151 research outputs found
Multi-Agent Learning in Repeated Double-side Auctions for Peer-to-peer Energy Trading
Distributed energy resources (DERs), such as rooftop solar panels, are growing rapidly and are reshaping power systems. To promote DERs, feed-in-tariff is usually adopted by utilities to pay DER owners certain fixed rates for supplying energy to the grid. Such a non-market based approach may increase electricity rates and create inefficiency. An alternative is a market based approach; i.e., consumers and DER owners trade energy in a peer-to-peer (P2P) market, in which electricity prices are determined by real-time market supply and demand. A prevailing approach to realize a P2P marketplace is through double-side auctions. However, the auction complexity in an energy market and the participantsâ bounded rationality may invalidate many well-established results in auction theory and hence, cast difficulties for market design and implementation. To address such issues, we propose an automated bidding framework based on multi-agent, multi-armed bandit learning through repeated auctions, which is aimed to minimize each bidderâs cumulative regret. Numerical results suggest the potential convergence of such a multi-agent learning game to a steady-state. We also apply the framework to three different auction designs (including uniform-price versus Vickrey-type auctions) for a P2P market to study the impacts of the different designs on market outcomes
Analyzing big time series data in solar engineering using features and PCA
In solar engineering, we encounter big time series data such as the satellite-derived irradiance data and string-level measurements from a utility-scale photovoltaic (PV) system. While storing and hosting big data are certainly possible using todayâs data storage technology, it is challenging to effectively and efficiently visualize and analyze the data. We consider a data analytics algorithm to mitigate some of these challenges in this work. The algorithm computes a set of generic and/or application-specific features to characterize the time series, and subsequently uses principal component analysis to project these features onto a two-dimensional space. As each time series can be represented by features, it can be treated as a single data point in the feature space, allowing many operations to become more amenable. Three applications are discussed within the overall framework, namely (1) the PV system type identification, (2) monitoring network design, and (3) anomalous string detection. The proposed framework can be easily translated to many other solar engineer applications
Building topological device through emerging robust helical surface states
We propose a nonlocal manipulation method to build topological devices
through emerging robust helical surface states in Z_2=0 topological systems.
Specifically, in a ribbon of Z_2=0 Bernevig- Hughes-Zhang (BHZ) model with
finite-size effect, if magnetic impurities are doped on the top (bottom) edge,
the edge states on the bottom (top) edge can be altered according to the
strengths and directions of these magnetic impurities. Consequently, the
backscattering between the emerging robust helical edge states and gapped
normal edge states due to finite-size confinement is also changed, which makes
the system alternate between a perfect one-channel conductor and a perfect
insulator. This effect allows us to fabricate topological devices with high
on-off ratio. Moreover, it can also be generalized to 3D model and more
realistic Cd3As2 type Dirac semimetals.Comment: 7 pages, 6 figure
Graph-based Multi-ODE Neural Networks for Spatio-Temporal Traffic Forecasting
There is a recent surge in the development of spatio-temporal forecasting
models in the transportation domain. Long-range traffic forecasting, however,
remains a challenging task due to the intricate and extensive spatio-temporal
correlations observed in traffic networks. Current works primarily rely on road
networks with graph structures and learn representations using graph neural
networks (GNNs), but this approach suffers from over-smoothing problem in deep
architectures. To tackle this problem, recent methods introduced the
combination of GNNs with residual connections or neural ordinary differential
equations (ODE). However, current graph ODE models face two key limitations in
feature extraction: (1) they lean towards global temporal patterns, overlooking
local patterns that are important for unexpected events; and (2) they lack
dynamic semantic edges in their architectural design. In this paper, we propose
a novel architecture called Graph-based Multi-ODE Neural Networks (GRAM-ODE)
which is designed with multiple connective ODE-GNN modules to learn better
representations by capturing different views of complex local and global
dynamic spatio-temporal dependencies. We also add some techniques like shared
weights and divergence constraints into the intermediate layers of distinct
ODE-GNN modules to further improve their communication towards the forecasting
task. Our extensive set of experiments conducted on six real-world datasets
demonstrate the superior performance of GRAM-ODE compared with state-of-the-art
baselines as well as the contribution of different components to the overall
performance. The code is available at https://github.com/zbliu98/GRAM-ODEComment: Published at Transactions on Machine Learning Research, 202
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