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The large AC generators in a power plant are core facilities for providing stable production and supply of electric power in many applications. The generator protection system has very important role in maintaining stability in a power system. The generator protection systems in South Korea have been imported and operated through a turn-key from overseas entirely. Recently, with increase in the power...
Application of local data at receiving node of the system to estimate and control its parameters were considered in the paper. Using Thevenin model some methods were developed, analysed and simulated allowing to estimate and control stability margin and voltage level. The results can be used to construct voltage controller on basis of power electronics.
This paper presents the results of the analysis of a vast fault records database. The fault records were obtained during numerous experiments performed from 2005 to 2011 in real resonant-earthed distribution networks. The purpose of these experiments was to provide data either for verifying distribution network safety during earth faults or for testing methods of earth fault location or elimination...
The main purpose of this paper is using artificial neural networks (ANNs) in wide area protection of power systems. In fact, implementation of an intelligent protection system of electric network for discrimination between fault and no-fault conditions and also recognition of fault type contains main structure of this paper. Proposed idea has been implemented on IEEE 8-busbars electric network that...
Distribution system operator (DSO) sometimes needs to operate the large network which means operating of the network with big capacitive current (in Czech Republic more than 800A). This operation puts the emphasis not only on the setting of the earth fault relays but on the safety of the point of fault too. The paper describes the theoretical analysis, simulation and tests in real compensated distribution...
Phasor Measurement Units (PMUs) have the potential to play an essential role in power system monitoring and operation in the future, particularly for power systems incorporating increasing amounts of distributed generation (DG) and possibly systems operating in islanded mode in the future [1]. Their ability to directly measure and provide the voltage and current phasors at the PMU location offers...
Modern microprocessor-based low-impedance differential relays use a percentage differential principle that utilizes traditional dual slope characteristics. Many differential mis-operations occur with these traditional methods as a result of CT saturation, DC offset, or current subsidence. One reason is because the traditional operating and restraining principles rely heavily on the current magnitude,...
Autoreclosure provides a means of improving power transmitting ability and system stability. The conventional reclosure adopts the fixed dead time interval strategy, that is, the reclosure is activated after a time delay to restore the system to normal as quickly as possible without regard to the system conditions; however, these simple techniques cannot give the optimal operating performance. For...
This paper deals with line protection challenges experienced in system having substantial wind generation penetration. Two types of WTGU: Doubly Fed (DFIG) and Squirrel Cage (SCIG) Induction Generators are simulated and connected to grid with single circuit transmission line. The paper summarizes analytical investigations carried out on the impedance seen by distance relays by varying fault resistances...
This paper presents a new multi-criteria stabilization algorithm of transformer differential protection. Proposed scheme bases on new criteria signals and appropriate operation thresholds. New algorithm employs fuzzy reasoning technique for better discrimination of inrush conditions. The developed stabilization algorithm has been tested with ATP-EMTP generated signals, proving to be reliable and much...
This paper proposes a supervised shutdown algorithm for an off-shore wind power plant (WPP) to meet a required rampdown rate of a grid code in a storm-driven situation. The algorithm determines the number of wind generators (WGs) to shutdown simultaneously by considering the required ramp-down rate of a WG without using a brake. Based on the wind direction and speed measured at a wind mast (WM), wind...
The new generation of current sensors, such as Rogowski coils, have performance characteristics that can improve design and operation of modern power systems. This paper presents novel solutions that integrate protection, control, and metering functions for power transformers and cables by sharing signals from the same Rogowski coils.
The paper describes a Transient Bias technique designed to overcome the effects of Current Transformer (CT) saturation, which might severely affect the behaviour of a protection system. This Transient Biasing, as the name implies, is only active during transient conditions in the power system, and it decays quickly once the transients disappear. A complementary algorithm for fast detection of external...
The paper presents a new pole slipping protection method that combines high efficiency of pole slip detection and sensitivity to many sources of potential pole slipping. To simplify the setup process the adaptive settings are calculated continuously. The new adaptive method utilizes active and reactive power measurements on machine terminals to ascertain that the synchronous machine is committed to...
Decentralized Energy Resources (DER) and especially wind farms became a challenge for protection, automation and control in the grids. Transmission system operators as well as distribution system operators require tests of Loss of Mains and other decoupling protection functions. In some countries certification of these functions is required. The units are equipped with a huge amount of internal protection...
With their increasing number, it is getting important that decentralized and renewable energy sources are supporting the stabilization of the system voltage after short voltage dropouts. Often, in the past, these generators were disconnected during network faults. This is not adequate anymore, as it would lead to a loss of a considerable amount of feed-in power. However, if the generators stay connected,...
The quest for intelligent, so called Smart Grid technology is seen by many as the key to future exploitation of renewable energy sources and the inclusion on the Grid of home grown generation from micro CHP systems. But, as Keith Hamilton, Group Managing Director of PBSI Group Limited explains, the prerequisite for the establishment of Smart Grids relies on a significant investment in equipment as...
The concentration of electric power at system buses adds to both the need for high-speed tripping in case of faults and the need to avoid false tripping in case of external faults. This combined need for both superior dependability and security has led to many enhancements and system modifications in bus protection. Bus configurations with multiple zones are particularly difficult to provide with...
When applied over asymmetrical or potentially asymmetrical channels (unequal channel propagation times in the transmitting and receiving directions), such as commercial-class SDH/SONET networks, line current differential schemes need an external time reference for current data alignment if the sensitivity of the differential scheme is to be preserved. Modern line differential schemes can handle a...
Accurate fault location on transmission lines becomes increasingly beneficial by reducing outage times and allowing faster restoration of scarce power system assets back into service. Having natural access to synchronized remote current data, line current differential protection schemes can incorporate multiterminal fault location algorithms, allowing for more accurate fault location compared with...
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