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There is a need for induction filter technology in the field of low-voltage distribution networks. This paper proposes an induction filter distribution transformer with a unique Dd0yn11 three-winding configuration. This approach allows for the control of load side harmonics in low-voltage distribution networks. At present, the induction filter technology proposed in the known literature is mostly used in the high-voltage power system, but there is still no research on the application of induction filter technology to the distribution transformer with Dyn11 under the low-voltage distribution network. In this paper, the wiring scheme of inductive filter distribution transformer and filter system in low-voltage distribution network is established firstly, then the mathematical relationship between the harmonic current generated by the load side and the current on the grid side is derived according to the winding model, and it can be deduced that the induction filter distribution transformer with its filtering system has good filtering performance and reactive power compensation characteristics. Finally, the experiment simulates the three-phase harmonic load, detects the current waveform and other parameters of the actual grid side of the new transformer, verifies the correctness of the theoretical analysis. The induction filter distribution transformer proposed in this paper provides a new solution for harmonic suppression and reactive power compensation in low-voltage distribution network, which fills the vacancy of the application of induction filter technology in low-voltage distribution network, This paper reveals that the inductive filter technique has a good filtering performance when applied to low-voltage distribution network. And it provides a reference for further research on improving power grid efficiency, saving energy cost and improving transformer electromagnetic environment under low-voltage distribution network.

This article presents the results of studies conducted at the Northwest Institute of Nuclear Technology, Xi’an, China, on centimeter-class vacuum breakdown characteristics under microsecond short pulses. First, a formula to calculate the vacuum breakdown field (${E}_{b}$) dependent on the electrode gap, electrode area, and pulsewidth is given. Then, basic breakdown characteristics in a gap range of about 2–4 cm are explored experimentally. As the applied voltage increases, an aging state exists between the micro-discharge and the first breakdown. The relationship between aging voltage ${U}_{a}$ and micro-discharge and first breakdown is ${U}$ (micro-discharge) $ < {U}_{a} < {U}$ (first breakdown). The effect of the electrode material on ${U}_{a}$ is as follows: ${U}_{a}$ (polyimide-covered TC4) $ < {U}_{a}$ (magnetic core) $ < {U}_{a}$ (stainless steel) $ < {U}_{a}$ (TC4) $ < {U}_{a}$ (LY4), where TC4 and LY4 are the titanium alloy and the aluminum alloy, respectively. It has also been experimentally verified that the smaller the roughness of the electrode, the higher the breakdown voltage and the longer the lifetime. In the end, certain experimental proofs that support the clump theory for the long-gap vacuum breakdown mechanism are summarized. All of the results in this article have practical value for long-gap vacuum insulation design. [ABSTRACT FROM AUTHOR]

By conducting vacuum breakdown experiments under 30 μs pulses with a uniform field for gap separations d ranging from 2.5 to 5.5 cm, it is found that the dependence of the breakdown voltage U b on d obeys the total voltage effect (TVE) relation U b =Cda, where a ranges from 0.76 to 0.84. By fixing d as 3.5 mm, U b for stainless steel (304C), titanium (TC4), and aluminum (LY14) electrode materials are obtained, and it is found that U b (304C)