Energy Quality and Efficiency of an Open Pit Mine Distribution System: Evaluation and Solution

Abstract

The operational availability of mining shovels is the focus of this work. The hypothesis is that energy quality is responsible for the frequent shut downs of the shovels. Previous engineering studies have highlighted a large presence of harmonics and reactive power in the mine loop electric system. A common solution proposed was to use a combination of active filters, larger mobile substations, shorter mining cables and equipment location constraints. The aim of this paper is to produce a precise diagnosis of the source and nature of the energy quality issues. Mine loop electric quality monitoring, system modeling, equipment technologies and shovel´s histograms are considered. Results are measured against IEEE standards and shovel´s voltage regulation susceptibility. With the diagnosis the goal was to produce a reliable cost effective solution. Different alternatives are crosschecked with this paper proposal. The solution presented provides energy quality well within shovel´s susceptibility and improves energy efficiency. The lower energy consumption pays the investment required and is currently under construction. I. Mining Cable (7.2[kV]) Power Line (13.8[kV])0093-9994 (c)

An Overview of Microgrids Challenges in the Mining Industry

“…Machinery used in this process, such as drills, shovels, draglines, and longwall mining machines are usually powered by a set of ac or dc machines supplied by a diesel or electrical generator. In the latter case, mobile sub-stations are used to plug the machinery into the distribution system, implying that the electrical network changes its topology according to the mine development [37], [38].…”

“…It is a well known fact that the use of power electronics converters, inside or outside of mining machinery, e.g. as active front end (AFE) or speed drives, helps to mitigate these power quality issues [37], [38], [41]. however, this technology also poses new problems from the microgrid point of view, as shown in Fig.…”

“…However, harmonic pollution in the distribution network can excite the system resonance frequencies, producing overvoltages. Therefore, active or passive filters should be included [38].…”

Power Quality Issues of Distorted and Weak Distribution Networks in Mining Industry: A Review

“…Radial distribution systems are most popular and a section of the primary distribution is established as a baseline consisting of overhead pole lines allowing mobility of the mining equipment [8]. An example of a radial power distribution system of an open pit surface mining industry is given in [20]. This type of system has the advantage of being inexpensive and flexible.…”

“…This type of system has the advantage of being inexpensive and flexible. Power is transformed in utility substation from transmission voltage of 220 kV to distribution voltage level of 13.8 kV [20].…”