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This paper studies and analyzes the power-quality measurement results due to the special operating characteristics of the wind turbines of a commercial onshore wind farm connected to the power grid of Taiwan Power System when Typhoon Matmo passed through Taiwan. This Kuan-Yuan onshore wind farm of 28.5 MW with 19 1.5-MW wind-turbine generator (WTG) based on doubly fed induction generator is connected to Kuan-Yin primary substation through two of four step-up main transformers of 161/69 kV, 200 MVA. The measured data were recorded from July 22, 2014 to July 29, 2014 for total seven days. During the measurement period, Typhoon Matmo just passed through Taiwan and the 19 WTGs were forced to stop. The power-quality measurement results due to the special operating characteristics of the wind turbines of the studied Kuan-Yuan wind farm subject to Typhoon Matmo were also recorded and studied. According to the measured results, the power quality of the studied Kuan-Yuan onshore wind farm during the measurement period can meet the grid code of Taiwan Power Company except the voltage flicker of ΔV10. The relationships of the recorded times and dates between the measured electrical quantities and power-quality results of the studied onshore wind farm and the Typhoon Matmo passed through Taiwan are also discussed. [ABSTRACT FROM AUTHOR]

The U-V or V-V winding connections of two single-phase distribution transformers are widely utilized in distribution systems to deliver power to various three-phase and/or single-phase loads. Such special winding connections of distribution transformers can cause three-phase voltage unbalance in distributions systems, which could also lead to unexpected trip of ground relay, extra power losses on distribution-system lines, reduced operating efficiency of induction-motor loads, etc. This paper proposes a distribution static synchronous compensator (D-STATCOM) to effectively improve the voltage unbalance of a distribution system connected with a microgrid system. The studied microgrid system contains various renewable-energy resources, a diesel-engine generator, and three distribution transformers with U-V and/or V-V winding connections. The simulation results show that the proposed D-STATCOM with the designed controller can effectively reduce voltage unbalance of the distribution system connected with the studied microgrid system when the distribution transformers have U-V and/or V-V winding connections. [ABSTRACT FROM PUBLISHER]

In this paper, two transparent thin-film transistors (TFTs) with distinct channel designs were fabricated. The first was a single-channel TFT (SC-TFT) with a typical 50-nm-thick amorphous indium–gallium–zinc oxide (a-IGZO) layer, and the second was a sandwich composite-channel TFT (CC-TFT) comprising three layers of 10-/30-/10-nm-thick Ti-doped GaZnO (GTZO)/a-IGZO/GTZO. In the CC-TFT, the bottom GTZO thin film in the composite channel exhibited a highly smooth surface, serving as a buffer template for superior IGZO channel layer thin-film growth. The top GTZO thin film had a high carrier concentration and served as both a carrier supplement and passivation layer for reducing the adsorption of moisture and oxygen molecules. The studies of material quality indicated that the CC-TFT exhibited improved a-IGZO thin-film quality; relative to the SC-TFT, the oxygen vacancy concentration of the composite structure was reduced from 25.1% to 18.2%. The CC-TFT demonstrated a high level of device performance, exhibiting an excellent field-effect mobility of 14.1 cm2/ \textV\,\cdot \, \texts , subthreshold swing of 0.33 V/decade, off current of 2.92 \times 10^-12 A, threshold voltage of 1.7 V, and on–off current ratio of 3.95 \times 10^7 . Stable device operation with nearly unaltered device characteristics was observed following a bias-stress test. [ABSTRACT FROM PUBLISHER]

The device performances of an amorphous indium gallium zinc oxide transparent thin-film transistor (a-IGZO TFT) were improved by using a Ti-doped GaZnO (GTZO) as the channel capping layer in this study. The GTZO thin film exhibited a high carrier concentration of \text1.5 \times \text10 ^21 \textcm ^- 3 and served as both a carrier supplement and passivation layer for reducing the absorption of oxygen and moisture as well as the back-channel charge trapping in the composite-channel TFT. An enhanced carrier mobility with high electron concentration in the composite GTZO/IGZO heterostructure was verified in the Hall measurement. The GTZO/IGZO composite-channel TFT was demonstrated to show an improved carrier mobility of 15.5 cm2/V-s, subthreshold swing of 0.35 V/decade, off current of 1.4 \times 10^- 11 A, threshold voltage of 1.4 V, and on/off current ratio of 1.2 \times 10 ^7 . Stable operation with unchanged device characteristics was observed following a bias-stress test. Thus, the fabricated GTZO/IGZO TFTs exhibited advantageous device performance and improved device operation stability. [ABSTRACT FROM PUBLISHER]