Application of 120MVar high power RSVG in EAF - Overseas steel plant

In March 2019, the company signed a commercial contract with an overseas steel plant to provide a complete set of power quality solutions for 130T electric arc furnace and supporting refining furnace. The top feeding mode is adopted by the on-site electric arc furnace. The capacity of the furnace transformer is 105MVA, and the grid access point is 35kV. 35kV busbar is supplied by 220kV/35kV special transformer with 160MVA capacity through short distance transmission line.

With data analysis and technical specifications confirmation, our company adopts 35kV/120MVar delta-connection cascade SVG device combined with FC fixed compensation equipment to comprehensively control the reactive power, harmonic, voltage imbalance, grid voltage fluctuation and flicker and other power quality problems in the smelting process of on-site electric arc furnace.

35kV/ 120MVar delta-connection cascade SVG device of the project is an outdoor container structure, including six power unit containers and one control and water-cooling system container. The power valve bank uses water-water cooling system which can provide good heat dissipation conditions for the power valve banksand ensure the safe and stable operation of the equipment.

Application of RSVG in EAF -- CangzhouLingang MITSUBISHI

Electric arc furnace (EAF) is a kind of electric furnace which uses the heat generated by electric arc to smelt metal. With the comprehensive ban of intermediate frequency furnace by the state, more and more EAFs have been applied in recent years, and most of them are ultra-high power. The load characteristics of electric arc furnace are nonlinear and time-varying, and its power quality is very poor, which will cause many system power quality problems, such as voltage flicker and fluctuation, large negative sequence component, more harmonics, low power factor and so on. Among many power quality problems caused by electric arc furnace, voltage flicker is the most difficult to control. Because voltage flicker is caused by the irregular fluctuation of reactive power and voltage, requirement for response speed and compensation accuracy of the compensation device are very high. Because SVC is based on semi controlled thyristor, the response time of SVC is usually more than 10 ms, and the best flicker suppression ratio that it can achieve is 2:1. The SVG based on VSC scheme has the advantage of fast response, which can theoretically achieve a flicker suppression ratio of more than 5:1. Although H-bridge cascaded SVG has been widely used in 10kV and 35kV medium voltage power systems, few SVGs have been successfully used in EAF load compensation in China.

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