Locating the origin of feeder level harmonics utilizing remote THD measurements

The drive for power delivery efficiency has led to many utility companies installing Voltage and VAr Optimization applications, which rely upon capacitor banks installed throughout a feeder to regulate voltage and substation VArs. Due to heating effects, harmonic currents that are injected by customers can inhibit the operational effectiveness of such applications. This paper describes a method for indentifying the originating locations of feeder level harmonics with the use of THD measurements retrieved remotely from capacitor banks and a single harmonic spectrum analysis. The authors utilize a simplified distribution system model to perform current injection calculations to match the measured feeder level distortion that is identified from remote monitoring. The spectrum analysis measurement is utilized to determine the individual harmonics of the THD measurements and to develop harmonic source parallel impedances. The process was applied to an existing Volt/VAr application that was frequently experiencing 9% voltage THD.