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931.
Wei‐Tzer Huang Kai‐Chao Yao Chun‐Ching Wu 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(Z1):S34-S41
The calculation of the magnitudes and phase angles of the bus voltage is a challenging task in real‐time applications for power systems. Voltage profile, which denotes the present conditions of a power system, is determined by executing the traditional AC power flow program or by searching the supervisory control and data acquisition system. The AC power flow program is not suitable for several real‐time applications, such as contingency analysis and security control calculations, because of its complexity and convergence problems. Fast computation is the major concern in such applications. In this paper, a new method based on sensitivity factors, referred to as Jacobian‐based distribution factors (JBDFs), is proposed for calculating the magnitudes and phase angles of bus voltages. This method requires setting up JBDFs and deriving optimal solution paths of bus voltage for non‐swing buses through dynamic programming under base‐case loading conditions. Under real‐time conditions, the proposed method initially calculates real and reactive power line flows via JBDFs, and then computes the voltage magnitudes and phase angles of non‐swing buses through the derived optimal solution paths. The excellence of the proposed hybrid calculation method is verified by IEEE test systems. Simulation results demonstrate that the proposed method exhibits fast computation and high accuracy. Thus, the method is suitable for real‐time applications. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
932.
Chawasak Rakpenthai Sermsak Uatrongjit 《IEEJ Transactions on Electrical and Electronic Engineering》2015,10(Z1):S19-S27
This paper presents a new hybrid state estimation method based on the concept of pseudo‐voltage measurements for a power system containing both conventional and synchronizing phasor measurements. Actual measurement data is employed to calculate the magnitude and phase of the pseudo‐voltage. In the proposed formulation, the measurement matrix describing the relations between the measured data and the state variables contains only 0 or 1. Then the state estimation problem is formulated based on the weighted least‐squares criterion, and its solution can be obtained without using iterative procedures. Comparisons with previous hybrid state estimation methods have been performed on IEEE 14‐bus, 57‐bus, and 118‐bus systems. Numerical experimental results indicate that the proposed approach yields solutions of comparable accuracy with other methods but with shorter computation times. Moreover, the proposed method also provides superior results in the presence of bad data. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
933.
One way of sustaining fuel cell technology is using renewable and sustainable energy means provided by biomass. This article explores switchgrass and poplar in a molten carbonate electrolyte direct carbon fuel cell. It investigates their electrochemical conversions and provides results of power density, current density, open circuit voltage (OCV) and other parameters. The biomasses were pyrolysed at 800°C to produce carbon fuels. Biomass carbon fuels were mixed with molten carbonate and subjected to different operating conditions (600–800°C) in the fuel cell. The electrochemical performances of the poplar fuel were better than those experienced with switchgrass fuel. At 800°C the OCV of poplar fuel (1.08?V) has higher output than switchgrass (0.87?V). The peak power density recorded for poplar fuel was 23.91?mW/cm2 while switchgrass fuel was lower at 21.60?mW/cm2. Poplar fuel (81.53?mA/cm2) gave a maximum current density with switchgrass fuel lower at 74.00?mA/cm2. 相似文献
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937.
分析民用10 kV 变配电系统中的过电压保护,对无间隙氧化锌避雷器的保护原理、设置原则、参数选择进行阐述。以10 kV 小电阻接地系统与经消弧线圈接地系统的避雷器选择为例,阐述避雷器参数的选型。 相似文献
938.
阐述三相四线配电回路中中性线中断("断零")引发的诸多电气危害,介绍国际上和国内对防"断零"危害的不同措施。作者赞同国际电工标准采取多种措施避免"断零"的发生,从根本上杜绝"断零"引发诸多电气危害的对策。对我国有关规范以过欠压防护电器防范"断零"的规定提出质疑。 相似文献
939.
将模糊控制与PI控制相结合,应用于双馈式风机网侧变换器控制中。采用外环电压模糊PI控制、内环电流控制的双闭环控制系统来克服运行时发电机参数发生变化带来的干扰。在Matlab/Simulink中搭建仿真模型进行仿真,结果表明:该方法在运行过程中可以很好地克服风速和电机参数变化的影响,定子端电压的波形、幅值、频率均达到并网要求,谐波含量少。 相似文献
940.
针对T型三电平逆变器在低电压穿越时存在的损耗分布不均,从而影响逆变器的可靠运行的问题,首先在T型三电平逆变器的损耗模型和热传递模型基础上,分析并比较了三电平逆变器在正常运行与低电压穿越时损耗分布和热应力,提出了一种适应低电压穿越的调制策略,通过合理分配冗余矢量,转移中间管的损耗,从而避免中间管过温而导致失效;然后,针对低电压故障和电压恢复过程中的存在三电平逆变器中点电压不均问题,改进了调制方式,通过在三电平逆变器低电压穿越的全过程,既实现了逆变器的损耗均匀分布,又减小中点电压的不平衡。最后,在250 k W的T型三电平光伏逆变器上进行了低电压穿越的实验验证。 相似文献