Simulation analysis for asynchronous operation capacity of turbogenerator under excitation-loss

Based on single-generator infinite-bus system model, the asynchronous operation capacities of a 600MW turbogenerator after direct short-circuit excitation-loss under 100%, 60% and 40% rated power operation conditions are researched. The parameters such as stator voltage, stator current, rotor current, active power and reactive power, speed are obtained after direct short-circuit excitation-loss. The results indicate that the turbogenerator can´t enter into the steady asynchronous stage under 100% rated power, and the stator current is attained 2.65 times rated current. The turbogenerator can enter into the steady asynchronous stage under 60% rated power, while the stator current is exceeded 1.1 times rated current. The asynchronous operation is allowed for short time under 40% rated power, because the stator current is less than permissible value of safety operation and the decreasing rate of terminal voltage is less than 10%. The conclusions can provide an important theoretical foundation for large turbogenerator design and asynchronous operation capacity analysis.