Reliability Worth Evaluation Research Articles

영구정전과 순간전압강하를 고려한 신뢰도 비용 평가

Power quality problems such as momentary interruptions and voltage sags do not great influence on loads at past. However, the interests in power quality problems increase as the use of sensitive loads with microprocessor like computers increases recently. Accordingly, power system reliability research focusing to sustained interruption and momentary interruption partially needs more accurate evaluation methods including momentary and instantaneous problems. That is, many sensitive loads being tripped by voltage sags result in interruption costs. In this paper, new reliability worth evaluation method is presented considering voltage sags. We calculated the magnitude of voltage sags using fault studies and the duration of voltage sags using the trip time of protective relays for each fault. Moreover, we includes the customer interruption cost resulted from sensitive load trip by voltage sags. Through case studies, we evaluate the effects of voltage sags for permanent faults.

04/02840 Rural distribution system reliability worth evaluation using individual customer outage cost characteristics: Billinton, R. and Wacker, G. International Journal of Electrical Power& Energy Systems, 2004, 26, (4), 235–240

04/02840 Rural distribution system reliability worth evaluation using individual customer outage cost characteristics: Billinton, R. and Wacker, G. International Journal of Electrical Power& Energy Systems, 2004, 26, (4), 235–240

Optimal Operating Strategy for Distributed Generation Considering Hourly Reliability Worth

This paper presents a method to determine optimal operating strategy for distributed generation (DG) incorporating reliability worth evaluation of a distribution system. The use of DG for peak shaving could reduce the overall system operating cost and its use as standby power could reduce the customer interruption cost. If the DG operating cost is less than the utility power cost at peak time, DG should be employed to reduce the overall system operating cost. However, when customer interruption cost is also an important concern, standby power strategy for DG may be better than peak shaving. The reliability worth and the power cost evaluations are needed to determine whether DG should be operated for peak shaving or as standby power. The hourly reliability worth is incorporated in the strategy proposed in this paper to determine the optimal operating decision for the DG. Using the approach proposed in this paper, the distribution companies could determine the optimal operating strategy for their DG.

Rural distribution system reliability worth evaluation using individual customer outage cost characteristics

Customer interruption costs are a function of both interruption and user characteristics. The specific customer characteristics at a load point in a distribution network can have a significant effect on the estimated customer outage costs at that load point and for the entire feeder. This paper illustrates the effects on outage cost estimates of using generalized sector customer outage cost estimates and actual customer specific outage cost functions. The data used in these analyses are from customer cost surveys conducted in Canada. A small distribution system is used to illustrate the possible variation in interruption cost estimates due to incorporating specific customer characteristics in the evaluation. The results presented clearly show that different customer compositions can result in significantly different feeder interruption cost estimates. The estimated interruption costs can be used in feeder design to create an optimal configuration based on reliability cost/worth analysis.

Comparative case studies for value-based distribution system reliability planning

Abstract This paper will develop a set of reliability worth evaluation models to evaluate the load point reliability worth indices for five different distribution types. The distribution substations, primary distribution systems, and the interaction between them contribute to the load point reliability worth indices. The reliability worth of the distribution systems are evaluated in terms of customer interruption costs, by using the sector customer damage function (SCDF). The most suitable system design is based on comparisons of the total system costs of the candidates under consideration. Four case studies are thoroughly examined in this paper. Also, the impact on customer interruption costs associated with customer type, substation configuration, and feeder configuration are investigated.

Distribution system reliability worth analysis with the customer cost model based on RBF neural network

Reliability worth analysis is an important tool for distribution systems planning and operations. The interruption cost model used in the analysis directly affects the accuracy of the reliability worth evaluation. In this paper, two interruption cost models including an average or aggregated model (AAM), and a probabilistic distribution model (PDM) are proposed by using the radial basis function (RBF) neural network with orthogonal least-squares (OLS) learning method. The residential and industrial interruption costs in AAM and PDM were integrated by the proposed neural network technique. A Monte-Carlo time sequential simulation technique was adopted for worth assessment. The technique is tested by evaluating the reliability worth of a Taipower system for the installation of disconnected switches, lateral fuses, transformers, and alternative supplies. The results show that the two cost models result in very different interruption costs, and PDM may be more realistic in modeling the system.

Radial distribution system reliability worth evaluation utilizing the Monte Carlo simulation technique

Conventional reliability worth evaluation using analytical methods can only provide the expected or average values of the worth indices. The actual shape of the statistical distributions associated with these indices are generally not considered. This paper describes a Monte Carlo simulation approach to a complex radial distribution system reliability worth evaluation. The results of a series of simulations studying the impacts of various probability distributions for restoration times on load point expected cost, interrupted energy assessment rate and their probability distributions are presented. Furthermore, different radial system operating philosophies are incorporated in the analysis and their impacts are analyzed.

Reliability worth assessments of electrical distribution networks

Reliability evaluation techniques have reached a stage at which they can be applied to real systems in a very effective and efficient manner. However, the economic impact of system reliability, or more specifically system unreliability, on users and customers is not so readily available. In order to achieve this, there is a need to know customer and user outage costs and their evaluation of reliability worth. During the past 5 years, major surveys of domestic, commercial and industrial customers have taken place in the UK in order to provide this information. These outage costs can then be used as input data to cost implications and worth assessments of system planning and operational decisions. This paper first reviews these outage cost data and secondly describes how this information can be used in system planning considerations. Although this paper deals with the electricity supply industry, the concepts are equally applicable to all types of systems.

Reliability worth assessment in a developing country-residential survey results

This paper presents the results of a residential customer survey conducted in service areas of the Nepal Integrated Electric Power System (NPS). The objective was to determine the power interruption costs incurred by the residential customers of a developing country, and extend the customer survey approach to reliability worth evaluation in a developing environment. Interruption cost estimates were obtained using in-person interviews with 944 sample customers. The results indicate the implications of service reliability to residential customers of Nepal, and show that reliability worth evaluation in a developing country is both possible and practical.

Electric service reliability worth evaluation for government, institutions and office buildings

This paper presents the results of an investigation conducted by the Power Systems Research Group at the University of Saskatchewan to determine the costs of electric service interruptions in the government, institution and office building sector. The methodology used to obtain customer interruption cost information in this sector and to analyze the results is also presented.

Application of chronological load modeling in composite reliability worth evaluation

This work describes the application of pseudo-sequential Monte Carlo simulation to the composite generation—transmission reliability evaluation of the Brazilian South-Southeast system using chronological load modeling. The resulting reliability indices, in particular the loss of load cost (LOLC), were compared with those produced by a sequential Monte Carlo scheme with chronological load model and by a non-sequential Monte Carlo simulation scheme using a multistate Markov load model. It is shown that the pseudo-sequential approach produced the same indices as the sequential approach, with a substantial reduction of computational effort. Those results were in turn quite different from the non-sequential Monte Carlo scheme, thus confirming the importance of an accurate load modeling.

Evaluation of reliability worth and value of lost load

Customers' perceptions of reliability may not always reflect the level of reliability purported by traditional reliability indices. This has been recognised and efforts have been made by the electricity supply industry (ESI) in the United Kingdom to relate ‘reliability investment’ with customers' marginal benefits obtained from such investment. A difficulty encountered during such earlier and recent efforts has been the lack of appropriate valuation of these benefits. With a view to correcting this paucity, the authors have conducted studies, based on customer surveys, aimed at assessing the customer outage costs (COC) due to electric service interruptions. The incremental values of these costs, ΔCOC, following reliability investment are considered proxies of reliability worth and customers' marginal benefits. The results of these studies have provided a very good insight into customers' concerns regarding supply interruptions, but most importantly a coherent method for evaluating the customer benefits (ΔCOC) has been developed and the required generic data for such evaluation generated. Using these data, a consistent method for calculating the value of lost load (VOLL) is also developed.

Evaluation of reliability worth in composite systems based on pseudo-sequential Monte Carlo simulation

This work describes a new methodology for calculating total system interruption costs in composite generation and transmission systems. The proposed approach, called pseudo-sequential simulation, is based on the nonsequential Monte Carlo sampling of system states and on the chronological simulation of only the sub-sequences associated with failed states. Case studies with the IEEE Modified Reliability Test System (MRTS) and a 415-bus system derived from the Brazilian Southeastern region are presented and discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evaluation of reliability worth in an electric power system

This paper illustrates the application of basic power system reliability evaluation techniques to the quantification of reliability worth. The approach presented links customer interruption cost estimates with predictable indices of power system reliability. The technique is illustrated by application in the areas of generation, composite generation and transmission, and distribution system assessment using a hypothetical test system.

Factors Affecting the Development of a Commercial Customer Damage Function

The assessment of reliability cost/reliability worth is an important aspect of power system planning and operation. Reliability cost evaluation has become a relatively well established procedure compared with reliability worth evaluation. This paper presents the results of an investigation of the effect of standby equipment on both the consumption and demand normalized outage costs in the commercial sector. The results of a comprehensive study to find the outage costs for respondents with and without standby systems, and the seasonal variation of these costs, are presented. The development of a localized customer damage function utilizing the data is explored.

Factors Affecting The Development Of An Industrial Customer Damage Function

Reliability cost/reliability worth assessment is an important aspect of power system planning and operation. Evaluation of reliability cost and its use by utility planners is becaning a standard procedure, while by cocmparison, evaluation of reliability worth is a relatively immnature and imprecise technique. This paper presents the results of an investigation of the effect, of standby equipment on consumption or demand normalized outage costs. A comprehensive study was conducted to find the outage costs for respondents with and without standby systems, ard the variation of the outage costs with time of the year, week and day. The paper then illustrates the development of a localized custamer damage function utilizing these data.