Abstract
Transient stability analysis is more difficult and of great importance because the power system becomes larger and larger. Therefore, accurate stability to contingency faults is demanded in power system planning and operation. The energy function method, which is one of the methods for transient stability assessment, can search the stability limit by one simulation. This method has an advantage of obtaining the result at high speed, but there are faults that enough accuracy is not obtained if this method is applied to general power systems. However, when generators are assumed as the classical model, the energy function method is available to first swing stability. Therefore, there is a problem of improving accuracy in the analysis for power systems that include controllers such as AVR and Governor.
In this paper, we consider the problems that occur when the energy function method with the classical model is applied to a more detailed generator model that includes controllers. It is pointed out that the cause of the inaccuracy comes from changes of internal voltages. Because the internal voltage is affected by AVR's action, an analytical technique is proposed for the treatment of the internal voltage. Moreover, it is proposed that the obtained first critical clearing time be revalued to obtain a more accurate critical clearing time.
