Dynamic var compensation of mine hoists for improvement of power quality and increase of productivity at LKAB Sweden

The hoisting system in the iron ore mine at LKAB in Kiruna is a fast changing load that affects power quality of the electrical system. In order to reduce the voltage variations and harmonic distortion to acceptable levels and at the same time increase production capacity it has been decided to install a static var compensator (SVC). The selection of ratings and configuration of the SVC has been based on a system study consisting of load- and power quality measurements as well as harmonic- and load-flow simulations. As a result of the study a SVC consisting of fixed harmonic filters and tyristor controlled reactor (TCR) has been selected. The results of simulations demonstrate that the selected SVC will reduce the voltage variations on the feeding 6 kV bus bar from 20% to less than 3% and at the 145 kV PCC from 6% to less than 2%. The total harmonic distortion will be reduced to less than 4,8% at the 6 kV bus bar and less than 1,5% at the 145 kV PCC. Thanks to the SVC, the production capacity of the hoisting system will increase by approx. 30%.