Simulation of the conducted interference derived from SVC based on the switching characteristics of thyristors

Based on the dynamic switching characteristics of thyristors, a simulation methodology is established to investigate the high-frequency conducted interference derived from SVC (Static Var Compensator) devices. With a nonlinear time-varying resistance as the kernel of the high-frequency macro model for thyristors, a concrete simulation model of SVC including a TSC (Thyristor Switched Capacitor) element and a TCR (Thyristor Controlled Reactor) element is further proposed. In the simulation model, the variation of nonlinear time-varying resistance is used to represent the dynamic switching characteristics of the thyristors. In addition, a digital correction algorithm for frequency domain compensation of the measuring probes is also incorporated as to ameliorate the accuracy of EMI (Electromagnetic Interference) prediction. The digital correction algorithms is an improved vector fitting methodology which is realized by introduction of the first-order derivative information to the coefficient matrix based on the previously available vector fitting methodology. The conducted interference by simulations correlates well with that from on-site measurements, which indicates that the dynamic switching characteristic of the thyristors is the main cause of high-frequency conducted emissions.