Improved surrogate modeling for multi-energy system design: Model architecture, sampling and scaling choices
Bibliographic record
Abstract
Multi-energy systems (MES) are a key concept for developing more sustainable energy systems, but optimizing their design is computationally burdensome. This paper explores the development of machine-learning (ML) based surrogate models for the optimal design of MES. Surrogates are simple models, often ML-based, used to approximate detailed simulations, in this case MES design optimizations. These models provide instant responses, enabling fast comparisons and explorations of trade-offs between design variables. No related work proposes an ML procedure tailored to properties of the MES design application. Most related works use surrogates to predict system cost and other objectives. However, few works have used them to directly predict the optimal system design, and those that do show poor performance. This paper provides an extensive methodology tailored to properties of MES design problems to improve surrogate performance on small datasets. Four components were found to significantly improve surrogate performance: a careful and objective-oriented selection of samples, the use of upsampling to balance datasets, the use of non-linear rescaling methods, and a specific neural-network architecture called Mixture-of-Experts. These work together to turn the original design variable distribution (i.e., of the output) into a Gaussian-like data distribution, that can be more easily learned by the neural-network. The resulting surrogate model almost instantly predicts optimal energy system designs with high precision. This was tested across a wide variety of different climates, building types and decarbonization goals. Such surrogate models will make it much easier to explore different MES design options. • Energy system design shows irregularities and sudden changes in design variables. • Irregularities and splits reduce the learnability via neural-network. • A large exploration of modeling parameters is tested over a large pool of cases. • A simple mixture-of-experts architecture often addresses the issue. • Upsampling and a novel sampling strategy support the surrogate model’s training.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.010 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".