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Basic Study on Islanding Detection Method for PV Systems by Harmonic Impedance Detection in Case of Including Induction Motor in Load System 下载免费PDF全文
YOSHIAKI YOSHIDA HIROKAZU SUZUKI KOJI FUJIWARA YOSHIYUKI ISHIHARA 《Electrical Engineering in Japan》2016,194(3):20-34
It is important that photovoltaic (PV) systems detect islanding caused by power system faults to ensure electrical safety. Thus we propose a novel islanding detection method which detects the harmonic impedance by injecting harmonic currents synchronized with the exciting current harmonics of the pole transformer. For the case in which an induction motor load is included in the load system, basic experiments on islanding detection and simulation analysis are conducted to verify the effectiveness of the proposed method. 相似文献
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For scalar quadratic optimal linear systems with a white gain coefficient, the influence of the uncertainty of the gain variance is analysed by means of elementary methods. First, the mean-square stability of the closed loop systems is analysed on the assumption that the controller is designed with an erroneous variance. It is shown that the use of an overestimated value of the variance less than a threshold value, which is infinite for the stable free systems, does not damage the stability of closed-loop systems. A relative underestimation error bound guaranteeing the stability of closed-loop systems is obtained. Secondly, performance of the controller designed with an erroneous variance is compared analytically with that of the certainty equivalence controller. An explicit relative overestimation error bound on the variance guaranteeing the superiority of the controller over the certainty equivalence controller is obtained. 相似文献
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HATSUE MORITAKA SHIGEHIRO NAITO KATSUYOSHI NISHINARI MIKI ISHIHARA HIROYASU FUKUBA 《Journal of texture studies》1998,29(4):387-396
Effects of various ingredients on the texture of milk jellies prepared from gellan gum, milk powder, sweetener were examined using a sensory test and physical measuring apparatus. The data were analyzed by use of the modification ofScheffé's mixture experiment method in rectangular experimental area in the Scheffé's triangle. "Hardness" and "smoothness" of milk jellies estimated by a subjective method were influenced by the content of gellan gum. The evaluations of "milk flavor" and "sweetness" estimated by a subjective method were varied with the content of sweetener and evaluated as higher for softer milk jellies. The correlation coefficients between "hardness" estimated by a subjective method and "smoothness", "milk flavor", and "sweetness" estimated by a subjective method were negative. 相似文献
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太阳能光伏发电系统发电量的预测方法 总被引:1,自引:0,他引:1
本文介绍太阳能光伏发电系统发电量的两种预测方法——日本工业标准中的预测方法和在模拟计算软件中使用的三维模拟计算法。 相似文献
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日本住宅用太阳能光伏发电系统介绍 总被引:1,自引:0,他引:1
本文通过介绍日本长野县Y先生住宅太阳能光伏发电系统,供业界了解日本住宅用太阳能光伏发电系统的系统设置、成本、实际发电量、卖电价格等内容。 相似文献
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MASAHIRO OGAWA JUN KANAMARU HIROKI MIYASHITA TORU TAMIYA TAKAHIDE TSUCHIYA 《Journal of food science》1995,60(2):297-299
Participation of the α-helix in setting was investigated using circular dichroism. The α-helicity of the actomyosin from eight species of fish decreased during incubation at 30°C or at 40°C. The extent and pattern of decrease differed among species. When rate of decrease was plotted vs rate of increase in strength of gel preincubated at 30°C or at 40°C, the two factors correlated closely. We propose that the unfolding of α-helix initiated setting. 相似文献
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Prediction of corrosion fatigue lives of aluminium alloy on the basis of corrosion pit growth law 总被引:1,自引:0,他引:1
S. ISHIHARA S. SAKA Z.Y. NAN T. GOSHIMA S. SUNADA 《Fatigue & Fracture of Engineering Materials & Structures》2006,29(6):472-480
Tension‐compression and rotating‐bending fatigue tests were carried out using aluminium alloy 2024‐T3, in 3% NaCl solution. The corrosion pit growth characteristics, and also the fatigue crack initiation and propagation behaviour were investigated in detail. The results obtained are summarized as follows: (i) Most of corrosion fatigue life (60–80%) is occupied with a period of corrosion pit growth at low‐stress amplitude. The corrosion pit growth law can be expressed as functions of stress amplitude σa and an elapsed time t. (ii) The critical stress intensity factor for crack initiation from the corrosion pit was determined as 0.25 . This value is the same as the threshold stress intensity factor range for crack propagation. (iii) Corrosion fatigue life can be estimated on the basis of corrosion pit growth law and crack propagation law. The estimated fatigue lives agree well with the experimental data. 相似文献
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Development of Electrolytic Capacitor Less Photovoltaic Grid Connected Inverter with Boost‐Up Type Active Buffer Circuit 下载免费PDF全文
HIROKI WATANABE KAZUHIRO KOIWA JUN‐ICHI ITOH YOSHIYA OHNUMA SATOSHI MIYAWAKI 《Electrical Engineering in Japan》2016,196(3):39-48
This paper proposes a configuration of a single‐phase voltage source inverter that features power decoupling capability. Generally, the converter connected to a single‐phase grid employs bulky dc link capacitors such as electrolytic capacitors in order to decouple the power ripple with twice the frequency of the power supply. The power ripple in the proposed circuit is compensated by an active buffer with small capacitors. In this paper, the fundamental operations of the proposed converter are confirmed by experimental results. From the experimental results, the output current total harmonic distortion (THD) is 3.51%, the ratio of the input current is 14.3%, and the output power factor is over 99%. In addition, the volume of the proposed circuit is reduced by 61% when the carrier frequency is 64 kHz compared to that with a carrier frequency of 16 kHz. Finally, from an evaluation of the power density using Pareto front curves, the proposed circuit achieves high power density in comparison with the conventional circuit. 相似文献