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Publications

2019

Reinforcement learning method for plug-in electric vehicle bidding

Authors
Najafi, S; Shafie Khah, M; Siano, P; Wei, W; Catalão, JPS;

Publication
IET Smart Grid

Abstract
This study proposes a novel multi-agent method for electric vehicle (EV) owners who will take part in the electricity market. Each EV is considered as an agent, and all the EVs have vehicle-to-grid capability. These agents aim to minimise the charging cost and to increase the privacy of EV owners due to omitting the aggregator role in the system. Each agent has two independent decision cores for buying and selling energy. These cores are developed based on a reinforcement learning (RL) algorithm, i.e. Q-learning algorithm, due to its high efficiency and appropriate performance in multi-agent methods. Based on the proposed method, agents can buy and sell energy with the cost minimisation goal, while they should always have enough energy for the trip, considering the uncertain behaviours of EV owners. Numeric simulations on an illustrative example with one agent and a testing system with 500 agents demonstrate the effectiveness of the proposed method.

2019

Optimal power consumption for demand response of thermostatically controlled loads

Authors
Halder, A; Geng, XB; Fontes, FACC; Kumar, PR; Xie, L;

Publication
OPTIMAL CONTROL APPLICATIONS & METHODS

Abstract
We consider the problem of determining the optimal aggregate power consumption of a population of thermostatically controlled loads such as air conditioners. This is motivated by the need to synthesize the demand response for a load serving entity (LSE) catering a population of such customers. We show how the LSE can opportunistically design the aggregate reference consumption to minimize its energy procurement cost, given day-ahead price, load forecast, and ambient temperature forecast, while respecting each individual load's comfort range constraints. The resulting synthesis problem is intractable when posed as a direct optimization problem after Euler discretization of the dynamics, since it results in a mixed-integer linear programming problem with number of variables typically of the order of millions. In contrast, in this paper, we show that the problem is amenable to continuous-time optimal control techniques. Numerical simulations elucidate how the LSE can use the optimal aggregate power consumption trajectory thus computed, for the purpose of demand response.

2019

Load Flexibility Forecast for DR Using Non-Intrusive Load Monitoring in the Residential Sector

Authors
Lucas, A; Jansen, L; Andreadou, N; Kotsakis, E; Masera, M;

Publication
ENERGIES

Abstract
This study examined three-dimensional, volumetric mean velocity fields and corresponding performance measurements for an isolated vertical-axis wind turbine (VAWT) and for co- and counter-rotating pairs of VAWTs with varying incident wind direction and turbine spacings. The purpose was to identify turbine configurations and flow mechanisms that can improve the power densities of VAWT arrays in wind farms. All experiments were conducted at a Reynolds number of ReD = 7.3 × 104. In the paired arrays, performance enhancement was observed for both the upstream and downstream turbines. Increases in downstream turbine performance correlate with bluff–body accelerations around the upstream turbine, which increase the incident freestream velocity on the downstream turbine in certain positions. Decreases in downstream turbine performance are determined by its position in the upstream turbine’s wake. Changes in upstream turbine performance are related to variations in the surrounding flow field due to the presence of the downstream rotor. For the most robust array configuration studied, an average 14% increase in array performance over approximately a 50? range of wind direction was observed. Additionally, three-dimensional vortex interactions behind pairs of VAWT were observed that can replenish momentum in the wake by advection rather than turbulent diffusion. These effects and their implications for wind-farm design are discussed.

2019

Analyzing the Adequacy of Readability Indicators to a Non-English Language

Authors
Antunes, H; Lopes, CT;

Publication
CLEF

Abstract
Readability is a linguistic feature that indicates how difficult it is to read a text. Traditional readability formulas were made for the English language. This study evaluates their adequacy to the Portuguese language. We applied the traditional formulas in 10 parallel corpora. We verified that the Portuguese language had higher grade scores (less readability) in the formulas that use the number of syllables per words or number of complex words per sentence. Formulas that use letters by words instead of syllables by words output similar grade scores. Considering this, we evaluated the correlation of the complex words in 65 Portuguese school books of 12 schooling years. We found out that the concept of complex word as a word with 4 or more syllables, instead of 3 or more syllables as originally used in traditional formulas applied to English texts, is more correlated with the grade of Portuguese school books. In the end, for each traditional readability formula, we adapted it to the Portuguese language performing a multiple linear regression in the same dataset of school books.

2019

Personalized pricing and advertising: Who are the winners?

Authors
Esteves, RB; Resende, J;

Publication
INTERNATIONAL JOURNAL OF INDUSTRIAL ORGANIZATION

Abstract
This paper investigates who wins and who loses when firms depart from a mass advertising/uniform pricing strategy (bench-mark model) to a targeted advertising/price discrimination one. Considering a duopoly market in which firms simultaneously compete in prices and advertising decisions, we examine the competitive and welfare effects of personalized pricing with targeted advertising by comparing equilibrium outcomes under customized advertising/ pricing decisions to the results arising under mass advertising and uniform pricing. We show that, when both firms compete in both market segments, all segment consumers are expected to pay higher average prices under the personalized advertising/pricing strategy. We also show that, in the context of our simultaneous game, targeted advertising with price discrimination might boost firms' profits in comparison to the case of mass advertising and uniform prices. The overall welfare effects of the personalized strategy are ambiguous. However, even when the personalized strategy boosts overall welfare, consumers might all be worse-off. Thus the paper gives support to concerns that have been raised re-garding the firms' ability to adopt personalized strategies to boost profits at the expense of consumers.

2019

Design of experiments in the methodology for interoperability testing: Evaluating AMI message exchange

Authors
Andreadou N.; Lucas A.; Tarantola S.; Poursanidis I.;

Publication
Applied Sciences (Switzerland)

Abstract
Interoperability is a challenge for the realisation of smart grids. In this work, we apply the methodology for interoperability testing and the design of experiments developed at the Smart Grids Interoperability Laboratory of the Joint Research Centre of the European Commission on a simple use case. The methodology is based on the Smart Grid Architecture Model (SGAM) of CEN/CENELEC/ETSI and includes the concept of Basic Application Profiles (BAP) and Basic Application Interoperability Profiles (BAIOP). The relevant elements of the methodology are the design of experiments and the sensitivity/uncertainty analysis, which can reveal the limits of a system under test and give valuable feedback about the critical conditions which do not guarantee interoperability. The design and analysis of experiments employed in the Joint Research Centre (JRC) methodology supply information about the crucial parameters that either lead to an acceptable system performance or to a failure of interoperability. The use case on which the methodology is applied describes the interaction between a data concentrator and one or more smart meters. Experimental results are presented that show the applicability of the methodology and the design of experiments in practice. The system is tested under different conditions by varying two parameters: the rate at which meter data are requested by the data concentrator and the number of smart meters connected to the data concentrator. With this use case example the JRC methodology is illustrated at work, and its effectiveness for testing interoperability of a system under stress conditions is highlighted.

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