The SMIB test case was built based on example 13.1 from Kundur
Power System Stability and Control book. It is is a well-known test
case in the power system community. It is very often used to
illustrate the transient or the small-signal stability of a
synchronous machine. It is also used to demonstrate the behavior of
a new regulation, such as a speed governor, a voltage regulation or
a power-system stabilizer.