Characteristics of the Static Zigzag-Triangle Frequency Converter

Abstract

The object of research is a static transformer frequency converter, which can be used to combine parallel-operating power systems having different operating frequencies. The aim of the work is to study operational characteristics and evaluate strategies and laws of the proposed device from the point of view of developing methods and means of power transmission improving quality via electrical communication, containing a frequency converter based on phase-shifting transformer made according to zigzag-triangle scheme and controlled by power keys. In order to achieve the above object, it is proposed to sectionalize control windings providing a 48-position with a discreteness of 2.5 °, and a 24-position with a discreteness of 5 ° switching in each 120 ° sector of "coarse" regulation. Structural simulation models were built and computational experiments were carried out for electrical communication combining two power systems with frequencies of 60 and 50 Hz and 50 and 49.6 Hz, respectively. The most significant results are: a new circuit version of the frequency converter, various strategies for controlling the conversion process. The two-channel frequency converter allows to reduce by 2 times the number of "coarse" control keys, which switch not after 60°, but after 120°. Also succeeded to reduce the switching step from 5 degrees to 2.5 degrees, which made it possible to improve the conversion quality. The significance of the obtained results is that during regulation the number of keys connected in series in operation remains equal to 4, which can significantly improve the reliability indicators of the control system.