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Cover: Class Wavelet Quality Power Disturbance Classification #6: Noise Robustness Test & Method Comparison
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Here is the final result, the model with 99% accuracy on clean signals actually drops below 50% when the signal is noisy. A simple trick during training brings the accuracy back to around 90%. Let's get started. Hello, welcome to the final episode of the Wavelet-based Power Quality Disturbance Classification series. Voltage recordings in the field always contain noise from sensors, converters, and interference. A model tested only on clean signals can be very misleading. Today we are testing the robustness of the three models against noise and looking for ways to make them resilient.
Create a test file named underscore noise dot py. We will use the same train and test split as in episode 5. The test data is created in four versions: clean, and with Gaussian noise at SNR 40, 30, and 20dB. The smaller the SNR, the higher the noise level, 20dB means noise power is 1 per 100 signal power. The training data is also created in two versions: clean, and with random noise between 20-50dB. This is NICE augmentation.
We will train the three models with both versions of the training data, then test them on all four versions of the test data. Run it, feature calculation and training will take a few seconds. The results are surprising. Models trained on clean signals are very fragile. At SNR 40dB, SVM accuracy drops to 71%, and at 20dB it drops to 23%. XGBoost also only reaches 51%. The cause is that noise increases the energy of high-frequency detail coefficients, so that normal signals appear like transients or NOC.
Now look at the models trained with NICE augmentation. Accuracy at SNR 40 and 30dB is around 97-98%, and at 20dB around 86-88%. XGBoost with augmentation is the most balanced. 99% on clean signal and remains high on noisy signal. The left graph shows the accuracy of the clean trained model which drops sharply, and the right graph shows the model with augmentation which is much more stable.
Done, and the series is also completed. We have built a complete research on the classification of power quality disturbance. Model for 9 disturbances, dataset according to IEEE-159, in straightaway flat transform, feature extraction of 32 features, classification with SVM, random forest, and XGBoost, up to noise robustness test with augmentation. For further research, try wave-flat denoising before feature extraction, real recorded data, more complex disturbances, or one-dimensional CNN directly from the signal. Thank you for following this series. Currently working on a thesis, dissertation, or research in the field of power quality and signal processing? Cerdas Inovasi Digital helps with machine learning implementation, from generating disturbance signals according to IEEE-159, wave-flat transformation, Feature extraction, up to classification with SVM, random forest, and XGBoost, as well as opening a Python programming course for electrical engineering. Want to master the entire series, from synthetic signals up to noise resistance testing? All 6 episodes, complete with step-by-step PDF guides and source code, are available for premium tutorial subscribers. Subscribe starting at Rp69.000 per month, save 28% with the 12-month package, or pay once Rp999.000 for lifetime access. Want just one class? Buy single classes with lifetime access. Subscribe now on the premium page cerdasinovasidigital.com. Contact us via WhatsApp, or visit cerdasinovasidigital.com. Thank you for watching, see you in the next episode.
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