2010
Autores
Bessa, RJ; Matos, MA;
Publicação
IET Conference Publications
Abstract
The increasing levels of wind power penetration motivated a revisitation of methods for setting operating reserve requirements for the next and current day. System Operators (SO) are now moving from deterministic intro probabilistic approaches, and including wind power forecasts in their decision-making problems. In this manuscript, a probabilistic approach that evaluates the consequences of setting each possible reserve level through a set of risk indices is compared with frequently used deterministic rules and a probabilistic rule where wind power uncertainty is described by a Gaussian distribution. The comparison is performed over a period of five months for a realistic power system, using real load and wind power generation data. Results highlight the limitations of deterministic rules, challenge the Gaussian assumption and illustrate the usefulness of risk indices derived from the probabilistic forecast and using a full probabilistic methodology.
2010
Autores
Bessa, RJ; Matos, MA;
Publicação
IET Conference Publications
Abstract
An aggregator agent for electric vehicles is a commercial middleman between a system operator and plug-in electrical vehicles (EV). For the system operator perspective, the aggregator is seen as a large source of generation or load, which could provide ancillary services such as spinning and regulating reserve. Generally these services will be provided in the day-ahead and intraday electricity markets. In addition, the aggregator also participates in the electricity market with supply and demand energy bids. In this paper, the integration of these concepts in an electricity market environment is discussed through proposing a framework for the information characterization (and availability) between aggregator, system operators and clients. A specific market (the Iberian Market - MIBEL) is discussed. In the sequence, the different degrees of availability of the relevant information are identified and characterized, including the variables that are necessary to forecast.
2010
Autores
Faria, JA; Nunes, E; Matos, MA;
Publicação
INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH
Abstract
The paper presents a method for the analysis and design of industrial production systems based on a joint assessment of the cost and the quality of service. The operation of a production system is seen as the accomplishment of a sequence of missions, each one corresponding to the cost-effective production and delivery of a specified quantity of products within a specified time frame. The paper shows that the probability of successfully accomplishing a mission is a non-linear function of the cumulative production downtime and that this time cannot be obtained using conventional Markov based techniques. The paper also introduces an analytical model and a procedure that allows the density function of the downtime to be obtained and shows how, using these tools, the production costs and the quality of service may be assessed and related to the internal design of the shop floor. The method seems to be particularly valuable in the analysis of production systems integrated in just-in-time supply chains, in which the reliability of the deliveries is an outstanding requirement.
2010
Autores
Costa, PM; Matos, MA;
Publicação
ENERGY POLICY
Abstract
The recent development of the concept of microgrid (mu Grid), associated to the emergent interest in microgeneration (mu Gen), has raised a number of challenges regarding the evaluation of the technical, economical and regulatory impacts of a high penetration of this kind of solutions in the power systems. In this paper, the topic of security of supply is addressed, aiming at evaluating the influence of mu Gen and mu Grids in the medium- and long-term availability of generation to serve the forecasted load. A Monte-Carlo based methodology is used to evaluate this influence and to assess the capacity credit of those entities.
2010
Autores
Pereira, AJC; Saraiva, JT;
Publicação
ELECTRIC POWER SYSTEMS RESEARCH
Abstract
This paper describes an approach to address the generation expansion-planning problem in order to help generation companies to decide whether to invest on new assets. This approach was developed in the scope of the implementation of electricity markets that eliminated the traditional centralized planning and lead to the creation of several generation companies competing for the delivery of power. As a result, this activity is more risky than in the past and so it is important to develop decision support tools to help generation companies to adequately analyse the available investment options in view of the possible behavior of other competitors. The developed model aims at maximizing the expected revenues of a generation company while ensuring the safe operation of the power system and incorporating uncertainties related with price volatility, with the reliability of generation units, with the demand evolution and with investment and operation costs. These uncertainties are modeled by pdf functions and the solution approach is based on Genetic Algorithms. Finally, the paper includes a Case Study to illustrate the application and interest of the developed approach.
2010
Autores
Pereira, AJC; Saraiva, JT;
Publicação
IET Conference Publications
Abstract
Generation expansion planning gained a new dimension with the advent of electricity markets. It is now an activity decoupled from transmission and there are several agents competing to generate electricity and aiming at maximizing their individual profits. In view of this, it becomes more important to develop tools to help generation agents to build their expansion plans, internalizing several uncertainties in the model, an being able to simulate different possible reactions of the other competitors, given their impact in the profits of the agent being modelled. In this paper, we present a long-term decision aid tool that uses System Dynamics to model the long run of electricity markets together with Genetic Algorithms to solve the individual expansion problem of generation agents given their mixed-integer nature. Apart from the detailed description of the developed approach, the paper also includes a Case Study based on a four generation agent system to illustrate its application.
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