The continuous proliferation of distributed generation is leading end users to look for new tools that help to design hybrid electrical energy systems (HEES). Thus, this work proposes a novel approach for optimal plan...
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The continuous proliferation of distributed generation is leading end users to look for new tools that help to design hybrid electrical energy systems (HEES). Thus, this work proposes a novel approach for optimal planning of HEES, which comprises the optimization of the type and capacity of distributed generation connected to the end user. The main objective is to minimize the project's total cost, considering the net metering scheme. To this end, the bioinspired meta-heuristic artificial immune system is proposed to optimally determine the number and type of photovoltaic panels. In addition, a nonlinear programming model is proposed to optimize the diesel generator and BESS capacity, considering the energy supply to the consumer by the HEES and the main distribution grid. Case studies involving commercial and residential customers in Brazil are introduced considering the normative resolutions from ANEEL, the Brazilian Regulatory Agency. Comparative analyses are made concerning an exhaustive search procedure and the commercial software Homer Pro, designed to optimize the operation of HEES systems. An important conclusion is that the proposed approach is as effective as the cutting-edge tools, with reasonable computational effort.
Grey wolf optimization (GWO) algorithm, when applied to multidimensional and nonlinear optimization problems, often encounters the problems of getting stuck into local optimums and slow rate of convergence. Aiming at ...
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We consider nonlinear optimization problems that involve surrogate models represented by neural networks. We demonstrate first how to directly embed neural network evaluation into optimization models, highlight a diff...
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We consider nonlinear optimization problems that involve surrogate models represented by neural networks. We demonstrate first how to directly embed neural network evaluation into optimization models, highlight a difficulty with this approach that can prevent convergence, and then characterize stationarity of such models. We then present two alternative formulations of these problems in the specific case of feedforward neural networks with ReLU activation: as a mixed-integer optimization problem and as a mathematical program with complementarity constraints. For the latter formulation we prove that stationarity at a point for this problem corresponds to stationarity of the embedded formulation. Each of these formulations may be solved with state-of-the-art optimization methods, and we show how to obtain good initial feasible solutions for these methods. We compare our formulations on three practical applications arising in the design and control of combustion engines, in the generation of adversarial attacks on classifier networks, and in the determination of optimal flows in an oil well network.
Optimal power flows play a key role in power system operation planning. While most papers in the literature focus on attaining optima, sequencing paths of optimal control adjustments that lead the sys-tem from an init...
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Optimal power flows play a key role in power system operation planning. While most papers in the literature focus on attaining optima, sequencing paths of optimal control adjustments that lead the sys-tem from an initial operating point towards the optimum remain scarcely accounted for. Thus, this work proposes a practical framework based upon power system steady-state analysis for sequencing strictly feasible paths of optimal control adjustments determined by the Optimal Reactive Dispatch (ORD) via Lagrange multiplier sensitivity analysis. The proposed framework is methodologically founded on the re-formulation of the ORD in terms of optimal control adjustments rather than optimal control values, suc-cessive Newton's power flow calculations to assure a strictly feasible path from the initial operating point towards the optimum, and successive resolutions of the reformulated ORD's associated dual problem to determine Lagrange multipliers along such sequence path. Thus, pondering optimal control adjustments by their respective Lagrange multipliers indicates which control action must be realised. Numerical re-sults for IEEE test-systems with up to 300 buses with an increased number of controllable variables are obtained to validate and illustrate the efficiency and robustness of the proposed framework.(c) 2021 Elsevier B.V. All rights reserved.
Multi-year generation and transmission expansion planning (MY-G&TEP) is a critical issue in power systems. The present paper considers the optimal placement of Fixed Series Compensation (FSC) and Phase Shifting Tr...
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Multi-year generation and transmission expansion planning (MY-G&TEP) is a critical issue in power systems. The present paper considers the optimal placement of Fixed Series Compensation (FSC) and Phase Shifting Transformer (PST) proposes a pool-market-based mathematical model (MY-G&TEP) for maximizing social welfare (SW) and reducing investment costs of transmission lines and new power plants. Following the determination of optimal strategy, the present paper compares the usefulness of PSTs and FSCs in the MY-G&TEP problem in three scenarios. Since MY-G&TEP is a complex hybrid, mixed-integer linear programming (MILP), and nonlinear optimization problem, the YALMIP toolbox and CPLEX solver have been applied to find the optimal solution, a globally optimized solution is obtained. For evaluation, the proposed model has been tested on the IEEE 24-bus and IEEE 57-bus systems, and the simulation results indicate that the installation of PST and FSC not only improves market conditions but also increases the flexibility of MY-G&TEP, and adding these FACTS devices to the studied system leads to an increase in the network's performance and enhancement of objectives of the proposed model.
This paper explains the derivation of Box-Jenkins model for the elastic drive system using Levenberg-Marduardt algorithm. The Box-Jenkins model which is the most flexible linear model has been chosen to identify the e...
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Optimal control of constrained unmanned aerial vehicle (UAV) trajectory optimization problem is one of the frontiers and hotspots of UAV research. The various constraints generated by physical limitations and obstacle...
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Space mission planning and spacecraft design are tightly coupled and need to be considered together for optimal performance;however, this integrated optimization problem results in a large-scale mixed-integer nonlinea...
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Space mission planning and spacecraft design are tightly coupled and need to be considered together for optimal performance;however, this integrated optimization problem results in a large-scale mixed-integer nonlinear programming (MINLP) problem, which is challenging to solve. In response to this challenge, this paper proposes a new solution approach to this problem based on decomposition-based optimization via augmented Lagrangian coordination. The proposed approach leverages the unique structure of the problem that enables its decomposition into a set of coupled subproblems of different types: a mixed-integer quadratic programming (MIQP) subproblem for mission planning, and one or more nonlinear programming (NLP) subproblem(s) for spacecraft design. Because specialized MIQP or NLP solvers can be applied to each subproblem, the proposed approach can efficiently solve the otherwise intractable integrated MINLP problem. An automatic and effective method to find an initial solution for this iterative approach is also proposed so that the optimization can be performed without a user-defined initial guess. The demonstration case study shows that, compared to the state-of-the-art method, the proposed formulation converges substantially faster and the converged solution is at least the same or better given the same computational time limit.
Strategic airlift is a crucial capability for any country that wants to protect its global interests around the world. Air refueling may offer more agile and efficient airlift capabilities by increasing cargo aircraft...
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Strategic airlift is a crucial capability for any country that wants to protect its global interests around the world. Air refueling may offer more agile and efficient airlift capabilities by increasing cargo aircraft payload and shortening airlift time. We investigated whether air refueling can shorten the total time of an airlift operation and decrease the number of cargo aircraft sorties required in a deployment scenario, especially where the distance between origin and destination is within the range of cargo aircraft. We introduced two mathematical models to compare the total airlift time and number of cargo aircraft required for given origin-destination and tanker base locations and total freight to be moved. We optimised initial cargo and fuel amount for cargo aircraft along with rendezvous point coordinates to minimise total airlift time. We used a numerical example to show that substantial airlift time and cargo aircraft sortie savings are possible through air refueling.
In this manuscript, designing of a modified version of variables double sampling plan for the application of measureable quality characteristics is proposed and this plan is designated as variables modified double sam...
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