Voltage-Current Ratio Difference Method: Recommended for IEEE Standard 1547 to Determine the Customer Harmonic Contribution

The harmonic current at the point of common coupling (PCC) related to distributed energy resources (DERs) results from their interaction with the utility. The IEEE Standard 1547 sets limits for the harmonic current caused by a converter-interfaced DERs. This harmonic current can be affected by harmonic voltage background as well as by utility harmonic impedance. This paper develops the "voltage-current ratio difference" method for determining the harmonic current caused by DERs directly based on the filed measurement data. This method has been explicitly presented in the original work for identifying the dominant equivalent harmonic source. The variation of the "voltage-current ratios" due to the connection of a known serial impedance between the utility and customer is the main basis of this method. Based on "voltage-current ratio difference" method, the value of harmonic current caused by DERs can be determined independent of utility and customer equivalent impedances.