Harmonic analysis study

In a harmonic analysis study, Eaton’s Power Systems Engineering (PSE) team models the power system and characteristic harmonics of the nonlinear load, for example a VFD. System impedances are calculated for the fundamental frequency as well as for each appropriate harmonic frequency.

For existing facilities, field measurements of the VFD current harmonic generation during the process operation are made quantifying daily and weekly load cycles. For new installations, the VFDs harmonic generation based upon the drive’s topology (6-pulse, 12-pulse, 18-pulse VFDs, etc.) is obtained from the manufacturer or our accurate library of models. 

Next, each harmonic current is then successively injected into the system impedance model, and the resulting harmonic currents and voltages are computed throughout the system. After establishing an accurate base case, various cases that consider system configurations and harmonic loadings are performed.

The following are calculated for each case study:

• Voltage and current distortion at key locations in the system
• IEEE Std 519 analysis at the point of common coupling between facility and utility
• IEEE Std 18 capacitor bank evaluations on the basis of voltage, current and kVA
• Frequency scans to determine parallel and series resonance frequencies
• The payback period of the cost for the recommended mitigation option

The following are calculated for each case study:

• Voltage and current distortion at key locations in the system
• IEEE Std 519 analysis at the point of common coupling between facility and utility
• IEEE Std 18 capacitor bank evaluations on the basis of voltage, current and kVA
• Frequency scans to determine parallel and series resonance frequencies
• The payback period of the cost for the recommended mitigation option