The electrical power system is highly nonlinear and dynamic by its nature. The state of the system is changing continuously due to load demand response, circuit breaker operation, fault, and atmospheric disturbances such as lightning. In such events, the system is forced to transition to a new state. During this transition, the energy stored in the power system and its components will be redistributed in a very short time and thus, the electrical equipment will be exposed to fundamentally different voltages and frequencies, resulting in higher stress in the equipment. This added stress may lead to equipment failure and poses an increased risk to system reliability.
Electromagnetic Transient (EMT) Study is a computer-based analysis and simulation tool used to determine voltage, current, frequency, and torque during the transient state of a power system. The transient phenomenon is classified by CIGRE based on the frequency range, as shown in the following table: