Robust Decentralized Design of H?-based Frequency Stabilizer of SMES

C. Vorakulpipat, M. Leelajindakrirerk


This paper presents a new robust decentralized design of frequency stabilizer forsuperconducting magnetic energy storage (SMES) based on an H? control. As an interconnectedpower system is subjected to load disturbances, system frequency may be severely disturbed andoscillate. To stabilize frequency oscillations, the active power control by SMES installed in a powersystem can be applied. The proposed decentralized control design translates interconnected powersystems installed with SMESs into a Multi-Input Multi-Output (MIMO) control system. The techniqueof overlapping decompositions is applied to extract the decoupled subsystem with Single-InputSingle-Output (SISO) from an MIMO system. As a result, a frequency stabilizer of SMES can beindependently designed to enhance the damping of the inter-area mode embedded in the decoupledsubsystem. In addition, to guarantee the robust stability of system against uncertainties such assystem parameters variations etc., the multiplicative uncertainty model is also incorporated.Consequently, H? control via a mixed sensitivity approach is applied to design the robust frequencystabilizer of SMES. Study results explicitly show that the robustness of the H?-based frequencystabilizer of SMES is superior to that of the PID based stabilizer under various load disturbancesand negative damping.

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