Artigos

Matriz energética brasileira: uma prospectiva

O artigo apresenta uma prospectiva do setor energético brasileiro para o período 2005-30. As projeções apontam que o consumo de energia crescerá a taxas superiores às das últimas décadas e que a expansão da oferta energética poderá superar o dobro da atual capacidade instalada em todos os segmentos, especialmente os de petróleo, gás natural, etanol e eletricidade

Energia renovável no Brasil: análise das principais fontes energéticas renováveis brasileiras

O livro “Energia Renovável no Brasil” apresenta as principais fontes de energia renovável que possuem grande potencial de participação na matriz elétrica brasileira: Energia Hidrelétrica, Solar, Eólica e Biomassa. Estabelecendo um panorama nacional e internacional, o livro realiza uma análise sobre as tecnologias e desafios relacionados ao aproveitamento de cada uma dessas fontes. Os leitores poderão aumentar sua percepção sobre os principais impactos ambientais, econômicos e sociais envolvidos na exploração dessas energias; conhecer o funcionamento, os fundamentos do dimensionamento e os principais componentes de cada sistema; se familiarizar com os incentivos governamentais e legislação pertinente; e conhecer o grande potencial que o Brasil possui com relação ao aproveitamento de suas fontes de energia renovável.

Ventos promissores a caminho

Potencial eólico brasileiro é três vezes maior do que o do parque nacional de energia elétrica; capacidade atual pode abastecer 22 milhões de residências.

Revising IEEE Standard C37.2

This article describes the experiences in revising and updating a key IEEE Standard C37.2 - Standardfor Electrical Power System Device Function Numbers, Acronyms, and Contact Designations. The article cites the historical evolution of this standard dating back to 1928. The wide utilization of modern, multifunction relays and many new functions made clear the need to update the 1996 version of thisstandard. In addition the interweaving of communication facilities into protection and control requirements had to be addressed from function and designation points of view. The article demonstrates the importance of the involvement of the members of the IEEE in standards and the need for continued input from these members to ensure relevance to present application needs, coherence, and compatibility with other industry standards and practices.

Can an eighty year old standard still be relevant? This one (IEEE C37.2) clearly is

The predecessor to ANSI IEEE C37.2 "standard electrical power system device function numbers and contact designations" was first published as AIEE No. 26 in 1928. Since then, it has been revised eight times, but in each case retained the original concept of device numbers 1 through 99 for substation control and protection devices. Those numbers have become the shorthand (or second language) of control and protection engineers. The 2007 revision broke from that pattern by adding thirteen acronyms (not numbers) for new functions not previously covered by IEEE C37.2. This revision also includes a method of describing the intra-substation communication systems now in common usage.

Transmission Line Models for Steady-State and Transients Analysis

This paper presents a summary of the main transmission line models currently in use for steady-state and time-domain transients simulations. The main characteristics and limitations of the models are explained based on a common derivation of the different models from the same basic line equations. General guidelines are suggested regardin the are of applicability of the models.

A tutorial on calculating source impedance ratios for determining line length

Classifying the length of a line is an important step in determining the transmission line protection philosophy and relay settings. The length of a line can be defined by physical distance, impedance, or its source impedance ratio (SIR). The SIR is the ratio of the source impedance, ZS, to the line impedance, ZL. The SIR is well established in the industry as the preferred method for classifying the electrical length of a line for the purpose of setting protective relays. Many references discuss setting criteria and performance specifications relative to the SIR. However, very few references define the proper method for calculating the source impedance to use in the ratio. The transmission system is a complex network with many sources and branches, and the topology of the network can have a major effect on the results, depending on the method used. This paper analyzes several methods in common usage and presents a simple method that provides a better result. The effect of the SIR on line relay settings and examples of various transmission network topologies are discussed.

A new simple calculator of load flow in A-C networks

LOAD-FLOW analysis in a-c networks is increasing in importance because of the greater use of loop circuits in transmission and distribution systems to obtain the advantages of network operation.

A Simple New Resistance Type A-C Load Flow Board

Exemplo do aparato utilizado para realização do estudo de fluxo de potência anterior ao desenvolvimento de métodos computacionais.

Review of load-flow calculation methods

A survey is presented on the currently available numerical techniques for power-system load-flow calculation using the digital computer. The review deals with methods that have received widespread practical application, recent attractive developments, and other methods that have interesting or useful characteristics. The analytical bases, computational requirements, and comparative numerical performances of the methods are discussed. Attention is given to the problems and techniques of adjustments in load-flow solutions, and the suitabilities of various methods for modern applications such as security monitoring and optimal load flow are examined.

DC Power Flow Revisited

Linear MW-only ldquodcrdquo network power flow models are in widespread and even increasing use, particularly in congestion-constrained market applications. Many versions of these approximate models are possible. When their MW flows are reasonably correct (and this is by no means assured), they can often offer compelling advantages. Given their considerable importance in today's electric power industry, dc models merit closer scrutiny. This paper attempts such a re-examination.

Comparison of ANSI and IEC 909 short-circuit current calculation procedures

A generalization of the methods used by both ANSI and IEC 909 is presented. The philosophical differences in calculation procedures are discussed. Although ANSI fault calculation methods are designed to determine a value to compare with the equipment ratings, the IEC 909 Standard presents a method that inherently more accurately models the fault currents that flow. The IEC method requires significantly more complex modeling of the power system fault contributions than the ANSI method requires. By understanding the calculation differences, the difference in equipment ratings becomes more meaningful.

Understanding Fault Characteristics of Inverter-Based Distributed Energy Resources

This report discusses issues and provides solutions for dealing with fault current contributions from inverter-based distributed energy resources.