Simultaneous compensation of reactive and harmonic components of line current using superconducting magnet energy storage

Abstract

A simple on-line compensation scheme to compensate the reactive, hannonic and sub-hannonic components of line current is proposed in this thesis. The on-line compensation scheme is based on the fact that if a current of equal amplitude but 180 degrees out of phase with respect to the reactive, hannonic and sub-hannonic components is injected in the line then these components will be eliminated. Aimed toward this scheme a closed loop feedback control circuit has been proposed. to estimate the combined waveshape of the reactive, hannonic and sub-hannonic components of line current. The approxjmation of this estimated wave .by some available functions such as pulse width modulated wave and the stepwise function using power electronic switching circuit is also studied in this work. The study reveals that the compensation using step-wise approximation provides better. performance than the approximation using pulse width modulated. wave. This work proposes a power electronic switching scheme using superconducting magnet energy storage (SMES) to inject current in the line based on the estimated wave and step-wise approximation. to compensate the reactive, hannonic and subhannonic components of line current. This thesis also includes the performance study of the proposed switching scheme using computer simulation program.