微电网HHT谐波检测与时频分析方法

摘要

In order to solve the problem to accurately detect complex non-stationary signals, such as micro-grid harmonic and mutation, a method based on Hilbert-Huang Transform(HHT)is presented. The method is about harmonic detection and time-frequency analysis for micro-grid. It fits extreme value curve by adopting shape-preserving piecewise cubic Her-mite interpolation, and implements Empirical Mode Decomposition(EMD)on harmonic signals, then a finite number of Intrinsic Mode Components(IMF)are obtained, and Hilbert transformation is conducted. The instantaneous frequency and amplitude of each IMF components are calculated finally. The time-frequency characteristics of micro-grid harmonic in non-stationary power signals are detected accurately. The simulation results show that the method can quickly and pre-cisely obtain the harmonic signal frequency components, amplitude and voltage mutation time. Compared with FFT and traditional HHT methods, it has higher accuracy and obvious time distinguishing feature, which meets the engineering application requirements for micro-grid harmonic computer detection.%为解决微电网谐波、突变等复杂非平稳信号的精确检测问题，提出一种基于Hilbert-Huang变换（HHT）的微电网谐波检测与时频分析方法。该方法采用保形分段三次埃尔米特插值法拟合极值点曲线，对谐波信号进行经验模态分解（EMD），得到有限个固有模态分量（IMF）并进行Hilbert变换，最终计算各个IMF分量的瞬时频率和瞬时幅值，实现微电网谐波等非平稳电能信号的时频特性精确检测。仿真结果表明，该方法能够快速、准确地获取谐波信号频率成分、幅度及电压突变时刻。相对于FFT变换及传统HHT方法具有较高的精度和时域区分特性，可满足微电网谐波微机检测的工程应用需求。