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Publicações

Publicações por CPES

2013

Assessment of the investment effort in HV and MV networks to reduce energy losses

Autores
Martins, JC; Da Silva, JR; Santos, CA; Branco, FC; Nuno Fidalgo, J; Matos, MA; Couto, MJ;

Publicação
IET Conference Publications

Abstract
In re-regulated markets, the maximization of profits creates the tendency to postpone investments in the network infrastructure, with negative effects on losses. In order to oppose this tendency, several countries adopt regulation directives that reward the distributors if losses are reduced and penalize them if losses increase. This is the case of Portugal which adopted loss penalty/reward scheme may be found in [1]. Given the current framework, EDP Distribuição (EDP Group), Portugal, a Distribution System Operator (DSO), has established a loss reduction program, which includes line reinforcement investments, among other actions. The main idea is to make the best investments in HV and MV network lines, considering the trade-off between benefits and costs. The ideal scenario would be, of course, to analyse all HV and MV networks and simulate possible reinforcement alternatives. However, the large number of MV feeders (about 4,000) makes this alternative unworkable. Thus, the first phase consists of developing a procedure to rank MV networks according to their potential to reduce losses. The highest scored networks are then analysed using a power system simulator. This analysis takes into account the different reinforcement alternatives and evaluates the investments costs and the saved energy over a period of 30 years - The economic time span usually considered by EDP Distribuição for this kind of operation. For the HV case, all networks were analysed. This paper synthetizes the main results obtained in these studies.

2013

A novel fuzzy-based expert system for RET selection

Autores
Barin, A; Canha, LN; Abaide, AD; Magnago, KF; Matos, MA; Orling, RB;

Publicação
JOURNAL OF INTELLIGENT & FUZZY SYSTEMS

Abstract
The aim of this work is to demonstrate a novel fuzzy-based expert system for selecting renewable energy technologies (RET). Fuzzy multi-rules and fuzzy multi-sets are used to evaluate the main operational characteristics of six types of RET fuelled by biogas from municipal solid waste (MSW) landfills. The construction of the fuzzy multi-rules and fuzzy multi-sets is based on the following method: Mamdani controller using the Max-Min (inference process) and Center of Gravity (defuzzification process). Several criteria are used for the investigation: costs, efficiency, cogeneration, life-cycle and environmental impacts. The fuzzy-based expert system considers three different settings with two different constraints: costs and environmental impacts. One of the most relevant aspects presented by this work is about the previous criteria rank. It was created according to the different relevance observed among the attributes. The purpose of the proposed arrangement is to facilitate the understanding of the methodology and to increase the possibility of incorporating the decision makers' preferences on the decision-aid process. These aspects are essential to strengthen the final decision.

2013

Global against divided optimization for the participation of an EV aggregator in the day-ahead electricity market. Part II: Numerical analysis

Autores
Bessa, RJ; Matos, MA;

Publicação
ELECTRIC POWER SYSTEMS RESEARCH

Abstract
This paper presents numerical analysis of two alternative optimization approaches intended to support an EV aggregation agent in optimizing buying bids for the day-ahead electricity market. A study with market data from the Iberian electricity market is used for comparison and validation of the forecasting and optimization performance of the global and divided optimization approaches. The results show that evaluating the forecast quality separately from its impact in the optimization results is misleading, because a forecast with a low error might result in a higher cost than a forecast with higher error. Both bidding approaches were also compared with an inflexible EV load approach where the EV are not controlled by an aggregator and start charging when they plug-in. Results show that optimized bids allow a considerable cost reduction when compared to an inflexible load approach, and the computational performance of the algorithms satisfies the requirements for operational use by a future real EV aggregation agent.

2013

A multi-energy modelling, simulation and optimization environment for urban energy infrastructure planning

Autores
Page, J; Basciotti, D; Pol, O; Fidalgo, JN; Couto, M; Aron, R; Chiche, A; Foumie, L;

Publicação
Proceedings of BS 2013: 13th Conference of the International Building Performance Simulation Association

Abstract
Tins paper presents a multi-energy modelling environment developed to simulate and optimize urban energy strategies, with a focus on urban energy infrastructure planning. A multi-scale approach is applied for modelling urban energy networks, considered as the backbone of urban energy infrastructure. This is complemented by the modelling of energy demand (to consider the costs and impacts of demand-side measures. The model is also linked to a set of optimization techniques in order to provide answers to urban energy infrastructure planning issues. Two case study applications follow the presentation of the chosen modelling principles to illustrate the type of answers that can be provided by the proposed modelling and optimization approach. Copyright © 2011 by IPAC'11/EPS-AG.

2013

A multi-scale optimization model to assess the benefits of a smart charging policy for electrical vehicles

Autores
Chammas, M; Chiche, A; Fournie, L; Nuno Fidalgo, JN; Couto, MJ;

Publicação
2013 IEEE GRENOBLE POWERTECH (POWERTECH)

Abstract
The recent development of electric vehicles (EVs) has brought a new set of problems regarding their integration in power networks, particularly in terms of the potential growth of peak load. The peak growth leads to the increase of losses and braches charging and to voltage drops. Conversely, optimizing EV charging policy creates new opportunities for both network safety and energy trading through the markets. This paper presents a multi-level framework combining two representations of a medium voltage (MV) network in order to optimize the EV charging policy. A minimizing cost approach is set, modeling day-ahead markets, and taking into account losses. The proposed methodology is tested on a typical MV network.

2013

Long term impact of wind power generation in the Iberian day-ahead electricity market price

Autores
Pereira, AJC; Saraiva, JT;

Publicação
ENERGY

Abstract
The Iberian power systems went through important changes at the legal, regulatory and organizational levels in the last 20 years. One of the most relevant ones was the increasing penetration of distributed generation, namely wind parks, together with the development of the common market involving Portugal and Spain. In Portugal, distributed generation is paid using feed in tariffs while in Spain it can choose between receiving a regulated feed in tariff or the market price plus a participation prize. The feed in scheme is now under discussion since it is argued that it represents an excessive cost that is internalized in the end user tariffs. However, this discussion is frequently conducted without complete knowledge of the real impact of wind power on the electricity market price, since it contributes to reduce the demand on the market thus inducing a price reduction. To clarify these issues we used a long term System Dynamics based model already reported in a previous publication to estimate the long term evolution of the market price. This model was applied to the Iberian generation system using different shares of wind power capacity to quantify the impact of wind power on the day-ahead electricity market price.

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