One of the most challenging tasks for network utilities is to reduce costs and improve reliability at the same time. In order to manage the task successfully advanced IT-solutions are needed providing reliability analysis as part of the planning process. This paper presents advanced reliability analysis for distribution network. A sophisticated failure rate model has been developed based on failure statistics of the network and engineer judgement. Practical fault management process and statistics has been analyzed in order to model the customer outage times in different fault situations. Outage cost model for different customer groups are used in order to reach financial results by the analysis. The practical implementation and some demonstration studies are presented in the end of the paper.
Voltage sags are a remarkable problem for some customers of power-distribution networks. From the customer point of view the harm caused by a single sag is nearly the same as harm caused by a short interruption due to fast reclosing but the number of sags is typically much greater than the number of interruptions. This paper presents voltage sag analysis integrated in network planning software. Enhanced failure rate model is developed to be used as origin of input data to analysis. Created cost model is used to define voltage sag costs confronted by customers. Integrated tool for voltage sag analysis is presented and its features are illustrated with couple of simple examples.
Customer flexibility plays a key role in the cost-efficient development of electricity distribution networks. Recently achieved results in a collaborative research project together with the academy and distribution utilities indicate that the economic value of flexibility can be significantly high in sparsely populated rural areas where there are challenges in reliability of supply (risk of major storms) and depopulation. The main target of this paper is to define the technical potential and economic value of customer flexibility in reliability of supply. The paper indicates that rural-area distribution networks offer a promising basis for flexibility. A significant proportion of distribution branch lines supply a relatively low number of customers. Thus, by selecting the best few per cent of all customers to the flexibility agreement, a relatively high share of network investments can be reconsidered from the perspective of scheduling, placement and technological choices of the network renewal. However, the results support a preliminary estimate that flexibility targets (customer nodes) have to be defined by the utility. Otherwise, if customer nodes are selected randomly, network areas committed to flexibility are not uniform enough to be able to take them effectively into account in the long-term development of the network infrastructure.
DOI: 10.1049/cp.2009.0881 ISBN: 978 1 84919 126 5 Location: Prague, Czech Republic Conference date: 8-11 June 2009 Format: PDF In this paper practical solution for transformer monitoring based on the temperature and ageing calculations is studied. The described monitoring methods are evaluated with measured data collected with implemented a pilot measurement system. The measurement system utilises an AMR-meter, which is commonly used in Vattenfall's network in Finland. The usability of the measurement data has been evaluated with temperature and ageing modelling software. Results of the evaluation indicate that the calculation methodology and the measurement system can be used also for larger scale monitoring purposes quite effectively if the functionality can be integrated for existing measurement systems. (4 pages) Inspec keywords: automatic meter reading; ageing; power transformers Subjects: Display, recording and indicating instruments; Transformers and reactors; Power and energy measurement
In this paper some scenarios dealing with power distribution will be presented and evaluated. Special attention is paid to reliability parameters, such as failure rate and outage costs. With assumptions of some set of scenarios long term planning case studies have been carried out using an advanced IT-tool. The studies show that profitability of investments to more reliable network depends strongly on the reliability parameters used.
Along with increasing importance of power quality the effect of overvoltage protection to short interruptions and voltage dips is of great importance. With advanced reliability analysis tool integrated to network information system, the effect of protection can be studied. The calculations which have been done shows that the investments on increased overvoltage protection is extremely profitable if theshort interruptions and voltage dips are taken into account as outage costs.
There are plenty of proper monitoring methods to evaluate the condition and possible incipient failures of a power transformer. For distribution transformer monitoring, the methods are usually too expensive and/or time consuming to use. However, cost-efficient methods for distribution transformer monitoring are needed and one possibility for this is to utilize loading and temperature information measured from the network. The monitoring methods presented in the paper are based on the existing IEC and IEEE standards and neural-network analysis. The methods are used to calculate the top-oil and hot-spot temperature as well as the loss of life of a transformer. The calculated results are verified with measured top-oil temperature values. The possibilities to utilize studied methods in a larger scale for distribution transformer monitoring are also discussed in this paper
There is an increasing need for electric utilities to be more effective and cost conscious. They are enforced to control trustworthily total lifetime costs caused by their network components without jeopardizing the reliability and security of the network. New distribution planning methods and procedures are needed in order to meet the expectations and performance targets of regulators, company owners and customers. One of the most challenging tasks for electrical utilities is the consideration of reliability as a part of long term planning of the network. An advanced IT-solution has been developed at Tampere University of Technology (TUT) in order to provide reliability analysis as a part of the network planning process. The software implementation and the developed models for reliability analysis are presented briefly in this paper. The focus of the paper deals with studies in which alternative plans for a new distribution network are generated and compared with the developed application. For each plan the total lifetime costs are calculated, including reliability costs. The optimal plan depends on the selection of reliability optimization criteria: the reliability costs may consist only of direct utility costs, but they can also include customer interruption costs and even the costs of voltage dips. The paper presents and evaluates the results of example studies and discusses the correlation between the utility strategy and optimal network structure.
