Passive Filter Design for Harmonics Produced by Thyristor Controlled Reactor (TCR)

Abstract

One of the conventional Static Var Compensators used for the power quality improvement is Fixed Capacitor-Thyristor Controlled Reactor (TCR). The variation of current obtained by the controlling of the gate firing instant of the thyristor. A TCR operating with α > 90 degree the current becomes non-sinusoidal and considerable amount of harmonics are generated, specifically 3rd , 5th and 7th harmonics. The delta connection of TCR, prevents the triplen (i.e. multiples of third) harmonics from percolating into the transmission lines. However, 5th and 7th order harmonics (and less dominating 11th , 13th , 17th etc.) filtered in order to prevent extravagant voltage change in the AC network. In mentioned project, switching model of 1-phase FC-TCR is prepared and simulated along with the different firing angle (α). To filter out generated harmonics in FC- TCR, passive filters are used, which provide low impedance path to harmonic current at particular frequency. The design procedure for this approach is based on stamping down the individual components of harmonic current by infixing a LC circuit (series) tuned at various harmonic orders between the source (ac) and the TCR (connected parallely) and filtering model. Further, 3-phase FC-TCR system is prepared and analyzed. Lastly, 3-phase FC-TCR is simulated in WSCC 9 bus system. The detailed analysis is also carried out for the filter design at different firing angle.