The application of superconducting magnet energy storage (SMES) to the stabilization of a power system with long-distance bulk power transmission lines which has the problem of poorly damped power oscillations is presented. Control schemes for stabilization using SMES capable of controlling active and reactive power simultaneously in four quadrant ranges are proposed. The effective locations and the necessary capacities of SMES for power-system-stabilizing control are discussed in detail. Results of numerical analysis and experiments in an artificial power-transmission system demonstrate the significant effect of the control by SMES on the improvement of power-system oscillatory performance. >

Application of superconducting magnet energy storage to improve power system dynamic performance

A novel damping scheme using superconducting magnetic energy storage (SMES) unit is proposed in this paper to damp subsynchronous resonance (SSR) of the IEEE Second Benchmark Model, system-1 which is a widely employed standard model for computer simulation of power system SSR. The studied system contains a turbine-generator set connected to an infinite bus through two parallel transmission lines, one of which is series-capacitor compensated. In order to stabilize all SSR modes, simultaneous active and reactive power modulation and a proportional-integral-derivative (PID) damping controller designed by modal control theory are proposed for the SMES unit. A frequency domain approach based on eigenvalue analysis and time-domain approach based on nonlinear model simulations are performed to validate the effectiveness of the damping method. It can be concluded from the simulation results that the proposed damping scheme can effectively suppress SSR of the studied system. >

Damping subsynchronous resonance using superconducting magnetic energy storage unit

The authors demonstrate that a superconductive magnetic energy storage (SMES) system can enhance large-scale utilization of photovoltaic (PV) generation. Results show that power output from a SMES system can be used to smooth out PV power fluctuations so that the combined PV/SMES output is dispatchable and free from fluctuations. Power generated from PV arrays is shown to be fully utilized under different weather conditions, and PV penetration is increased to significant levels without adversely affecting the power system. Coupled with PV generation, a SMES system is even more effective in performing diurnal load leveling. A coordinated PV/SMES operation scheme is proposed, and its demonstration under different weather conditions is discussed. >

Enhancing the Utilization of Photovoltaic Power Generation by Superconductive Magnetic Energy Storage

The authors demonstrate that a superconductive magnetic energy storage (SMES) system can provide a significant positive impact on electric power transmission. By using SMES, transmission-line loadings during heavy load hours can be reduced if the SMES system is located near the major load. Transmission losses as well as the fuel cost for the losses over a 24 hr period can also be decreased. An SMES scheme, the SMES-DC link, is introduced for energy storage and control of power flow. The operation of this scheme and the benefits it provides are described. >

Impact of superconductive magnetic energy storage on electric power transmission

Application of a superconducting coil for transient stability enhancement

Superconductive Magnetic Energy Storage (SMES) is one of the effective measures to suppress system instabilities in electric power networks because of its fast response at exchanging electric power. Two types of experiments, dynamic and transient, have been performed to suppress instabilities by using an SMES unit on a model power system. The test system has a 60 kVA synchronous generator, a double-circuit transmission line connected to an infinite bus, and an SMES unit with an SCR converter. They simulate a salient pole synchronous generator of 600 MVA and a transmission line of 275 kV with 380 km in length. The SMES unit whose maximum stored energy is 100 kJ can exchange energy matched with the model system. The SMES unit could effectively suppress these instabilities by exchanging energy.

Experimental study of power system stabilization by superconducting magnetic energy storage

A small-scale Superconducting Magnetic Energy Storage(SMES) unit was constructed using small magnets and a high-voltage converter, and the characteristics of this unit were examined. The high output voltage of the converter makes it possible for even a small magnet to charge and discharge large power. Moreover, converter control provides adequate protection during quenching. AC and DC filters can be eliminated from the converter system, and ripple voltage does not harm the superconducting magnet. These features demonstrated the potential of an SMES unit as a power system stabilizer and a peak load power supply.

Characteristics of superconducting magnetic energy storage (SMES) energized by a high-voltage SCR converter

Superconducting energy-storage magnets must withstand high-frequency ripple voltage, because, in order to obtain high response of energy transfer, their DC power supplies do not have filters. Moreover, the magnets should transfer the heat generated by AC losses rapidly away from the conductor to achieve high-frequency operation. We made two superconducting magnets of 20KJ stored energy level. The magnets were charged up and discharged 46 times in 4.6-sec. periods. The maximum charge rate was 8.03T/sec. The AC losses were calculated and compared with the latent heat of the liquid helium evaporated during coil operation.

T. Ishikawa

Papers

Experimental study of power system stabilization by superconducting magnetic energy storage

Characteristics of superconducting magnetic energy storage (SMES) energized by a high-voltage SCR converter

High ramp rate characteristics of pulsed superconducting magnet