Compare : Dynamic Stability and Transient Stability

In this article, the comparison between steady state stability and dynamic state stability is given. First, let understand the term stability and instability in the power system

Stability and Instability

Stability

• The stability of the power system is ability of system to regain stable state after being some form of disturbance.

Instability

• Out of step or loss of synchronism

The power system stability can be classified as

Steady State Stability & Dynamic State Stability

• Small disturbance is continuously occurring on the power system, which does not cause the system to lose synchronism but it causes natural oscillations. It is called as dynamically stable state. 
• The system amplitude increases to certain level and die out quickly. 
• The oscillating amplitude are large and persists for long time for 5 to 10 second and up to 30 second. 
• This type of stability creates serious threat to power system operation.
•  The dynamic stability can improve by power system stabilizers. 
• The study of dynamic stability is done by computer simulation.

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Transient state stability

• The transient state stability is defined as the ability of power system to return its original stable state after large disturbance. 
• It may be fault on the system, sudden change of load, switching operation etc. 
• It also causes large changes in power angles, rotor speed and power transfers. 
• The machine falls out of step due to sudden large disturbance is called as transient state instability. 
• This type of large disturbance occurs in very short time period of one second. 
• The transient state instability is always less than the steady state stability.
• It depends upon type of fault, location of fault, rapidity of clearing fault and method of clearing.