[en] In this paper a new approach for transmission pricing is presented. The contribution of a contract on power flow of a transmission line is used as extent-of-use criterion for transmission pricing. In order to determine the contribution of each contract on power flow of each transmission line, first the contribution of each contract on each voltage angle is determined, which is called voltage angle decomposition. To this end, DC power flow is used to compute a primary solution for voltage angle decomposition. To consider the impacts of system non-linearity on voltage angle decomposition, a method is presented to determine the share of different terms of sine argument in sine value. Then the primary solution is corrected in different iterations of decoupled Newton-Raphson power flow using the presented sharing method. The presented approach is applied to a 4-bus test system and IEEE 30-bus test system and the results are analyzed. (author)

[en] Er bestaan vragen en dilemma's rond de belemmeringen om tot een 'doelmatige' gasmarkt te komen. Die vragen betreffen met name de verhouding tussen de doelmatigheid van de gasvoorziening enerzijds en het streven naar marktwerking anderzijds. Het eerste aspect adresseert vragen omtrent de mogelijkheden tot efficiente marktwerking in de Europese gasindustrie, gegeven een aantal fundamentele karakteristieken en publieke belangen. Het laatste aspect heeft te maken met de beperkte toegang voor andere shippers tot flexibele gasbronnen, tot gasopslag en/of tot (andere) flexibiliteitdiensten. Het doel van dit onderzoek is inzicht te krijgen in de werking van de markt voor seizoensflexibiliteit, knelpunten te analyseren en mogelijke oplossingsrichtingen aan te reiken op korte en lange termijn. In hoofdstuk twee wordt uitgelegd wat onder seizoensflexibiliteit wordt verstaan. In hoofdstuk drie wordt vervolgens de markt beschreven. Hoofdstuk vier gaat in op de knelpunten om tegemoet te komen aan de uitdagingen op korte en lange termijn. Op basis van het voorgaande worden in hoofdstuk vijf aanbevelingen geformuleerd die moeten toelaten de korte en lange termijn uitdagingen te realiseren. In de bijlagen wordt dieper ingegaan op verschillende thema's: (1) Europese markt voor seizoensflexibiliteit met specifieke aandacht voor Duitsland, Frankrijk, Italie en het Verenigd Koninkrijk; (2) de Nederlandse gasmarkt; (3) het Nederlandse reguleringskader voor seizoensflexibiliteit; en (4) de visies van de marktpartijen

[en] In 2004, the total energy consumption in Thailand increased 8.8 per cent, from 47,806 to 60,260 ktoe. Long-range Energy Alternatives Planning (LEAP) is an accounting tool that simulates future energy scenarios. According to a Business As Usual (BAU) case, the overall energy demand in Thailand is estimated to increase from 61,262 to 254,200 ktoe between 2004 and 2030. Commercial energy consumption, which comprises petroleum products, natural gas, coal and its products, and electricity, increased by 9.0 per cent in Thailand in 2004, and new and renewable energy increased by 7.8 per cent. Nearly 60 per cent of the total commercial energy supply in Thailand was imported and increased for a fifth year in a row. The changes in energy consumption can be attributed to population growth and increase in economic activity and development. 10 refs., 5 tabs., 14 figs

[en] Maintenance optimisation is essential to achieve cost-efficiency, availability and reliability of supply in electric power systems. The process of maintenance optimisation requires information about the costs of preventive and corrective maintenance, as well as the costs of failures borne by both electricity suppliers and customers. To calculate expected costs, information is needed about equipment reliability characteristics and the way in which maintenance affects equipment reliability. The aim of this Ph.D. work has been to develop equipment reliability models taking the effect of maintenance into account. The research has focussed on the interrelated areas of condition estimation, reliability modelling and maintenance modelling, which have been investigated in a number of case studies. In the area of condition estimation two methods to quantitatively estimate the condition of disconnector contacts have been developed, which utilise results from infrared thermography inspections and contact resistance measurements. The accuracy of these methods were investigated in two case studies. Reliability models have been developed and implemented for SF6 circuit-breakers, disconnector contacts and XLPE cables in three separate case studies. These models were formulated using both empirical and physical modelling approaches. To improve confidence in such models a Bayesian statistical method incorporating information from the equipment design process was also developed. This method was illustrated in a case study of SF6 circuit-breaker operating rods. Methods for quantifying the effect of maintenance on equipment condition and reliability have been investigated in case studies on disconnector contacts and SF6 circuit-breakers. The input required by these methods are condition measurements and historical failure and maintenance data, respectively. This research has demonstrated that the effect of maintenance on power system equipment may be quantified using available data. However, realising the full potential of these methods requires the gathering and utilisation of failure and maintenance data as well as condition measurements to be improved

[en] With the development of restructured power systems, the conventional 'same for all customers' electricity price is getting replaced by nodal prices. Electricity prices will fluctuate with time and nodes. In restructured power systems, electricity demands will interact mutually with prices. Customers may shift some of their electricity consumption from time slots of high electricity prices to those of low electricity prices if there is a commensurate price incentive. The demand side load shift will influence nodal prices in return. This interaction between demand and price can be depicted using demand-price elasticity. This paper proposes an evaluation technique incorporating the impact of the demand-price elasticity on nodal prices, system reliability and nodal reliabilities of restructured power systems. In this technique, demand and price correlations are represented using the demand-price elasticity matrix which consists of self/cross-elasticity coefficients. Nodal prices are determined using optimal power flow (OPF). The OPF and customer damage functions (CDFs) are combined in the proposed reliability evaluation technique to assess the reliability enhancement of restructured power systems considering demand-price elasticity. The IEEE reliability test system (RTS) is simulated to illustrate the developed techniques. The simulation results show that demand-price elasticity reduces the nodal price volatility and improves both the system reliability and nodal reliabilities of restructured power systems. Demand-price elasticity can therefore be utilized as a possible efficient tool to reduce price volatility and to enhance the reliability of restructured power systems. (author)

[en] This paper presents an adaptive fuzzy control scheme for a class of continuous-time single-input single-output nonlinear systems with unknown dynamics and disturbance. Within this scheme, the fuzzy systems are employed to approximate the unknown system's dynamics. The proposed controller is composed of a well-defined adaptive fuzzy control term that uses the adaptive fuzzy approximation errors and disturbance. Based on a Lyapunov synthesis method, it is shown that the proposed adaptive control scheme guarantees the convergence of the tracking error to zero and the global boundedness of all signals in the closed-loop system. Moreover, the proposed controller allows initialization by zero of all adjusted parameters in the fuzzy approximators, and does not require the knowledge of the lower bound of the control gain and upper bounds of the approximation errors and disturbance. Simulation results performed on an inverted pendulum system are given to point out the good performance of the developed adaptive controller. (author)

[en] This article examines how wide-area monitoring can help avoid frequency-swings in the European electricity grid. Increasing power trading and the extension of the UCTE are discussed as the source of possible short-term frequency-swinging, which can occur when faults occur in the grid. Measures that can be taken to prevent such swinging are examined. A GPS-synchronised, wide-area monitoring and control system (WAM and C) is described that, since 2001, has monitored mains phase-shifts and other relevant data. Also a system operated since 2003 by Swissgrid is briefly described. A selection of curves used in the analysis of a frequency-swinging event in Switzerland are provided

[en] This paper compares conditions and costs for RES-E grid connection in selected European countries. These are Germany, the Netherlands, the United Kingdom, Sweden, Austria, Lithuania and Slovenia. Country specific case studies are presented for wind onshore and offshore, biomass and photovoltaic power systems, as based on literature reviews and stakeholder interviews. It is shown that, especially for wind offshore, the allocation of grid connection costs can form a significant barrier for the installation of new RES-E generation if the developer has to bear all such costs. If energy policy makers want to reduce the barriers for new large-scale RES-E deployment, then it is concluded that the grid connection costs should be covered by the respective grid operator. These costs may then be recouped by increasing consumer tariffs for the use of the grid. (author)

[en] The International Association of Science and Technology for Development (IASTED) hosted this conference to provide a forum of discussion for international researchers and practitioners interested in the planning, operation and control of European power and energy systems. The conference featured 9 sessions entitled: (1) security assessment, (2) power system planning, (3) renewable energy sources, (4) power quality, (5) power system operation, (6) electricity markets, (7) power system analysis, (8) energy, and (9) flexible alternative current transmission system (FACTS) devices. Participants from around the world also presented recent advances in distributed power generation, load shedding; fault diagnosis; energy storage; power system stability; and security of supply. All 79 conference presentations have been catalogued separately for inclusion in this database. refs., tabs., figs

[en] In a centralized power system, the operator is responsible for scheduling maintenance. There are different types of maintenance, including corrective maintenance; predictive maintenance; preventive maintenance; and reliability-centred maintenance. The main cause of power failures is poor maintenance. As such, maintenance costs play a significant role in deregulated power systems. They include direct costs associated with material and labor costs as well as indirect costs associated with spare parts inventory, shipment, test equipment, indirect labor, opportunity costs and cost of failure. In maintenance scheduling and planning, the cost function is the only component of the objective function. This paper presented the results of a study in which different components of maintenance costs were modeled. The maintenance models were formulated as an optimization problem with single and multiple objectives and a set of constraints. The maintenance costs models could be used to schedule the maintenance activities of power generators more accurately and to identify the best maintenance strategies over a period of time as they consider failure and opportunity costs in a deregulated environment. 32 refs., 4 tabs., 4 figs