摘要
太阳辐射与地球自转是风能的源泉,也决定了风能的复杂性。太阳辐射引起风的周期性季节变化,同时风还受到地形和障碍物的多重影响。因而风能是极其不稳定的资源,加大了估测和利用的难度。然而常规能源以煤、石油、天然气为主,他们不仅资源有限,而且造成了严重的大气污染。因此,对可再生能源的开发利用,特别是对风能的开发利用已受到世界各国的高度重视。
本文主要研究如何使风能最大效率的转化为电能,其中包括两方面：一是风机部分,完成由风能到机械能的转换；二是发电机部分,完成由机械能到电能的转换,及控制风机转速实现最大功率吸收。根据贝兹理论当风机转速与风速成最佳叶尖速比时功率利用系数可达设计数值,因而控制叶尖速比成为提高风能利用效率的关键。
爬山算法以其实现方法简单(既不需要测量风速也不需要测量风机机械功率特性)占据了最大风能捕捉的主要地位。为了缩短爬山算法的计算周期,提高直驱永磁风力发电系统最大风能捕捉的响应速度,提出一种优化爬山算法。该算法在变步长爬山算法盲目搜索的基础上添加数据存储输出功能,构造了与电机转速对应的最大输出功率表,避免重复的计算,同时结合功率反馈控制来实现系统最大功率追踪
最后用SIMULINK仿真工具建立了永磁风力发电系统的仿真模型,介绍了PI参数的调节,分别运用了最佳电流给定爬山算法和最佳功率给定爬山算法对系统进行最大功率跟踪仿真,并与传统爬山算法进行对比,证明了本文提出的爬山算法响应速度和稳定性远远超过传统爬山算法,能适应变速恒频风力发电的最大风能捕获。
Wind power come from both the sun power and earth rotation, which reflect on it complexity. The sun makes the wind change seasonal, and the wind is reflected by the landform and obstacle. So it is variable, and hard to estimate or use. Conventional energy are coal oil and natural gas. It is not only restricted, but also causing serious air pollution. Therefore, the utilization of renewable energy especially wind power development is regarded by many country in the world.
This paper focus on how to convert the wind power to electricity mostly, which include both side:firstly, turbine side which realize the conversation from wind power to machine power; secondly, generator side, which realize the conversation from machine power to electricity, and control the turbine speed to absorb the maximum wind power. The power use coefficient reach the decide value when the turbine speed and the wind speed achieve the optimal ratio, according to the Betz theory. Therefore, how to control the turbine speed is the key.
Hill climb search algorithm does need the wind speed or the turbine characteristic to realize maximum power capture, therefore are widely used in wind power generation. An optimized hill-climb search based on power-perturbation was brought forward to shorten the algorithm period, which advanced the maximum wind power capture response speed of the direct-drive permanent magnet wind power generation (D-PMSG). The algorithm added in data storage and output function and formed an updated Max-Power work table related to the motor speed to avoid repeated HCS based on variable step hill-climb search (HCS).Which, was also integrated with power fed back control to track the Max-Power.
At last, set up the wind power system model by SIMULINK tool, introduce how to adjust PI parameter, use both optimal current enactment HCS and optimal power enactment HCS strategy to realize maximum power absorb. The optimal power enactment HCS strategy this paper mentioned is proved more efficiency and reliable than the tradition maximum power control algorithm.
引文
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