Power System Economics

The long-term electric power demand forecasting is based on a set of basic premises that includes the macroeconomic scenarios, the growth of the population and of the number of households. The latter is the main determinant to calculate the number of residential customers served by the utilities. This paper presents the headship rate method and its projections for the number of households in Brazil for the years 2010 and 2020. These projections are based on the long term forecasting of the age pyramid of the Brazilian population provided by the Brazilian Institute of Geography and Statistics (IBGE). In order to forecast the number of residential customers in the next ten years, the projections for the number of households are combined with the goals established by the Brazilian Electricity Regulatory Agency (ANEEL) for universalization access to electricity.

This work describes a methodology for long-term electricity demand forecast in the residential sector. The methodology has been used in the power market studies of some Brazilian distribution utilities. The methodology is based on decomposition of the total electricity residential consumption in three components: average consumption per consumer unit, electrification rate and number of households. Then, the forecast for the total electricity consumption in residential sector is the product of forecasts for these three components. The prediction for the number of households is based on demographic models while the future trajectory of the electrification rate is defined by the targets for achieving the universal access to electricity. The product of these two components provides a forecast to the number of residential customers. The average consumption per unit consumer depends on the macroeconomic scenarios for GDP, average household income and income distribution. The proposed methodology provides a framework to integrate macroeconomic scenario, demographic projection and assumptions for ownership and efficiency of electric appliances in a long-term demand forecast. In order to illustrate the application of the proposed methodology, this paper presents a ten-year demand forecasts for the residential sector in Brazil.

Energy storage components improve the energy efficiency of systems by reducing the mismatch between supply and demand. For this purpose, phase change materials are particularly attractive since they provide a high energy storage density at a constant temperature which corresponds to the phase transition temperature of the material. Nevertheless, the incorporation of phase change materials (PCM) in a particular application calls for an analysis that will enable the researcher to optimize performances of systems. Due to the non-linear nature of the problem, numerical analysis is generally required to obtain appropriate solutions for the thermal behavior of systems. Therefore, a large amount of research has been carried out on PCMs behavior predictions. The review will present models based on the first law and on the second law of thermodynamics.

This article gives the complete information about the Reactive Power compensation given to the distribution system for reducing the Power Losses. In this article, a case study of MPPKVVCL, Jabalpur, India substation of 8MVA at 33/.4 kV data is taken with shunt capacitor bank and without shunt capacitor bank at peak hours is consider. It is seen from load curve that with the switch in of shunt capacitor bank, current of about
10- 12 Ampere is dropped in 11 kV line. This drop of current reduces the burden on the devices of the 11 kV feeder. Also current saved is used for other customers for providing Electrical Power. Further MATLAB simulation is done to show the current drop in 11 kV feeder line with the inclusion of shunt capacitor bank. Also, Annuity is used for Economic analysis for understanding the lifecycle cost saving with the inclusion of shunt capacitor bank is calculated. Nonetheless, this methodology can be used for any configuration knowing the actual saving with the inclusion of shunt capacitor in the distribution system.

MATPOWER is an open-source Matlab-based power system simulation package that provides a high-level set of power flow, optimal power flow (OPF), and other tools targeted toward researchers, educators, and students. The OPF architecture is designed to be extensible, making it easy to add user-defined variables, costs, and constraints to the standard OPF problem. This paper presents the details of the network modeling and problem formulations used by MATPOWER, including its extensible OPF architecture. This structure is used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits. Simulation results are presented for a number of test cases comparing the performance of several available OPF solvers and demonstrating MATPOWER's ability to solve large-scale AC and DC OPF problems.

Through looking back to the transformative processes of the past 25 years, this study outlines the determining characteristics of the current international power relations, predominantly with an analytical approach. It seeks to answer the following questions: how should we approach the analysis of the international system, the changes that have occurred during the past 25 years, and today’s power relations? In doing so, the author offers an overview of how international power relations have transformed from the break-up of the bipolar world order to the current multipolar setup; how the concept of power and its elements have evolved; and how the range of influential actors of the international system has broadened, in overall changing the hierarchical structure of the whole system. Finally, the study also offers an analytical picture of the most important characteristics of international relations, identifying where the stakes for Europe and the European Union currently lie, as its course of development is also the primary strategic determinant of the future of Hungary.

With the development of modern power systems, economic dispatch problem has received an increasing attention. The economic dispatch is an optimization problem to find the most economical schedule of the generating units while satisfying load demand and operational constraints. In this paper, Tabu Search is applied to economic dispatch problem. The proposed method has been demonstrated through a six-unit system. The results of the proposed method are compared with those of an Improved Hopfield NN approach (IHN) [1], a Fuzzy Logic Controlled Genetic Algorithm (FLCGA) [2], an Advance Engineered-Conditioning Genetic Approach (AECGA) [3] and an Advance Hopfield NN approach (AHNN) [4].

The general design for the real-time electricity market presented in this paper optimizes and prices both real and reactive power simultaneously in an AC setting, where all assets-generation, load and transmission-are allowed to bid and are financially settled at the locational price times energy consumed or produced. The result is that transmission lines are compensated for both capacity and admittance, providing incentives for efficient operation of transmission-related assets such as FACTS devices, if price-taking behavior is assumed. Losses are incorporated into the design and become an operating cost for transmission. The market design is shown to be revenue neutral and, under some assumptions, nonconfiscatory.

The article estimates the costs of plug-in electric vehicles (EVs) in a future power system as well as the benefits from smart charging and discharging EVs (smart EVs). To arrive in a good estimate, a generation planning model was used to create power plant portfolios, which were operated in a more detailed unit commitment and dispatch model. In both models the charging and discharging of EVs is optimised together with the rest of the power system. Neither the system cost nor the market price of electricity for EVs turned out to be high (36e263 V/vehicle/year in the analysed scenarios). Most of the benefits of smart EVs come from smart timing of charging although benefits are also accrued from provision of reserves and lower power plant portfolio cost. The benefits of smart EVs are 227 V/vehicle/year. This amount has to cover all expenses related to enabling smart EVs and need to be divided between different actors. Additional benefits could come from the avoidance of grid related costs of immediate charging, but these were not part of the analysis.

Marginal cost pricing is widely recognized as the core of any sound approach to economic valuation of transmission services. This paper presents results that help to recognize and to compute the several components of the spot prices, so that the contributions of each user to the network costs can be identified and understood.

This paper examines bidding strategies in a bilateral market in which generating companies submit bids to loads. A load accepts electricity delivery from the generator with the lowest bid at its bid price as long as this price is not higher than the load's willingness to pay. Necessary and sufficient conditions of Nash equilibrium (NE) bidding strategy are derived based on a generic generating cost matrix and the loads' willingness to pay vector. The study shows that in any NE, efficient allocation is achieved. Furthermore, all Nash equilibria are revenue equivalent for the generators. Based on the necessary and sufficient conditions, this problem is formulated as an optimal assignment problem. Network optimization techniques are applied to calculate NE bid prices for the generators.

HISTORICAL crossroads. Decisions must soon be made about the direction of grid development so that it can meet extraordinary economic challenges, critical needs for energy security, and essential requirements for a sustainable way of life. This is a defi ning moment in terms of our nation's commitment to providing an electric energy system, including a bulk transmission network, that can meet the societal needs of the 21st century and beyond. A major evolutionary step in the grid's design, planning, and operation is needed, one that adopts new design concepts and innovative technologies that can be integrated into a modern infrastructure. The American Recovery and Reinvestment Act of 2009 (ARRA) provided a number of opportunities to achieve these far-reaching objectives. This article describes a vision of-and the steps needed to reach-the national objective of having a smart grid infrastructure. Our focus is on new concepts and related technological considerations in developing smart grid solutions that will meet the seven objectives of the smart grid, as identifi ed by the U.S. Department of Energy (DOE): 1) enabling informed participation by customers 2) accommodating all generation and storage options 3) enabling new products, services, and markets 4) providing the level of power quality required to meet the full range of needs in the 21stcentury economy 5) optimizing asset utilization and operating efficiently 6) addressing disturbances through automated prevention, containment, and restoration 7) operating resiliently against all hazards. To achieve these goals, smart research and development efforts must harmonize four principal aspects of the future grid: ✔ Expansion of the electricity grid infrastructure: This includes building new infrastructure to replace aging infrastructure while expanding grid capacity, improving the operation and efficiency of the existing infrastructure, and developing novel concepts, technologies, and applications. The smart grid will integrate renewable generation and distributed energy sources. It will also enable creative options for customers to participate in system operations by offering their loads and storage capability (e.g., from plugin hybrid electric vehicles) as resources. Customers also want options for making their own usage more energy and cost efficient (such as through building energy management systems).

The reform process in the electricity sector of any country has as main objective the design of a power market capable to induce a reliable and efficient energy supply, translated into adequate tariffs. Brazil started its reform process in 1996, inspired by similar schemes in the electricity sector of more developed countries. However, the existence of particularities in the country's hydroelectric energy market, such as weak spot price signals for system expansion and difficulties to determine benchmark prices, avoided a smooth transition to a fully deregulated market. In 2004, a revisited power sector model was launched, aiming at alleviating the difficulties of the first model. The core of the new proposals lies on the use of contract obligation and energy supply auctions as the backbone for the efficient contracting and supply adequacy. Supply auctions were held in 2004-2005, with a volume of about 20,000 average MW contracted involving about 60 billion USD in financial transactions. This work discusses the implementation of auctions of energy contracts and call options in Brazil as part of the mechanisms to ensure supply adequacy adopted in the second stage of its power sector reform

A detailed AC OPF-based formulation for procuring, pricing, and settling energy and ancillary service in simultaneous auctions by integrated market systems is presented. The paper provides clear definitions of Locational Marginal Prices for energy and Ancillary Service Marginal Prices in terms of Lagrange multipliers. The characteristics of the prices are analyzed especially when economic substitution among ancillary services is required. The paper also evaluates the conditions under which opportunity costs are incurred to units that provide ancillary services. It is particularly shown that the intuitive belief that the provision of regulation down service does not incur opportunity cost to the provider, in general, is not true.

Summary form only given. This work presents a methodology for calculating the optimal generation capacity reserve and siting in power systems planning. The proposed methodology is based on a least-cost planning approach which considers along the planning horizon, the capacity reserve investment costs and the operational expected costs, comprising thermal generation and interruption costs. This problem is solved by using the Benders decomposition technique in which investment and operation subproblems solutions are obtained iteratively and separately thus allowing the use of tailor-made algorithms for each subproblem. The operation subproblem corresponds to a probabilistic evaluation of the minimum operation cost in composite generation/transmission systems, in which the system states are selected through Monte Carlo simulation or state enumeration and the system performance is analysed by a nonlinear optimal power flow solved by an interior point algorithm. The proposed methodology is illustrated in a case study with a modification of the IEEE Reliability Test System (MRTS).

The firm energy of generation plants is a critical component in some electricity markets. It is usually calculated by the regulator and sets a cap to the amount a plant can trade in capacity markets (or auctions), in order to avoid free-riding behaviors. Firm energy is a systemic property and, in case of hydro plants, a synergy is observed whenever a cooperative operation occurs, i.e., the firm energy of a system is greater than the sum of the individual plants. This immediately raises the question of how to divide the system's firm energy among the individual hydro plants. The objective of this work is to investigate the application of different allocation methods of firm energy rights among hydro plants using a game-theoretic framework. It is shown that there is not an optimal and unique approach to make this allocation. The paper investigates the advantages and disadvantages of different methods, such as marginal allocation, average production during the critical period, incremental allocation, finally recommending the Aumann-Shapley as the allocation method. This method is tested for the Brazilian power system, which has around 100 hydro plants. The results obtained are compared with the current allocation adopted by the electricity regulatory agency of Brazil.

Currently, there is a national push for a smarter electric grid, one that is more controllable and flexible. Only limited control and flexibility of electric assets is currently built into electric network optimization models. Optimal transmission switching is a low cost way to leverage grid controllability: to make better use of the existing system and meet growing demand with existing infrastructure. Such control and flexibility can be categorized as a “smart grid application” where there is a co-optimization of both generators or loads and transmission topology. In this paper we form the dual problem and examine the multi-period N-1 reliable unit commitment and transmission switching problem with integer variables fixed to their optimal values. Results including LMPs and marginal cost distributions are presented for the IEEE RTS 96 test problem. The applications of this analysis in improving the efficiency of ISO and RTO markets are discussed.

Modern operation of power systems is based with priority and on economical aspects. The most efficient operation of a power system is based on the unit commitment and economic dispatch concepts, which are governed by well established economical criteria. This seemingly simple approach is not always possible for various reasons, e.g. in the case of autonomous power systems (APS) usually located in small-medium size islands. In reality, the aim of an APS is to cover the hourly electrical demand, while is taking into account the maintenance of the involved generating units, so they are available in appropriate time periods. Usually, a specific operating policy is followed, which determines the way the generating units should be loaded, depending on the structure of the network involved. For the proper operation of an APS a method is developed, in this work, which generally is based on such a policy of APS operation and in addition attempts to make a compromise between economic and maintenance constraints. The proposed method is applied successfully to an APS of a medium size Hellenic island.

Optimal Power Flow (OPF) is one of the main functions of Power Generation Operation and Control. It determines the optimal settings of generating units, bus voltage, and transformer tap and shunt elements in Power System with the objective of minimizing total production costs or losses while the system is operating within its security limits. The aim of this paper is to propose a methodology (GA-Matpower-OPF) that solves OPF including both active and reactive power dispatches. It is based on combining the Genetic Algorithm (GA) to obtain a near global solution, and the package of Matlab m-files for solving power flow and optimal power flow problems (Matpower) to determine the optimal global solution. This method was tested on the modified IEEE 57 bus test system. The results obtained by this method are compared with those obtained with GA or Matpower separately.

South America has emerged in recent years as one of the most dynamic regions for natural gas and electricity development. The continent boasts natural gas reserves and highgrowth energy markets. The need to diversify away from heavy investments in hydropower and expensive oil is driving many countries to promote the use of natural gas, especially for power generation. On the other hand, challenges are being observed such as competition between hydro-and thermal generation, the breaking of cross-country natural gas agreements, competition between natural gas and other resources for power generation and electric transmission, and others. More recently, LNG started to be considered an option to ensure the adequacy of natural gas supply for power generation. Brazil and Chile are leading the implementation process of regasification facilities. However, the region has also potential to become an exporter of LNG in the medium-term once the potential gas reserves that require deep drilling become commercially available. This paper discusses the introduction of LNG in South America, focusing on the markets, the prices and the security of supply.

Ancillary Services are essential to the reliability and security of power system operation in any competitive electricity market environment. Procurement of ancillary services must take into account effective use of the capacity under emergency conditions, delivery time, transmission limitations, and local area requirements. Regional procurement of ancillary services is an approach that results in effective distribution of reserves and ensures continuous reliability in the event of a contingency occurring anywhere in the system. However, most ISOs procure and price ancillary services based on the least-cost service with little regard to zonal dispersion. In general, such an approach is not sufficient to ensure continuous reliability and security of the power system This paper presents a new methodology and numerical examples for procuring and pricing ancillary services on a regional basis, with an explicit representation of imports in a simultaneous energy/reserve market environment.

Energy storage components improve the energy efficiency of systems by reducing the mismatch between supply and demand. For this purpose, phase change materials are particularly attractive since they provide a high energy storage density at a constant temperature which corresponds to the phase transition temperature of the material. Nevertheless, the incorporation of phase change materials (PCM) in a particular application calls for an analysis that will enable the researcher to optimize performances of systems. Due to the non-linear nature of the problem, numerical analysis is generally required to obtain appropriate solutions for the thermal behavior of systems. Therefore, a large amount of research has been carried out on PCMs behavior predictions. The review will present models based on the first law and on the second law of thermodynamics. It shows selected results for several configurations, from numerous authors so as to enable one to start his/her research with an exhaustive overview of the subject. This overview stresses the need to match experimental investigations with recent numerical analyses since in recent years, models mostly rely on other models in their validation stages.

Brazil has a large potential for wind: it is estimated that nearly 140,000 MW of wind energy generating capacity could be built in the country. In December 2009 a specific auction to contract wind power was carried out. The motivation of this auction was to take advantage of the 2008-2009 world financial crisis that has lowered equipment cost as well as to foster competition among the interested investors, thus starting the development of this technology in the country in a larger scale. The product offered -a 20 year energy contract -has particular characteristics that try to accommodate wind variability and mechanisms to penalize productions above/below a given annual energy threshold. The objective of this work is to discuss the wind power auction in Brazil. We describe the auction motivation, product, organization, procedure, results and present our critical analysis. The information presented in this work may be useful for other countries willing to adopt the same mechanism.

The reconstruction or revitalization of electrical substations gives the possibility to introduce very powerful new switch gears, and as a result, to simplify the substation circuit diagram. Taking into account these tendencies, the authors propose a systematical method for establishing the optimal structure of electrical substations for increasing the operational level of reliability at the lowest economic cost. The graph theory is used to solve this particular problem. A (multi)graph will be associated to the network under study, where the bus system are taken for nodes, while the power lines and the (auto)transformers are considered as branches. By developing this model, the task of finding the critical equipment is reduced to the determination of (multi)graph critical nodes (articulation points) and critical branches (isthmuses). The paper presents an original method that, using the determination of critical equipment (systems of buses, transformers, power lines), indicates the most appropriate (minimal) structure for electrical substation circuit diagrams.

The adequacy problem in electricity market is becoming a very important issue as there is neither theoretical proof nor practical evidence of correct delivering of sufficient and timely generation capacity when it is needed in a real (imperfect) environment. In contrast, classical market design seems to fail when facing high demand growth and/or large hydro share as seen in several Latin American countries such as Chile, Brazil, Colombia and Peru among others. Currently, various mechanisms have arisen across this region with the intention of stimulating energy procurement and new investment. These are mainly based on long-term contract and options obligations, which are allocated through auctions. Auction theory then becomes very important to ensure optimal allocation and efficient prices for both the new generation and the end user. However, difficulties arise when applying pure auction theory because basic hypotheses are not met by most electricity markets. The objective of this paper is to address and discuss the Latin American experience with auction design for long-term contracts focusing on practical design and theory. The different mechanisms and auctions for ensuring supply adequacy are listed along with theoretical justification as part of the potential solution for the adequacy problem that different economies have proposed.

In practice, locational marginal prices (LMPs) are usually calculated by assembling their three components: the reference price, the congestion price, and the loss price. Explicit formulas for calculating the three components based on the single-slack power-flow formulation can be found in the literature. This letter presents the formulas for calculating the three components based on a distributed-slack power-flow formulation.

The California ISO is in the process of migrating from a decentralized and zonal based market system to a centralized and nodal based market system. This is an effort motivated by the standard market design proposed by the U.S. federal energy regulatory commission and by the operational problems encountered by the California ISO over the past five years using a zonal-based model. This paper explains why the California ISO has decided to move from the zonal market system to a nodal market system from an operational perspective.

This paper presents a methodology to improve the power system economical dispatch from a voltage stability margin perspective. The time horizon under discussion is the short-term operation planning. The proposed method is based on active/reactive power re-dispatch for normal operation, and also minimum load shedding strategies in case of critical contingencies. The actions are taken in the direction provided by modal participation factors computed for generator and load buses. The generators with negative impact on system margin, which are indicated by the modal index, are penalized with high costs on the objective function of the optimal power flow program used to run the re-dispatch process. Results of this work show a decrease on system losses and significant increase on voltage stability margin as well as on system reactive reserves. In addition, this work presents a study considering critical contingencies, for which is proposed an optimal load shedding strategy also based on modal participation factors to identify the most adequate buses for load shedding purposes. Finally, the proposed methodology is applied considering a typical hour-to-hour daily load curve, and the method presented very good performance since it considerably increases voltage stability margin for the insecure intervals.

One of the impediments to large-scale use of wind generation within power systems is the non-dispatchability and its variable and uncertain real-time availability. Operating constraints on conventional generators such as minimum generation points, forbidden zones, and ramping limits as well as system constraints such as power flow limits and ancillary service requirements may force a system operator to curtail wind generation in order to ensure feasibility. Furthermore, the pattern of wind availability and electricity demand may not allow wind generation to be fully utilized in all hours. One solution to these issues, which could reduce these inflexibilities, is the use of real-time pricing (RTP) tariffs which can both smooth-out the diurnal load pattern in order to reduce the impact of binding unit operating and system constraints on wind utilization, and allow demand to increase in response to the availability of costless wind generation. We use and analyze a detailed unit commitment model of the Texas power system with different estimates of demand elasticities to demonstrate the potential increases in wind generation from implementing RTP.

the integrated sugar/ethanol/electricity production has launched a new business model -the bioelectricity industrywith a potential to become a "mainstream" energy supply option in the near future in Brazil. Besides being clean, the bioelectricity plants have been winning several hundred MWs in long-term contracts auctioned by distribution companies under the Brazilian power sector framework. These contracts have been awarded on a competitive basis, without any subsidy policy. In addition, bioelectricity plants comply with the requirements of the CDM for selling emission reduction credits. The objective of this work is to discuss the bioelectricity achievements in Brazil.

The implementation of auctions of long-term firm energy call options and forward contracts as part of the instruments adopted in emerging countries to ensure resource adequacy is discussed. These mechanisms are being implemented in Latin American nations (Brazil, Chile, Peru, El Salvador & Panama) and fast-growing economies in Europe such as Turkey. Brazil has led this process and in overall has auctioned about 25,000 average MW of contracts, involving about 65 billion USD in financial transactions, while Chile has carried out its first auction in 2006, involving about 1,300 average MW (30% of energy sales of the main interconnected Chilean system expected for 2010). Overall, this mechanism is proving to be adequate to attract investments and ensure resource adequacy.

Currently, there is a national push for a smarter electric grid, one that is more controllable and flexible. The full control of transmission assets are not currently built into electric network optimization models. Optimal transmission switching is a straightforward way to leverage grid controllability: to make better use of the existing system and meet growing demand with existing infrastructure. Previous papers have shown that optimizing the network topology improves the dispatch of electrical networks. Such optimal topology dispatch can be categorized as a smart grid application where there is a cooptimization of both generators and transmission topology. In this paper we present a co-optimization formulation of the generation unit commitment and transmission switching problem while ensuring -1 reliability. We show that the optimal topology of the network can vary from hour to hour. We also show that optimizing the topology can change the optimal unit commitment schedule. This problem is large and computationally complex even for medium sized systems. We present decomposition and computational approaches to solving this problem. Results are presented for the IEEE RTS 96 test case.

Coal and hydro will be the main sources of electric energy in Chile for the near future, given that natural gas from neighbouring Argentina is not longer available and LNG price projections leave it only as a backup fuel. The country has limited energy resources, importing more than 73% of its energy. Hydroelectric untapped resources are significant, but they are mostly located in the extreme south of the country, in unpopulated areas of great unspoiled beauty. Non governmental organizations both within the country and from the US are strongly opposing the use of these resources. Renewables, which are only at an early stage, are argued as an alternative, but do not represent a solution with rates of growth of electricity demand over 6% a year. This summary discusses the issues being faced and the environmental dilemma faced by the country, where both coal and hydro produce some kind of impact. The role of the State and the private sector in determining the country's energy matrix arises as another central discussion ⋅ .

The objective of this work is to discuss the generation options and challenges to meet an increasing electricity demand in Brazil. Emphasis will be put on the challenge of conciliating generation system expansion and environmental constraints under a cost-effective framework.

Brazil presents a remarkable potential for the development of renewable energies. Besides large-scale hydro plants, the wind power plants, small hydros and cogeneration from sugarcane bagasse are the mainstream options. These sources have increased their participation in the country's energy matrix due to their attractive characteristic such as smaller environmental impact and lower construction periods (in general less than 3 years), which is suitable in a context of an uncertain load growth, since it offers an attractive option and mitigates the associated risks. The development of these resources requires the availability of a transmission system sufficiently robust in order to allow the flow of the electricity produced by these resources. Because these plants are distributed geographically over a large (dispersed) area, their connection to the transmission grid is complex. In order to turn feasible the connection of these plants, a complex and integrated technical and regulatory scheme of planning and pricing of transmission-distribution networks was developed. The objective of this work is to present and discuss the technical and regulatory questions associated to the connection of renewables in the Brazilian power system and what has been proposed to address these issues.

The worldwide development of natural gas industry resulted in an integration process between electrical and gas sectors in several countries. In Brazil, this process has been taking place in a consistent manner, especially on account of the increase in gas consumption for industrial use and of the installation of thermoelectric plants. Due to the predominance of hydro plants in electric power generation, thermoelectric energy production is basically dependent on hydrology and, as a result, presents a wide annual variability. Consequently, the investment applied to gas production and transportation infrastructure may become under-utilized during a large part of the time; thus, it is important to find mechanisms apt to improve its utilization. In this respect, the present work investigates the creation of a flexible market for gas, where contracts for flexible gas supply would be offered to industrial users, who would receive the gas assigned to thermal power plants when the latter are not dispatched, and would resort to an alternate fuel when these plants are dispatched. The attractiveness of such a contract would depend, of course, on its price. The purpose of this work is to develop a stochastic model for pricing flexible gas supply contracts, taking into account the uncertainty associated to the supply -dependent on the dispatch of the thermal power plants, which have the priority of use of the gas -and the risk profile of potential consumers.

It is widely accepted that generation operation planning can be advantageously modelled through market equilibrium representation. When several areas or countries are intended to function as a whole market, cross-border congested lines require implementation of a management methodology. Of the ones proposed in the literature, this paper is focused on market splitting and explicit auctions.

Genetic algorithms are relatively new, however they represent a powerful technique based on biological concepts and are very suitable for solving optimization problems. One such optimization problem is power system security with consideration of economic dispatch. This paper presents a new approach based on constrained genetic algorithms to solve such optimization problems. The operation of power systems demands a high degree of security in order to keep the system operating satisfactorily when subjected to disturbances, while at the same time it is required to take economic aspects into account. A pattern recognition technique is used first to assess dynamic security. Linear classifiers that determine the stability of electric power systems are presented and added to other system stability and operational constraints. The problem is formulated as a constrained optimization problem in a way that ensures a secure and economic system of operation. A genetic algorithm is then used to solve the formulated optimization problem. The method is tested using two different test systems and the results obtained show that the it is very useful for solving such problems.

A crise na União Europeia e os programas de austeridade subsequentes fizeram emergir uma miríade de movimentos sociais, diversos na sua natureza e nos seus propósitos. O que se pretende aferir neste artigo é a relação e a conexão existentes entre o Estado, o poder económico, a sociedade civil e os movimentos sociais neste contexto específico de crise. Procuraremos, nesta breve abordagem, explanar alguns elementos de originalidade intrínsecos aos movimentos sociais hodiernos, patentes na sua forma de participação e organização, assim como aplicar estas questões teóricas relevantes ao contexto português. A parte empírica, dada a escassez de estudos de caso existentes, será apoiada no último inquérito do European Social Survey, de 2012. Analisando um conjunto de perguntas aí explícitas, podemos compreender, de forma indirecta, algumas das dinâmicas que caracterizam estes movimentos.The crisis in the European Union and the subsequent austerity programs have unleashed a myriad of social ...

Different ex post methodologies have been proposed to allocate network losses. Under day-ahead pool-based electricity markets, the implementation of these procedures implies an access-pricing framework based on half-hour or hourly locational prices. Since every allocation procedure modifies the locational prices in a different way, the initial market equilibrium point is altered as a result of the price elasticity of demand. This implies that some form of cross-subsidy appears among market agents, affecting economic variables as social welfare and network remuneration. This paper aims to contribute to the regulatory assessment by means of an analysis based on the social welfare theory in order to ensure a non-discriminatory access to the network. A base scenario is obtained through an optimal power flow study with the purpose of simulating an efficient energy market, and four allocation philosophies have been considered: incremental, roll-in-embedded, tracing based and circuit based. The methodology has been tested in two test cases: an illustrative three-bus network and the IEEE RTS 24-bus test network.

This paper presents a new optimization technique based on quantum computing principles to solve a security constrained power system economic dispatch problem (SCED). The proposed technique is a population-based algorithm, which uses some quantum computing elements in coding and evolving groups of potential solutions to reach the optimum following a partially directed random approach. The SCED problem is formulated as a constrained optimization problem in a way that insures a secureeconomic system operation. Real Coded Quantum-Inspired Evolution Algorithm (RQIEA) is then applied to solve the constrained optimization formulation. Simulation results of the proposed approach are compared with those reported in literature. The outcome is very encouraging and proves that RQIEA is very applicable for solving security constrained power system economic dispatch problem (SCED).

the objective of this work is to discuss the modeling of auctions of long-term electricity supply contracts for new capacity in Brazil. The modeling of risks such as price-quantity (hydrological) risk, project completion risk, environmental constraints, climate change and regulatory risks are discussed. An analytical model will be developed to price these risks and case studies will be presented for real projects that have participated in the Brazilian contract auctions for new capacity. We also discuss selection of projects with different risks.