Dynamics of multilevel inverter based series compensator for transmission lines

Series VAr compensators are proving to be a viable alternative to shunt compensators for enhancing power transmission and distribution capability. This paper proposes a compensator structure based on a multilevel cascade of single-phase inverter bridges that can be coupled to the transmission system without transformers. The individual bridges are switched at very low frequencies resulting in high efficiency and are fed from independent self-controlled DC buses. Advantages of the chosen series compensator include low injected voltage harmonic distortion and fast response to changes in the compensation level. Gating and control schemes are discussed. Results are obtained by simulation using MATLAB power system block set. The results are satisfactory