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The proposal of this paper aims to beginning the definition of a formal abstract specification providing a framework, for electric power system software developers to create software, that enables their users to access and process electric network data structures, from a variety of sources and zoning levels. In this framework the user will be able to dealing with a variety of perspectives in power...
This paper present the results of a survey of load, no-load losses and dielectric strength of 123 new and repaired distribution transformers tested by the High Voltage Laboratory of the Federal University of Itajuba within a Research and Development Project in partnership with the AES-SUL - Distribuidora Gaucha de Energia S.A.. Based on these results were defined transformer efficiency curves. These...
Modern digital protective relays generate various flies and reports which contain abundant data regarding fault disturbances and protection system operation. This paper presents an expert system based application for automated analysis of digital relay data. In this application, forward chaining reasoning is used to predict expected protection operation while backward chaining reasoning is employed...
Relay misoperations play an important role in cascading blackouts. Power swing and out-of-step conditions caused by large disturbances in the system may result in relay misoperations. This effect is analyzed and simulated in this paper. Synchronized sampling based fault location (SSFL) algorithm was proposed as part of an advanced fault analysis tool to give precise fault information and verify relay...
Unintentional islanding in distribution networks due to the presence of DG is one of the major safety concerns for the grid interconnection of generators. The present paper looks at the current protection and safety requirements and new activities in selected European countries with a focus on inverter based generation. By means of a field study carried out in a real LV network with a high DG penetration,...
This paper describes the way of implementing the hysteresis model in a transient simulation algorithm. The hysteresis model is not dependent on an integration step, thus it can be incorporated in a state-space form of a stiff differential equations system. The developed algorithm is based on a i-stable backward differentiation formulas-BDF numerical method. This method suppresses numerical oscillations...
The paper presents the evaluation of the possibility of application of the newly developed at STRI Insulator Selection Tool (IST) program for the statistical dimensioning of outdoor insulation based on field data collected at the test station. The 1ST program is a promising tool using Koeberg Insulator Test Station (KIPTS) data at ESKOM. Tested by 10 principally different insulators, it provides reasonable...
The subject of power frequency magnetic fields has become very popular during recent years. This is mainly due to two facts: the increasing usage of display units which represent a very sensitive interference victim and the increasing public concern with respect to adverse health effects caused by such fields. Switchgear installations act as one of the prominent sources of power frequency magnetic...
This paper presents an analytical method for the reliability evaluation of distribution system, including the distributed generations. Unlike the large sized generations of transmission system, the distributed generations have complexities in analyzing and determining the operation. In the process of evaluate reliability, it could be shown that the analytical method is simpler than the Monte-Carlo...
According to the idea of phase space reconstruction of scalar time series, phase space reconstruction of multivariate time series based on the short-term electric load is presented. The good time delay is chosen for each scalar time series by mutual information. The method to get the minimum embedding dimension is based on minimum forecasting errors. The choice of optimal neighbor points is presented...
The number of wind turbines connected to the Irish electrical power systems has been increasing rapidly over the last number of years. There are two main reasons for such a growth. Firstly, Ireland has signed the Kyoto protocol and aims to meet its obligation to reduce greenhouse gases (one of the biggest emitter of such gases are conventional power stations), and secondly, commercially viable wind...
From the viewpoint of monitoring the distribution network can be divided into operatively observable and unobservable part. The observable part is controlled and monitored by SCADA. Generally the data available with the help of SCADA will need correction by means of state estimation technique. For supporting the estimation procedure additionally the automatic meter reading (AMR) data from the unobservable...
In 2001 the ";Concept of HVDC Power Transmissions and Bach-to-Backs use in UPS of Russia and for its Interconnection with Electric Power Systems of Other Countries"; was developed and approved by Scientific Council of JSC ";UPS of Russia";. Within the framework of this concept surveyed more than 30 possible HVDC installations. One of the most perspective spheres of HVDC transmissions'...
The aim of this paper is to implement different grounding system (GS) models in order to compare its influence on the calculation of overvoltages in transmission lines, produced by direct lightning strikes. The models studied were a lumped DC resistance, a non linear resistance, and a synthesized circuit based on the frequency response of the GS. The latest model is proposed by the authors and takes...
A new approach is presented for the estimation of the topological state of power system networks. The quantities to be estimated include Boolean variables, allowing to choose among topologies, as well as real variables. These topologies are extracted from the history of each substation. The method is based on transforming the nonlinear constraints into linear inequalities. The final problem is solved...
The fundamental frequency is an important parameter required for efficient power system control and protection functions. Prony's method gives fast and accurate frequency estimation when input signal has very high signal to noise ratio. For practical measurements when signal to noise ratio is low, frequency estimation based on Prony's method is very sensitive to noise and results are biased. This...
This paper presents the implementation of different learning possibilities and the mixing of traditional evaluated learning programs with hypermedia systems in the area of renewable energy sources. Virtual Reality Modelling Language (VRML) has developed a standard for characterizing three dimensional objects which are particularly for transfer to the internet, and it is feasible in any e-learning...
This paper describes the technological assessment employed in the development of new wind power generation systems, which facilitate stable, controllable energy supply systems in a diversified and competitive energy market. The concept of a new wind power generation system is presented and possible solutions to technical problems for the development of new wind power systems are discussed.
The paper demonstrates the online optimal management of PEM fuel cells for onsite energy production to supply residential loads. Classical optimization techniques are based on offline calculations and can not provide the necessary computational speed for online performance. In this paper a Decision Tree (DT) algorithm is employed to obtain the optimal, or quasi- optimal, settings of the fuel cell...
Least squares method applied to an SLG fault currents, identifies its resistance value, position and inception angle. In short networks the error of the fault position is several percent of the fault distance in case of fault resistances below a few hundred ohms. The algorithm performances worsen both with rising feeders' length and with growing differences between them. The results were tested within...
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