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It has been suggested that the recommended flicker planning levels provided in IEC 61000 3-7 and IEEE 1453 are too restrictive for high-voltage and extra-high-voltage networks. The premise of this argument is based on a perceived increase in low-voltage (LV) flicker compatibility level. Some believe that flicker measurements made in Europe over a period of several years support the notion of an increased LV compatibility level; however, measurements performed by the authors in North America indicate otherwise. Analysis of authors' measurements suggests that the lack of customer complaints is due primarily to the effect of flicker transfer coefficients, rather than a presumed increase in LV compatibility level, and supports the continued use of Pst95\%=1.0 as the LV flicker compatibility level. [ABSTRACT FROM AUTHOR]

Large disturbing loads such as electric arc furnaces (EAF) create fluctuations in source voltage at the point of common coupling (PCC). These voltage fluctuations. then propagate throughout the power system with varying degrees of attenuation. The amount of attenuation is, in general, a function of system impedance and load composition, and can be characterized by what is known as a ificker transfer coefficient. The frequency response of synchronous generators near 60 Hz has a significant effect on flicker propagation, particularly in networked HV or EHV systems. To date, information available in the literature has not adequately described this phenomenon from a theoretical perspective or shown how to take this affect into consideration when computing flicker transfer coefficients. The following paper addresses these issues by: 1) providing a formal description of a synchronous generator model that can be used to determine flicker transfer coefficients when traditional modeling methods may not be appropriate and 2) providing a novel way of calculating flicker transfer coefficients using the described machine model. Synchronized flicker measurements, made at an EAF installation and nearby generating facility in the Southern Company service area, were used to validate the results of the proposed method. [ABSTRACT FROM AUTHOR]

A time-domain model of an AC electric arc furnace (EAF) was developed for power system (flicker) planning studies. The proposed model was implemented in the Electro Magnetic Transient Program (EMTP), and it focuses on the behavior of the EAF during the early stages of the melt cycle, thus providing an accurate prediction of the short term flicker created by the EAF, specifically Pst99%. The primary advantages of the proposed model over existing models are: 1) it uses system data that is readily available to the planning engineer; 2) it is a three phase model and can accurately model imbalance and predict flicker at the point of common coupling (PCC) as well as remote buses in the power system; and 3) its accuracy has been verified using synchronized flicker measurements of an actual EAF. Existing time-domain EAF models that are used in flicker planning studies require measurement or statistical data that is difficult to obtain during the planning stages of a project. Frequency domain methods are a popular means of estimating the flicker created by an EAF; however, when these methods are used in flicker planning studies, the operational uncertainty of the EAF introduces error into the calculations. Also, in many cases, frequency domain methods struggle to accurately predict the flicker level at buses remote from the PCC. Thus, a time-domain EAF model which can accurately predict Pst99% at points of interest and uses readily available system information is needed. The following paper describes such an EAF model. Validation of the proposed model is performed by comparing simulation results with flicker measurements of an actual EAF that were time synchronized using global positioning systems (GPS). [ABSTRACT FROM AUTHOR]