The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The fast development in both microprocessor and transducer technologies has enabled fault detection techniques to be considered which were impractical in the past and encouraged interest in the utilization of fault generated transients for protection. This paper presents an integrated approach for high-speed protection of transmission lines. The technique uses a fault transient detector unit at the...
This paper presents a new DC feeder protection based on wavelet transform. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The remote short-circuit current is determined mainly by the steel rail impedance, which is time varying due to the skin effect. In contrast, impedances of the traction motor and the contact wires, and the...
In this paper, a new genetic algorithm (GA) method is presented to solve the optimization problem in coordination of overcurrent and earth fault relays. In addition to optimal coordination of overcurrent relays, earth fault relays are also coordinated by GA, considering critical fault condition for the relays located in two sides of network's transformers. The objective function is developed by adding...
Short circuit current is one of the major threats for power system stability. Power system should have the ability to detect and clear these faults within a specified time. The protection system can clear the faults only if the interruption capability of the circuit breakers is higher than the fault level. Expansion of the grid and installation of new power on the scale that is envisaged will require...
This paper presents a simulation model of DC traction system which is based on bilateral power supply mode. The model of two substation rectifiers in one track section has been proposed which is according to practical situation. The modeling was conducted with respect to the variations of the starting-up process and short circuit conditions. By comparing and investigating the simulation results of...
Fixed speed wind turbine generator system (WTGS) uses induction generator as wind generator. Besides some of its advantages, it suffers greatly to meet the requirements of new wind farm grid code due to the dependency on reactive power. Some flexible AC transmission systems (FACTS) devices have been proposed recently for compensating the reactive power of induction generator during network disturbances...
This document describes the determination of the saturated inductance of a transformer, which is the slope of the saturation curve Phi(I) under highly saturated conditions. This parameter, which has a strong impact on the overvoltages when energizing a transformer, has been determined from analytic formulae for a shell-type transformer. Comparisons with the values derived from an electromagnetic 3D...
In a research project a fault data collection device for substations with a communication interface according to IEC 61850 was developed. The IEC 61850 standard is the future of substation automation networking. This standard has no models for signaling faults included up to date. Therefore, specific logical nodes were defined by using attribute types of the standard. These additional nodes were implemented...
Fault location (FL) is one of the most important diagnostics tasks in transmission and distribution networks. Due to long distances of the power lines, the search and repair can take a long time, while modern microprocessor technology can help automate the FL process and give a precise (up to a span) location of the fault. The fault extinction time is reduced dramatically. In this report, the basic...
In the paper new sensitive algorithms for detection of internal inter-turn faults in power transformers are described. Such faults are extremely difficult to detect since they induce negligible increase of the currents at the transformer terminals, although the currents flowing at the fault place are very high and dangerous for the transformer. The algorithms developed are based on the differential...
Dynamic voltage restorers (DVR) have been successfully applied for voltage dip mitigation in the last years. Especially in systems with nonlinear loads and wind turbine generation DVR units support the power quality enhancement. The reliability and quality of DVR operation depends mostly on fast and accurate voltage dip detection. Detection methodologies must be able to detect a voltage dip as fast...
This paper investigates the influence of a synchronous distributed generation on a Brazilian real network. The distributed generation represents a small hydro power plant with total capacity of 30 MW. The model of the network is developed in a professional computer software package. Simulations are carried out considering voltage dependency of static loads and different DG penetration levels. The...
Increasing complexity of interconnected electricity grids with a high integration level of dispersed generators leads that ldquobusiness as usualrdquo operating modes and regular devices in distribution networks are not efficient enough to ensure the centralized management of a large amount of information and high-level functionalities (advanced distribution automation-ADA) for future electricity...
The paper presents extensive simulation studies with respect to a typical EHV transmission line systems, the proposed protection technique is able to give correct responses for various system and fault condition. Furthermore, the protection scheme offers not only fast protection for individual line section, but also integrated protection for all lines connected to the substation, therefore it could...
This paper discusses the detailed switch-timing for converter protection schemes of doubly-fed induction generator (DFIG) to enhance the fault ride-through (FRT) capability. A new combined protection scheme with crowbar and series dynamic resistor (SDR) is used as proposed in former papers. Protection resistance values are calculated after the analysis of rotor fault current for practical application...
A new algorithm designated for locating faults on a double-circuit line is presented. It is assumed that the fault location function is incorporated into the current differential relay at the particular line end. Besides three-phase currents measured synchronously at both line ends, which are utilized by the protective relays, the fault locator is supplied with three-phase voltage from the local line...
This paper deals with halogen luminaries, ones of the main used lighting sources in residential area. The use of these artificial light sources leads towards different operational constraints in the low voltage power systems, such as inrush currents, harmonics or high frequency perturbations. Hence, the aim of the work is the characterization and modeling of halogen luminaries in ATP-EMTP, in order...
Problems occur when zones overlap in the conventional step distance protection scheme. If the same zones from different relays overlap, discriminating between the real fault location and the virtual one is difficult, and malfunction can occur. In this case, the zone length or time delay is usually modified to separate the overlapped zones. However, these changes affect the coordination of the power...
Distance relays are widely used as main and back-up protection for transmission lines. Their operation is based on impedance measurement at the relaying point, which can be affected by several factors, including pre-fault line loading and short circuit levels at the line ends. Continues demand for electricity energy leads to increase in short circuit levels along the power systems, which itself causes...
The paper describes relaying problems in transmission systems with a high degree of series compensation. The usability of and limits for the use of distance protection will be discussed and experiences gained from real-time tests are presented. The possibilities offered by modern relays, so called two-in-one relays, consisting of communication based differential protection combined with backup distance...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.