【作者】 胡斗猛；

【导师】 葛立峰；

【作者基本信息】 安徽大学 ， 检测技术与自动化装置， 2010， 硕士

【摘要】 电压凹陷指电网供电电压的均方根值在短时间内突然下降的事件。作为最受关注的电能质量问题之一,电压凹陷无论是对工业用户还是对电网本身,都带来了极大的危害：从用户的角度来说,电压凹陷造成工业上广泛使用的电压敏感性仪器设备停机甚至损坏,给用户带来巨大的经济损失；从电网本身的角度来说,电压凹陷给目前备受关注的清洁能源发电并网问题带来了巨大的挑战。以风力发电为代表的清洁能源发电,在并网后其发电机组与电网之间的相互影响愈来愈显著,尤其是当电网因故障产生电压凹陷时,会给发电机组带来巨大的损害；同时,电网也需要风电机组在电压凹陷期间,能够继续保持并网,即具备低电压穿越能力,以防止风电机组解列给电网造成严重的冲击,加剧电网系统的恢复难度。本文从对电压凹陷的分析入手：首先分析了电压凹陷产生的主要原因和电压凹陷因不同故障在电网不同位置的特性,然后介绍了电压凹陷的基本分类和变压器对电压凹陷的传播,并提出了常用的电压凹陷检测方法和补偿方法。在分析电压凹陷的基础上,文章提出了风电并网的低电压穿越概念：风电机组的低电压穿越能力,指在风机并入电网后,当并网点遭遇电压凹陷,发电机仍然能够保持并网,直到电网恢复正常。并提出保护风电并网的安全,应该从两个方面入手：首先加强对电网电压凹陷的检测和补偿,减小其对风电并网的危害；其次，加强风电机组的低电压穿越能力,以期在遭遇电压凹陷时,风电机组能够继续并网运行。文章分析了电压凹陷给风电机组带来的危害,同时以双馈感应式风电机组为例,介绍了风电机组低电压穿越的方法。最后,将电压凹陷与低电压穿越结合起来,提出电压凹陷检测方法在风电机组低电压穿越中的应用,并结合我国对低电压穿越的要求,对几种检测方法进行比较,得出在何种条件下使用何种检测方法最为合理的结论。更多还原

【Abstract】 Voltage dips are short-duration reductions in voltage magnitude. As one of the most concerned issues in power quality, voltage dip has done tremendous harm to both users and power grid. To users, it may cause halts or damages for those voltage-sensative equipments that are widly-used in industury, which will bring about great finacial losses; To the power grid itself, it has made a huge challenge the grid-connection of clean energy generation, which has gained increasing concerns nowadays.When wind power generation, as the representative of clean energy generation, is put into the mode of grid-connected generation, the mutual influence between the grid and the wind turbine is to be more and more prominent, especially when the voltage dip appears because of the hitch of the grid, which will do enomorous harm to the turbines; meanwhile, the wind turbine, during the period of voltage dip, is required to keep in grid-connection, i.e. the function of LVRT, in case of the surge to the grid caused by disconnection of the wind turbine, which will increase the difficulty of recovering the grid system.Starting from the analysis of the voltage dip, the present thesis firstly analyzes the causes and features of voltage dip at different positions of the grid caused by different hithes, and secondly introduces the types of voltage dip and its transmission in the grid done by the transformers; Last but not the least, the thesis puts forward the approches of testing and compensation the voltage dip. On the basis of the analysis of the voltage dip, the present thesis puts forward the notion-LVRT of grid-connetion of the wind power generation:the ability of the LVRT of grid-connetion of the wind turbine refers to the situation when the wind turbine merges into the state grid and the grid experiences the voltage dip, the generator still keeps grid-connetion of wind generation till normal. And claims that the protection of it should be from two aspects-first, the testing and the compensation of the voltage dip in the gid have to be strengthened in order to reduce the harm towards the grid-connection; Second, the fuction of wind turbine’s LVRT should be strengthened to make the turbines keep working for the grid-connection in face of the voltage dip.The present thesis analyzes the harm to the wind turbines brought by the voltage dip, and uses "the dubly-fed-induction wind turbine" as the example to introduce the transient characteristic of the wind turbine’s being in the period of voltage dip. Finally, by using the method of putting together the voltage and the LVRT, the author puts forward the application of test of the voltage dip to LVRT, and by comparing different testing methods according the national requirements on LVRT, the author draws the conclusion that how to apply the most approperiate method of testing according to different curcumstances.更多还原