Development of a wavelet-based algorithm to detect and determine ...
Development of a wavelet-based algorithm to detect and determine ...
Development of a wavelet-based algorithm to detect and determine ...
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Chapter 7<br />
Algorithm <strong>to</strong> <strong>determine</strong> certain kind <strong>of</strong><br />
disturbances<br />
The discrete <strong>wavelet</strong> transform, which was described in the former chapter, is now<br />
used <strong>to</strong> <strong>detect</strong> <strong>and</strong> <strong>to</strong> <strong>determine</strong> certain kind <strong>of</strong> disturbances in power networks.<br />
7.1 Theory<br />
For the theory <strong>of</strong> the discrete <strong>wavelet</strong> transform is fully explained in chapter 6. The<br />
discrete <strong>wavelet</strong> transform <strong>to</strong>gether with multiple level decomposition is used for the<br />
analyze <strong>of</strong> disturbance recordings.<br />
By using the DWT <strong>and</strong> observing the particular features <strong>of</strong> the several decomposition<br />
levels <strong>of</strong> a signal, some important conclusions can be drawn. These information can<br />
be used <strong>to</strong> <strong>detect</strong> <strong>and</strong> <strong>to</strong> identify the disturbance. A digital program is developed <strong>and</strong><br />
written with the <strong>wavelet</strong> <strong>to</strong>olbox in MATLAB.<br />
Each disturbance occurred in the power network results in specific frequencies in the<br />
voltage waveform. Thus only the voltages have <strong>to</strong> be analyzed.<br />
The program works in five steps as follows:<br />
Step 1: Evaluation <strong>of</strong> the square <strong>of</strong> the <strong>wavelet</strong> coefficients <strong>of</strong> the recorded distur-<br />
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