A Stochastic Analysis of Turbine Generator Shaft Torsional Torque considering Power System Load Capacity

When the electrical disturbance occurs such as network fault, the circuit breaker clearing and reclosing operation are followed in power system. The fault current will affect to generator stator current and generator air-gap torque. The turbine shafts will also fluctuate, because the turbine is connected with the generator stator through electromagnetic forces. If this transient torque of turbine generator shaft system continues, the crack may be initiated in turbine generator shaft system and the shaft system break down. In general, there are two analysis methods that deterministic analysis method and stochastic analysis method. In this paper, the stochastic analysis method, which is considered circuit breaker operation time, is used for transient torque of turbine generator shaft system analysis by using ElectroMagnetic Transient Program (EMTP). The load capacity in power system is also considered because it is one of the influence factors, which decide magnitude of transient torque of turbine generator shaft system. Furthermore, through this stochastic analysis result, we derive zone of vulnerability for turbine generator protection aspects.