Proposal of a Current Harmonics Canceler for Thyristor Converter/Inverter

Abstract

There are some problems in many separately controlled, large scale thyristor converters/inverters on the same electric power system. This paper proposes a new method for canceling the existing electric current harmonics by installing a “current harmonics canceler” on the thyristor converter/inverter. The current harmonics canceler cancels the two current harmonics through phase angle control between the power source angle and the converter/inverter angle, and through control of the voltage level of the converter/inverter. The characteristics of harmonics at the initial phase angle were analyzed in the cases of 6 pulse and 12 pulse converter models by digital computer simulation. As the result of the simulation, we found the existing current harmonics were canceled by installing the “current harmonics canceler” on the thyristor converter/inverter. Further more, we found that the application of it is limited due to the phase angle difference between two current harmonics.