Gas turbine generator synchronous voltage extracting method

This invention relates to a method for withdrawing synchronous voltages from a gas-turbine generator and a network system, in which, in a high voltage system with a neutral point connected to the earth directly, the phase voltage of an assistant secondary winding of a bus voltage mutual inductor connected with the network system, namely the open-delta winding is 100V, which is same to the interphase voltage of type-Y winding of a voltage mutual inductor of the generator side, and the network system is used to test the phases of C-N phase voltage of the assistant secondary winding of the bus voltage mutual inductor namely the open-delta winding and c-b interphase voltage of the generator side the same and test the phase the same of A-N that of the mutual inductor and a-c interphase voltage of the generator side and the phase of B-N and b-a the same so as to withdraw synchronous voltages from the star winding combination of the open-delta winding of the voltage mutual inductor of the network side and that of th