A Method for Estimating the Current–Flux Curve of a Single‐Phase Transformer for Electromagnetic Transient Simulations of Inrush Currents

Oyanagi, Ryohei; Noda, Taku; Ichikawa, Masatoshi

doi:10.1002/eej.23102

Cited by 8 publications

(3 citation statements)

References 11 publications

(23 reference statements)

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“…Refs. [18–23]). For the no‐load state, the voltage u M can be assumed to equal the primary voltage, which means that it is sinusoidal with the given frequency f .…”

Section: Theoretical Preconditionsmentioning

confidence: 99%

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Shilyashki

Pfützner

Bengtsson³

et al. 2022

IET Electric Power Appl

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Traditionally, products of electrical SiFe steel are focussed on applications for frequencies of 50-Hz. However, the recent developments of electric drive systems yielded a strong extension of the range from f = 16 2/3 Hz up to ca. 500 Hz. In spite of high industrial relevance, the literature offers the corresponding data on the material's magnetic energy losses in very rare ways. This paper reports a first comparative, multi-parametric study on eight different steel products that comprise non-oriented steels (NO), grain-oriented steels (GO) and scribed grain-oriented steels (SGO). Consistently at IEC-standardized samples, they were analysed for the whole frequency range that was split into low frequency (LF) and medium frequency (MF), with 80 Hz as the border. Data is presented on time-averaged total losses P, on the corresponding hysteresis losses P H and eddy current losses P E . LF proved to be governed by P H and MF rather by P E , however, with strong variations. Further, instantaneous magnetization power functions p(φ) were determined for basic insights into the involved temporal developments of energy dissipation. GOsteels yielded profiles close to rectified co-sinus functions that can be fully attributed to dissipative losses. On the other hand, p(t) of NO-steels and SGO-steels prove to include negative segments that reflect potential energy power, in the course of alignments of atomic moments in instants of high induction. Examples of industrial relevance of the accumulated data are steel production technology, product categorization, failure tracing and energy conversion. K E Y W O R D Seddy current effects, grain orientation, hysteresis losses, instantaneous losses, instantaneous power, magnetization power, silicon iron | INTRODUCTIONElectrical steel sheets of silicon iron are of high industrial relevance, due to their almost universal use for soft magnetic cores of electric machines. Traditionally, the production of core steel is focussed at applications for grid frequencies f of 50 and 60 Hz, respectively. As a matter of fact, almost all literature on aspects of magnetic energy losses are concentrated on these values. On the other hand, in recent times, word-wide developments were started to implement electric drive systems in general ways. This involves a large range of frequency f, starting with 16 2/3 Hz, up to 400 Hz. In some detail, it includes the following frequency key values: 16 2/3 Hz for train drives 25 Hz for train drives in countries like North America 50 Hz world-wide, the most frequent general grid frequency 60 Hz the grid frequency in parts of America and Asia 80 Hz being relevant for f-controlled drives, among others 400 Hz for aircrafts, sub-marines etc. 500 Hz (or even higher) for currently developed drive systemsThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…Refs. [18–23]). For the no‐load state, the voltage u M can be assumed to equal the primary voltage, which means that it is sinusoidal with the given frequency f .…”

Section: Theoretical Preconditionsmentioning

confidence: 99%

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Shilyashki

Pfützner

Bengtsson³

et al. 2022

IET Electric Power Appl

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“…Though hysteresis mechanisms are of clearly non-linear nature, R M tends to be assumed as a constant, with single exceptions, like in reference [4] that discusses an induction generator. Constant R M is even assumed for calculations of transient problems, like that of inrush currents [5][6][7][8][9][10]. Attempts to consider the involved non-linearity are rare, like that reported in [11] where Preisach principles are introduced.…”

Section: Introductionmentioning

confidence: 99%

Practical Aspects of Instantaneous Magnetization Power Functions of Silicon Iron Laminations

Pfützner

Shilyashki

Bengtsson³

et al. 2022

J. Electr. Eng. Technol.

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Magnetic energy loss P of SiFe steel represents a key factor for the efficiency of soft magnetic machine cores. Traditionally, they are operated with 50 Hz (or 60 Hz), a frequency value that yields rather balanced portions of hysteresis loss and eddy current loss. In equivalent circuits of transformers, P tends to be represented by a magnetic power resistance RM, as a constant. For the most important case of sinusoidal induction B of 50 Hz, this would correspond to an instantaneous magnetization power function p(t) that is sinusoidal as well, however, with 100 Hz (or 120 Hz). On the other hand, from complex, non-linear mechanisms of hysteresis, it is obvious that p(t) should be strongly non-sinusoidal, even for exactly sinusoidal B(t). So far, almost all corresponding instantaneous investigations were restricted to calculated modelling of loss portions and transient modelling. On the other hand, for the first time, the present study was focussed on functions p(t) as measured at IEC-standardized samples of industrially relevant steel. Practical evaluations are discussed with respect to the revealed “history” of magnetization processes, as well as for product characterization. For these tasks, a novel digitized “Low-mass Single Sheet Tester” was developed that was applied for both non-oriented steel (NO) and grain-oriented steel (GO), for 50 Hz. Interpretations proved to be favoured by relating p(t) to total P, according to an instantaneous power ratio. As a result, both steel types revealed strongly non-sinusoidal power functions, with short durations of negative p. Negative p proved to be most pronounced for NO steel, as a measure for the onset of reversible turns of atomic moments. As a consequence, p(t) comprises strong upper harmonics of 200 Hz and even 300 Hz. Based on theoretical considerations, we split p(t) in a dissipative loss power function pL(t) and in a potential energy power function pP(t). Finally, we used p(t) to determine the corresponding power resistance RM(t) that proves to be a distinctly nonlinear function as well. It resembles a rectified co-sinus, also exhibiting short negative spikes that reflect the crystallographic dis-orientation of the polycrystalline material.

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“…Abdulsalam et al provide a new method for estimation of the saturation curve from the waveform data of the transformer inrush current and claimed that there was close agreement between the simulation and measurement results of the magnetizing and inrush current. Oyanagi et al proposed a method to convert the current‐time curve to the current‐flux characteristic, which is important for transient analysis. The method is essentially based on the measurement of the peak current and the magnetic flux in the iron core.…”

Section: Introductionmentioning

confidence: 99%

Modified method for transformer magnetizing characteristic computation and point‐on‐wave control switching for inrush current mitigation

Yahiou

Bayadi

Babes

2019

Circuit Theory & Apps

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Summary This paper proposes a new model for the low‐frequency transient analysis of a transformer, with a modified equation for calculation of the flux‐current characteristic representing the saturation inductance of the transformer. The model is based on the V‐I (voltage‐current) no‐load curves and uses the no‐load reactive power losses. To validate the model, it was used to simulate the no‐load magnetizing current in steady‐state condition, as well as the transient inrush current at network frequency. Evaluation was done both by comparing the simulation results obtained with the proposed model and those available in the relevant literature, and by practical measurements. The experimental results presented in this paper were obtained via a laboratory setup and a data acquisition system based on the dSPACE board 1104. Moreover, a control switching to mitigate the transient inrush current in a transformer was developed and applied experimentally in the laboratory and also in the simulations. This control strategy was performed by taking into account the residual flux at the opening instant of the related circuit breaker. A comparative study was carried out showing the validity of the proposed model and the mitigation technique.

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A Method for Estimating the Current–Flux Curve of a Single‐Phase Transformer for Electromagnetic Transient Simulations of Inrush Currents

Cited by 8 publications

References 11 publications

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Time‐averaged and instantaneous magnetic loss characteristics of different products of electrical steel for frequencies of 16 2/3 Hz up to 500 Hz

Practical Aspects of Instantaneous Magnetization Power Functions of Silicon Iron Laminations

Modified method for transformer magnetizing characteristic computation and point‐on‐wave control switching for inrush current mitigation

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