Derating calculating method for application of common transformer into harmonic condition
A calculation method and transformer technology, applied in the field of transformers, can solve problems such as excess redundancy, over-temperature, waste, etc., and achieve the effect of ensuring reliable operation and improving safety factor
Active Publication Date: 2019-09-03
福建省大岩电子科技有限公司
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Problems solved by technology
[0004] However, some users often do not consider the harmonic content of the back-end load when selecting a transformer, or know that the back-end load has harmonic content and use an estimation method to select a transformer with a larger capacity. The result is that either the capacity is insufficient and the temperature is too high , or there is too much margin and waste
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[0026] The present invention is further described in conjunction with the following examples.
[0027] Depend on figure 1 Know; A kind of common transformer described in the present embodiment is applied to the derating calculation method under the harmonic condition, comprises the following steps:
[0028] Step A: Measure the input current harmonic frequency THD of the load, and calculate the harmonic loss factor K;
[0029] Step B: Measure the DC resistance R of the winding of the transformer product at room temperature DC , and then calculate the DC resistance loss P DC ;
[0030] Step C: Measured at frequency f 1 and the respective load losses P1 and Px of the products at frequency fx, and decompose the winding eddy current loss Pwe1 and the stray loss of structural parts Pse1;
[0031] Step D: From the harmonic loss factor K, DC resistance loss P DC Calculate the fundamental eddy current loss factor Pwe1 with the winding eddy current loss Pwe1 * and the eddy curren...
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The invention relates to the technical field of transformers, in particular to a derating calculating method for application of a common transformer into a harmonic condition. The method comprises: step A, measuring an input current harmonic frequency spectrum THD of a load and calculating a harmonic loss factor K; step B, measuring a DC resistance RDC and calculating a DC resistance loss PDC; step C, decomposing a winding eddy current loss Pwe1 and a structural part stray loss Pse1; step D, calculating a fundamental eddy current loss factor Pwe1* and a harmonic eddy current loss factor Pwe*;and step E, calculating a derating coefficient THDF under a harmonic load. With the provided method, a common transformer can work reliably under the harmonic load condition, so that the safety factorof the system is improved; and a phenomenon that the temperature is too high due to the insufficient capacity and wasting is caused by the excessive redundancy in transformer selection by the commonuser under the harmonic load condition is avoided.
Description
technical field [0001] The invention relates to the technical field of transformers, in particular to a derating calculation method for common transformers applied under harmonic conditions. Background technique [0002] At present, with the rapid development of power electronics technology, more and more nonlinear loads are applied to various fields. Due to its nonlinear characteristics, the electromagnetic compatibility performance of the equipment is reduced, the grid-side input current is severely distorted, and a large number of harmonics are generated and released to the grid or front-end equipment, which brings harm to the grid and other electrical equipment. Various harmonic voltages or nonlinear loads existing in the power grid will generate additional harmonic losses in the transformer coils at the front end. When these harmonic losses are large enough, the temperature of the transformer will rise, and even exceed its allowable operation The temperature not only r...
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CPCG01R31/00
Inventor 冉瑞刚叶立斌李经伟
Owner 福建省大岩电子科技有限公司