K.D. Sim

3 MJ/750 kVA SMES System for Improving Power Quality

The purpose of this study is to develop a superconducting magnet energy storage system (SMES), which protects sensitive loads on the power system, when an interruption or voltage sag occurs. Industries have many sensitive machines, and keeping the power in a good condition is very important for nonmilitary machines also. Korea Electrotechnology Research Institute (KERI) has developed a 3 MJ/750 kVA SMES system to improve power quality in sensitive electric loads. It consists of an IGBT based power converter, NbTi mixed matrix Rutherford cable superconducting magnet, and a cryostat with HTS current leads. The operating current of the 3 MJ SMES magnet was 1000 A. The SMES system is tested under short time power interrupt to verify the feasibility of the SMES system as a 750 kVA power converter

Conceptual Design of HTS Magnet for a 5 MJ Class SMES

Superconducting magnetic energy storage (SMES) systems with High Temperature Superconducting (HTS) wires have been actively developed world-wide. A 600 kJ class SMES with Bi-2223 HTS wire has been in development as a national project since 2004 and is currently approaching the final testing stage of the first of three phases. In the second phase of the project, several MJ class HTS SMES will be developed. In this paper, designs of magnets for 5 MJ class SMES with DI-BSSCO and YBCO coated conductor are presented and compared.

Fabrication and test of a 3MJ SMES magnet

For quite a long time many research and developments of superconducting magnetic energy storage (SMES) system have been doing for the enhancement of power quality control of a sensitive electric load. Korea Electrotechnology Research Institute (KERI) has developed a 3MJ, 750 kVA SMES system to improve power quality in sensitive electric loads. This paper describes the design, fabrication and experimental results for the 3MJ SMES magnet made by using the design code of a SMES device that we developed. A computer code was developed to find the parameters of the SMES magnet, which has a minimum amount of superconductor for the same stored energy. And the 3MJ SMES magnet was designed based upon those. In addition, the 3MJ SMES magnet that was ramp up to 1kA without quench.

Design of HTS Transmission Cable With Cu Stabilizer

More than three HTS cable development and installation projects are proceeded over the world. A 22.9 kV/50 MVA class HTS cable system has been developed in Korea during last 3 years. And the HTS cable system for commercialization will be developed and installed on the real or test power grid within 2 years. Every HTS cable system has to satisfy the fault-current specifications of the power grid in order to protect the cable itself from the fault current. HTS cable composed of HTS tapes has some capacity of enduring the fault current by bypassing the fault-current through its Ag-sheath. But it may not be enough. So, some Cu stabilizer is generally introduced inside the conductor layers and outside the shield layers of HTS cable core for some higher fault current grade. In this paper, the design method of HTS cable with Cu stabilizer will be introduced. And the fault current capacity of HTS cable and its eddy current loss generated from the stabilizer will be calculated. And the impedance change of HTS cable in the fault current state will be calculated

Insulation studies and experimental results for high Tc superconducting power cable

In this paper, we studied electric insulation characteristics of synthetic Laminated Polypropylene Paper (LPP) in liquid nitrogen (LN/sub 2/) for the application to high temperature superconducting (HTS) cable. And, we selected the insulation paper/LN/sub 2/ composite insulation type for the electric insulation design of a HTS cable. Furthermore, we compared the breakdown characteristics of the butt gap and bent mini-model cable that comes into being in this kind of cryogenic insulation type. It is necessary to understand the winding parameter of insulation paper/LN/sub 2/ composite insulation.

The Optimal Design of 600 kJ SMES Magnet Based on Stress and Magnetic Field Analysis

In the development of large scale superconducting magnetic energy storage (SMES) systems, the problem of mechanical stresses induced in the windings by Lorentz force becomes more critical as dimensions of system and magnetic field increase. In this paper, an optimal design process of a 600 kJ SMES magnet combined with mechanical stress analysis is presented. A stress analysis method based on electromagnetic finite element analysis (FEA) is explained in detail. The results of the analysis led to the development of an optimum design, electro-magnetically and mechanically, of a single-pole double pancake coil (DPC) type 600 kJ SMES magnet. The stress in each DPC are described along with recommendations for winding tension in the manufacturing process to minimize radial and hoop stress in each DPC.

Characteristic Analysis of a Sample HTS Magnet for Design of a 300 kW HTS DC Induction Furnace

A large-scaled induction furnace for nonferrous metal billets is operated with commercial frequency, and it does not have such high energy efficiency of 50%-60% due to the considerable energy loss of copper coils to generate magnetic fields. Despite the additional efforts to improve the efficiency, it has limitation to increase it, physically. In this paper, a design specification for a 300-kW HTS dc induction furnace (HTS DC IF) was presented, and the characteristic analysis of the sample HTS magnet was conducted. The characteristic resistance, the charging and the discharging time were calculated and measured. Detailed investigations of the sample model on voltage characteristics of ten voltage taps and temperature characteristics were conducted. The test results will be applied to the full-scale HTS DC IF.

Simulation and Experimental Demonstration of a Large-Scale HTS AC Induction Furnace for Practical Design

Preheating for nonferrous metals in industry is realized through induction furnaces with a large capacity at commercial frequency. The energy efficiency of this process is about 50%-60% due to enormous energy loss through the copper coils. An ac induction furnace applying 2G high-temperature superconducting (HTS) magnets has been suggested in order to achieve higher efficiency. The most important factor in this technology is the ability to predict and minimize the ac loss, which is generated in HTS magnets during operation. In this paper, we demonstrate the simulation and experimental results of a large-scale HTS ac induction furnace for practical design. The HTS ac induction furnace was designed and simulated through a finite-element method (FEM) tool and an equivalent circuit model. The inductors were designed by using 2G HTS magnets, with consideration given to the ac loss generated in the magnet. To predict the ac loss of the magnet, the FEM was used, and the results were compared with those of the fabricated HTS magnets. The simulation and experimental results will be applied to fabricate a full-scale HTS ac induction furnace.

Economic Feasibility Study of an HTS DC Induction Furnace

Conventional induction furnaces have been in operation in nonferrous metal and related industries with poor energy efficiencies of only 50-60%. Moreover, the efficiency of atmosphere furnace, one of the various heating facilities for metal billets, is about 20%. For ensuring high energy efficiency in these heating furnaces fields, as one of the better counterplans, a novel dc induction heating method using HTS magnets has been suggested. To realize the HTS dc induction furnace (HIF) in the industrial field, the most important issue is to guarantee economic favor in comparison with two different types of conventional furnaces. In this paper, we performed an economic feasibility study of an HIF in terms of electricity fee minimization. Net present value, internal rate of return, and pay-back period methods were used to evaluate the investment returns of an HIF. All indicators related to direct benefits were calculated and analyzed for finding economic feasibility. The analysis results will be applied to decision making process for the commercialization of the HIF.

Design and Manufacturing of a Conduction-Cooled Sample Holder for a Superconducting Property Measurement System

We had developed four years ago a superconducting property measurement system (SPMS) that can be used to acquire electrical and thermal properties of high-temperature superconductor (HTS) tape samples. The SPMS was composed of the sample holder for mounting an HTS tape and 3 T HTS magnet, both cooled individually by conduction using a cryocooler. The maximum dimension of the HTS tape sample that could be loaded on the sample holder was 15 mm in width and 250 mm in length. The conduction-cooled sample holder was again fabricated to increase the maximum test current up to 800 A. Maximum transport current was 763 A in magnetic field intensity 3 T. The measuring temperature range was 15-50 K.