Determining the load composition in commercial buildings based upon harmonic current characteristics

Problems related to power system harmonics are a concern in commercial buildings where there is a proliferation of nonlinear loads such as fluorescent lamps, personal computers, and adjustable speed motor drives. In most cases, one piece of office equipment will not cause any harmonics problems. However, a large concentration of single phase loads can be the source of harmonic related problems such as voltage distortion, increased neutral current in four wire systems, and overheating of transformers.;This research develops and presents procedures for estimating the load composition in commercial buildings that contains both linear and nonlinear loads using field measurements of current waveforms and their harmonic spectra. A nonlinear solution technique is used to determine the set of weighting coefficients for the load candidates that minimizes the mean squared error between measured and estimated currents. The weighting coefficients represent the fraction of load of the candidate load types. Both single phase and three phase measurements may be used in the analysis. The procedure is coded into programs LDCOMP1 and LDCOMP3.;Load composition information can give valuable insight to how each individual load contributes to the total load. The energy consumption levels of each load type can be checked for energy auditing purposes. Power system engineers can plan for future power quality requirements by predicting the impact that the expansion of certain load types may have on the system.;To determine the impact that these loads have on the electric supply, program HAICC, Harmonics Analysis for Industrial and Commercial Customers, is developed to analyze harmonic voltage distortion generated at the utility-customer interface. HAICC is a useful tool that may be used by field engineers to determine whether harmonic voltage and current limits at a facility service entrance comply with recommended harmonics limits. If compliance is not achieved, HAICC can be used to study harmonic filtering options that can achieve compliance.