过电压是威胁电缆线路安全的重要因素。由于海底长电缆线路的高电容特性,可能产生较为严重的过电压。结合工程实际,基于ATP-EMTP对两种典型的海上风电场及其输电的220 k V海底长电缆线路进行建模,并对海缆参数进行修正,对不同系统容量...过电压是威胁电缆线路安全的重要因素。由于海底长电缆线路的高电容特性,可能产生较为严重的过电压。结合工程实际,基于ATP-EMTP对两种典型的海上风电场及其输电的220 k V海底长电缆线路进行建模,并对海缆参数进行修正,对不同系统容量、不同长度、不同电缆类型下的海底电缆线路的工频过电压及2%统计合闸过电压进行仿真计算,同时计算了断路器发生一次重燃的分闸过电压。结果发现,在仅配置避雷器的情况下就能将操作过电压抑制在安全范围内,决定海底长电缆线路绝缘水平的主要因素是工频过电压。展开更多
For the planning,operation and control of multiterminal voltage source converter(VSC)based high-voltage direct current(HVDC)(VSC-MTDC)systems,an accurate power flow formulation is a key starting point.Conventional pow...For the planning,operation and control of multiterminal voltage source converter(VSC)based high-voltage direct current(HVDC)(VSC-MTDC)systems,an accurate power flow formulation is a key starting point.Conventional power flow formulations assume the constant frequencies for all asynchronous AC systems.Therefore,a new feature about the complex coupling relations between AC frequencies,DC voltages and the exchanged power via VSC stations cannot be characterized if VSC-MTDC systems are required to provide cross-regional frequency responses.To address this issue,this paper proposes a comprehensive frequency-dependent power flow formulation.The proposed approach takes the frequencies of asynchronous AC systems as explicit variables,and investigates the novel bus models of the interlinking buses of VSC stations.The proposed approach accommodates different operation modes and frequency droop strategies of VSC stations,and considers the power losses of VSC stations.The effectiveness and generality of the developed approach are validated by a 6-terminal VSC-HVDC test system.The test system presents the characteristics of the coexistence of numerous VSC operation modes,the absence of slack buses in both AC and DC subsystems,and diversified grid configurations such as point-to-point integration of renewable energy sources and one AC system integrated with multiple VSC stations.展开更多
基于短时傅里叶变换(short time Fourier transform,STFT)算法的布里渊光时域反射仪(Brillouin optical time domain reflectometer,BOTDR)可实现快速温度检测,但存在频率泄漏和栅栏效应,导致测温精度较差。针对上述问题,在搭建STFT-BO...基于短时傅里叶变换(short time Fourier transform,STFT)算法的布里渊光时域反射仪(Brillouin optical time domain reflectometer,BOTDR)可实现快速温度检测,但存在频率泄漏和栅栏效应,导致测温精度较差。针对上述问题,在搭建STFT-BOTDR测温系统的基础上,通过窗函数和运算点数优化,抑制了STFT算法所引发的频率泄漏,实现了STFT-BOTDR测温精度提升。实验中设置时域窗口长度为1.6 m,窗口滑动步进为0.5 m,对比了不同窗函数与运算点数下的测量精度。结果表明,当采用汉宁窗且运算点数为1024时,可实现9.6 km光纤末端温度变化的准确检测与定位,误差为1.012℃;测量精度为±2.5 MHz。而未采用窗函数时测量精度为±12.5 MHz,无法实现温度变化准确测量。研究结果为STFT-BOTDR温度检测系统精度优化提供了借鉴。展开更多
基于FPGA的运动控制卡采用脉冲加方向的闭环控制方式,具有结构简单,集成度高、实时性好等优点。从硬件的构成、设计和算法实现等方面入手,阐述了运动控制卡的设计和开发。用硬件描述语言VHDL(very high speed integrated circuitHDL)和...基于FPGA的运动控制卡采用脉冲加方向的闭环控制方式,具有结构简单,集成度高、实时性好等优点。从硬件的构成、设计和算法实现等方面入手,阐述了运动控制卡的设计和开发。用硬件描述语言VHDL(very high speed integrated circuitHDL)和原理图结合的方式对FPGA编程实现系统的主要硬件逻辑和算法,从而提高了系统的灵活性和移植性。在硬件算法上,采用乒乓操作处理高速的分频倍数数据流,提高了系统的实时性和控制精度;并且提出了一种基于加二计数器的分频算法,实现任意分频倍数的分频。利用嵌入式调试工具SignalTap对运动控制卡进行硬件调试和仿真,给出了相应的误差分析。展开更多
文摘过电压是威胁电缆线路安全的重要因素。由于海底长电缆线路的高电容特性,可能产生较为严重的过电压。结合工程实际,基于ATP-EMTP对两种典型的海上风电场及其输电的220 k V海底长电缆线路进行建模,并对海缆参数进行修正,对不同系统容量、不同长度、不同电缆类型下的海底电缆线路的工频过电压及2%统计合闸过电压进行仿真计算,同时计算了断路器发生一次重燃的分闸过电压。结果发现,在仅配置避雷器的情况下就能将操作过电压抑制在安全范围内,决定海底长电缆线路绝缘水平的主要因素是工频过电压。
基金supported by the National Key Research and Development Program of China(No.2017YFB0902200)National Natural Science Foundation of China(No.U1766201)State Grid Technology Project(No.SGGSKY00FJJS1600209)。
文摘For the planning,operation and control of multiterminal voltage source converter(VSC)based high-voltage direct current(HVDC)(VSC-MTDC)systems,an accurate power flow formulation is a key starting point.Conventional power flow formulations assume the constant frequencies for all asynchronous AC systems.Therefore,a new feature about the complex coupling relations between AC frequencies,DC voltages and the exchanged power via VSC stations cannot be characterized if VSC-MTDC systems are required to provide cross-regional frequency responses.To address this issue,this paper proposes a comprehensive frequency-dependent power flow formulation.The proposed approach takes the frequencies of asynchronous AC systems as explicit variables,and investigates the novel bus models of the interlinking buses of VSC stations.The proposed approach accommodates different operation modes and frequency droop strategies of VSC stations,and considers the power losses of VSC stations.The effectiveness and generality of the developed approach are validated by a 6-terminal VSC-HVDC test system.The test system presents the characteristics of the coexistence of numerous VSC operation modes,the absence of slack buses in both AC and DC subsystems,and diversified grid configurations such as point-to-point integration of renewable energy sources and one AC system integrated with multiple VSC stations.
文摘基于FPGA的运动控制卡采用脉冲加方向的闭环控制方式,具有结构简单,集成度高、实时性好等优点。从硬件的构成、设计和算法实现等方面入手,阐述了运动控制卡的设计和开发。用硬件描述语言VHDL(very high speed integrated circuitHDL)和原理图结合的方式对FPGA编程实现系统的主要硬件逻辑和算法,从而提高了系统的灵活性和移植性。在硬件算法上,采用乒乓操作处理高速的分频倍数数据流,提高了系统的实时性和控制精度;并且提出了一种基于加二计数器的分频算法,实现任意分频倍数的分频。利用嵌入式调试工具SignalTap对运动控制卡进行硬件调试和仿真,给出了相应的误差分析。
