The impact of load characteristics and the low-voltage load shedding schedule on dynamic voltage stability is studied for part of the power grid in Beijing. The research is conducted on a real-time digital simulation (RTDS) system and based on the projected data for the power grid in the Northern China region. We show that under severe shortage of active power, the larger proportion of asynchronous motors in the total load is, the more likely voltage collapses; while the larger proportion of fixed impedance in the total load is, the more likely frequency collapses. Therefore, load characteristics has significant impact on the voltage stability. Proper application of the low-voltage load shedding schedule will improve the power grid stability