Abstract: The paper, taking 330 kV power supply division of Yulin power grid as the research object, investigates the influence of conventional fossil-fuel steam power units and doubly-fed wind turbines on system short-circuit current and contribution amplitude of various wind farm installed capacity to system bus short-circuit current, and also analyzes the contribution amplitudes of system station, collection station,series system, T-connection mode to system bus three-phase short-circuit current. According to the research, compared with the conventional fossil-fuel steam power unit, the doubly-fed wind turbine provides lower short-circuit current for the system. However, as the wind farm installed capacity increases by 50 MW, the three-phase short-circuit current of grid-connected bus increases by about 0.34 kA. Moreover,although the system bus short-circuit current increases with the rise of the wind farm installed capacity, the amplification decreases. Among four wind farm grid-connection modes, the collection station contributes to the lowest amplification for system short-circuit current, while the system station does the highest.

    Key words: large-scale wind power; doubly-fed wind turbine; short-circuit current; grid-connection mode; restrictions