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Publicações

Publicações por João Tomé Saraiva

2015

Economic Evaluation of Generation and Storage Solutions in Low Voltage End User Installations

Autores
Soares, RA; Saraiva, JT;

Publicação
2015 12TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
Storage technologies are expected to assume an increasing relevance in the next few years, given the widespread number of available options, the possible applications and the reduction of investment costs. Therefore and apart from the well-known hydro pumping stations, the installation of storage is being considered as an increasingly viable option namely in distribution networks and also in end user installations. This paper reviews the recently passed Portuguese legislation on self-consumption and details a model to evaluate the economic interest of installing batteries together with PV panels according to several possible business models. The simulations suggest that the tariffs currently applied and the investment costs turn these options still not attractive so that a final simulation was developed to evaluate the break even value of the tariffs to turn the investments on storage paid in a reasonable horizon.

2018

Technical-economic analysis for the integration of PV systems in Brazil considering policy and regulatory issues

Autores
Vilaca Gomes, PV; Knak Neto, NK; Carvalho, L; Sumaili, J; Saraiva, JT; Dias, BH; Miranda, V; Souza, SM;

Publicação
ENERGY POLICY

Abstract
The increasing integration of distributed renewable energy sources, such as photovoltaic (PV) systems, requires adequate regulatory schemes in order to reach economic sustainability. Incentives such as Feed-in Tariffs and Net Metering are seen as key policies to achieve this objective. While the Feed-in Tariff scheme has been widely applied in the past, it has now become less justified mainly due to the sharp decline of the PV system costs. Consequently, the Net Metering scheme is being adopted in several countries, such as Brazil, where it has is in force since 2012. In this context, this paper aims to estimate the minimum monthly residential demand for prosumers located in the different distribution concession areas in the interconnected Brazilian system that ensures the economic viability of the installation of PV systems. In addition, the potential penetration of PV based distributed generation (DG) in residential buildings is also estimated. This study was conducted for the entire Brazilian interconnected system and it demonstrates that the integration of distributed PV systems is technical-economic feasible in several regions of the country reinforcing the role of the distributed solar energy in the diversification of Brazilian electricity matrix.

2016

Economic Evaluation of Combined Generation and Storage Solutions in Low Voltage Portuguese Consumers

Autores
Soares, RA; Saraiva, JT;

Publicação
2016 13TH INTERNATIONAL CONFERENCE ON THE EUROPEAN ENERGY MARKET (EEM)

Abstract
This paper presents the results that were obtained in the scope of a consultancy study developed by INESC TEC for a Portuguese distribution network company to evaluate the interest of installing storage devices and PV panels in LV installations. We conducted simulations for consumers with annual demands of 5000 kWh (Type C consumers) and 7500 kWh (Type B consumers). In general, we concluded that the installation of storage devices is still of little economic interest given the current investment level and the tariffs paid to inject electricity in the networks. The largest NPV values were obtained when only installing PV panels in Type B consumers, the larger ones, and selling the surplus energy to the network.

2016

Impact of the feed-in generation in the prices of the Iberian electricity market in 2013

Autores
Gonçalves, P; Saraiva, JT;

Publicação
IET Conference Publications

Abstract
Power industry has been deeply restructured in recent decades. Along this period vertically integrated structures evolved to more disaggregated models in which some activities are now provided under competition as generation and retailing while some others are provided under regulated monopolies as network transmission and distribution. Simultaneously, most countries started to encourage the use of renewable sources, namely to cope with environmental issues and to enlarge the energy independency. Having in mind these ideas and given the development of the Iberian Electricity Market and the increase of the installed capacity in units paid by feed-in tariffs, it becomes important to estimate the impact of this feed-in generation in the market prices. This paper describes the approach that was developed to estimate this impact and the implemented software application. This application was then used to evaluate the impact on prices on all trading hours of 2013 of the Portuguese photovoltaic generation, the Portuguese wind generation, all the Portuguese feed-in generation and also all the Iberian feed-in generation.

2018

Simultaneous co-integration of multiple electrical storage applications in a consumer setting

Autores
Metz, D; Saraiva, JT;

Publicação
ENERGY

Abstract
In a consumer setting, storage systems can be dispatched in order to shift surplus generation to periods when a local generation deficit exists. However, the high investment cost still makes the deployment of storage unattractive. As a way to overcome this problem existing literature looking at storage installed at the grid-level suggests dispatching the storage device for multiple applications simultaneously in order to access several value streams. Therefore, in this work, a Mixed Integer Linear Program is developed in order to schedule the operation of a storage device in a consumer context for multiple objectives in parallel. Besides shifting locally generated energy in time, the peak demand seen by the electric grid is reduced and the storage device is operated to provide primary reserve control. The model is applied in a case study based on the current German situation in order to illustrate the value contribution of stacking multiple services. When pursuing multiple applications simultaneously, the revenues of storage can be increased significantly. However, the revenues are not additive due to conflicting operations which originates a revenue gap as illustrated in the paper.

2013

A discrete evolutionary PSO based approach to the multiyear transmission expansion planning problem considering demand uncertainties

Autores
da Rocha, MC; Saraiva, JT;

Publicação
INTERNATIONAL JOURNAL OF ELECTRICAL POWER & ENERGY SYSTEMS

Abstract
This paper presents a multiyear dynamic model to the Transmission Expansion Planning, TEP, problem to identify the most suitable set of projects as well as their scheduling along the planning horizon. The candidate plans are evaluated using a fitness function that incorporates operation and investment costs plus a set of penalty terms. These terms are associated with the level of losses, non-zero values for the power not supplied namely for the entire system and for n - 1 contingencies, financial limits, maximum number of projects to implement in each year or all along the horizon and the capability to accommodate not only the expected demand, but also uncertainties affecting the demand forecasts. Given the discrete nature of the problem, we adopted an enhanced approach of the PSO algorithm to solve it. This includes an evolutionary adaptation of the PSO movement rule as well as several modifications to ensure that along the iterative process each candidate solution is technically feasible given its discrete nature. The paper also reports the results of a set of tests to evaluate several design decisions related with the development of the Discrete Evolutionary PSO, DEPSO, as well as to compare the results of its application to the TEP with results reported by other researchers.

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