Low second-harmonic content in transformer inrush currents - Analysis and practical solutions for protection security

Hodder, Steven; Kasztenny, B.; Fischer, Normann; Xia, Yu

doi:10.1109/cpre.2014.6799037

Cited by 51 publications

(42 citation statements)

References 3 publications

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“…AC flux exists, there is a coexistence of odd and even harmonics in AC excitation current. This coexistence is present in the transformer inrush current as well, as it has been reported in [7].…”

Section: Introductionsupporting

confidence: 72%

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Experimental Detection of Transformer Excitation Asymmetry through the Analysis of the Magnetizing Current Harmonic Content

Pjevalica¹,

Petrovic²,

Pjevalica³

et al. 2016

ElAEE

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The presence of a low DC voltage in a power grid produces an excitation asymmetry for the distribution transformers, resulting in unwanted half-cycle saturation that may impair transformer safety, reliability and efficiency, especially in increasing the reactive power, stray losses and iron losses. This paper highlights a diagnostic method based on the phase value of the particular even harmonics of a transformer excitation current as the basic marker of an excitation asymmetry. In order to achieve a straightforward insight into the nature of even harmonics behaviour, a novel method of decomposition an excitation current waveform into its unhysteretic (pure magnetization) and hysteretic components has been included in the harmonic analysis.

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Section: Introductionsupporting

confidence: 72%

“…There is one more important result of the above proposed AC excitation current decomposition. Based on (6), (7) and since DFT of the unhysteretic AC excitation current component gives the cosine coefficients (Ak) only, the following expressions are true for the AC excitation current peak values:…”

Section: Experimental Results Analysismentioning

confidence: 99%

Experimental Detection of Transformer Excitation Asymmetry through the Analysis of the Magnetizing Current Harmonic Content

Pjevalica¹,

Petrovic²,

Pjevalica³

et al. 2016

ElAEE

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show abstract

“…CMC 256 provides different platforms to test the relay with its zones setting, transmission line parameters, and time delay. Moreover, an advanced distance test displays the amplitude and phase of the three phase currents and voltages determined by the fault type and the fault location [11]. The distance relay is a universal short-circuit protection.…”

Section: Relay Report and Simulink Resultsmentioning

confidence: 99%

“…It is acceptable for near faults, because the distance to the zone limit is long [13,16]. For faults close to the zone limit, an underreach is not permitted; the relay will trip in the second zone with a time delay [11]. Figure 12 shows the relation between the tripping time and the THD of the voltage.…”

Section: Distance Relay: Tripping Time Vs Thd Levelmentioning

confidence: 99%

“…The harmonic distortions in the power system and the associated problems caused by non-linear loads were briefly discussed. A review related to various methodologies for detecting and measuring harmonics based on this review of a new hybrid method for detecting and measuring harmonics is introduced in these references [10][11][12]. Few studies explore the research associated with quantifying the cost of reliability and power quality.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Harmonics Impact on Digital Relays

Wannous

Toman

2018

Energies

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This paper presents the concept of the impact of harmonic distortion on a digital protection relay. The aim is to verify and determine the reasons of a mal-trip or failure to trip the protection relays; the suggested solution of the harmonic distortion is explained by a mathematical model in the Matlab Simulink programming environment. The digital relays have been tested under harmonic distortions in order to verify the function of the relays algorithm under abnormal conditions. The comparison between the protection relay algorithm under abnormal conditions and a mathematical model in the Matlab Simulink programming environment based on injected harmonics of high values is provided. The test is separated into different levels; the first level is based on the harmonic effect of an individual harmonic and mixed harmonics. The test includes the effect of the harmonics in the location of the fault point into distance protection zones. This paper is a new proposal in the signal processing of power quality disturbances using Matlab Simulink and the power quality impact on the measurements of the power system quantities; the test simulates the function of protection in power systems in terms of calculating the current and voltage values of short circuits and their faults. The paper includes several tests: frequency variations and decomposition of voltage waveforms with Fourier transforms (model) and commercial relay, the effect of the power factor on the location of fault points, the relation between the tripping time and the total harmonic distortion (THD) levels in a commercial relay, and a comparison of the THD capture between the commercial relay and the model.

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Current signal processing-based methods to discriminate internal faults from magnetizing inrush current

Etumi

Anayi

2020

Electr Eng

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Two new methods, Current Change Ratio (CCR) and Percentage Area Difference (PAD) were proposed to solve a problem of how to distinguish between internal faults and inrush condition when transformer is switched on. This problem may delay operation or may mal-operate some protection schemes like deferential protection. The methods were concluded after observing and analyzing the behavior and shape of large number of both inrush and internal fault signals that had been obtained using a model transformer in a laboratory. The methods were practically tested on a three phase transformer with rated power of 20kVA at Cardiff University's laboratory and the data were processed using LabVIEW and MATLAB programs. The results showed that internal faults can be correctly distinguished from inrush condition within a short time (from 5ms to 10ms), particularly the minor internal faults such as the inter-turn fault which is submerged to inrush current and make it is too difficult to be detected. The advantages of these algorithms are simple in design and faster than the second harmonic method which is the most popular method used for solving this problem.

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Low second-harmonic content in transformer inrush currents - Analysis and practical solutions for protection security

Cited by 51 publications

References 3 publications

Experimental Detection of Transformer Excitation Asymmetry through the Analysis of the Magnetizing Current Harmonic Content

Experimental Detection of Transformer Excitation Asymmetry through the Analysis of the Magnetizing Current Harmonic Content

Evaluation of Harmonics Impact on Digital Relays

Current signal processing-based methods to discriminate internal faults from magnetizing inrush current

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