G. Wojtasiewicz

Design and testing of 230 V inductive type of Superconducting Fault Current Limiter with an open core

A single-phase, 230 V Superconducting Fault Current Limiter using two Bi2223 HTS tubes with the total critical current 2.5 kA situated in vacuum insulated cryostat has been described in this paper. We designed and manufactured the inductive SFCL with an open core as core shielded type acquired the optimal design parameters by using Finite Element Method. We tested the limiter performances at liquid nitrogen temperature 77 K. We proved that the performances of properly designed limiter with open core could be comparable to the limiter with closed core.

Properties comparison of superconducting fault current limiters with closed and open core

The high-T/sub c/ superconducting fault current limiter (SFCL) can be classified into resistive, inductive and hybrid types. The inductive type HTSFCL seems to show most prospect due to the simple design (construction) of the secondary superconducting winding in the form of ceramic type BSCCO and for the reduction of current leads. In an inductive type SFCL, ferromagnetic cores for magnetic flux are applied, however open cores are also taken into consideration in order to simplify the construction. The results of experimental and computational investigations of inductive SFCL parameters are presented in this paper.

Tests and Performance Analysis of Coreless Inductive HTS Fault Current Limiters

Superconducting fault current limiters (SFCL) are designed to protect the electrical grid from faults that result from lightning strikes, downed power lines and other system interruptions. The rapid increase of impedance of the SFCL reduces the short current in the circuit. Several coreless constructions of inductive SFCLs have been tested. The space between the windings is the thick of the polyimide film kapton insulation to increase the coupling and reduces the leakage reactance. Both primary and secondary windings have been immersed in liquid nitrogen. The presented solutions reduce the size and the weight of the device. A few limiters based on HTS 1G and HTS 2G tapes has been described, tested and compared.

Analysis of Transformer Type Superconducting Fault Current Limiters

The inductive type SFCLs and the transformer type SFCLs need the iron cores. In both, the fault current is transformed from the primary winding to the secondary winding. The difference is in the secondary windings. The superconducting materials for every kind of SFCL should have both high value of resistivity in the resistive state,rhotau , and high critical current density . The paper shows, that the transformer SFCL can be made using every type of commercial HTS elements. The inductive SFCLs need the HTS materials with very large value of the rhotauJc parameter.

Experimental and Numerical Analysis of Electrothermal and Mechanical Phenomena in HTS Tube of Inductive SFCL

The superconducting fault current limiter (SFCL) can be successfully used to limit the short-circuit current level in electrical networks to 5 (or less) times of rated current level. The inductive SFCL works like transformer with shorted secondary winding in a shape of HTS tube. The SFCL 625-A consists of superconducting Bi-2223 tube (critical current=625 A at 77 K), iron core and copper primary winding. The numerical model using the thermal physical domain of CAD package FLUX2D has been used to analyze of temperature distribution in HTS tube during the fault. The numerical model using the magnetodynamic physical domain of FLUX2D package was used to analyze the mechanical force in HTS tube during fault. We attempt to provide explanation why HTS tubes quite often break during current limitation

The 15 kV Class Inductive SFCL

The Superconducting Fault Current Limiter (SFCL) is one of the most attractive devices for the electrical power network. The inductive SFCL consists of two coaxial windings and an optional magnetic core. The primary winding, connected in series to the circuit, is conventionally made of the copper wire, the secondary is made of a superconductor. The 15 kV class SFCL has been designed. It consists of 7 units. The primary copper winding of units has 27 turns/unit and the operating current is 1 kA. The HTS winding of units is wound with 140 turns of YBCO coated conductor SF12050 tape (SuperPower Inc.). The HTS winding has an internal diameter of 0.455 m. The SFCL is cooled in the liquid nitrogen bath. In this paper, we have described the numerical model and the numerically calculated electric parameters of the 15 kV class inductive type SFCL in the stand-by state and during current limitation.

Experimental and numerical analysis of energy losses in resistive SFCL

The resistive SFCL (superconducting fault current limiter) is a superconducting device which may operate both in superconducting state and in normal conducting (resistive) state. The paper presents FEM numerical model (in FLUX2D) of resistive SFCL made using Bi-2212 bifilar coil (NEXANS) cooled by pool boiling cooling technique (liquid nitrogen, 77 K). Real geometry of resistive SFCL is replaced by equivalent, due to energy and current density, geometry of numerical model. The electro-thermal numerical model of resistive SFCL can be used to estimate the energy and maximum temperature in limiter and the time to switch off the current to protect against damage.

Superconducting Winding for Inductive Type SFCL Made of HTS Tape With Increased Resistivity

Currently produced and available HTS tapes with increased resistivity, like 2nd generation YBCO 344S tape made by American Superconductors, have enough parameters, e.g., resistivity, critical current density, to build inductive type current limiters to limit faults in medium-voltage power grid. The paper describes the assumption for 6,9 kV/1.15 kA superconducting fault current limiter with superconducting secondary winding made of high resistivity HTS tape as well as the results of numerical analysis.

Design and Numerical Analysis of the 15 kV Class Coreless Inductive Type SFCL

Superconducting fault current limiters (SFCLs) are the most attractive devices for the power network, because limiters can be used to limit the short current in electrical network. This paper presents the design, the numerical model, and the calculated electrical parameters of the new 15-kV class SFCL prototype. The coreless superconducting fault current limiter consists of three windings: a primary and secondary windings made of SF12050 tape and a parallel connected primary copper winding. All windings are inductively coupled and intended to work in liquid nitrogen. The transient magnetic FEM-circuit numerical models of SFCL were used to analyze the current, resistance, and temperature of SFCL in the limitation state.

Experimental Investigation of a Model of a Transformer-Type Superconducting Fault Current Limiter With a Superconducting Coil Made of a 2G HTS Tape

A superconducting fault current limiter (SFCL) reduces the short-circuit current level in a power system and thus provides protection for and significantly reduces the wear and tear of circuit breakers and other substation power equipment. This paper describes a design and test results of a model of a transformer-type superconducting fault current limiter (TrSFCL) with a 1-phase 10 kV copper transformer and a secondary winding shorted by a superconducting current limiting coil made of 2G HTS tape. Special regard is given to the ability of this device to limit a short-circuit current thanks to the parameters of both the HTS coil and the 2G HTS tape used, and in particular to its resistivity in the resistive state at a temperature of 77 K.