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In this paper, a systematic risk-based transmission line expansion approach is studied. The approach addresses three objectives: load-driven expansion, security-enhancement expansion and risk-based expansion. The first problem identifies transmission expansions necessary to correct inadequacy; the second problem identifies transmission expansion necessary to correct insecurity; the third problem balances...
This paper provides an approach to the problem of power distribution network renewal planning where the challenge to the decision maker is to determine the most cost- effective multi-year development plan in terms of what feeders in the network to refurbish, by which renewal alternative and at what time in the planning horizon. The problem is subjected to several constraints of service requirements...
The objective of this paper is to introduce analytical models for accurate prediction of failure probabilities of existing shield wires and to recommend a time window for wire replacement at an acceptable failure threshold. Ductile and strength tests results and failures records of shield wires were examined to determine the trend of wires deteriorations as they age. Since most of failures occurred...
This paper describes a method for predicting circuit breaker time-to-failures using a probabilistic operational model that incorporates generation capacity growth. Increases in generation capacity may cause fault current levels to approach or exceed circuit breaker ratings. This condition may increase the probability of a circuit breaker failure. Circuit breaker failures result in common-mode multiple...
The problem of choosing the optimal location and size for shunt capacitors in unbalanced distribution systems can be formulated as a mixed, non-linear, constrained optimization problem and is usually solved in deterministic scenarios. However, distribution systems are stochastic in nature, leading thus to inaccurate deterministic solutions. To take into account the unavoidable uncertainties which...
The latest political initiatives on energy saving are forcing distributors to implement actions that increase the energy efficiency of their system. Among these actions distributors can drive the development of the distributed generation (DG) on their networks. The inclusion of the energy saving goal among the terms of the objective function makes the DG allocation problem more and more complicated,...
This work presents a procedure to validate sags monitoring results based on a stochastic assessment of voltage sag indices. The main practical use of this methodology is to analyze the accuracy of sag indices obtained from very short monitoring periods. Probabilistic models of several factors can be taken into account: lines and busbars fault rate, pre-fault voltage, fault type distribution, fault...
This paper introduces the infeed modeling requirements for investigations on energy storage in power systems with complex spatial dependence structures between stochastic infeeds. It is shown that synthesizing multivariate time series, including correct modeling of persistence and spatial dependence, is crucial for obtaining statistically relevant results. A suited new multivariate time series model...
This paper presents an Bayesian approach for the estimation of sojourn time distribution parameters. Expert opinion and condition monitoring data can be used as source of information for the estimation. It is shown how expert opinion and data can be combined and how estimates for the parameters can be calculated by means of numerical methods. It is also discussed how expert uncertainty and systematic...
A Markovian approach already developed in a previous paper by some of the authors to evaluate the energy production and power availability of a wind turbine is utilized to size a hybrid wind-diesel stand alone system. The wind turbine power time variability is taken into account by means of a discrete reduced number of contiguous power classes, each corresponding to an opportune range of values, starting...
There is an increasing trend towards using the concept of risk assessment as an important tool in distribution system asset management. In an ongoing R&D project (RISK DSAM), the main objective is to investigate how information about risk exposure can improve maintenance and reinvestment decisions in an electrical distribution company. As the popularity of Bayesian networks (BN) is increasing,...
This paper reports new results in adopting entropy concepts to the training of mappers such as neural networks to perform wind power prediction as a function of wind characteristics (mainly speed and direction) in wind parks connected to a power grid. Renyi's Entropy is combined with a Parzen Windows estimation of the error pdf to form the basis of three criteria (MEE, MCC and MEEF) under which neural...
The electric power market is restructuring to be price-based and auctions are considered a good pricing mechanism to be used. To assure that the market functions satisfactorily, strictness of guarantee of sellers' deliveries and buyers' receipts must be taken care properly by the central coordinator. This paper proposes market mechanisms for single-class auctions, which specifies the minimum strictness...
For many years, the electric power industry treated electricity as a unique commodity sold to costumers. Nowadays, the new electricity industry has identified several key ancillary services. Under this new scenario, the producer's primary goal is the selection of services in which to participate via assessing the potential profits as part of the decision-making. Purchasing additional information can...
This paper proposes a new estimation technique of the load duration curve (LDC) which takes into account recent modifications of the load demand in the Tunisian power system (STEG) related to the increasing of the air conditioning load. This approach is based on the estimation of the hourly peak load distribution by asymmetric generalized Gaussian distribution (AGG). Numerical results indicate that...
In this study hourly wind speed time series data of Eskisehir region, Turkey have been used for stochastic generation of wind speed data using the transition matrix approach of the Markov chain process. Previous work on synthetic data generation did not focus on the effects of different choices of wind states. In this work, it was observed that increasing the number of states has a significant benefit...
This paper addresses the generation expansion-planning problem describing a model that generation companies can use to get insight to this problem and to more completely study and characterize different investment decisions. In the last 20 years, the generation activity evolved from a situation in which it was part of vertical companies to unbundled market agents that face a much more risky and uncertain...
This paper demonstrates a methodology for the optimal use of phase shifting transformers (PSTs) for the minimisation of the risk of congestion on power system lines. The methodology proposes as a first step the use of Monte-Carlo simulation for the assessment of the power flow distributions in the lines. It is shown that by using PSTs these distributions are shifted by specific factors that can be...
This paper presents a new methodology for determining the optimal number of spare transformers (pole-mounted type) to be stored in regional centers of distribution companies, in order to balance reliability and cost criteria. The proposed method is based on chronological Monte Carlo simulation to evaluate reliability indices like probability, frequency and duration of failures in distribution systems...
Electric utilities schedule power transformers in high voltage load stations (customer delivery or regional supply systems) for planned outages such as unit refurbishment, unit replacement, etc. that may last for a few weeks. During the planned outage time, companion units may fail causing a complete loss of supply to customers. Mobile unit transformers (MUT's) could be used in these emergency situations...
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