1,170 research outputs found
Cooperative coevolution of Elman recurrent neural networks for chaotic time series prediction
Cooperative coevolution decomposes a problem into subcomponents and employs evolutionary algorithms for solving them. Cooperative coevolution has been effective for evolving neural networks. Different problem decomposition methods in cooperative coevolution determine how a neural network is decomposed and encoded which affects its performance. A good problem decomposition method should provide enough diversity and also group interacting variables which are the synapses in the neural network. Neural networks have shown promising results in chaotic time series prediction. This work employs two problem decomposition methods for training Elman recurrent neural networks on chaotic time series problems. The Mackey-Glass, Lorenz and Sunspot time series are used to demonstrate the performance of the cooperative neuro-evolutionary methods. The results show improvement in performance in terms of accuracy when compared to some of the methods from literature
Artificial intelligence in wind speed forecasting: a review
Wind energy production has had accelerated growth in recent years, reaching an annual increase of 17% in 2021. Wind speed plays a crucial role in the stability required for power grid operation. However, wind intermittency makes accurate forecasting a complicated process. Implementing new technologies has allowed the development of hybrid models and techniques, improving wind speed forecasting accuracy. Additionally, statistical and artificial intelligence methods, especially artificial neural networks, have been applied to enhance the results. However, there is a concern about identifying the main factors influencing the forecasting process and providing a basis for estimation with artificial neural network models. This paper reviews and classifies the forecasting models used in recent years according to the input model type, the pre-processing and post-processing technique, the artificial neural network model, the prediction horizon, the steps ahead number, and the evaluation metric. The research results indicate that artificial neural network (ANN)-based models can provide accurate wind forecasting and essential information about the specific location of potential wind use for a power plant by understanding the future wind speed values
A Review on Artificial Intelligence Applications for Grid-Connected Solar Photovoltaic Systems
The use of artificial intelligence (AI) is increasing in various sectors of photovoltaic (PV) systems, due to the increasing computational power, tools and data generation. The currently employed methods for various functions of the solar PV industry related to design, forecasting, control, and maintenance have been found to deliver relatively inaccurate results. Further, the use of AI to perform these tasks achieved a higher degree of accuracy and precision and is now a highly interesting topic. In this context, this paper aims to investigate how AI techniques impact the PV value chain. The investigation consists of mapping the currently available AI technologies, identifying possible future uses of AI, and also quantifying their advantages and disadvantages in regard to the conventional mechanisms
Problem Decomposition and Adaptation in Cooperative Neuro-Evolution
One way to train neural networks is to use evolutionary algorithms
such as cooperative coevolution - a method that decomposes the network's
learnable parameters into subsets, called subcomponents. Cooperative
coevolution gains advantage over other methods by evolving particular
subcomponents independently from the rest of the network. Its success
depends strongly on how the problem decomposition is carried out.
This thesis suggests new forms of problem decomposition, based on a
novel and intuitive choice of modularity, and examines in detail at what
stage and to what extent the different decomposition methods should be
used. The new methods are evaluated by training feedforward networks
to solve pattern classification tasks, and by training recurrent networks to
solve grammatical inference problems.
Efficient problem decomposition methods group interacting variables
into the same subcomponents. We examine the methods from the literature and provide an analysis of the nature of the neural network optimization problem in terms of interacting variables. We then present a
novel problem decomposition method that groups interacting variables
and that can be generalized to neural networks with more than a single
hidden layer.
We then incorporate local search into cooperative neuro-evolution. We
present a memetic cooperative coevolution method that takes into account
the cost of employing local search across several sub-populations.
The optimisation process changes during evolution in terms of diversity and interacting variables. To address this, we examine the adaptation
of the problem decomposition method during the evolutionary process. The results in this thesis show that the proposed methods improve performance
in terms of optimization time, scalability and robustness.
As a further test, we apply the problem decomposition and adaptive
cooperative coevolution methods for training recurrent neural networks
on chaotic time series problems. The proposed methods show better performance
in terms of accuracy and robustness
Recurrent error-based ridge polynomial neural networks for time series forecasting
Time series forecasting has attracted much attention due to its impact on many practical
applications. Neural networks (NNs) have been attracting widespread interest as
a promising tool for time series forecasting. The majority of NNs employ only autoregressive
(AR) inputs (i.e., lagged time series values) when forecasting time series.
Moving-average (MA) inputs (i.e., errors) however have not adequately considered.
The use of MA inputs, which can be done by feeding back forecasting errors as extra
network inputs, alongside AR inputs help to produce more accurate forecasts. Among
numerous existing NNs architectures, higher order neural networks (HONNs), which
have a single layer of learnable weights, were considered in this research work as they
have demonstrated an ability to deal with time series forecasting and have an simple
architecture. Based on two HONNs models, namely the feedforward ridge polynomial
neural network (RPNN) and the recurrent dynamic ridge polynomial neural network
(DRPNN), two recurrent error-based models were proposed. These models were
called the ridge polynomial neural network with error feedback (RPNN-EF) and the
ridge polynomial neural network with error-output feedbacks (RPNN-EOF). Extensive
simulations covering ten time series were performed. Besides RPNN and DRPNN, a
pi-sigma neural network and a Jordan pi-sigma neural network were used for comparison.
Simulation results showed that introducing error feedback to the models lead
to significant forecasting performance improvements. Furthermore, it was found that
the proposed models outperformed many state-of-the-art models. It was concluded
that the proposed models have the capability to efficiently forecast time series and that
practitioners could benefit from using these forecasting models
Perspectives on adaptive dynamical systems
Adaptivity is a dynamical feature that is omnipresent in nature,
socio-economics, and technology. For example, adaptive couplings appear in
various real-world systems like the power grid, social, and neural networks,
and they form the backbone of closed-loop control strategies and machine
learning algorithms. In this article, we provide an interdisciplinary
perspective on adaptive systems. We reflect on the notion and terminology of
adaptivity in different disciplines and discuss which role adaptivity plays for
various fields. We highlight common open challenges, and give perspectives on
future research directions, looking to inspire interdisciplinary approaches.Comment: 46 pages, 9 figure
The Application of Nature-inspired Metaheuristic Methods for Optimising Renewable Energy Problems and the Design of Water Distribution Networks
This work explores the technical challenges that emerge when applying bio-inspired optimisation methods to real-world engineering problems. A number of new heuristic algorithms were proposed and tested to deal with these challenges. The work is divided into three main dimensions: i) One of the most significant industrial optimisation problems is optimising renewable energy systems. Ocean wave energy is a promising technology for helping to meet future growth in global energy demand. However, the current technologies of wave energy converters (WECs) are not fully developed because of technical engineering and design challenges. This work proposes new hybrid heuristics consisting of cooperative coevolutionary frameworks and neuro-surrogate optimisation methods for optimising WECs problem in three domains, including position, control parameters, and geometric parameters. Our problem-specific algorithms perform better than existing approaches in terms of higher quality results and the speed of convergence. ii) The second part applies search methods to the optimization of energy output in wind farms. Wind energy has key advantages in terms of technological maturity, cost, and life-cycle greenhouse gas emissions. However, designing an accurate local wind speed and power prediction is challenging. We propose two models for wind speed and power forecasting for two wind farms located in Sweden and the Baltic Sea by a combination of recurrent neural networks and evolutionary search algorithms. The proposed models are superior to other applied machine learning methods. iii) Finally, we investigate the design of water distribution systems (WDS) as another challenging real-world optimisation problem. WDS optimisation is demanding because it has a high-dimensional discrete search space and complex constraints. A hybrid evolutionary algorithm is suggested for minimising the cost of various water distribution networks and for speeding up the convergence rate of search.Thesis (Ph.D.) -- University of Adelaide, School of Computer Science, 202
A new framework for electricity price forecasting via multi-head self-attention and CNN-based techniques in the competitive electricity market
Due to recent technical improvements, the smart grid has become a feasible platform for electricity market participants to successfully regulate their bidding process based on demand-side management (DSM) perspectives. At this level, practical design, implementation, and assessment of numerous demand response mechanisms and robust short-term price forecasting development in day-ahead transactions are all critical. The accuracy and effectiveness of the day-ahead price forecasting process are crucial concerns in a deregulated market. In this market, the reason for low accuracy is the limitation of electricity generation compared to the electricity demand variations. Hence, this study proposes a suitable technique for forecasting electricity prices using a multi-head self-attention and Convolutional Neural networks (CNN) based approach. Further, this study develops a feature selection technique using mutual information (MI) and neural networks (NN) to choose suitable input variable subsets significantly affecting electricity price predictions simultaneously. The combination of MI and NN reduces the number of input features used in the model, thereby decreasing the computational complexity of the NN. The actual data sets from the Ontario electricity market in 2020 are acquired to verify the simulation results. Finally, the simulation results proved the efficiency of the proposed method by demonstrating increased accuracy by attaining the lowest average value for MAPE and RMSE with a value of 1.75% and 0.0085, respectively, and compared to results obtained by recent computational intelligence approaches. By attaining accurate electricity price results, the significance of this study can be summed up as aiding the electricity industry's operators in administering effective energy management, efficient resource allocation, and informed decision-making.© 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
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