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Normally, fault resistances come out with errors in the fault calculation algorithm on conventional Mho distance protection scheme which might force the relay to under-reach/over-reach based on the network conditions. With a constrained shape, Mho Directional distance elements can provide more resistive coverage while discriminating between forward and reverse faults. In this work, the recurring effect...
Protective systems require a faithful reproduction of primary current on the Current Transformer (CT) secondary side. Saturation is a common problem in a steel core CT. Current transformer (CT) saturation leads to inaccurate current measurement and, therefore, may cause malfunction of protective relays and control devices that use currents as input signals. This paper have invested an efficient practical...
Evaluation of relay misoperations provides an opportunity to improve the design of backup protection schemes. Existing generator station backup protection schemes use distance protection (21) or voltage controlled/restrained overcurrent protection (51V) elements for clearing phase faults that are not cleared by either line protection or generator protection. Many schemes also use transformer ground...
Due to the increasing penetration of Distributed Generation (DG) units in the power grid, traditional protection philosophies in distribution systems need to be updated. Distance protection offers an interesting choice in microgrid protection since it is independent of variations in source impedance. However, there are several constraints in applying conventional distance protection on the distribution...
Synchronous motors are rarely designed to operate asynchronously for extended periods of time. When a synchronous motor experiences a mechanical load exceeding its pull out torque, it enters asynchronous operation, under which the interaction between the stator and rotor magnetic fields causes damaging mechanical stress and vibrations. Also, induced currents in the rotor cause extra heating that quickly...
The improved use of renewable power generation and the coordinated connection with electrical networks and loads bring a new concept, the microgrids. In general, a microgrid can operate in both grid connected mode and islanding mode. Ensuring the continuity of protection in both operation modes is a great technical challenge. Dealing with different short circuit currents level depending on the operation...
The method of symmetrical components simplifies analysis of an electric circuit during the fault and represents an important tool for the protection engineers. In this paper, the symmetrical components of the fault current are used in a new feeder protection method for the maritime applications. The new method is effective against the phase-phase fault and relies on evaluation of the ratio of negative-sequence...
Microgrids have gained more popularity with advancement in renewable energy technology, mainly solar. While the boom in renewable technology has provided an alternative solution for energy crisis and depleting conventional sources, their intermittent nature has raised various control and protection issues. In both AC and DC microgrids, protection issues remain similar except the fact that in DC microgrids...
Focus on the design of IC test board based on ATE, discuss about the structure of test board, and some common signal like digital, analog, DPS, etc. That we normally will meet in the IC test board design, research the key points for test board design, and how to improve and ensure the design quality.
The increasing share of distributed generation poses risks to the selectivity and reliability of power system protection. To begin with, this paper presents a selection of currently faced challenges, which lead to errors in locating of faults and secure functionality. As a result of the theoretical analyses, adaptive settings based on the current state of the protected electrical system are deducted...
Integration of Distributed Generations (DGs) including Renewable Energy Sources (RES)into the existing distribution network poses several challenges to the existing protection schemes of the distribution system. One such challenge is the increase in the fault current level of distribution system. This generally, exceeds the breaking capacity of existing fuses and circuit breakers. Consequently, the...
Industrial power systems, whether low voltage (LV) or medium voltage (MV) systems, are the backbone of any industrial facility. To keep production going and minimize downtimes, they are required to be very reliable. Therefore, it is important to deploy various protection systems to detect and react appropriately to any abnormal condition that can lead to a failure to deliver power or to a hazardous...
This paper investigates the effect of varying fault impedances in the context of Distributed Generation (DG) influences on distribution overcurrent protection infrastructure (specifically fuse-recloser protection). The assessment includes an investigation into a DG source integration evaluation method to determine the effects of varying fault impedances. The assessment and evaluation techniques used...
We consider a wireless sensor network that uses inductive near-field coupling for wireless powering or communication, or for both. The severely limited range of an inductively coupled source-destination pair can be improved using resonant relay devices, which are purely passive in nature. Utilization of such magneto-inductive relays has only been studied for regular network topologies, allowing simplified...
Working Group D-3 "Considerations in Choosing Directional Polarizing Methods for Ground Overcurrent Elements in Line Protection Applications": John Appleyard, Jeffrey Barsch, Gabriel Benmouyal, Art Buanno, Randy Crellin, Randy Cunico, Normann Fischer, Michael Fleck, Robert Frye, Charles Henville, Meyer Kao (Chair), Shoukat Khan, Gary Kobet, Alex Lee, Don Lukach, Walter McCannon, Joe Mooney,...
Bus protection is one of most challenging applications because it requires highest degree of security and dependability. Unforeseen during engineering and not detected during commissioning potential problems can cause a blackout in the large geographical area. This paper will discuss several common problems and solutions for the low impedance bus differential protection to increase security and dependability...
Mho elements constitute the main component of transmission line protection in North America and many countries overseas. Distance elements based on incremental quantities and derived from the same base equations as mho elements emerged about two decades ago as a way to improve the speed of distance elements. This paper compares the intrinsic protective properties of mho and incremental distance elements,...
Negative-sequence overcurrent (51Q) elements can add sensitivity to transformer and feeder protection. Because these elements do not respond to balanced load current, they can be set below phase overcurrent elements. However, certain loads may cause higher than expected negative-sequence current to flow because their negative-sequence impedance is quite low when compared to their positive-sequence...
In addition to the advantages of distributed generation (DG) sources, also it would have disadvantages such as harmonic distortions generation and changing in short-circuit current. Harmonic distortion generation may exceed from permissible harmonic level and cause problem. Furthermore, the change in short-circuit current can cause performance of incorrect in the over-current relays. In first, this...
The common form of bus differential protection is to use either a high impedance differential relay or a biased low impedance differential relay. Bus protection using a feeder overcurrent blocking scheme is also widely used in the sub-transmission and distribution levels due to the high cost of the complete bus differential protection solution. IEEE Working Group C-14 of the Power System Relaying...
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