9.1 Transient Stability—Equal Area Criterion
Equal area criterion (EAC) is the graphical interpretation of transient stability of the system. This method is only applicable to a single machine connected to an infinite bus system or a two-machine system. The concept of EAC is derived from the fact that the stored kinetic energy in the rotating mass tries to substantiate the imbalance between the machine output and input. A single machine connected to a large system such as an infinite bus is considered to explain the EAC concept.
9.1.1 Mathematical Approach to EAC
Consider a synchronous machine connected to an infinite bus. Neglecting the damping effect, the swing equation is rewritten below.
where Pa is ...