风电机组低压穿越中的电力电子技术(上)

Power Electronics for Low Voltage Ride-through of Wind Turbines

为了降低大规模风电并网对电力系统的影响,世界各国的电网运营商相继制定新的并网准则对并网风电场的输出特性作出严格规定,并网导则中的一项重要内容是要求风电场具有低压穿越(LVRT)能力。电力电子技术是提高风电场低电压穿越能力的重要手段,对于变速风电机组,电力电子设备已成为其标准配置,在低电压穿越过程中起到至关重要的作用;对于定速风电机组,电力电子设备是使其满足并网导则的必要部件。本文以我国并网导则为例,介绍LVRT导则对风电机组输出特性的相关要求;分析电网电压跌落对不同类型风电机组的影响;在此基础上,针对不同类型的风电机组,介绍提高其LVRT能力的电力电子技术,并对LVRT技术中当前存在的问题和未来的发展方向进行了讨论。

To mitigate the impact of large grid-connected wind farms on power systems, grid operators in many countries have developed new grid codes which strictly demand the output characteristics of wind farms. During the grid codes, an important item is that wind farms have to provide low voltage ride-through （LVRT） capability. Power electronics are playing an important role in improving the LVRT capability of wind farms. For variable speed wind turbines, power electronics devices have become inherent parts, which are of great importance for LVRT; for fixed speed wind turbines, power electronics devices are necessary in order to satisfy the grid codes. In this paper, the LVRT requirements are first introduced, taking China for example. Then, the impacts of grid voltage dips on different kinds of wind turbines are analyzed. Afterwards, the power electronics based LVRT technologies for different kinds of wind turbines are reviewed respectively. Finally, the existing problems and future trends of LVRT technologies are discussed.