SYSTEM FOR DETECTING INTERNAL WINDING FAULTS OF A SYNCHRONOUS GENERATOR, COMPUTER PROGRAM PRODUCT AND METHOD

摘要

A system, method and computer program product for monitoring including detecting internal faults especially inter-turn faults of a synchronous generator (1) and thus protecting the synchronous generator (1). The synchronous generator (1) comprises a winding (20, 23, 26) for each phase (a-c) of a power network (3), a terminal (5a-c) for each phase (a-c) arranged on a terminal side (4) of the synchronous generator (1), and connected to the respective winding, the terminals (5a-c) on the terminal side (4) is connected to an electrical power network (3), and the synchronous generator (1) is arranged to input power to the electrical power network (3) by means of the terminals (5). The method comprises measuring (301, 501) the voltage (Va, Vb, Vc) of each phase at the at least one each terminal and the current (Ia, Ib, Ic) of each phase at the terminal, determining (302, 305, 306, 502-506) whether the synchronous generator suffers from an internal fault in any of its phases. The determining includes transforming (302, 502) the measured phase currents (Ia, Ib, Ic) and the measured phase voltages (Va, Vb, Vc) into symmetric sequence currents (I1, I2, I0) and symmetric sequence voltages (V1, V2, V0), respectively. The method further includes monitoring (305, 505) at least one of the following variables: a negative sequence residual voltage (?V2); a zero sequence residual voltage (?V0); a negative sequence coupling impedance (Z2C); a zero sequence coupling impedance (Z0C); wherein each of the variables is calculated from symmetric sequence components (I1, I2, I0, V2, V0) and at least one generator specific impedance (Z00, Z22), and determining (306, 504, 506) whether the synchronous generator suffers from a winding fault, or not, from the calculated at least one residual voltage (?V0, ?V2) or coupling impedance (Z0C, Z2C). The detecting system comprises a measurement circuit (40) arranged for measuring terminal phase voltages (Va, Vb, Vc) and terminal phase currents (Ia, Ib, Ic) measurements; a mathematical transformation provider (42) for transforming each phase voltages (Va, Vb, Vc) into symmetrical sequence voltage components (U1, U2, U0) and each phase currents (Ia, Ib, Ic) into symmetrical sequence current components (I1, I2, I0), and a winding fault determiner (44) adapted to detect internal winding faults in the synchronous generator from the negative sequence components (U2, I2), or the zero sequence components (U0, I0), of the voltages and currents.