J.S. Zhang, Y. Zhang, X.H. Zong, and Z.G. Wu (PRC)
Load modeling, induction motor, transient voltage stability, mechanical load characteristics, motor load proportion
The influences of induction motor load models, mechanical load characteristics and the proportion of total motor load on transient voltage stability after large disturbances are examined using a Transient Security Assessment Tool (TSAT) and the data of the China Southern Power Grid. The results show that the first order mechanical transient model gives more optimistic transient voltage behaviour than the third order electro mechanical transient model under the specified simulation conditions. Induction motor models that include the polynomial mechanical torque are ineffective for the transient voltage dips recovery after a large disturbance compared to models with constant or exponential mechanical torque representation. Therefore, the transient voltage performance obtained with the constant mechanical torque is not always pessimistic. Motor stalling increases and transient voltage instability therefore occurs with the increased proportion of total motor load in the system. The study shows that induction motor loads should be included in the composite load models for the transient voltage security evaluation of the China Southern Power Grid if reliable results are obtained.
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