Inductance Calculation Method And Electromagnetic Characteristi C Analysis Of Integrated Filtering Winding Distribution Transformer

With the rapid development of the national economy and the steady improvement of the people's living standards,the large number of non-linear loads makes the harmonic pollution in the power supply and distri bution systems very serious.It is urgent to adopt effective measures and methods for suppression and governance.For urban pre-installed substations,ships and other physical space-constrained occasions,the hollow inductors in passive filters are integrated into distribution transformers,That is,the integrated filtering winding distribution transformer scheme,which can effectively suppress harmonics,and can also solve the problem of the large space occupied by filters.The harmonics of the power distribution system were investigated and analyzed in this paper.Aiming at the problem of harmonic pollution in l ow-voltage distribution network and the space limitation of box-type substation,based on the theory of non-orthogonal decoupling and the implementation method,a scheme of integrated filtering winding distribution transformer is proposed.Then according t o the winding arrangement of the integrated filtering winding distribution transformer,the mathematical model of its electromagnetic decoupling was deduced.Finally,two calculation methods of the inductance value of the integrated filtering winding are analyzed,and the coupling principle of the integrated filter ing winding is also analyzed.According to the physical dimensions and electrical parameters of the integrated filtering winding distribution transformer,three-dimensional finite element simulation model of the integrated filtering winding distribution transformer is established.The inductance matrix and the coupling coefficient matrix of the integrated filtering winding distribution transformer are calculated by finite element electromagnetic field simulation software.The inductance,linearity and coupling degree of the integrated filtering winding were tested by engineering prototype..Comparing the simulation and experimental results,these small magnetic coupling values and linear voltage-current curves verify that the proposed transformer integrated filter ing winding has ideal decoupling performance and inductance linearity.Finally,the field-circuit coupled simulation model of the traditional distribution transformers and the integrated filtering winding distribution transformers is built.The harmonic electromagnetic characteristics of the traditional distribution transformers under the two operating conditions of non-input and input compensation capacitors are analyzed.The results show that the harmonics of the traditional distribution transformers are not suppressed after the capacitors are input,and the internal electromagnetic environment of the transformer has not improved either.Then analyze the harmonic electromagnetic characteristics of the integrated filtering winding distribution transformer under the conditions of non-access and access filter.The simulation results show that the filter branch formed by the integrated filter ing winding and the external capacitor works normally,and has a good filtering effect;the internal electromagnetic environment of the transformer is effectively improved.Finally,the effect of the integrated filtering winding distribution transformer applied in a 10 kV side of a residential area was analyzed.The results of on-site operation verified the correctness of the theory of the integrated filtering winding distribution transformer and its good filtering performance.The noise was also measured at the box substation and at the nearest household.The noise measurement results meet the relevant requirements and effectively solved the household's trouble caused by the excessive noise of the distribution transformer at night.