Self-shunt-excited excitation system based on modular multilevel converter

The utility model provides a self-shunt-excited excitation system based on a modular multilevel converter. The system comprises the modular multilevel converter, an isolation level and an excitation coil, an alternating-current port of the modular multilevel converter is directly connected with a generator terminal of a synchronous generator, a direct-current port of the modular multilevel converter is connected with a high-voltage side port of the isolation level, and a low-voltage side port of the isolation level is connected with a port of the excitation coil. The system has excellent expandability, can be conveniently expanded to high voltage class and power level, is suitable for high-voltage and high-power applications, and can provide positive damping for a power system by means of direct-current excitation and controlling alternating-current side reactive power, so that low-frequency/ultralow-frequency oscillation of the power system is suppressed effectively, and stability of the power system is improved.