A contribution for modeling static VAr compensators in iterative harmonic analysis

Static VAr compensator (SVC) with thyristor-controlled reactors (TCR) are used to control the voltage at bus SVC, while the nonlinear harmonic source is connected to the TCR busbar. This specific situation requires special treatment of the voltage control characteristic in the iterative harmonic analysis (IHA). A voltage control characteristic reduced to the TCR busbar is proposed. Under this condition, the operating point of the TCR in the IHA is treated in a way so the firing angle is adjusted to satisfy the voltage regulation characteristic. In this paper, a frequency domain TCR model is presented by means of a set of analytical expressions for harmonic currents and their sensitivities with respect to the harmonic voltages. An additional nonlinear equation is also derived for obtaining the firing angle under distorted voltage. A scheme of checking coherent operating points of TCR is also included for IHA.