Flicker Source Detection using Correlation Coefficients

Flicker is a common problem associated with loads that draw a high amount of fluctuating current, such as arc furnaces. Because such loads are typically fed from high and medium-voltage levels, the flicker they produce affects a large number of customers. Normative documents have been developed to guide utility engineers on the limits of flicker at any point on the system. However, due to the cause-and-effect nature of loads that impact the power system, it is often difficult to determine whether a load is the cause of an aberrant condition or responding to it. There is a lack of clear understanding about the various techniques available to identify the source of flicker, and, more importantly, there is no easy method or algorithm that utilities can follow using commercially available equipment. This paper proposes to bridge this gap in knowledge. It presents a new method in which voltage and current measurements from the point of common coupling are filtered to isolate the flicker frequencies and then correlation coefficients are used to pinpoint the source of flicker. The method has the advantage of fast calculation speeds and easy implementation. This paper presents the details of implementation of this approach, along with laboratory data that validates this method. Finally the paper closes with a discussion of the conclusions and the avenues for future research in this field.