Calculation of Leakage Magnetic Field and Short-Circuit Impedance of Power Transformer

Han, Fang; Li, Yan; Sun, Xin; Li, Longnv

doi:10.4028/www.scientific.net/amr.986-987.1767

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…Even if the tap-mode balances the ampere-turns height at the end, the radial magnetic flux leakage component By2 generated in the split-zone will still generate axial force Fy2 to expand the split-zone and increase the asymmetry of winding height, as shown in Figure 1(b). The axial force Fy1 at both ends of the coil is equal in magnitude and points to the middle, compressing the pads between the coils [16]. Under the action of axial force, the fiber inside the pad is gradually broken, and plastic deformation occurs, which increases the compression rate of the pad.…”

Section: Expression Of Axial Bending Forcementioning

confidence: 99%

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

Zhu

Wang²,

Gao³

et al. 2023

J. Phys.: Conf. Ser.

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To improve the study on the influence of transformer windings and pad support on transformer short-circuit resistance, the calculation method of wire bending elastic modulus is analyzed, and the sample test is carried out: The influences of the unbalance of the two ends of the wire between the number of wires wound and the span of adjacent pads on the force-deflection curve, the bending force at the selected deflection, and the elastic modulus of bending were analyzed. The results showed that: Increasing the number of wires and decreasing the height difference of adjacent pads can improve the bending force and bending elastic modulus of wires, the axial stability, and short-circuit resistance of transformer windings. When the height of the adjacent pad is not balanced, the axial force can increase the compression degree between the pad and the wire, and reduce the span of the wire. Under the action of force, the wire yields twice, which further reduces the bending force and elastic modulus of the wire. This research can provide test data support for improving the installation of transformer winding pads and theoretical evaluation of short-circuit tolerance.

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Section: Expression Of Axial Bending Forcementioning

confidence: 99%

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

Zhu

Wang²,

Gao³

et al. 2023

J. Phys.: Conf. Ser.

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show abstract

“…In the case of input voltage of 2000 Hz and above, the transformer winding can be approximately equivalent to a passive two-port network composed of RLC. At this time, the iron core of the transformer plays a smaller role and the winding plays a larger role [18]. In this paper, the short circuit impedance method, the frequency response method, and the oscillatory wave method are used to evaluate the performance of transformer windings in the frequency range of 0-10 MHz.…”

Section: Broadband Equivalent Circuit Model Of Transformermentioning

confidence: 99%

Simulation test of transformer short-circuit impedance based on equivalent model at different frequencies

Song¹,

Gu²,

Zheng³

2022

J. vibroeng.

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A distribution transformer is one of the most important equipments in the power grid, and its operational status is directly related to the security and stability of the entire power system. The performance of transformer windings determines the service life of the transformer. It is of great significance to evaluate the performance of transformer windings accurately, reliably, and effectively after the short-circuit test of the transformer. Aiming at the problem that the natural vibration frequency of the transformer measured before and after the short circuit may not be the same under the impact of the short circuit of the transformer, this paper puts forward the evaluation method for the performance evaluation of the winding of the transformer after the short circuit test and adopts the method of combining the analytic hierarchy process with the fuzzy evaluation method to quantitatively obtain the score for the performance evaluation of the winding. And that evaluation language is given according to the score. Finally, the evaluation of the transformer winding performance after the short-circuit test is realized. The evaluation results show that this method can effectively get the performance index of the transformer winding, without the need for hanging cover inspection, and solve the subjectivity of human eye observation to objectively, accurately, and quantitatively describe the performance state of the transformer winding. The method is favorable for power grid monitoring and maintenance personnel to accurately evaluate the operation stability of the transformer and has very positive significance for improving the short-circuit impact resistance of the transformer and ensuring the safety and stability of the operation of a power system.

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“…In References [7,8], to improve the accuracy of the measurements of the micro-deformation of magnetostriction, the vector magnetostrictive characteristics of SSS in the alternating magnetization mode and in the AC/DC hybrid mode were studied using the laser measurement method. In Reference [9], using the measured magnetostrictive curves of SSS, the magnetostrictive force of the EHV transformer core at different times was calculated; then, the intensity and distribution of the vibration and noise were analyzed using the magnetostrictive force and thermal stress. He Qiang et al measured and analyzed the modal vibration and noise of a 110 kV transformer core without load and pointed out that the magnitude of the vibration and noise differed because of the magnetostrictive anisotropy in various parts of the core.…”

Section: Introductionmentioning

confidence: 99%

Research on the Magnetostrictive Characteristics of Transformers under DC Bias

et al. 2023

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Direct current (DC) bias leads to increased vibration and noise in transformers. One of the main causes is the magnetostrictive effect of the transformer core. To address this phenomenon of magnetostriction, firstly, a transmission line model (TLM) of a single-phase transformer under DC bias is developed using transmission line theory and Jiles–Atherton (J–A) ferromagnetic hysteresis theory, taking into account the winding copper loss, core eddy current loss, and leakage effect. Secondly, the time-domain simulation of the single-phase transformer based on the Newton–Raphson iterative method is carried out, and the magnetostriction characteristics of the transformer under different DC and its variation law are analyzed. Finally, the results show that the DC bias results in magnetostrictive distortion and vibration acceleration curve distortion, the left and right wings of the magnetostrictive butterfly curve are no longer symmetrical, the slope of the vibration acceleration image increases significantly, and the degree of distortion is positively correlated with the magnitude of the DC. In addition, the peak values of the magnetostrictive deformation and vibration acceleration become larger under DC bias, leading to an increase in the vibration and noise of the transformer. The research object of this paper is the single-phase transformer, and the research method can also be applied to the study of three-phase transformers.

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Calculation of Leakage Magnetic Field and Short-Circuit Impedance of Power Transformer

Cited by 6 publications

References 1 publication

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

Simulation test of transformer short-circuit impedance based on equivalent model at different frequencies

Research on the Magnetostrictive Characteristics of Transformers under DC Bias

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