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Future power systems face several challenges; one of them is the use of high power converters that decouple new energy sources from the AC power grid. This decreases the total system inertia affecting its ability to overcome system frequency's disturbances. The wind power industry has created a controller to enable inertial response on wind turbines generators: Artificial, Emulated, Simulated, or...
Distance relays used for transmission line protection can mal-operate on power swing. This paper presents protection schemes for out of step detection based on synchronized phasor measurement. Voltages and currents at both the ends of a transmission line are used to derive the parameters required for designing these schemes. The proposed schemes can distinguish stable and unstable power swing and...
This paper presents collected events to demonstrate the use of synchrophasor data to update and improve system models and system operation. Examples are given of responses to events captured using wide-area synchrophasor measurements. Phase angle, frequency, and voltage responses are displayed with discussion of the events, synchrophasor data views, and insights to be gained from the different data...
Transformer differential protection schemes normally use multi slope characteristics to provide stability during CT saturation with 2nd harmonic restraint or blocking for inrush conditions. This paper presents new algorithms that have been developed to improve the performance of the differential protection. Extensive testing has been used to demonstrate that the transient bias algorithm can reduce...
This paper builds upon the earlier research which proposed the use of satellite communication media to achieve improved performance of the Loss-Of-Mains (LOM) protection by eliminating nuisance tripping and ensuring reliable islanding detection. The focus of this paper is the practical development of the laboratory based trial of the satellite based LOM protection and the experimental assessment of...
Effective voltage control is essential for the satisfactory operation of distribution networks. The increased connection of distributed generation to existing distribution networks challenges the current methods of controlling network voltages. Network voltage is primarily controlled by changing tap position of the primary transformers. The transformer secondary voltage will be automatically increased...
Transformers are critical to the successful operation of the electrical power systems. Their reliability and availability is therefore key to flawless and optimum power generation and transmission. Effective condition monitoring is essential to evaluate transformer performance and safe operating conditions. Over the past few years many stand-alone devices have been developed for transformer condition...
In the last two decades there has been a continuous increase in the amount of Distributed Generation (DG) connected to the power network. This has resulted in a number of technical challenges for network protection including: sympathetic tripping of DG interface protection; blinding of feeder over-current (OC) protection; and deterioration of feeder OC protection grading. While the available literature...
This paper discusses potential extreme scenarios which could result in unstable conditions on the main interconnected electricity transmission system of Oman. Case studies on loss-of-stability scenarios between different parts of the network are examined. The objectives of the study are to identify possible locations of the electrical centre of swing and to develop an approach for controllable system...
This paper aims to present the modeling and simulation of numerical differential protection of power transformers using the software ATP/ATPDraw and its MODELS environment. In order to validate the relay model, simulations were carried out using a simplified electrical power system whose parameters were obtained from a real system. The results reveal the advantages of using this type of modeling,...
At present, gas protection and current differential protection are generally used as the main protection for traction transformer in China high-speed railway. Overcurrent protection with busbar low-voltage start-up is used as the backup protection installed at HV side and LV side of transformer. This paper introduces the principle of overcurrent protection with busbar low-voltage start-up, and then...
This paper presents a new impedance based fault location method in the case of phase to phase and three phase faults. This method utilized the measured impedance by distance relay and super imposed current factor, which is the ratio of post-fault current to super imposed current, to discriminate the fault position on the line. This method is robust against the fault resistance. The presented method...
Injection-based 100% stator earth-fault protection has been used for many years. However traditionally signals with frequency between 10Hz and 25Hz have been injected into the stator winding. To inject such a signal, either a dedicated grounding transformer with secondary grounding resistor or injection on primary side of the grounding circuit, is normally used. This paper will present a novel approach...
To feed electric train, the structure of traction power supply system is very different from utility grid. The single-phase traction loads result in some problems, such as negative sequence, harmonics, reactive power and crossing neutral sections. Based on the existing traction power supply system, the active power filter is used to construct cophase traction power supply system. It not only eliminates...
IEC 61850 is the new standard for communications in substations that defines a new generation of protection applications based on high speed peer-to-peer communications between different substation devices. Accelerated protection schemes use permissive or blocking signals exchanged between relays at the two or more ends of the protected transmission line in order to provide fast fault clearing for...
This paper proposes a Multi-agent System (MAS) approach to coordinate overcurrent relays, aiming to protect distribution systems with distributed generators. The connection of distributed generation (DG) units causes a reduction in the efficacy of protection systems coordination and, in some cases, an increase of operating times. Coordination studies aim to guarantee the protection selectivity in...
Based on the basic voltage and flux equations of the Doubly Fed Induction Generator, this paper derived expressions of short-circuit current of wind turbines, which are expressed by transient equations of stator and rotor flux. The transient equations of stator and rotor flux were functions of initial values of stator and rotor flux and transient time constants of stator and rotor windings. The initial...
Transmission line parameter is important for obtaining power network structure, generating power system node admittance matrix or impedance matrix to calculate power flow, calculating short-circuit current, and setting relaying protection devices. But actually, transmission line parameters applied in power system are mostly experience values or offline measuring values provided by manufacturers, they...
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