三相五柱式非晶配电变压器铁心内部磁密分布

The flux distribution of three-phase five-limb amorphous wound cores for distribution transformers

研究了三相五柱式结构非晶合金卷铁心在不同励磁磁密下内部的磁密分布。在低励磁磁密下,铁心内部的实际磁密沿叠厚方向并不均匀,由内侧到外侧逐渐降低,当励磁磁密为0.8 T时,内框铁心和外框铁心的内外侧实际磁密差值最大分别可达0.44 T和0.28 T。随着励磁磁密的增高,各个铁心内部实际磁密分布趋于平缓,内外侧实际磁密差值也随之减小。各个铁心内部的实际磁密还存在明显的三次谐波分量,其含量随着励磁磁密的增高而增高。在低励磁磁密下,各个铁心内部磁密的三次谐波分布较为平缓,随着励磁磁密接近饱和,三次谐波分布变得不均匀,其含量由内侧到外侧逐渐降低,在励磁磁密为1.5 T时,内框和外框铁心的内外侧磁密三次谐波含量差值达到了4.3%和4%。对三相五柱铁心三次谐波来源进行了分析。

Magnetic flux distribution in three-phase five-limb amorphous wound cores for distribution transformers is investigated.At low exciting flux,the actual flux is un-uniform across the core buildup and decreases gradually from the innermost to the outermost.At the exciting flux of 0.5 T,the flux discrepancy in the buildup of the inner cores and outer cores reaches 0.44 T and 0.28 T respectively,and the discrepancy decreases as the exciting flux increases.There are remarkable third harmonics in magnetic flux in the cores.The content of the third harmonics increases as the exciting flux increases.At low exciting flux,the third harmonics distribution is practically uniform in the cores.As the exciting flux increases toward saturation,the content of the third harmonics becomes un-uniform across the cores buildup and decreases gradually from the innermost to the outermost.When the exciting flux is 1.5 T,the difference of the third harmonics content in the buildup of the inner and outer cores reaches 4.3%and 4.4%respectively.The sources of the third harmonics of three-phase five-limb cores are analyzed.