Extension on IEC 61000-3-6’s General Summation Law to Estimate Harmonic Current at PCC Based on Probability Distribution

Measurements of current harmonics at the point of common coupling (PCC) of individual customer facilities are necessary to assess limit compliance. However, customers do not always have access to their PCC, forcing them to take measurements downstream and make estimations. This letter expands the capabilities of the general summation law introduced in IEC/TR 63000-3-6 from transmission systems to individual customer facilities, allowing them to accurately perform such estimations. The main difference with these facilities and whole transmission systems is a smaller number of harmonic sources. Guidelines to perform the proposed estimations are given. Typical cases are simulated and the probabilities which support the proposed summation exponents are analyzed.