Journal of Electrical Engineering
Vol.2 No.02(2014), Article ID:13466,8 pages
DOI:10.12677/JEE.2014.22002

Detection and Localization of Power Quality Disturbances Based on Complex Wavelet

Zhaogang Wu1, Jiangang Yao1, Tangbing Li2, Qiang Chen1, Zheng Yang1, Wenlong Gong3

1College of Electrical and Information Engineering, Hunan University, Changsha

2Jiangxi Electric Power Research Institute, Nanchang

3Hunan HDHL Electrical & Information Technology Co., Ltd., Changsha

Email: wuzhaogang163@163.com, yaojiangang@126.com

Received: Mar. 26th, 2014; revised: Apr. 1st, 2014; accepted: Apr. 8th, 2014

ABSTRACT

Detection and localization of power quality disturbance signals provide a basis to analyze the causes of the disturbance. This paper presents a complex wavelet-based power quality disturbance detection and localization. First of all, the amplitude and phase of complex wavelet coefficients are extracted by discrete complex wavelet transform, and then, the composite information of amplitude and phase is used to achieving fast and accurate positioning of 5 kinds of transient power quality disturbance signals. Under the condition of noise and disturbance characteristics is not obvious, this paper proposes an auxiliary positioning method based on signal preprocessing. Simulation shows, under the condition of noise, the method can achieve fast and exact positioning of power quality disturbance signals.

Keywords:Power Quality, Disturbances Location, Complex Wavelet Transform, Assisted Positioning

1湖南大学，电气与信息工程学院，长沙

2江西省电力科学研究院，南昌

3湖南湖大华龙电气与信息技术有限公司，长沙

1. 引言

2. 小波变换和多分辨分析

2.1. 连续小波变换

(1)

2.2. 离散小波变换

(2)

3. 复小波变换以及在扰动信号定位原理

3.1. 复小波变化

MATLAB工具箱的复小波只能实现连续变换，很难应用于实际，因此需要构造出能实现离散变换的正交复小波。小波理论和滤波器组(Filter Banks)之间关系的揭示，使得滤波器理论对小波变换进行小波函数的构造以及小波变换应用范围等方面开辟了一条新的途径，也为以滤波器理论为基础的各种新型小波的出现提供了可能和理论基础[2] 。小波实际上就是一种具有特定性质的带通滤波器，而离散正交小波基对应的就是满足一定条件的完全重构滤波器[3] 。因此可通过设计滤波器来构造相应的小波，实数滤波器系数对应实小波，复数波系数对应复小波。

3.2. 复小波定位原理与复小波的选取

4. 离散复小波定位方法

4.1. 扰动信号的生成和参数设置

4.2. 辅助定位方法

Table 1. db4 complex wavelet filter coefficients

Figure 1. A flowchart of assisted positioning methods

5. 仿真分析

Figure 2. Voltage swell CWT

Figure 3. Voltage sags CWT

Figure 4. Voltage interruption CWT

Figure 5. Transient impulse CWT

Table 2. Disturbance in real time and the CWT positioning time

Figure 6. Transient oscillation CWT

Figure 7. Voltage swell CWT under noisy conditions

Figure 8. Positioning voltage swell in assisted methods

Figure 9. Positioning voltage swell in mixture methods

6. 结论

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