基于谐波提取技术的风机频率自适应研究

Research on frequency adaptive of fans based on harmonic extraction technology

为解决风机受谐波干扰引起电压畸变和频率波动从而影响风机并网稳定运行的问题,提出频率自适应锁相方法,以谐波提取电路为基础,设计具有滤除风机谐波功能的NSOGI (new second-order generalized integrator)锁相环。首先,在谐波提取电路中加入基波谐振电路,验证谐波提取前后锁相环的锁频精度;其次,在传统锁相环基础上加入直流抑制器,对输入信号的频率进行跟踪;最后,进行理论和仿真分析,对比DSOGI-FLL谐波提取前后电路中的频率偏差,验证2种锁相环的锁频精度。结果表明:在谐波提取电路中加入基波谐振电路,减少了谐波对基波源的影响,提升了谐波提取的效果;在抑制风机电压畸变和直流谐波方面,NSOGI锁相环效果较好,锁频精度较高,验证了方法的可行性和正确性。采用NSOGI对电压和频率进行控制,能够提升供电可靠性,改善并网电能质量,为风机并网稳定运行提供了理论参考。

In order to solve the problem of voltage distortion and frequency fluctuation caused by harmonic interference of wind turbines which affects the stable operation of wind turbines connected to the grid, a frequency adaptive phase lock methodwas proposed.Based on the harmonic extraction circuit, the NSOGI(new second-order generalized integrator) phase locked loop was designed.Firstly, the fundamental resonance circuit was added to the harmonic extraction circuit to verify the frequency locking accuracy of the phase-locked loop before and after the harmonic extraction.Secondly, a DC suppressor was added to the traditional phase-locked loop for tracking the frequency of the input signal.Finally, the theoretical and simulation analysis were conducted and the frequency deviation in the circuit before and after DSOGI-FLL harmonic extraction was compared to verify the frequency locking accuracy of the two phase-locked loops.The results show that the addition of the fundamental resonance circuit to the harmonic extraction circuit reduces the influence of harmonics on the fundamental wave source and improves the effect of harmonic extraction.In terms of suppressing wind turbine voltage distortion and DC harmonics, the NSOGI phase-locked loop has good effect and high frequency locking accuracy, which verifies the feasibility and correctness of the method.Using NSOGI to control voltage and frequency can improve power supply reliability and improve grid-connected power quality, which provides theoretical reference for the stable operation of wind turbines connected to the grid.