Modular active power-line conditioner

Active power-line filtering is conventionally performed by injecting equal- but-opposite of the distortion into the line. The power converter used for this purpose is rated based on the magnitude of the distortion current and operated at the switching frequency dictated by the desired filter bandwidt h. Fast switching at high power, even if technically possible, causes high switching losses. In this paper, a new modular approach to active harmonic filtering is proposed. The method utilizes two linear adaptive neurons (ADA LINEs) to process the signals obtained from the line. The first ADALINE (th e Current ADALINIE) extracts the harmonic components of the distorted line current signal and the second ADALINE (the Voltage ADALINE) estimates the f undamental component of the line voltage signal. The outputs of both ADALIN Es are used to construct the modulating signals of a number of current-sour ce inverter (CSI) modules, each dedicated to eliminate a specific harmonic. The power rating of the modules will decrease and their switching frequenc y will increase as the order of the harmonic to be filtered is increased. T he overall switching losses are minimized due to the selected harmonic elim ination and balanced "power rating"-"switching frequency" product. Power lo sses are also reduced by adjusting the I-dc in each CSI module according to the present magnitudes of the individual harmonics to be filtered. Speed a nd accuracy of ADALINE, self-synchronizing harmonic tracking, optimum I-dc value and minimal converter losses, high reliability and flexibility and sp eed and low dc energy requirement of the CSI, result in superb performance of the proposed active conditioner. The theoretical expectations are verifi ed by digital simulation using EMTDC simulation package.