改进的VMD-HT在电能质量扰动检测中的应用

Application of Improved VMD-HT in Power Quality Disturbance Detection

针对电能质量扰动检测精度低和抗干扰性弱的问题,提出了一种基于能量收敛因子与PSO优化的VMD-HT方法。首先通过改进的VMD方法自适应地选择k和α的最优取值,然后通过Hilbert变换求取VMD分解后IMF分量的瞬时幅值-频率仿真图,定位扰动发生的起止时刻,实现电能质量扰动的检测。通过加入白噪声模拟实际电能质量扰动和随机改变电能质量扰动数学模型的起止时刻,进行大量检测仿真实验。结果显示,其暂态振荡扰动信号在含20 dB白噪声的环境下发生的起止时刻检测精度相较于HHT分别提高了0.007 s和0.006 s,且其检测误差在0.003 s内的概率达到99.84%。复合电能质量扰动等检测仿真实验结果也表明,改进的VMD-HT方法相较于传统的HHT方法具有更好的检测效果,避免了因EMD容易发生模态混叠的现象导致检测精度低、抗干扰性弱和容错性差的问题。

To solve the problems of low power quality disturbance detection accuracy and weak anti-interference,a VMD-HT method based on energy convergence factor and PSO optimization was proposed in this paper.Firstly,the improved VMD method was used to adaptively select the optimal values of k andα,and then the Hilbert transform was used to obtain the instantaneous amplitude-frequency simulation diagram of the IMF component after VMD decomposition,and to locate the start and end moments of the disturbance to realize the power quality disturbance detection.By adding white noise to simulate the actual power quality disturbance and randomly changing the start and end time of the power quality disturbance mathematical model,a large number of detection simulation experiments were conducted.The detection accuracy of the start and end moments of the transient oscillation disturbance signal in an environment containing 20 dB white noise,compares with the HHT,increased by 0.007 s and 0.006 s respectively,and the probability of its detection error within 0.003 s reaches 99.84%.The detection simulation results of composite power quality disturbances also showed that the improved VMD-HT method had better detection effect than the traditional HHT power quality disturbance detection method,and could avoid the problems of low detection accuracy,weak anti-interference and poor fault tolerance due to the phenomenon that EMD was prone to modal aliasing.