改进滑模极值搜索控制在风能转换系统最大功率追踪的应用

Application of Improved Sliding Mode Extremum Seeking Control in MPPT of Wind Energy Conversion System

针对传统的滑模极值搜索控制算法在永磁风能转换系统的最大功率追踪过程中存在稳态振荡、突变风速下跟随性差的问题,提出了无稳态振荡的改进滑模极值搜索控制算法。为改善追踪精度,导出了直流侧参考电压稳态振幅与算法参数间的数学关系,并对其进行优化。采用无需载波就可以直接产生开关信号的功率滑模控制器来改善系统的跟随性,免去了风能转换系统传统PI控制器中的参数调整过程。最后,以MATLAB为平台搭建了小型永磁风能转换系统,证实了所提方法的有效性和实用性。

Considering that the problems of steady oscillations and poor followability at step wind speed occur in the maximum power point tracking(MPPT)process of permanent magnet wind energy conversion system(WECS)when using the traditional sliding mode extremum seeking control(SMESC)algorithm,an improved SMESC algorithm is proposed,which eliminates the steady-state oscillations.To improve the tracking accuracy,the mathematical relation between the steady-state amplitude of the DC-side reference voltage and the parameters of the algorithm is deduced and optimized further.In addition,a sliding mode power controller,which can generate the switching signal directly without a carrier signal,is implemented to improve the followability of WECS.In this way,the process of parameter adjustment in the traditional PI controller of WECS is eliminated.Finally,the validity and practicability of the proposed algorithm are verified through a small-scale permanent magnet WECS built in MATLAB.