Development of a model for predicting flicker from electric arc furnaces

Owing to the characteristics of electric-arc phenomena electric arc furnace loads can result in serious electrical disturbances on a power system. Low level frequency modulation of the supply voltage of less than 0.5% can cause annoying flicker in lamps and invoke public complaints when the frequency lies in the range of 6-10 Hz. There is a need therefore to develop better techniques to predict flicker effects from single and multiple arc furnace loads and the effects of compensation schemes. The authors discuss the nature of arc furnace loads, and describe the instrumentation, field measurements, and signal analysis techniques which were undertaken to develop an arc furnace model. A single-phase furnace model is proposed suitable for use on digital simulation programs such as the EMTP or other appropriate commercial software simulation programs. Representative results based on actual furnace input data are included to show the validity of the model