Topic
Power-system protection
About: Power-system protection is a research topic. Over the lifetime, 6353 publications have been published within this topic receiving 117961 citations.
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TL;DR: A simple synchrophasor estimation algorithm is proposed considering power system steady state, dynamic conditions, and protection requirements and performs satisfactorily during system faults, which is an important requirement for protection applications.
Abstract: In this paper, a simple synchrophasor estimation algorithm has been proposed considering power system steady state, dynamic conditions, and protection requirements. The new IEEE Standard C37.118.1-2011 for synchrophasor measurements includes the dynamic performance requirements for the phasor measurement units. It is shown that the proposed method satisfies all the steady state and dynamic requirements of the new IEEE Standard. Presently, synchrophasors are mainly used for wide area monitoring. Increasingly, synchrophasors are being considered for protection applications in smart grids. Protection applications require shorter response times and lower overshoot/undershoot values for estimated phasors during large disturbances. It is shown that the proposed method performs satisfactorily during system faults, which is an important requirement for protection applications. A detailed performance comparison with the existing phasor estimation algorithms has also been presented.
50 citations
12 Oct 2003
TL;DR: In this paper, a dc-link voltage regulator is proposed to suppress the overvoltage during power line faults, which is characterized by compensating for a time delay inherent in each current controller, and for a power flow imbalance occurring during power lines faults.
Abstract: A voltage-source back-to-back system for the purpose of achieving power flow control and/or line-frequency change in transmission systems has the attractive features of reliable and continuous operation, even during power line faults. However, an overvoltage appearing across the dc link during the faults should be limited to as low a value as possible because it does affect the power device ratings. This paper proposes a dc-link voltage regulator for effectively suppressing the overvoltage during power line faults. This regulator is characterized by compensating for a time delay inherent in each current controller, and for a power flow imbalance occurring during power line faults. The validity of the proposed regulator is confirmed by theory and computer simulation.
50 citations
TL;DR: In this paper, the applicability of memory-polarized distance relay mho elements to the protection of MOV (metal oxide varistor) protected series-compensated lines is shown.
Abstract: It is shown that the applicability of memory-polarized distance relay mho elements to the protection of MOV (metal oxide varistor) protected series-compensated lines is dependent on the system configuration, line loading, the location of the potential source, and the magnitude of memory polarization. For a configuration with compensation at one end of a line, the results indicate certain advantages in using the potential from the line side of the capacitor, and the use of a relatively large magnitude of memory polarization. The presence of a conducting MOV enhances the performance of the mho element both in terms of security on reverse faults and dependability on forward faults. The results obtained pertain to the proposed application in the Ontario Hydro system of a relatively large amount of compensation at one terminal in each circuit of a double-circuit line. >
50 citations
05 Oct 1997
TL;DR: A summary of the IEC protection against electric shock is provided by appropriate basic measures as follows: (1) for protection both in normal service and in case of a fault (against both direct and indirect contact), use low and safe voltage of 50 V and below; (2) forprotection in normal services (against direct contact), insulation and/or enclose live parts or use isolation distance; and (3) protection in case a fault, prevent conducting parts not normally energized from becoming live as mentioned in this paper.
Abstract: This paper provides a summary of the IEC protection against electric shock. This protection is provided by appropriate basic measures as follows: (1) for protection both in normal service and in case of a fault (against both direct and indirect contact), use low and safe voltage of 50 V and below; (2) for protection in normal service (against direct contact), use insulation and/or enclose live parts or use isolation distance; and (3) for protection in case of a fault (against indirect contact), prevent conducting parts not normally energized from becoming live. This is accomplished by grounding and automatic disconnection of the supply, by use of Class II equipment (as double or equivalent insulation), or by separating the supply from ground, IEC publication 364-4-41 "Electrical installations of buildings", (Part 4, Chapter 41) classifies types of system grounding as TN-system, TT-system, and IT-system. Development of this summary is based on actual hazard risk analysis of potential incidents to suggest criterion by which the appropriate measures can be applied to avoid or mitigate injury or damage.
50 citations
01 Dec 2014
TL;DR: In this article, the effects of two line-to-line and lineground fault types from various fault locations to operation of the DC system are presented, and strong and weak points of four main types of protection devices (including fuses, no-fuse circuit breakers, power-electronic protection devices and protective relays) are mentioned.
Abstract: In this paper, common DC-fault detection methods have been reviewed. Effects of two line-to-line and line-to-ground fault types from various fault locations to operation of the DC system are presented. In addition, operation principle, strong and weak points of four main types of protection devices (including fuses, no-fuse circuit breakers, power-electronic protection devices and protective relays) are mentioned. Each different type of protection devices has the ability to protect and isolate different components of the DC microgrid (e.g. power converter, PV system, battery system, capacitor and others) under fault occurrences. The paper analyses possible protection coordination strategies of protection devices to ensure safety of any components in the DC microgrid. These summarized coordination strategies can be suitable for any DC microgrid configurations. In the next content, an effective protection coordination system of a real community-sized DC microgrid is developed, which use fast-acting fuses to replace no-fuse circuit breakers already installed at some certain locations in the DC microgrid. Aims of this improved protection coordination system are to shorten critical fault clearing time and get the cost effectiveness while still ensuring high selectivity, dependability and safety of the DC microgrid. As a result, the no-fuse circuit breakers placed at locations such as: output of PV arrays, output of the battery, output of the fuel-cell system, and terminals of power converters are efficiently replaced by the fast-acting fuses. Additionally, protection devices located at load feeders are suggested to use the relays to optimise the coordination time between main and back-up protection in case of faults occurring at the load feeders.
50 citations