A system comprising a wind power generator, an isolating transformer and a wind power conversion system electrically connected between- the wind power generator and the isolating transformer, the wind power conversion system comprising: plural first converting circuits (10, 20, 50)-adapted to perform a power converting task to convert and transmit the electric energy in bilateral directions, and comprising respective first generator-side terminals and respective first network-side terminals, wherein the first generator-side terminals are electrically connected with the wind power generator, and the first network-side terminals are electrically connected with corresponding secondary windings (Np) of plural secondary windings (Np) of the isolating transformer; and a second converting circuit (11, 21, 31, 41) comprising plural second generator-side terminals and a second network-side terminal, wherein the second network-side terminal is electrically connected with a corresponding secondary winding (Np) of the plural secondary windings (Np) of the isolating transformer, and the second generator-side terminals are serially connected with the corresponding first generator-side terminals of the first converting circuits (10, 20, 50) and electrically connected with the wind power generator through the first converting circuits (10, 20, 50), wherein the second converting circuit (11, 21, 31, 41) is selectively operated in a non-crowbar mode or in a crowbar mode, wherein when the second converting circuit (11, 21, 31, 41) is operated in a non-crowbar mode, the second converting circuit (11, 21, 31, 41) performs the power converting task to convert and transmit the electric energy in bilateral directions so that the power converting task of the plural first converting circuits (10, 20, 50) is shared by the second converting circuit (11, 21, 31, 41). plural first converting circuits (10, 20, 50)-adapted to perform a power converting task to convert and transmit the electric energy in bilateral directions, and comprising respective first generator-side terminals and respective first network-side terminals, wherein the first generator-side terminals are electrically connected with the wind power generator, and the first network-side terminals are electrically connected with corresponding secondary windings (Np) of plural secondary windings (Np) of the isolating transformer; and a second converting circuit (11, 21, 31, 41) comprising plural second generator-side terminals and a second network-side terminal, wherein the second network-side terminal is electrically connected with a corresponding secondary winding (Np) of the plural secondary windings (Np) of the isolating transformer, and the second generator-side terminals are serially connected with the corresponding first generator-side terminals of the first converting circuits (10, 20, 50) and electrically connected with the wind power generator through the first converting circuits (10, 20, 50), wherein the second converting circuit (11, 21, 31, 41) is selectively operated in a non-crowbar mode or in a crowbar mode, wherein when the second converting circuit (11, 21, 31, 41) is operated in a non-crowbar mode, the second converting circuit (11, 21, 31, 41) performs the power converting task to convert and transmit the electric energy in bilateral directions so that the power converting task of the plural first converting circuits (10, 20, 50) is shared by the second converting circuit (11, 21, 31, 41).