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Ke G.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Yan C.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Lin Z.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Yuanxing G.,Beibei District Supply Bureau of Chongqing Electrical Power Corporation
Proceedings of the 2011 14th European Conference on Power Electronics and Applications, EPE 2011 | Year: 2011

Aiming at the Z-source inverter used in the micro-grid and its grid-connected control research, the photovoltaic system was taken as the example. The inverter integrated three functions including MPPT (Maximum Power Point Tracking), step-up/down DC-side voltage and output grid-connected. In order to overcome the system instability caused by zero point of Z-source net in the right half-plane, the paper proposed nonlinear control method based on differential geometry theoretic, which overcomes the non-minimum phase behavior. When the input condition of the photovoltaic system changes, this control method could make the Z-source inverter DC side output track the MPP rapidly, steadily and little overshoot, and the inverting side output three-phase voltage transmit rapidly and steadily, then improved the quality of grid-connected current. The simulation contrast and experiment result proved the proposed method in the paper is correct and effective. © 2011 EPE Association - European Power Electr. Source


Liao R.-J.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Gu J.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Hao J.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Yang L.-J.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology | Ma Z.-Q.,State Key Laboratory of Transmission and Distribution Equipment and Power System Safety and New Technology
Gaodianya Jishu/High Voltage Engineering | Year: 2011

In order to understand the influence laws of copper on oil-paper insulations, thermal aging of four combinations oil-paper insulation samples at 110 °C and 130 °C was tested, where observations on #25 naphthenic oil-paper insulation and #25 paraffinic oil-paper insulation samples both in the absence and presence of copper were compared, respectively. Aging parameters including oil acidity, breakdown voltage of oil, and water content of paper were measured during the aging process. The content of copper products dissolved in oil and deposition on paper versus aging time was also analyzed. Results show that copper can increase the oil acidity and the water content of paper. The higher the temperature, the more dramatically copper influence becomes. Compared with #25 naphthenic oil, #25 paraffinic oil has higher oil acidity. The content of copper products dissolved in oil increases with aging time and then decreases. The longer the aging time, the more copper products will deposit on paper. The copper products can permeate from inner layer to the outer layer of paper. Source

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