电力系统具有良好的稳定性是保证电网正常运行的关键,充分应用Power World Simulator电力系统仿真软件对我国西北某地区实际电网进行安全稳定性分析。根据给定的实际电网运行数据搭建电网模型并进行潮流计算,将潮流计算结果与静态安全...电力系统具有良好的稳定性是保证电网正常运行的关键,充分应用Power World Simulator电力系统仿真软件对我国西北某地区实际电网进行安全稳定性分析。根据给定的实际电网运行数据搭建电网模型并进行潮流计算,将潮流计算结果与静态安全理论相结合,对该地区电网模型进行N-1静态安全性分析。针对线路负载率过高以及节点母线电压越限的情况,提出解决措施以达到提高电网运行稳定性的目的。展开更多
Our purpose in this study was to present a method for estimating the specific loss power (SLP) in magnetic hyperthermia in the presence of an external static magnetic field (SMF) and to investigate the SLP values esti...Our purpose in this study was to present a method for estimating the specific loss power (SLP) in magnetic hyperthermia in the presence of an external static magnetic field (SMF) and to investigate the SLP values estimated by this method under various diameters (D) of magnetic nanoparticles (MNPs) and amplitudes (H<sub>0</sub>) and frequencies (f) of an alternating magnetic field (AMF). In our method, the SLP was calculated by solving the magnetization relaxation equation of Shliomis numerically, in which the magnetic field strength at time t (H(t)) was assumed to be given by , with H<sub>s</sub> being the strength of the SMF. We also investigated the SLP values in the case when the SMF with a field-free point (FFP) generated by two solenoid coils was used. The SLP value in the quasi steady state (SLP<sub>qss</sub>) decreased with increasing H<sub>s</sub>. The plot of the SLP<sub>qss</sub> values against the position from the FFP became narrow as the gradient strength of the SMF (G<sub>s</sub>) increased. Conversely, it became broad as G<sub>s</sub> decreased. These results suggest that the temperature rise and the area of local heating in magnetic hyperthermia can be controlled by varying the H<sub>s</sub> and G<sub>s</sub> values, respectively. In conclusion, our method will be useful for estimating the SLP in the presence of both the AMF and SMF and for designing an effective local heating system for magnetic hyperthermia in order to reduce the risk of overheating surrounding healthy tissues.展开更多
大规模风电并网导致宽频谐振问题日渐凸显,业内多认为电缆电容效应、控制器参数变化等是导致谐振的主要因素,而关于静止无功发生器(static var generator, SVG)、风功率变化与高频谐振内在因果关系研究尚未展开。针对低风速风场系统高...大规模风电并网导致宽频谐振问题日渐凸显,业内多认为电缆电容效应、控制器参数变化等是导致谐振的主要因素,而关于静止无功发生器(static var generator, SVG)、风功率变化与高频谐振内在因果关系研究尚未展开。针对低风速风场系统高频谐振问题,首先基于谐波线性化理论,考虑功率外环作用,建立SVG和双馈风机(doubly-fed induction generator, DFIG)的序阻抗模型。其次将风速变化纳入风机变流器建模,并建立空载电缆投入时风速变化与SVG阻抗的联系。然后利用阻抗交互揭示风机变流器阻抗变化对SVG阻抗特性的影响机理,指出区域内空载电缆投入后,低风速不仅降低系统在高频的鲁棒性,而且扩大了SVG高频负阻尼范围,导致系统高频谐振风险增加。最后,基于STARSIM-HIL搭建含SVG的双馈风场电磁仿真模型,并进行软硬件在环实验。实验结果证明了理论分析的正确性。展开更多
通过对现有功耗测试仪的检测原理和高速电力载波(High Speed Power Line Communication,HPLC)单元的组网特性进行分析,针对HPLC所采用的正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)进行深入研究,结合实际应用情...通过对现有功耗测试仪的检测原理和高速电力载波(High Speed Power Line Communication,HPLC)单元的组网特性进行分析,针对HPLC所采用的正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)进行深入研究,结合实际应用情况,基于峰值采集技术和设定阈值法,通过对电流电压进行AD采样,分析所发送报文长度,确定电流曲线的特性,捕捉其动态分量,经曲线拟合、数据处理后,获得该通信单元的工作状态,并提出了优化方案。该方案根据HPLC传输原理OFDM的传输特性,确定了动态功耗所持续时间,从而避免了功耗测试仪的错误判断。通过对本地通信单元中央协调器(Central Coordinator,CCO)的检测,验证了该方案的准确性和有效性。展开更多
文摘电力系统具有良好的稳定性是保证电网正常运行的关键,充分应用Power World Simulator电力系统仿真软件对我国西北某地区实际电网进行安全稳定性分析。根据给定的实际电网运行数据搭建电网模型并进行潮流计算,将潮流计算结果与静态安全理论相结合,对该地区电网模型进行N-1静态安全性分析。针对线路负载率过高以及节点母线电压越限的情况,提出解决措施以达到提高电网运行稳定性的目的。
文摘Our purpose in this study was to present a method for estimating the specific loss power (SLP) in magnetic hyperthermia in the presence of an external static magnetic field (SMF) and to investigate the SLP values estimated by this method under various diameters (D) of magnetic nanoparticles (MNPs) and amplitudes (H<sub>0</sub>) and frequencies (f) of an alternating magnetic field (AMF). In our method, the SLP was calculated by solving the magnetization relaxation equation of Shliomis numerically, in which the magnetic field strength at time t (H(t)) was assumed to be given by , with H<sub>s</sub> being the strength of the SMF. We also investigated the SLP values in the case when the SMF with a field-free point (FFP) generated by two solenoid coils was used. The SLP value in the quasi steady state (SLP<sub>qss</sub>) decreased with increasing H<sub>s</sub>. The plot of the SLP<sub>qss</sub> values against the position from the FFP became narrow as the gradient strength of the SMF (G<sub>s</sub>) increased. Conversely, it became broad as G<sub>s</sub> decreased. These results suggest that the temperature rise and the area of local heating in magnetic hyperthermia can be controlled by varying the H<sub>s</sub> and G<sub>s</sub> values, respectively. In conclusion, our method will be useful for estimating the SLP in the presence of both the AMF and SMF and for designing an effective local heating system for magnetic hyperthermia in order to reduce the risk of overheating surrounding healthy tissues.
文摘通过对现有功耗测试仪的检测原理和高速电力载波(High Speed Power Line Communication,HPLC)单元的组网特性进行分析,针对HPLC所采用的正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)进行深入研究,结合实际应用情况,基于峰值采集技术和设定阈值法,通过对电流电压进行AD采样,分析所发送报文长度,确定电流曲线的特性,捕捉其动态分量,经曲线拟合、数据处理后,获得该通信单元的工作状态,并提出了优化方案。该方案根据HPLC传输原理OFDM的传输特性,确定了动态功耗所持续时间,从而避免了功耗测试仪的错误判断。通过对本地通信单元中央协调器(Central Coordinator,CCO)的检测,验证了该方案的准确性和有效性。