Research On Distinguish And Measure Of Dynamic Voltage Quality Based On The Improved D-q Transform Without Delay

This paper firstly introduces the definition and classify of modern power quality and the phenomena of dynamic voltage quality. And then an improved d-q transform without delay is put forward based on other's research accomplishments. Dummy three-phase voltages are gained by the derivative of any phase voltage, which is the improved d-q transform without delay. For one thing, for the data that is adopted by the improved d-q transform without delay is same time, the errors are greatly decreased. For another thing, the characteristic that is acquired by the improved d-q transform without delay has explicit physical meaning. And this method is sensitive to mutation of signal and can magnify certain signals. Above all, it has good real time. In this paper, the improved d-q transform without delay combined with the wavelet, Db9 that has good band-pass is used to distinguish from the dynamic voltage quality including sag, swell, interruption, pulse, high-frequency oscillation and low-frequency oscillation. Then satisfying results are got from the simulations of software and hardware. Based on above researches, the theory is applied to the measure of voltage sags and a primary design of the measure device about voltage sags is made.