The impact of Sawmill operations on power quality: Case study of Merensky Northern Timbers Sawmill Ltd

Sawmill loads are disturbing loads. When connected to a power system, they constitute sources of harmonics, voltage fluctuations and flicker. In this paper, measurements of power quality parameters carried out in a case study of MERENSKY Northern Timbers Sawmill Ltd at Tzaneen, Limpopo Province of South Africa are reported. The report indicates that, due to some mitigation measures implemented by the plant operator, Pst flicker levels were substantially in compliance with NRS 048-2 requirements. On the other hand, Plt values were found to be high. Two mathematical models were developed for the large multi-rip sawmill plant. First, a constant impedance model was developed from the measurements. Then, a third-order induction motor model was formulated. The models are suitable for use independently in simulation studies to determine rough equipment immunity and other specifications during the planning stages of supply networks to sawmills.