Steady-state assessment

An important part of power quality is steady-state (and quasi-steady-state) waveform distortion. The resulting information is sometimes presented in the time-domain (e.g. notching) and more often in the frequency-domain (e.g. harmonics and interharmonics). Randomly varying non-linear loads, such as arc furnaces, as well as substantial and varying harmonic (and interharmonic) content, cause voltage fluctuations that often produce flicker. The random nature of the load impedance variation with time prevents an accurate prediction of the phenomena. However, the EMTP method can still help in the selection of compensating techniques, with arc models based on the experience of existing installations. Another application of the EMTP method for steady-state assessment is its use in developing accurate harmonically coupled models for other modelling frame-works, such as the harmonic domain. This is desirable as frequency-domain techniques are more amendable for simulating very large power systems.