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This paper proposes a new design guideline for reliability improvement of distribution networks using distributed energy resource (DER). The proposed guideline is advised to maintain CDI values of all customers under a certain pre-defined threshold value. The impact of the switching devices failure on the reliability is also considered and proper corrections are made on various threshold values within...
There are two fundamentally different forms of uncertainty in power system reliability assessment. Aleatory uncertainty arises because the study system can potentially behave in many different ways. The component failure and repair processes are random and create variability known as aleatory uncertainty. There are also limitations in assessing the actual parameters of the key elements in a reliability...
Maintenance managers of today's electrical distribution systems are faced with the problem of where their maintenance resources will be utilized best. In previous work the authors have developed a method for maintenance policy optimization for electrical networks. This paper presents results from an application study performed for a distribution system, including both urban and rural parts, for this...
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...
Value at Risk (VaR) is an appropriate method in financial world for evaluating risks. The method measures the losses within a considered time interval and a defined confidence level in actual currency. The simplicity and objectivity of VaR concludes to the idea to apply this method for power systems risk assessment. In this paper the methodology is applied for risk evaluation in the context of asset...
Better modelling and forecasting of very short-term power fluctuations at large offshore wind farms may significantly enhance control and management strategies of their power output. The paper introduces a new methodology for modelling and forecasting such very short-term fluctuations. The proposed methodology is based on a Markov-switching autoregressive model with time-varying coefficients. An advantage...
Sweden was re-regulated in 1996 followed by new laws and regulations. These new circumstances have become incentives to adopt more comprehensive and quantitative analysis methods applied on Electrical Distribution Systems (EDS). This paper provides a systematic presentation of the current risk management at a Distribution System Operator (DSO) as an integrated part of the net planning process. The...
In this paper it is proposed an efficient contingency screening and ranking algorithm for assessment and classification of multiple contingencies of an Electric Power System using the Rough Set theory. The developed methodology produces a classification of the system operation in five possible states: normal, alert, emergency, in-extremis and restorative. These different operating states correspond...
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...
Renewable energy grid connection is hampered by transmission capacity limitations and public opposition to new transmission development. This paper presents a methodology to find the optimal positions on an existing transmission system network to connect 'firm' wind capacity to reach desired renewable energy penetration targets in a secure, least-cost manner. The methodology accounts for geographical...
Interruptions in the supply of electricity to customers are inevitable but it is important to measure, monitor and minimize the costs incurred. In this paper it is shown that customer interruption costs (CIC) depend on a variety of factors. They include the type of country and locality in which the interruptions occur. Actual costs depend on the types of appliances that are interrupted and the sectors...
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...
This paper presents an evaluation technique incorporating the impact of the diversified demand side load shift on the system reliability and nodal reliabilities of restructured power systems. In this technique, demand and price correlations are represented using a demand-price elasticity matrix which consists of self/cross-elasticity coefficients. The diversity of customers is represented using different...
A combination of diagnostic techniques was carried out for a 232 MVA hydro-generator stator. These techniques included quality assessment of the electrical contact between semi-conductive (S/C) coating of stator bars and the magnetic iron core, partial discharge (PD) measurements, polarization and depolarization currents and finally stator bar dissection. The analytic hierarchy process (AHP), a multi-criteria...
The original method of switchyard types optimization for transmission network (330 and 110 kV) is structured in the article reviewing the following aspects: 1) the principle of the method; 2) switchyard's reliability criteria; 3) algorithm of criteria calculation. This method and algorithm are appropriate for switchyard types optimization of transmission network, applying pilot technology LDM-T&G'08.
The output of a power system analysis mostly requires extensive knowledge and correct handling of input uncertainties. Analytical approaches often depend on simplified models whereas Monte Carlo based sampling methods are often time consuming. This paper presents an uncertainty analysis based on a limited number of well chosen samples which are used to model a stochastic response surface, based on...
Wind energy on a power system alters the unit commitment and dispatch problem, as it adds a stochastic element due to the uncertainty of wind power forecasts. By explicitly taking into account the stochastic nature of wind power, it is expected that better schedules should be produced, thereby reducing costs on the system. This paper compares a stochastically optimised unit commitment and dispatch...
Uncertain wind power forecasts is a disadvantage in an electricity market where the majority of the trading is performed several hours before the actual delivery. This paper presents a model which can be used to study how changes in the trading arrangement-in particular changing the delay time between closure of the spot market and the delivery period or changing the imbalance pricing system-would...
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