current limiter,which does not involve any additional circuit hardware and software.Experimental investigations and simulation analyses clarify the feasibility of using this superconductor-based protection scheme to implement the self-acting fail-safe protection of DC-DC converters.Further system-level simulations explore the SFCL to suppress the over-current and stabilize the bus voltage of a photovoltaic based DC micro grid,particularly facing millisecond-level transients and faults.Our experimental and theoretical investigations lay some technical bases to establish a superconductor-semiconductor-coupled interdisciplinary application from the view from the applied superconductivity,to power electronics,and to micro grids.
文摘高温超导限流器(SFCL)是一种限制电网短路电流的有效措施,500 k V SFCL设备研制已有较大发展,对500k V SFCL接入电网系统的工程方案进行了研究,首先介绍了SFCL的工作原理,结合220 k V和35 k V SFCL投入电网的运行情况分析了SFCL的故障类型,接着针对500 k V SFCL的设备特点和电网要求,提出了一种主接线方案,该方案具有可靠性高,运行灵活,施工方便等特点,并给出了2个适用于不同工程环境情况下的平面布置方案。
文摘随着电力负荷快速增长,电力系统的故障电流水平持续上升,甚至超出了现有断路器的开断能力;为有效限制故障电流,超导故障限流器(superconducting fault current limiter,SFCL)逐渐投入应用。SFCL在正常运行时呈现零阻抗,故障发生后迅速转为高阻抗,可作为配合断路器开断的理想选择,提高电力系统的运行安全性。介绍了一种磁偏置型超导故障限流器(magneto-biased superconducting fault current limiter,MBSFCL),提出了考虑短路电流非周期分量影响的MBSFCL设计方法,对于MBSFCL的制造具有一定的指导意义。通过搭建仿真模型,验证了所提出方法的可行性,并对MBSFCL的限流特性进行了深入分析,讨论了不同非周期分量对断路器的开断影响,以及MBSFCL中电感、电阻参数变化对短路电流及其分量的限流效果影响。分析结果表明,在所提出MBSFCL设计方法中必须考虑非周期分量,且MBSFCL的电阻参数变化对短路电流的抑制效果更为显著。
文摘在建立饱和铁心型高温超导故障限流器(saturated iron-core type high temperature superconductive fault current limiters,SR-SFCL)电磁暂态仿真计算模型基础上,对电网发生短路故障后SR-SFCL一次绕组与励磁绕组的电流、电压过渡过程进行了定量计算,深入研究了一次绕组与励磁绕组电流、电压的特征和相互关系,分析了限流器对短路电流交流分量初始值、冲击电流和稳态短路电流的限制效果。研究指出:SR-SFCL对稳态短路电流具有很好的限制作用,充分发挥限流效果的关键是缩短励磁回路的灭磁时间,灭磁时间与一次电流、灭磁电阻取值等因素关系密切。
文摘电阻型超导限流器R-SFCL(resistive superconducting fault current limiter)在柔性直流系统中的优化配置是超导限流器应用的关键技术。通过对电阻型超导限流器在模块化多电平换流器型直流系统中的应用场景分析,得到R-SFCL不同安装位置对其限流能力的影响,并改进了超导限流器和直流断路器配合下换流站闭锁初期的多端柔性直流系统短路电流迭代计算方法,在此基础上提出了基于人工免疫算法的R-SFCL柔性直流系统中的优化配置计算方法。最后,通过五端柔性直流系统实例研究,给出了该系统中R-SFCL的最佳安装位置、安装数量、限流电阻大小和限流效果。