2022
Autores
Cabral, M; Fonseca, TF; Cerveira, A;
Publicação
FORESTS
Abstract
The success of forest management towards achieving desired outcomes depends on various factors and can be improved through forest planning based on optimization approaches. Regardless of the owner type (state, private or common land) and/or governance model, the number of owners or management bodies considered in most studies is low, typically involving one owner/management body or a very small group. This study extends the approach of formulating a Forest Management Plan (FMP) to a large forest area, consisting of areas with different management bodies. The FMP model returns the harvest schedule that maximizes the volume of wood harvested during the planning horizon, while ensuring (1) sustainability and environmental constraints at the overall scale and (2) independent revenues for each management body. The FMP is tested in a real forested area, consisting of 22 common lands, governed by local communities for a planning period of 30 years. The results show that our approach is appropriate for several management bodies. When evaluating the impact of grouping areas (and their owner bodies) on the total volume removed, a comparison of the FMP model with an alternative model that allows for independent management (FMP-IND) showed significant differences, in terms of total volume removed at the end of the horizon. Global management leads to a reduction of about 8.6% in the total removed volume; however, it will ensure a heritage of well-diversified stands, in terms of age classes. The results highlight the importance of managing multi-stakeholder forest areas as a whole, instead of being managed independently, if the aim is to assure more sustainable management of forest resources in the mid and long term.
2021
Autores
Teixeira, R; Cerveira, A; Baptista, J;
Publicação
INTERNATIONAL CONFERENCE ON ELECTRICAL, COMPUTER AND ENERGY TECHNOLOGIES (ICECET 2021)
Abstract
The increase in the world's population combined with the development of new economies has led to a large scale increase in the demand for energy resources. New technologies have emerged that allow for the maintenance of the energy supply. Renewable sources and energy storage systems (ESS) are emerging as a crucial option for the development of Smart Grids. Using a Mixed Integer Linear Programming (MILP) optimization model, the effects of renewable production sources and storage systems on an electrical grid were studied, in order to maximize the profit of a Virtual Power Plant (VPP). The obtained results allowed us to verify the efficiency of the proposed method. The placement of renewable producers and the ESS, as well as the management optimization of the purchase and transfer process of the stored energy definitely increased the profit of VPP. The use of these technologies also improves the voltage profile and decreased the active power losses by 84% along with the network.
2021
Autores
Ribeiro, R; Cerveira, A; Baptista, J;
Publicação
INTERNATIONAL CONFERENCE ON ELECTRICAL, COMPUTER AND ENERGY TECHNOLOGIES (ICECET 2021)
Abstract
Nowadays, power distribution systems face some challenges related to power losses minimization and voltage stability improvement along the networks. These challenges can also be a big opportunity to develop smarter and more efficient distribution networks, ensuring the continuity of service and the power quality supplied to consumers. At the same time, there are several international standards that regulate the power quality levels required for distribution networks.This paper addresses deeply these issues and provide a solution to solve both of these problems using Distributed Generators (DG) on optimal locations of the grid. The proposed method will analyze the injection of both real and reactive power in a regulated IEEE-69 bus system. In the first stage, the voltage and loss sensitivity of the load flow analysis is calculated using a MatLab algorithm. In a second stage, the methodology uses the voltage stability index (VSI) to obtain the optimal location of the DGs to ensure the best results of both, power loss and voltage stability for the grid. The obtained results show the good effectiveness of the proposed method.
2022
Autores
Ferreira, V; Cerveira, A; Baptista, J;
Publicação
Renewable Energy and Power Quality Journal
Abstract
Distribution grids currently face news paradigms where Power Quality (PQ) has become one of the most important aspects for distribution system operators (DSO) and consumers. To ensure a PQ within the limits defined by international standards, there is a permanent need to monitor all parameters associated with the distributed voltage by the grid. This task is carried out using the installation of Power Quality Monitors (PQM) at strategic points of the grid. The main aim of this paper is to define a methodology to optimize the best location for the PQM installation. To achieve this target the Monitor Reach Area (MRA) matrix is calculated and an Integer Linear Programming (ILP) optimization model was used to find the best solution. Two case studies were carried out, in which residual voltage values were observed when three-phase short circuits are applied to all nodes. The results obtained show the good effectiveness of the developed method, presenting solutions that allow the total monitoring of the studied networks, using the smallest possible number of PQMs. In this way, it is possible for the DSO to keep the network monitored in real-time with huge efficiency gains. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.
2022
Autores
Jesus, B; Cerveira, A; Baptista, J;
Publicação
Renewable Energy and Power Quality Journal
Abstract
Currently, there has been a great development of the wind energy market, which is accompanied by an increase in the number of wind farms at sea, the offshore wind farms. Therefore, it is crucial to ensure that efficiency in energy production is maximum and that the levelized cost of energy (LCOE) is minimal. In this paper, a mixed-integer linear programming model (MILP) is proposed to find the best wind farm layout taking into account the wake effect in order to maximize energy production. The design of an offshore wind farm located at the North Sea is considered as a case study, contemplating three situations regarding the number of wind turbines to be installed and to determine the best positioning of them in order to maximize energy production, taking into account the wake effect and the lowest LCOE. © 2022, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.
2022
Autores
Rocha, J; Dominguez, C; Cerveira, A;
Publicação
OPTIMIZATION, LEARNING ALGORITHMS AND APPLICATIONS, OL2A 2022
Abstract
Reducing the costs associated with health care services is on the agenda, if possible, improving their quality. The Lean management approach has proven to provide good results in creating value and reducing waste. This paper is based on an exploratory case study in the logistic operations of a Northern Portuguese hospital, focusing on the delivery plans of products needed between the central warehouse and the internal medicine ward. Using PDCA improvement cycles and other lean tools, this study analyzed the actual delivery system, identified inefficiencies, and proposed and evaluated some solutions. The aim was to address different types of waste, such as the time the ward head nurse spent to launch orders and perform the reception/arrangement of the products or the excess of products leaving the central warehouse. Although a daily delivery with a fixed stock level seems to be a good delivery system for a large group of products, the recorded or possible failures have led us to devise an optimization model to improve the deliveries. The preliminary results suggest that a weekly plan with a daily delivery of products (to be repeated every week) is even more optimal, not only because it relieves the head nurse of logistical tasks but also because it takes into account the units of products per package. Although this model can be generalized to other nursing wards, some limitations are addressed, namely its non (daily) standardization, leading to some complexity in its handling by the logistic central warehouse operators.
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