抄録
Recently, electric power demand is rapidly increasing and will be in the future. In the large power systems with complex configuration, undamped power swing with low frequency tends to occur. Therefore several stabilizing control schemes, e. g. a power system stabilizer (PSS), have been investigated so far.
On the other hand, superconducting magnetic energy storage (SMES) has been expected as an effective apparatus in power systems since a SMES located in power systems is capable of leveling load demand, compensating for load changes, maintaining bus voltages and stablilizing power swings. The effectiveness of each function, however, depends upon the location of the SMES in the power system because the output power from the SMES is distributed according to the impedance ratio of the transmission line at the SMES location. Therefore, it is rather difficult for realize a SMES to server for two different purpose at the same time.
This paper proposes a combination of SMES with a high speed phase shifter (HSPS). The HSPS, which consists of a phase shift transformer and a set of power converters, is capable of controlling the power flow of the transmission line by adjusting the phase angle of phase shift transformer. Therefore, it is expected that the combination of SMES and HSPS can realize a highly effective controller independent of its location. Numerical examples demonstrate that the proposed apparatus located far from a generator in a long distance bulk power transmission system is capable of stabilizing the power swing as effectively as the SMES located at the generator terminal. In addition, the effectiveness on the load change compensation as well as on the power system stabilization is confirmed numerically.
