A 30 MJ (8.4 kWh) Superconducting Magnetic Energy Storage (SMES) unit with a 10 MW converter has been installed and commissioned at the Bonneville Power Administration (BPA) substation in Tacoma, Washington. This is the first large-scale application in the US of superconductivity in an electric utility system. The unit, which is capable of absorbing and releasing up to 10 MJ of energy at a frequency of 0.35 Hz, was designed to damp the dominant power swing mode of the Pacific AC Intertie. This paper describes the electrical characteristics of the magnetic energy storage unit, its modes of operation, results of device tests, means for controlling real and reactive power, and some initial power system response tests. A short summary of the operating history of the unit over the first eleven months is also presented.

Commissioning tests of the Bonneville Power Administration 30 MJ superconducting magnetic energy storage unit

The last couple of years have seen an expansion on both applications and market development strategies for SMES (superconducting magnetic energy storage). Although originally envisioned as a large-scale load-leveling device, today's electric utility industry realities point to other applications of SMES. These applications-transmission line stabilization, spinning reserve and voltage control-are likely to open the door to SMES commercialization in the electric utility sector. In the industrial sector, power quality concerns are already driving the development of a market for micro-SMES devices, and load-leveling at an industrial scale is fast becoming a potential application. Work recently completed as part of the US SMES program, as well as ongoing design activities, point to self- (or cold-) supported SMES as the design option in the near-future. This is a major departure from the earth-supported SMES systems first envisioned 25 years ago for utility load-leveling. The path to commercialize SMES is not likely to include a large 'demonstration' unit, or model, but rather follow an evolutionary process in which bigger and better units will be fielded in response to specific applications. This paper reviews the developments in the US SMES program that have taken us to where we are today, briefly reviews SMES-related activities around the world, and points out trends in applications and development of SMES.

Superconducting storage systems: an overview

It is shown that, in a sustainable energy future, energy for the electricity grid will probably be derived largely from the renewable sources of wind and solar radiation. Because both are intermittent, any infinite busbar grid supplying a metropolitan area must necessarily be buffered from these intermittencies by massive energy storage on the gigawatt-day level. It is then demonstrated that, under presently foreseeable scientific capabilities, only underground pumped hydro and advanced adiabatic compressed air energy storage appear capable of meeting anticipated technological and economic constraints. Neither has ever been constructed and tested; but even so it is predicted that underground pumped hydro ultimately will prove to be superior.

Parking the power: Strategies and physical limitations for bulk energy storage in supply–demand matching on a grid whose input power is provided by intermittent sources

The integration of wind turbines into modern power grids has significantly increased during the last decade. Wind turbines equipped with doubly fed induction generators (DFIGs) have been dominating wind power installation worldwide since 2002. In this paper, a superconducting magnetic energy storage (SMES) unit is proposed to improve the dynamic performance of a wind energy conversion system equipped with DFIG during voltage sag and voltage swell events. The converter and the chopper of the SMES unit are controlled using a hysteresis current controller and a fuzzy logic controller, respectively. Detailed simulation is carried out using MATLAB/SIMULINK software to highlight the impact of the SMES unit in improving the overall system performance under voltage sag and voltage swell conditions.

Application of SMES to Enhance the Dynamic Performance of DFIG During Voltage Sag and Swell

Aqueous intercalation-type electrode materials for grid-level energy storage: Beyond the limits of lithium and sodium

The 30 MJ superconducting magnetic energy storage (SMES) system was installed in the Bonneville Power Administration (BPA) Tacoma Substation in 1982-83. Operation of the unit since that time has been for over 1200 hours. Specific tests to explore the SMES system's thermal and electrical characteristics and the control functions were conducted. The coil heat load with current modulation was determined. A converter with two 6-pulse bridges interfaces the superconducting coil to the power bus. Equal bridge voltage amplitude and constant reactive power modes of operation of the system were run with computer control of the SCR bridge firing angles. Coil energy dump tests were performed. Electrical grid system response to SMES modulation was observed, and full power SMES modulation was undertaken.

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J. Rogers

Papers

Operation of the 30 MJ superconducting magnetic energy storage system in the Bonneville Power Administration electrical grid