Reactive power compensation of coal mining excavators by using a new generation STATCOM

This paper deals with the development and implementation of a current-source converter based static synchronous compensator (CSC-STATCOM) applied to VAr compensation problem of coal mining excavators. It is composed of a ±750 kVAr full-bridge current source converter with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a δ/Y connected coupling transformer for connection to medium voltage load bus. Each power semiconductor switch is composed of an asymmetrical IGCT connected in series with a reverse blocking diode and switched at 500 Hz to eliminate 5^th, 7^th, 11^th, and 13^th current harmonics produced by CSC. Operating principles, power stage, and design of DC link, and input filter are also described in the paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAr consumption of electric excavators, resulting in nearly unity pf on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with IEEE Std. 519-1992.