The utility model provides a self-parallel excitation system based on three single-phase H-bridge converters. The system comprises three single-phase H-bridge converters, an isolation level, and an excitation coil. The three single-phase H-bridge converters comprise three single-phase converters. Input ends ABC of the three single-phase H-bridge converters are directly connected with an end of a synchronous generator. Output ends of the three single-phase H-bridge converters are connected with input ends of the isolation level, and the other port of the isolation level is connected with the excitation coil. The three single-phase H-bridge converters whose structure and control strategy are simple are used, and the three single-phase H-bridge converters are suitable for high-voltage and high-power places, so an exciting transformer on a high-voltage AC side can be removed, and positive damping can be provided for an electric power system through DC excitation and control of reactive power on an AC side, thereby effectively restraining low frequency/ultralow frequency oscillation of the electric power system and improving stability of the electric power system.