Research and application of cascade D-STATCOM for impact load compensation

The electric arc furnace and other impact loads not only bring about serious impact of reactive power but also inject numerous harmonic to power grid. Distribution static synchronous compensator (D-STATCOM) has gradually earned respect and application in reactive power and harmonic compensation of impact load owing to its rapid response speed. This paper analyzes the problem of power quality brought by electric arc furnace load according to measured data and designs cascade D-STATCOM compensation scheme, which can compensate reactive current and simultaneously suppress low-frequency harmonic current. And then, frequency dividing detection method and current tracking control method based on phase instantaneous value are proposed against the characteristic of high capacity and low switching frequency of D-STATCOM. Besides, electric arc furnace load model is established based on the manner of scene recorded data playback and simulation of D-STATCOM compensation effect is carried out. The proposed scheme has successfully applied in the distribution network of Jiangxi province and achieved good results.