Design of Robust Frequency Stabilizers of Superconducting Magnetic Energy Storages

When large load disturbances occur in a power system, a system frequency may be heavily perturbed and oscillatory. To stabilize frequency oscillations, the active power controlled by superconducting magnetic energy storage (SMES) can be applied. In this paper, a new robust design of a frequency stabilizer equipped with SMES is presented. The frequency stabilizer is based on a second-order lead/lag compensator. To enhance the robust stability of the controlled system against uncertainties such as system parameters variations, various load changes etc., the multiplicative uncertainty is included in system modeling. As a result, the robust stability can be easily guaranteed in terms of the multiplicative stability margin (MSM). Control parameters of the frequency stabilizer are tuned by a tabu search, so that the desired damping ratio of the target inter-area mode and the best MSM are obtained. Simulation studies confirm the high robustness of the frequency stabilizer against system uncertainties