Low voltage ride through (LVRT) capability has become more and more an issue for newly integrated wind turbines. The LVRT programs described in this paper developed field tests for newly installed wind turbines on win...Low voltage ride through (LVRT) capability has become more and more an issue for newly integrated wind turbines. The LVRT programs described in this paper developed field tests for newly installed wind turbines on wind farms in Northeast China. It is therefore different from other papers that only validate LVRT control strategies through running computer software simulations. To examine a single wind turbine's LVRT capability, the wind turbine's terminal voltage dip was realized by using a grid voltage dip emulator, which was located on the 690 V side of the generator transformer. In this paper, by artificially making various grid faults, the dynamic behavior of DFIG and PMSG wind turbines are analyzed and compared, control strategies such as active/passive crowbar and chopper protection schemes are verified, and new active/reactive power compensation methods are investigated and compared.展开更多
The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scal...The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength;while, the <111> sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.展开更多
文摘Low voltage ride through (LVRT) capability has become more and more an issue for newly integrated wind turbines. The LVRT programs described in this paper developed field tests for newly installed wind turbines on wind farms in Northeast China. It is therefore different from other papers that only validate LVRT control strategies through running computer software simulations. To examine a single wind turbine's LVRT capability, the wind turbine's terminal voltage dip was realized by using a grid voltage dip emulator, which was located on the 690 V side of the generator transformer. In this paper, by artificially making various grid faults, the dynamic behavior of DFIG and PMSG wind turbines are analyzed and compared, control strategies such as active/passive crowbar and chopper protection schemes are verified, and new active/reactive power compensation methods are investigated and compared.
基金financially supported by the State Grid Corporation of China (No. 52110416001z)the National Natural Science Foundation of China (No. 51331007)
文摘The trade-off relation between the strength and the electrical conductivity has been a Iong-standing dilemma in metallic materials. In the study, three key principles, i.e.elongated grains, sharp texture and nano-scale precipitates, were presented for preparing Al wire with high strength and high electrical conductivity based on the specially designed experiments for breaking the mutually exclusive relation between the strength and the electrical conductivity. The results show that the elongated grains could lead to a higher electrical conductivity in Al wire without sacrificing the strength;while, the <111> sharp texture can efficiently strengthen the Al wire without influencing the electrical conductivity. Furthermore, nano-scale precipitates with proper size can simultaneously improve the strength and electrical conductivity of Al alloy wire. Under the guidance of the above three key principles, Al wires with high strength and high conductivity were prepared.
