风力机控制建模及仿真研究

The Control Modeling & Its Simulation Research on Wind Turbines

考虑到化石燃料的枯竭及其带来的环保问题,风能因其廉价、环保、可再生,而被认为是目前世界上最具发展潜力的新能源。由于风能能量密度低,风能利用效率的提高成为目前风力发电面临的一个急待解决的问题。通过对风力机的运行状态进行调节可以改变风力机的输出功率,使风力机运行在不同状态时都能够最大限度的输出功率,从而实现风能的有效利用。本文以研究双馈式异步风力发电机发电原理为目的,重点研究风力机的工作原理。通过研究风力机各个参数的物理意义及之间的关系,推导出风力机输出功率与风速,叶尖速比,发电机转速及桨距角之间的关系。通过研究风力机的运行过程,推导出桨距角的控制原理及实现,并给出任意风速下的风力机运行状态。目前控制风力机输出功率的方法主要有两种,一种是基于风力机输出功率与风速之间的关系建立起来的;另一种是基于风力机输出功率与转速之间的关系建立起来的。本文对这两种方法进行分析,从实际角度指出这两种方法的不足之处,并做出了基于功率-转速关系将风力机的运行过程四分段的假设。以某风场G58-850KW风力机为例,通过已知数据对理论推导进行验证,结果表明基于功率-转速关系的四分段假设是完全可行的。通过对G58-850KW风力机进行PSCAD仿真,实现风速连续变化时风力机各个参数的连续输出,为双馈式异步风力发电机的研究提供了可靠的数据来源。

In view of fossil fuel’s drying up and its inherent contaminant to the environment,wind energy has become one of the fastest growing and effective energy source,for it is abundant,secure,clean and renewable. In consideration of the low density of wind energy,the exaltation of the efficiency of wind energy has become a problem which is urgently needed to resolved for wind power generation. The output power of the wind turbine can be changed by the regulation of the running status of the wind turbine,which can remain the output power maximum when the different conditions,and realize the most valid exploitation of the wind energy .This paper is in the purpose of studying the principle of generating electricity of the doubly-fed induction generators for wind turbines,and studying the work principle of the wind turbine as a key. By researching the physical meaning and the relations of each parameter of the turbine,the relations between the output power of the turbine,wind speed,tip speed ratio,rotational speed of the machine and the pitch angle can be deduced. By researching the running process of the turbine,the controlling principle and movement process of the pitch angle can be deduced,and the running status of the turbine can be known at arbitrary wind speed. At present there are two main kinds of methods to control the output power of wind turbine,one is established based on the relation between the output power of the turbine and the wind speed;Another is established based on the relation between the output power of the turbine and the rotational speed of the machine. This paper carries on the analysis to these two kinds of methods,points out the shortages from the actual angle,and makes the assumption of four segments of the running process of the turbine based on the relation between the power and rotational speed. Taking the G58-850KW turbine as an example,the deduction in theory can be verified by the known datum,and the result enunciates that the method of the four segments based on the relation between the power and rotational speed is completely feasible.Through simulate the G58-850KW turbine in PSCAD,the continuous output of each parameter of the turbine can be realized with the continuous variety of the wind speed. And the dependable datum can be provided for the doubly-fed induction generators for wind turbines.