Superconducting Magnetic Energy Storage System System Research Articles

Frequency Regulation of Micro-grid Connected Hybrid Power System with SMES

This paper presents the frequency regulation analysis of a micro-grid connected hybrid power system based on solar Photovoltaic (PV), Wind and Diesel-Engine Generator (DEG) with Superconducting Magnetic Energy Storage system (SMES) unit. Abrupt change in load demand and power fluctuations from PV and wind power source causes frequency variability in the system. In order to mitigate this issue, the hybrid power system incorporates along with the energy storage devices. A case study of the impact of SMES operations on the performance of frequency stability of hybrid system has been carried out. Simulation of a Hybrid Power System (HPS) model has been carried out in two different scenarios with the two phases. First is the steady state investigation of HPS using PI controller with step load change response. Second is the dynamic performance study throughout a typical day with arbitrary variation in load demands. Controller parameters are tuned with Genetic Algorithm based optimization approach. The limits on the inductor (coil) current due to the possibilities of discontinuous conduction in the presence of large disturbances and limited storage capacity have also been incorporated. HPS has analyzed in the Matlab Simulink environment. Simulation results indicate that SMES system can contribute towards the frequency stability in both cases for variable power generations from renewable sources and irregular demand loads.

Unit Coil Development for Y-SMES

A superconducting magnetic energy storage system (SMES) for electric power system control has been developed using Yttrium (Y)-based coated conductor of high performance in Ic and mechanical properties, in order to fulfill the requirements for large capacity and cost reduction of the SMES. The target stored energy of the coil required for the SMES system of 100 MVA output power is 2 GJ class. The conceptual designed coil of toroid type consists of one hundred eighty unit coils of 2.8 m outer diameter and each unit coil is connected to each converter of a multi-cell type. Due to this design concept, the main unit coil specifications of 2 kA current, 2 kV voltage, 600 MPa hoop stress tolerance and 3 W/m2 heat flux around 20 K can realize the SMES system. Coiling technologies have been developing using Y-based wire for SMES. A small multi-layer coil was manufactured and its electromagnetic force characteristics were verified by 600 MPa class hoop stress tests. A bundled-conductor coil of 650 mm class diameter was also manufactured and its current characteristics were verified by 2 kA class large current tests.

Cryocooler cooled HTS current lead for a 35 kJ/7 kW-class high- Tc SMES system

Within 863 program of China, a 35 kJ/7 kW-class high- T c superconducting magnetic energy storage system (SMES) was completed in Nov. 2005. It operates at 100 A in the cryogenic environment of 20 K and is cooled by conduction cooling. It is essential to minimize heat loss from room temperature and to optimize the ohmic heating of current leads. So, 100 A hybrid type current leads, consisting of conventional copper parts and high- T c superconducting (HTS) parts, were designed, fabricated and tested. The HTS parts of the leads were made of Bi-2223 cylindrical bulk and the copper parts were winded into just like a sparse solenoid to prolong the path for heat transfer. The current leads were cooled directly by a two-stage cryocooler. And, a series of experiments were carried out. The experimental results show a good according with the simulation, which verify that the hybrid current lead meets the requirements of high- T c SMES.

Design of power control system using SMES and SVC for fusion power plant

A SMES (Superconducting Magnetic Energy Storage System) system with converter composed of self-commutated valve devices such as GTO and IGBT is available to control active and reactive power simultaneously. A SVC (Static Var Compensators) or STATCOM (Static Synchronous Compensator) is widely employed to reduce reactive power in power plants and substations. Owing to progress of power electronics technology using GTO and IGBT devices, power converters in the SMES system and the SVC can easily control power flow in few milliseconds. Moreover, since the valve devices for the SMES are equivalent to those for the SVC, the device cost must be reduced. In this paper the basic control system combined with the SMES and SVC is designed for large pulsed loads of a nuclear fusion power plant. This combined system largely expands the reactive power control region as well as the active one. The simulation results show that the combined system is effective and prospective for the nuclear fusion power plant.

Field Test Results of the 5 MVA SMES System for Bridging Instantaneous Voltage Dips

A superconducting magnetic energy storage system (SMES) was developed and has been tested in the field (at a large LCD TV plant in Japan) in order to confirm its performance at bridging instantaneous voltage dips, its long-term reliability and its standby loss. The developed SMES system can store up to 7.34 MJ of magnetic energy in superconducting coils using a NbTi Rutherford conductor with a maximum electric output of 5 MVA. The field tests began in July 2003. During operation, the performing compensatory action of the SMES system on instantaneous voltage dips within the actual system was confirmed. Through the field tests of the SMES system, technical proof of the specifications required to provide instant, effective compensation for instantaneous voltage dips was verified

Development and Performance Results of 5 MVA SMES for Bridging Instantaneous Voltage Dips

The superconducting magnetic energy storage system (SMES) of output 5 MVA has been developed to bridge instantaneous voltage dips. The field examination is executed by setting up this system at the new and large liquid crystal factory in Japan. The developed SMES system can store up to 7.34 MJ of magnetic energy in superconducting coils using the NbTi Rutherford conductor. The maximum output of the developed SMES is 5 MVA, and the system can discharge the output for one s. The operating current of the coil is 2.7 kA, and the rated voltage is 2.5 kV. The field examination was started in July 2003. During the field test, we will confirm the performance of bridging instantaneous voltage dips by SMES, the long-term drive reliability and the standby loss characteristic.

Conceptual design of SMES system equipped for IPP plant

The superconducting magnetic energy storage system (SMES) has been studied on its advantages over another type of energy storage system. Considering the advantages of SMES, it is recognized that SMES is one of the advanced energy storage systems for future power plants. In this paper, a SMES system equipped for an independent power producer (IPP) power plant is proposed and the operational scenario of the total plant is discussed. Also, some types of SMES coil for this study are designed in size or other parameters and the quantitative comparison among them is mentioned.

Adaptive automatic generation control with superconducting magnetic energy storage in power systems

An improved automatic generation control (AGC) system employing self-tuning adaptive control for the main AGC loop and the superconducting magnetic energy storage system (SMES) is presented. Computer simulations on a two-area interconnected power system showed that the proposed adaptive control scheme was very effective in damping, oscillations caused by load disturbances and its performance was quite insensitive to controller gain parameter changes of the SMES system. A performance evaluation of control schemes using adaptive and nonadaptive controllers in the main AGC and in the SMES control loops is presented. The improvement in performance resulting from the adaptive scheme was particularly pronounced for load changes of random magnitude and duration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>