Case Study on Harmonics Generated by Personal Computers: Analysis and Mitigation

Nonlinear loads connected to a sinusoidal source inject harmonic currents into the source. Harmonics are periodic waves having frequencies that are integer multiples of fundamental frequency. Personal Computers (PCs) being electronic nonlinear load draw nonsinusoidal currents. During the operation of PCs, a large amount of harmonics are generated which severely affect the power quality. For the evaluation of those generated harmonics, an experiment has been performed in the computer lab. Initially, a Power Quality Analyzer is connected to the output side of Uninterrupted Power Supply (UPS) to capture the live signals. Various events are generated and their corresponding responses are recorded. One single event is modelled in ETAP using the actual experimental data to develop benchmark model. This model is validated by generating another event and comparing results with the experimental setup. Then, a number of events are generated and analysed. A filter design is then suggested to reduce the harmonic content. Simulation results with filter and without filter are discussed.