Measurement and characterization of the radiated interference produced by a static var compensator

Due to frequent switching of the thyristors in a static Var compensator installed within a power substation, large amount of broadband electromagnetic emissions are being generated, which results in electromagnetic contamination to both the power grids and the victim electronic devices positioned nearby. Based on optical fiber, circuit and field transducers, an advanced acquisition system is established to implement on-site measurements so as to characterize the electromagnetic interference (EMI). An improved vector fitting method is utilized to obtain equivalent transfer functions of the antennas so that digital correction can be made to trace back the actual electromagnetic emissions. The switching bursts of the EMI data within a power cycle are analyzed to give the frequency and amplitude range of the radiated interferences. Further, time-frequency analysis methodologies, such as instantaneous frequency analysis, short-time Fourier transform and Wigner-Ville distribution, are used to present even more and useful information to characterize the electromagnetic environment within the SVC-based substations.