Protective Relaying

Elmore, Walter A.

doi:10.1201/9780203912850

Cited by 101 publications

(22 citation statements)

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“…One of the main ways of decreasing the statistics of failures and extending the service life of transformers is the use of relay protection devices based on current transformers [3][4][5] and nonconventional high-sensitive protection devices based on inductive measuring transducers [2,6]. Such devices can be improved, in particular, their sensitivity to turnto-turn faults can be increased, by means of receiving information about characteristic features of currents in the transformer windings in the form of the spectrum of harmonic Energies 2024, 17, 1710 2 of 15 components of the currents during transformer operation.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection

Kolesnikov,

Novozhilov,

Rakhimberdinova

et al. 2024

Energies

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In this work, a mathematical model of a three-phase nonlinear transformer is suggested. The model enables simulating the transformer operation with allowance for its nonlinearity and covers needs of the relay protection. Our model has been developed on the basis of a mathematical model with phase coordinates, where differential equations are composed by the Kirchhoff’s phase-voltage law. Based on this model, we first compose a mathematical model for simulating steady-state operation modes of a transformer, taking into account the asymmetry and nonlinearity of its ferromagnetic core. In this model, the initial values of inductances and mutual inductances of loops are determined from the main phase inductance calculated by the experimentally found no-load current, and their current values are determined from the currents in windings and the magnetic fluxes in legs of the transformer core. The magnetic fluxes are calculated by the nodal-pair method. This improved mathematical model is verified through a comparison between the calculated harmonic components of the phase currents and the experimental results. The harmonic components are calculated with the use of Fourier expansion of the calculated phase currents. Their experimental values are determined with a spectrum analyzer. The calculated and experimental harmonic components of the currents of phase A during no-load and rated-load operation of the transformer are tabulated. The comparison of these results shows that the mathematical model of a three-phase transformer we suggest makes it possible to simulate currents in transformer windings under steady-state operation modes with accuracy acceptable for relay protection.

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Section: Introductionmentioning

confidence: 99%

Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection

Kolesnikov,

Novozhilov,

Rakhimberdinova

et al. 2024

Energies

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“…The previous literature stated that the negative sequence current based method is not going to be more sensitive than the phase current differential protection [25]. It also has been claimed that the negative sequence current scheme is suited for careful customized application.…”

Section: Contributionmentioning

confidence: 99%

Section: Sequence Network Connections and Symmetrical Components For mentioning

confidence: 99%

“…When a few turns are shorted in one phase, then the impedance of the shorted phase is not equal to the impedances of the other two phases [25], [29]. According to reference [25], the impedance change in one phase can be represented as a shunt unbalance as shown in Figure 2.17 for a grounded transformer. As it was mentioned before in Chapter 1, the traditional differential relay is not sensitive enough to detect minor internal turn-to-turn faults in the power transformer because the changes in the phase current are quite small.…”

Section: Sequence Network Connections and Symmetrical Components For mentioning

confidence: 99%

“…According to reference [25], the changes in impedance of the total phase circuit for a shorted turn is very difficult to calculate because of the power transformer actions. In accordance with their estimations when the impedance in the faulted phase changes by 3%, the negative and zero sequence currents will not be sufficiently large enough and will be less than 1%.…”

Section: Ngaopitakkul and Kunakorn Presented An Algorithm Based On A mentioning

confidence: 99%

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Turn-to-turn fault detection in transformers using negative sequence currents

Babiy

Gokaraju

Garcia

2011

2011 IEEE Electrical Power and Energy Conference

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A power transformer is one of the most important and expensive components in any power system. Power transformers can be exposed to a wide variety of abnormal conditions and faults.Internal turn-to-turn faults are the most difficult types of faults to detect within the power transformer. The IEEE Standards documents have revealed that there is no one standard way to protect all power transformers against minor internal faults such as turn-to-turn faults and at the same time to satisfy basic protection requirements: sensitivity, selectivity, and speed.This thesis presents a new, simple and efficient protection technique which is based on negative sequence currents. Using this protection technique, it is possible to detect minor internal turn-toturn faults in power transformers. Also, it can differentiate between internal and external faults.The discrimination is achieved by comparing the phase shift between two phasors of total negative sequence current. The new protection technique is being studied via an extensive simulation study using PSCAD®/EMTDC™ 1 software in a three-phase power system and is also being compared with a traditional differential algorithm.Relay performance under different numbers of shorted turns of the power transformer, different connections of the transformer, different values of the fault resistances, and different values of the system parameters was investigated. The results indicate that the new technique can provide a fast and sensitive approach for identifying minor internal turn-to-turn faults in power transformers.

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Distance Protection

Sanaye‐Pasand¹,

Ahmadi²

2022

Wiley Encyclopedia of Electrical and Electronics Engineering

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With the increasing demand for electricity and expansion of power networks, transferring large capacities of electrical energy over long‐distance transmission lines became necessary. Since these lines pass through different geographical environments, they are exposed to a variety of hazards. Among them, electrical faults are the most common ones that can disturb network performance and cause system outages. If these faults are detected in the early stages and the faulty part is rapidly separated from the entire network, further damages to the network will be prevented. Distance protection is the main protection principle for transmission lines and interconnected sub‐transmission networks. In addition, it can be used as the backup protection for the adjacent lines, busbars, and transformers. Since this protection proves its reliable performance, it has been used for many years in the industry. As the hardware technology progressed from original electromechanical to static and now up to digital microprocessor‐based types, the implemented algorithms were also improved. In modern distance protection devices, in addition to fault detection, there are other functions for phase selection, fault location, power swing detection, communication schemes, and so on. In this chapter, an overview of this protection algorithm is presented, and its different aspects are investigated.

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Protective Relaying

Cited by 101 publications

References 0 publications

Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection

Mathematical Model of a Nonlinear Power Transformer for Needs of Relay Protection

Turn-to-turn fault detection in transformers using negative sequence currents

Distance Protection

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