Plant for melting and/or heating metal material, and method to supply electrical energy to said plant

A method to supply electrical energy in a plant for melting and/or heating metal materials, comprising an induction furnace and electric power supply means for supplying electrical energy to said induction furnace, wherein said electric power supply means comprise a transformer connected to an alternating current mains power network, a rectifier located downstream of said transformer to transform the alternating current at exit from the transformer into direct current, a converter located downstream of said rectifier to transform the direct current at exit from said rectifier into alternating current, and a coil for melting and/or heating metal material, and wherein said induction furnace comprises a regulation circuit, located downstream of said converter and upstream of said coil and configured to reduce reactive power and transfer maximum active power to said coil, said at least one regulation circuit comprising at least one inductor and at least one capacitor, or a bank of capacitors, said method comprising:

• providing electrical energy to the induction furnace in addition, or as an alternative, to electrical energy supplied by the mains power network, by means of an alternative energy source, different and independent from the mains power network and associated with said induction furnace;
• and
• selecting one, the other, or both between said mains power network and said alternative energy source as a function of one or more parameters,
• wherein said alternative energy source is connected to said induction furnace by means of at least one direct current connection system located upstream of said converter, and
• wherein said at least one direct current connection system comprises a DC-link circuit configured to accumulate and filter electrical energy to provide a stable and clean direct voltage to an input of the converter.