The method can be used for the regulation of power in an alternating current electrical network (ACNW; ACNW1, ACNW2), using a conversion system (PCS) having at least two terminals (1,2; 1,2,3; 1,2,3,N) for connection to the network, wherein each of said terminals has a corresponding electrical potential. Each of the potentials of these terminals has an upper and a lower envelope, the difference between which, or envelope voltage (VEP,EN), is a variable positive continuous quantity having a maximum value (VEA) called the envelope amplitude.The method comprises the operations of: defining at least an upper range (ER) of voltage values, comprising said maximum value or envelope amplitude (VEA) and having a width (VE; VEE) which is substantially smaller than the envelope amplitude (VEA); using a structure (PCS) including at least a first static converter (ES) capable of regulating the electrical power by the regulation of the envelope voltage (VE; VEE) in the aforesaid upper range (ER); this upper range (ER) having a width determined in such a way that the at least one static converter (ES) regulates more than one half of the mean active electrical power exchanged with the network (ACNW; ACNW1, ACNW2).