A Harmonic Suppression Device For Mid-frequency Induction Furnaces

With the development of the economy in china, the steel industry is growing rapidly. More and more furnaces for steel-making are invested to the industry, and the capacities also become larger. The furnaces will produce more harmonic waves, voltage flashing changes, unbalance of three phases, low power factor etc unfavorable impacts which can influence the quality of electric energy in power system. The suppression of harmonic becomes more and more important.The paper is based on the real background of a steel factory in zhejiang province. The electrical system of furnaces for steel-making (Arc Furnace& Mid-frequency induction heater) is introduced in this passage. The harmonic analysis is researched and some measures about harmonic suppression are put forward.The generation of the furnace harmonic and its harmful influence are discussed in this paper. The national standard of the quality of electric energy and harmonic waves is also involved in the paper .The ways of harmonic suppression are involved.The electrical system of furnaces for steel-making (Arc Furnace& Mid-frequency induction heater) is introduced in this passage, including working characteristic, the structure of circuit and harmonic analysis.A method for harmonic suppression which keeps with the system of the steel factory is put forward in this paper. An improved passive filter with filter resistance, capacitor and hollow inductor is applied in this method. The passive filter with Thyristor Controlled Capacitor (TSC) is installed on the side of the low-voltage system .In order to get better effect of harmonic suppression, hollow inductors of series connection are installed on the side of the high-voltage systemThe software of MATLAB is employed to make the simulation for the scheme of harmonic suppression. We go on experiment of various work conditions with the improved passive filter. The simulation and experimental result have proved that this scheme is correct and feasible.