考虑能量集中度的分布式系统谐振检测方法研究

Resonance Detection Method for Distributed System Considering Energy Concentration

随着大规模光伏、风电等分布式电源的并网,系统的谐振频率分布不仅受自身逆变器的影响,还受并联逆变器之间以及逆变器和电网之间谐振耦合的影响。电网谐振现象的发生,严重影响了电网安全稳定运行,因此需要研究一种谐振检测方法,改善分布式系统的电能质量问题。针对分布式系统的谐振检测问题,在建立分布式光伏并网系统模型的基础上,提出了一种考虑能量集中度的谐振检测方法。该方法通过小波变换(Wavelet Transform,WT)得到能量集中度明显的频带范围,然后利用FFT对该频带范围的正确性进行验证。仿真验证了该谐振检测方法的正确性和有效性。

With large-scale photovoltaic, wind power and other distributed power grid,the resonance frequency distribution of the system is affected not only by the inverter, but also by the resonant coupling between the parallel inverters and the inverter and the power grid.The occurrence of power grid resonance has seriously affected the safe and stable operation of the power network.Therefore, it is necessary to study a resonance detection method to improve the power quality of distributed systems.Aiming at the problem of resonance detection of distributed system, a method of resonance detection considering energy concentration is proposed based on the establishment of the model of distributed photovoltaic grid-connected system.The Wavelet Transform (WT) is applied in this method to obtain the frequency band range with obvious energy concentration.Then it uses fast fourier transform (FFT) to verify the correctness of the frequency band range.Finally, the accuracy and efficiency of the grid-connected photovoltaic resonance detection method based on WT is verified by simulation.