Assessment of total transfer capability subject to transient stability energy margin

This paper presents a method to assess total transfer capability (TTC) by using energy function. TTC assessment is to calculate TTC by using the repeated power flow (RPF) method. TTC is limited not only by the violation of system voltage and thermal limits, but also restricted by transient stability limit. The transient energy margin is the difference between the transient energy and the critical energy. In order to calculate energy margin, two values of the transient energy function have to be computed. The first value is transient energy that is the sum of kinetic and potential energy at the end of fault. The seconds is critical energy that is potential energy at controlling UEP. The method proposed is applied to 4 machines systems to demonstrate its effectiveness.