arXiv subjects

Juan-Andrés Pérez-Rúa

Publications and source records attributed to Juan-Andrés Pérez-Rúa.

3 recordsLinked to original sources

arXiv2021

Solver-Free Heuristics to Retrieve Feasible Points for Offshore Wind Farm Collection System

A set of solver-free heuristics for the offshore wind collection system problem are presented. Currently, methods of this type are not able to cope with typical constraints, and most of their variations minimize only for accumulated cable length. The first algorithm is a two-steps decision process, where the output is the design of a tree network satisfying cable thermal limits constraints, but vulnerable to violate planarity constraints. Subsequently, a cable crossings repair heuristic is introduced in order to fix infeasible points from the first heuristic. Finally, a refining heuristic (negative cycle cancelling refining heuristic) takes over to improve feasible points. The latter iteratively swaps cables, intending to find cycles with negative costs that will lead to investment savings. The sequence of heuristics supports the most important restrictions of the problem. The applicability of the workflow is empirically demonstrated by means of a set of large-scale real-world offshore wind farms. The numerical results indicate that: (i) feasible points can be retrieved in computing times in order of seconds, and (ii) warm-starting can help solvers to converge significantly faster for problems with solution time in order of several hours.

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arXiv2020

Closed-Loop Two-Stage Stochastic Optimization of Offshore Wind Farm Collection System

A two-stage stochastic optimization model for the design of the closed-loop cable layout of an Offshore Wind Farm (OWF) is presented. The model consists on a Mixed Integer Linear Program (MILP) with scenario numeration incorporation to account for both wind power and cable failure stochasticity. The objective function supports simultaneous optimization of: (i) Initial investment (network topology and cable sizing), (ii) Total electrical power losses costs, and (iii) Reliability costs due to energy curtailment from cables failures. The mathematical optimization program is embedded in an iterative framework called PCI (Progressive Contingency Incorporation), in order to simplify the full problem while still including its global optimum. The applicability of the method is demonstrated by tackling a real-world instance. Results show the functionality of the tool in quantifying the economic profitability when applying stochastic optimization compared to a deterministic approach, given certain values of failure parameters.

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arXiv2019

Global Optimization of Offshore Wind Farm Collection Systems

A mathematical program for global optimization of the cable layout of Offshore Wind Farms (OWFs) is presented. The model consists on a Mixed Integer Linear Program (MILP). Modern branch-and-cut solvers are able to solve large-scale instances, defined by more than hundred Wind Turbines (WTs), and a reasonable number of Offshore Substations (OSSs). In addition to the MILP model to optimize total cable length or initial investment, a pre-processing strategy is proposed in order to incorporate total electrical power losses into the objective function. High fidelity models are adapted to calculate cables current capacities, spatial currents. The MILP model is embedded in an iterative algorithmic framework, consisting in solving a sequence of problems with increasing size of the search space. The search space is defined as a set of underlying candidate arcs. The applicability of the method is illustrated through 10 case studies of real-world large-scale wind farms. Results show that: (i) feasible points can quickly be obtained in seconds, (ii) points near the global optimum with an imposed maximum tolerance, are calculable in reasonable computational time in the order of hours, and (iii) the proposed method compares favorably against a state-of-the art method available in literature.

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