A.M.L. da Silva

Transmission loss allocation: I. Single energy market

This paper presents a new methodology for allocating transmission losses to the participants of a single energy market. The proposed approach is based on the incremental transmission loss concept and is implemented through two models: basic and extended. In the basic model, the total system losses are estimated through the linear DC load flow equations, while the extended model uses the exact AC formulation. The concept of center of losses is used; a fictitious bus in the system network where all transactions are compensated for transmission losses. Both models provide a sharing of transmission losses among generators and loads based on a predefined proportion, for instance 50%:50% for each participant class. Some important aspects related with the allocation fairness and transparency are illustrated by numerical applications with the IEEE Reliability Test System. The extension of this methodology to interconnected energy markets is treated in a companion paper.

Transmission loss allocation. II. Multiple interconnected energy markets

For pt.I see ibid., vol.18, no.4, p.1389-94 (2003). This paper presents a new methodology based on the incremental transmission loss concept for allocating electric losses to generators and loads, participating in multiple interconnected energy markets. The main objective is to generalize the formulation proposed in the companion paper, Part I, in order to identify through a decomposition technique, the amount of losses that each participant in the market causes on all system areas. The concept of interchange losses is introduced: the total amount of losses that occurs outside a given market whose agents are responsible for causing them. Some criteria to share these losses among the market agents are presented and discussed. The IEEE Reliability Test System is used to illustrate the proposed methodology.

A Cluster and Gradient-Based Artificial Immune System Applied in Optimization Scenarios

The main objective of this paper is to use artificial immune systems (AIS) in optimization problems. For this purpose, two major immunological principles presented in the literature are revisited: hypermutation, which is responsible for local search, and receptor edition, used to explore different areas in the solution space. This paper presents three major modifications divided into two different goals. The first goal is to speed up the convergence of each individual. This is done through a new hypermutation approach that uses the numerical information provided by the optimization system to drive the cloning process to interesting directions into the solution space. The second goal regards the reduction of the computational effort necessary to simulate the whole population. This is accomplished by adding to the AIS algorithm two more features of the natural immune system: maturation control and memory cells. The maturation control analyzes the antibodies and, during the convergence process, eliminates possible redundancies, represented by individuals driving to the same local optimum. The last proposed improvement is the use of memory cells in dynamic-optimization scenarios. In such situations, a repertoire of successful cases is used to forecast part of the initial population. Combining these concepts together decreases the number of antibodies, generations, and clones, consequently speeding up the convergence process. Applications illustrate the performance of the proposed method.

Evolution Strategies to Transmission Expansion Planning Considering Unreliability Costs

This paper presents a new methodology to solve transmission expansion planning (TEP) problems based on evolution strategies (ES), but other heuristics are also used to assist the search process. The TEP problem includes the search for the least cost solution, bearing in mind investments and interruption costs. Unreliability costs are considered through the index LOLC-loss of load cost. Moreover, the dynamic nature of the TEP is accounted for by the proposed methodology. Case studies on a small test and on a real sub-transmission network (CEMIG Company, Brazil) are presented and discussed

Chronological Monte Carlo-Based Assessment of Distribution System Reliability

Regulatory authorities in many countries, in order to maintain an acceptable balance between appropriate customer service qualities and costs, are introducing a performance-based regulation. These regulations impose penalties, and in some cases rewards, which introduce a component of financial risk to an electric power utility due to the uncertainty associated with preserving a specific level of system reliability. In Brazil, for instance, one of the reliability indices receiving special attention by the utilities is the maximum continuous interruption duration per customer (MCID). This paper describes a chronological Monte Carlo simulation approach to evaluate probability distributions of reliability indices, including the MCID, and the corresponding penalties. In order to get the desired efficiency, modern computational techniques are used for modeling (UML-Unified Modeling Language) as well as for programming (object-oriented programming). Case studies on a simple distribution network and on real Brazilian distribution systems are presented and discussed

Reciclagem de escória cristalizada para a produção de argamassa

All discarded residues of the steelmaking industries and the cut of ornamental stone constitute a serious problem, once they occupy large ground areas that in turn become economically inactive. Usually, the solutions found out by the companies to discard such residues are the sanitary landfill and municipal solid wastes; however, in the structure of great cities, there are no spaces for this kind of disposal due to agglomeration of peoples in the urban centers and the high valuation of ground lots in some areas. These residues are found in great volume in the center-western region of Minas Gerais state and they donx92t find adequate final destination. The waste question is also relevant, once the discarding of industrial residues results in loss of goods that could be otherwise recycled and, by this way, generate other production goods. In this context, the present work aims at to contribute for the recycling of the residues generated in the referred region in order to prepare mortar for civil construction. The thermal behavior of the slag/granite and slag/slate composites was experimentally analyzed with the objective to find some application of these materials in the ground of civil engineering. With these thermal behavior results, an investigation was carried out of the viability of substituting the slag/granite composites for the hydrated lime, through the assays of water retention in the cool state and of the axial and of axial compressive strength in the hardened state with the objective to contribute for a new use of the new use of the residue.

Reliability evaluation of distribution systems considering automatic reclosers

This paper presents a new methodology to evaluate in a predictive way the reliability of distribution systems, considering the impact of automatic recloser switches. The developed algorithm is based on state enumeration techniques with Markovian models and on the minimal cut set theory. Some computational aspects related with the implementation of the proposed algorithm in typical distribution networks are also discussed. The description of the proposed approach is carried out using a sample test system. The results obtained with a typical configuration of a Brazilian system (EDP Bandeirante Energia S.A.) are presented and discussed