Impacts of small synchronous generators at medium voltage on transient stability of bulk power system

Nowadays penetration level of distributed generation in type of small synchronous generators is considerable in power systems. Without accounting for uncertainty factor in dynamic parameters of small synchronous generators, stability assessment of these generators in wide-area power system is uncertain and time consuming by itself. So, regarding small generators in medium voltage level, stability assessment of bulk power systems should be carried out with some simplification accompanied acceptable tradeoff. This paper proposes two approaches for modeling the reduction of subtransmision network including small synchronous generator. The effect of the proposed reduction methods on the transient stability evaluation of bulk power system has been investigated. The proposed approaches have been demonstrated on two types of test system, IDRC 24-bus and Iran national test systems.