Job interview and viva Topics for Electrical and electronics Engineers (Part-4).

Electrical engineering interview topic:Job interview and viva Topics for Electrical and electronics Engineers (Part-4).

In this topic we know about Power System Stability,Steady State Stability,Static Stability,Dynamic Stability and Steady State Stability Criterion

13. Power System Stability: 

 In the large power system there might be some disturbance always. The system has the tendency for the system to develop forces for bringing the system in a normal or stable condition. The ability of the system to obtain the normal or stable condition after getting disturbed is called Power System Stability.

The stability has mainly two types: 

1. Steady State Stability.

2. Transient Stability.

14. Steady State Stability:  

The ability of being stable after a small disturbance in the system is called Steady State Stability.

The Steady State Stability is concerned with the very small power changes .which are changed gradually.

The Steady State Stability has two types:

1. Static Stability

2. Dynamic Stability.

·        Static Stability: 

In the Static Stability there is a large duration phenomenon with small disturbance. This is the inherent stability that can achieve with out the help of automatic control devices.

·        Dynamic Stability: 

In the Dynamic Stability there is a small duration phenomenon with large disturbance. This Dynamic Stability refers to artificial stability. This artificial stability is given to an inherently unstable system by the help of automatic control devices.

15. Steady State Stability Criterion:

The rate (dP/dδ) of the differential power increased is obtained per differential load angle increased. This are called as electrical stiffness or the synchronizing power coefficient of a synchronous machine. This is considered as the measure of the stability of the system.

The Steady State Stability has basically three Criterion or state.

When,

·        (dP/dδ) > 0 ; Direct State Synchronous Stability.

·        (dP/dδ) = 0 ; Steady State Stability.

·        (dP/dδ) < 0 ; The System is unstable.
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