EFFECTS OF STEEL PLANTS WITH THREE-PHASE INDUCTION FURNACES ON POWER DISTRIBUTION QUALITY OF THE EXISTING 33 kV NETWORK IN NIGERIA

This study aimed at evaluating and analyzing the voltage and current distortions on the introduction of a steel production plant in a typical 33 kV distribution system in Nigeria, with a view to assisting decisions made in the present system operation and planning effective service delivery in terms of quality. A three phase induction furnace was developed using MatLab Simulink software and the effects of steel plant loads on the quality of electric power system supply to electricity users on the same distribution network was analyzed in terms of total harmonic distortions of voltage and current. In order to evaluate voltage magnitude profile on the network, load flow computation and analyses were carried out on the 33 kV distribution network before and after the introduction of steel plant loads, using Successive Approximation Method. The results showed critical voltage magnitude profile below -5% of nominal voltage at the receiving end nodes. With the aid of the Matlab Simulink model, inadmissible voltage and current distortions of 15.47% and 10.35% were measured. Passive filter was proposed, designed and simulated, in order to mitigate these distortions caused by the steel production plant loads. By simulation, the installation of the designed passive filter gave a reduction of the distortions to permissible values. Further, for every 1 MW load increment when the steel plant is connected, network losses increased by 94%; however, for every of Mvar of filter capacity, loss reduction in the network is 5.1 MW.