Measurement of voltage flicker magnitude and frequency using a Kalman filtering based approach

Voltage flicker is the fluctuation of the magnitude of the voltage at a load bus. This fluctuation includes deterministic and random variations. The characteristic of the instantaneous voltage flicker depends on the size and type of the load that is producing the voltage flicker. Arc furnace operation has generally been recognized as a major source of voltage flicker. Arc furnaces are used to melt and refine steel and other materials. This paper proposes a method to measure the low frequency modulation of the 60/50 Hz signal using a Kalman filtering approach. The method allows for random and deterministic variation of the modulation. The outputs of this method are the voltage flicker magnitude and frequency. These parameters become then the basis for controlling the voltage flicker to an acceptable limit. Details of the model and the results of the approach for typical cases are presented. The approach utilizes a combination of linear and extended Kalman filter models.