The authors have designed and fabricated a 6.9kV–500kVA 3-phase HTS reactor, based on the elemental technologies achieved in the previously developed single-phase HTS transformers, which were focused on the reduction of AC loss for enhancing efficiency as well as the creation of a disk winding method for coil downsizing. This paper describes the results obtained from an experiment conducted to verify the performance of the HTS reactor and to identify its characteristics when connected to the grid.

The authors have developed a solenoid model coil used for superconducting magnetic energy storage (SMES) for power system control, aimed at drastically reducing the costs of the SMES system. The single solenoid model coil of 2.9 MJ is designed with the rated current of 9.6 kA, a maximum magnetic field of 5.5 T and coil charge rates equivalent to those of the practical 100 MW/54 MJ class SMES. The coil is characterized by the use of an aluminum stabilized NbTi CIC (Cable-in-conduit) conductor. The experimental SMES consists mainly of a 2.9 MJ coil, the cooling system for the CIC conductor and the 1 MW class AC/DC converter. The SMES is connected to 6 kV distribution lines at a substation. In the field test, the SMES's 17 ms responses for the step input of active and reactive power were ascertained. Furthermore, its function of compensating for load fluctuation in the 6 kV distribution line was confirmed. The test results show the realization of a practical SMES system for power line control

The authors are engaged in technological endeavors to create a coil at a drastically reduced cost with the aim of making it practical for SMES for power system stabilization. With focus on its novel conductor material and uniquely shaped coil, which were exclusively developed with the target of reducing the cost of the coil, an experimental model coil was devised. It is characterized by a single solenoid coil made of aluminum stabilized NbTi CIC. Experiments such as a rated 9.6 kA current-carrying test and current interrupting test were conducted to examine the performance of the model coil. The test results proved that the SMES model coil would perform as initially designed.

We designed and fabricated a 4 kJ conduction-cooled high-Tc superconducting (HTS) pulse coil. The coil is wound with an interlayer-transposed 6-strand parallel conductor which is composed of Bi-2223 silver alloy-sheathed multi-filamentary wires. We had developed a complete 3.6 MJ/1 MW low-Tc superconducting (LTS) SMES system for testing on a power line at Imajuku substation. Aiming at the feasible operation of SMES applying a HTS coil, we made a SMES system set-up in which HTS coils were serially connected to 3 LTS coils of the SMES. The SMES including the HTS coil was connected to Imajuku substation's power system, to made operational tests of compensation for load fluctuation at the 6 kV power line. The test results lead to the feasibility of the HTS SMES for practical use in future power systems.

The authors have developed a 1 kWh/1 MW module-type SMES system (ESK), linked to the actual power system, that was tested at Imajuku Substation in Fukuoka. The practical use of SMES at field sites requires ensuring its reliability, as well as reducing costs with minimum component set-ups. In order to quantitatively verify its reliability and performance limit, two kinds of tests were conducted on ESK: a long-term and over-load operation. In the long-term operation test, a DC500 triangle waveform up to 1000 A was applied to ESK 10,000 times. Further, the compensation ability for distribution line load fluctuation was observed for three days. The results revealed that ESK functioned adequately and in a stable manner. In the other test, a power output 1.2 times that of the rated output was attained, along with an energy storage capacity 1.44 times the rated value. This allowed us to confirm the over-load operation limit of ESK.