Inhomogeneity effects in HTS coated conductors used as resistive FCLs in medium voltage grids

Abstract

Abstract.For Resistive Fault Current Limiters (RFCLs) based on high temperature superconducting coated conductors (HTS-CCs), inhomogeneity, in terms of critical current and geometrical imperfections such as stabilizer and substrate thicknesses, plays a very important role and it may limit the penetration of such devices into the electrical market. This paper presents an electro-thermal model, developed in SimPowerSystem TM , able to describe the transient respond of HTS-CC candidates with different degrees of inhomogeneity, both in terms of critical current and of thickness stabilizer. Critical current inhomogeneity has been modeled with Gaussian distributions. Layers thicknesses used in the simulations have been chosen by fitting the temperature dependence of real tape resistances. Our approach considers relative inhomogeneity positions as well as thermal conduction along the HTS-CC length. The model is tuned using experimental measurements made on ReBaCuO coated conductors. A new dynamical thermal calibration of the model is proposed using finite element method calculations. Inhomegeneity effects with different possible faults (e.g. three phases and single phase short-circuit) are presented. Inhomogeneity Effects in HTS-CCs Used as RFCLs in MV Grids2

MV Power Grids Integration of a Resistive Fault Current Limiter Based on HTS-CCs

“…The device has been simulated in two applications in two different typologies of existing medium voltage grids: RFCL used as busbars coupler and RFCL used as transformer feeder. This contribution is the continuation of previous works [2], [3], where the effects of symmetrical and unsymmetrical short-circuits on inhomogeneous HTS-CCs have been extensively analyzed. …”

“…Symmetrical and unsymmetrical faults have been simulated inserting fictitious resistance (RF ) in the fault location. The model of the RFCL has been developed in SimPowerSystem TM and is reported in details in previous works [2], [3]. The parameters of the limiter are reported in table I.…”

Impact of the Normal Zone Propagation Velocity of High-Temperature Superconducting Coated Conductors on Resistive Fault Current Limiters

“…The Gaussian distribution we considered in our example is characterized by an average value of 380 A and a standard deviation over length (σ) equal to 6.59%. As explained in details in our previous work [9], the array of critical current levels (G1) that represents the Gaussian distributions of I c takes into account the critical current levels and their corresponding probability. In our example, the Gaussian distribution is discretized in 16 levels of I c , and the probability assigned to each I c level is given by the number of blocks with the same level of I c (Fig.…”

Heat transfer monitoring between quenched high-temperature superconducting coated conductors and liquid nitrogen

“…In this case, the heat transfer to LN 2 is negligible; hence T exp will tend to the adiabatic case. However, the most dangerous situation is when the fault current through HTS-CCs is around their [2]. In this situation and in recovery under load conditions [5], the HTS-CCs are prone to high risk of thermal runaway.…”

“…Commercial HTS-CCs are not perfectly homogeneous in term of critical current ( ) as can vary up to ±20% along their length [2]. Moreover, the thermal stability of RSFCLs when operating close to strongly depends on optimal cooling conditions of the conductors weakest points.…”