Calculation of Magnetic Field in J-TEXT with an Unsaturated Iron Core

A study of the magnetic field with an unsaturated iron core in tokamak equilibrium using a spool model is described in detail. The application of this model to the J-TEXT tokamak shows that the calculated results are in good agreement with those measured experimentally. At present this scheme is used to give the plasma configuration during J-TEXT＇s operation.

AC loss study on a 3-phase HTS 1 MVA transformer coupled with a three-limb iron core

High-temperature superconducting(HTS)technology provides an alternative approach to achieve compact transformers.Addressing AC loss in the HTS winding is crucial for HTS transformer applications.Most numerical AC loss studies on HTS transformers have neglected the influence of iron cores.This work carries out an AC loss study to explore the impact of an iron core on the HTS windings in a 3-phase HTS 1 MVA transformer coupled with it.AC loss simulations for the transformer winding both with and without the iron core are conducted by adopting the three-dimensional(3D)T-A homogenization method.When the iron core is incorporated,the saturation magnetic fields of iron materials,flux diverters(FDs)with different geometries,and variations in turn spacings in the LV winding composed of Roebel cables are considered to investigate their influence on the AC loss of the transformer winding.The inclusion of the iron core leads to a 1.2%increase in AC loss for the transformer winding while simulating at the rated current.We attribute this slight difference to the non-inductive winding structure of the transformer winding,where a strong magnetic field generated in the space between the LV and HV windings effectively shields the influence of the iron core.

A Design Model of Core Snubber for EAST NBI

A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equivalent circuit, the ranges of three key parameters, i.e., secondary side resistance, leakage inductance and snubber inductance, are determined. By con- sidering the saturation of the magnetic material, a design principle is Mso presented. A nearly 1：10 core snubber is tested. It is proved that a high permeability core with secondary resistor can restrain the discharge current effectively.

Studies on the active SISFCL and its impact on the distance protection of the EHV transmission line

The active saturated iron-core superconductive fault current limiter(SISFCL)is a good choice to decrease fault current.This paper introduced the principles and impedance characteristic of the active SISFCL.Then,it shows the current-limiting effects of the SISFCL.Besides,the impact of the active SISFCL on the distance protection of the EHV transmission line is evaluated.Based on that,the coordination scheme of the distance protections is proposed.A 500 kV double-circuit transmission system with SISFCLs is simulated by Electro-Magnetic Transients Program including DC(EMTDC).Simulation tests demonstrate the correctness and validity of theoretical analyses.