Trung Dung Nguyen
Industrial University of Ho Chi Minh City (IUH)

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Dynamic Multi-Scale Ensemble iTransformer for Day-Ahead Electric Load Forecasting Tuan Anh Nguyen; Trung Dung Nguyen
Buletin Ilmiah Sarjana Teknik Elektro Vol. 8 No. 4 (2026): August
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/biste.v8i4.17107

Abstract

Accurate day-ahead electric load forecasting is essential for reliable power-system operation, yet high-resolution demand exhibits nonlinear short-term variations alongside strong daily and weekly recurrence. This study addresses the difficulty of representing these complementary temporal patterns within a single forecasting model. The research contribution is a validation-driven Dynamic Multi-Scale Ensemble iTransformer framework that integrates a tuned iTransformer with explicit daily, weekly, multi-week, and load-profile references, removes highly redundant candidates, and adaptively combines the retained forecasts across load states and forecast-horizon blocks. The framework uses only historical load observations and follows a chronological, leakage-free protocol for model tuning, candidate selection, weight optimization, strategy selection, and final testing. It was evaluated on New South Wales electricity demand data sampled at 5-minute intervals, using the previous 288 observations to forecast the next 288 observations. The proposed model achieved the best overall performance among the six evaluated methods. It yielded an MAE of 478.485 MW, an RMSE of 690.116 MW, a MAPE of 7.031%, an sMAPE of 6.718%, and an R² of 0.8484. Its MAPE was lower than those of Seasonal Naive (7.979%) and the standalone iTransformer (8.691%), corresponding to relative reductions of 11.88% and 19.10%, respectively. CNN, Persistence Naive, and LSTM achieved MAPEs of 12.419%, 17.596%, and 19.830%, respectively. These results show that explicit multi-scale temporal references and validation-optimized adaptive fusion complement the learned iTransformer representation, thereby improving deterministic day-ahead load forecasting accuracy.
Hybrid Stacking of Multilayer Perceptron, Convolutional Neural Network, and Light Gradient Boosting Machine for Short-Term Load Forecasting Trung Dung Nguyen; Nguyen Anh Tuan
Buletin Ilmiah Sarjana Teknik Elektro Vol. 7 No. 4 (2025): December
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/biste.v7i4.14410

Abstract

Short-term load forecasting (STLF) is essential for scheduling, dispatch, and demand-side management. Real-world load series exhibit rapid local fluctuations and calendar or exogenous influences that challenge single-model approaches. This study proposes a hybrid stacking framework combining a Multilayer Perceptron (MLP), a 1-D Convolutional Neural Network (CNN), and a Light Gradient Boosting Machine (LightGBM), integrated through a ridge-regression meta-learner. The CNN extracts local temporal patterns from sliding windows of the load series, and the MLP processes tabular features such as lags, rolling statistics, and calendar/holiday indicators. At the same time, LightGBM captures nonlinear interactions in the same feature space. Base learners are trained using a rolling TimeSeriesSplit to avoid temporal leakage, and their out-of-fold predictions are used as inputs for the meta-learner. Early stopping regularizes the neural models. Experimental backtests on Queensland electricity demand data (89,136 half-hourly samples) demonstrate that the stacked model achieves markedly lower forecasting errors, with MAPE ≈ 0.81%, corresponding to a 24% reduction compared to CNN (MAPE ≈ 1.07%) and a 32% reduction compared to MLP (MAPE ≈ 1.19%). Regarding runtime, LightGBM is the fastest (25s) but least accurate, while the stacked model requires longer computation (2488s) yet delivers the most reliable forecasts. Overall, the proposed framework balances accuracy and robustness, and it is modular, reproducible, and extensible to additional exogenous inputs or base learners.
Hybrid Bayesian–Hyperband Optimization of a One-Dimensional Convolutional Neural Network for Short-Term Load Forecasting Trung Dung Nguyen; Nguyen Anh Tuan
Buletin Ilmiah Sarjana Teknik Elektro Vol. 7 No. 4 (2025): December
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/biste.v7i4.14824

Abstract

Short-term load forecasting (STLF) plays a crucial role in power system operation and electricity market planning. However, the forecasting accuracy of convolutional neural network (CNN) models strongly depends on properly tuned hyperparameters such as filter numbers, batch size, and loss function, while exhaustive tuning is computationally expensive. This paper proposes a one-dimensional CNN (1D-CNN) for STLF whose key hyperparameters are optimized by a hybrid Bayesian Optimization–Hyperband framework (BO-TPE-HB). The framework combines the Tree-structured Parzen Estimator (TPE), which guides the search towards promising regions of the hyperparameter space, with Hyperband’s multi-fidelity early-stopping strategy to terminate weak configurations early and save computation. The proposed approach is evaluated using half-hourly electricity load data from the Australian Energy Market Operator (AEMO) for New South Wales (NSW) and Victoria (VIC) from 2009 to 2014. Using a rolling-origin time-series cross-validation scheme on the training set and a chronologically separated hold-out test set, BO-TPE-HB explores 100 candidate configurations of a 4-layer 1D-CNN with a sliding window of 48 time steps. Model performance is assessed using MAE, MSE, RMSE, MAPE, and total hyperparameter optimization runtime. Experimental results show that the BO-TPE-HB–tuned CNN achieves test MAPE of 1.350% (MAE 105.98 MW, RMSE 143.71 MW) for NSW and 1.615% (MAE 89.13 MW, RMSE 124.25 MW) for VIC, outperforming Random Search, standalone TPE, and standalone Hyperband in terms of both prediction accuracy and computational efficiency, while requiring substantially less tuning time than plain Bayesian Optimization. These findings highlight that combining probabilistic search with resource-efficient early stopping provides a practical and reproducible way to enhance CNN-based STLF, and can be extended to multivariate inputs or other deep learning forecasting architectures in future work.
A Hybrid Ensemble Empirical Mode Decomposition–Temporal Convolutional Network Framework with LightGBM Residual Correction for Day-Ahead Electric Load Forecasting Trung Dung Nguyen; Tuan Anh Nguyen
Buletin Ilmiah Sarjana Teknik Elektro Vol. 8 No. 5 (2026): October
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/biste.v8i5.17013

Abstract

Accurate day-ahead load forecasting is essential for generation scheduling, reserve allocation, electricity-market operation, and reliable power-system management. However, half-hourly electricity demand is nonlinear and non-stationary, with short-term fluctuations, daily and weekly periodicity, and slowly varying trends occurring simultaneously. This study proposes a unified hybrid framework that combines ensemble empirical mode decomposition, a temporal convolutional network, and validation-calibrated LightGBM residual correction for direct day-ahead forecasting. The main contribution is the coordinated use of multi-scale signal representation, direct multi-output temporal learning, and controlled residual correction within a single forecasting pipeline. Ensemble empirical mode decomposition separates the original load series into nine intrinsic mode functions and one residue, which are organized as a synchronized ten-channel input. The temporal convolutional network then maps a seven-day historical window of 336 half-hourly observations directly to the subsequent 48 load values, avoiding recursive error propagation. LightGBM is subsequently trained to estimate structured residuals using the base forecast, forecast horizon, calendar variables, historical lags, rolling statistics, and decomposition-derived features. To limit overcorrection, the residual model is trained on an earlier validation subset, while a separate chronological calibration subset selects the correction coefficient, which was 0.30 in the reported experiment. Experiments using Queensland electricity-demand data from 2015 to 2019 yielded an RMSE of 156.92 MW, an MAE of 116.48 MW, a MAPE of 1.8825%, a WAPE of 1.8746%, and an R² of 0.9692 for the proposed framework. Under the stored offline evaluation setting, these error values were lower than those reported for the standalone LightGBM and raw-series temporal convolutional network baselines. Because the baseline pipelines contain closely matched but not completely identical test-origin sets, the comparisons are interpreted descriptively rather than as fully paired statistical evidence. In addition, EEMD is applied offline to the complete series; therefore, the reported results represent a decomposition-assisted benchmark rather than a strictly causal real-time forecasting implementation. The findings suggest that multi-scale representation, temporal convolution, and calibrated residual learning can provide complementary benefits under the considered experimental setting.