基于IEC标准和粒子群优化谱估计的谐波检测方法

摘要

Accurate harmonic analysis is an important prerequisite of harmonic pollution control and power quality improvement.In IEC 61000-4-7 standard,the harmonic group method is recommended for harmonic measurement in the case of nonsynchronous sampling.While for inter-harmonics measurement,it makes great simplification and is unable to get the accurate information of inter-harmonic frequency and amplitude.Aiming at this problems,an improved method based on IEC standard and spectrum estimation combined with PSO can realize accurate detection of harmonics and inter-harmonics.Due to the fact that the content of harmonics in actual power grid is much larger than that of the inter-harmonic components,and their frequencies are relatively fixed,firstly,the parameters of fundamental and harmonic components are estimated accurately by using the “harmonic group” method recommended by IEC standard.Secondly,after the fundamental and harmonic components are filtered out,the output voltage signal is reconstructed in time domain,and high precision spectrum analysis is conducted for the reconstructed inter-harmonic signal by using spectrum estimation theory,the frequency and amplitude parameters of interharmonics is obtained by combining PSO method.This improved method can detect inter-harmonics components adjacent to the harmonics and significantly reduce the influence of harmonics on inter-harmonics.Simulation results based on Matlab verify the effectiveness of the algorithm.%准确的谐波分析是治理谐波污染和改善电能质量的重要前提.IEC 61000-4-7标准采用谐波群的方法对非同步采样情况下的谐波进行测量,而对于间谐波的测量则作了很大的简化,无法准确获得间谐波的频率和幅值信息.针对这一问题,提出了基于IEC标准和粒子群优化谱估计的改进方法,实现谐波和间谐波的准确检测.由于实际电网中谐波的含量远大于间谐波,且其频率相对固定,因此首先采用IEC标准推荐的“谐波群”方法精确估计基波和谐波参数;其次,对滤除基波和谐波成分的电压信号进行时域重构,采用谱估计理论对重构的间谐波信号进行高精度频谱分析,再结合粒子群优化得到间谐波的频率和幅值参数.该方法也可准确检测出频率邻近谐波的间谐波分量,大大减小了谐波对间谐波的影响.基于Matlab的仿真验证了该算法的有效性.