Answer / iamdon

Majority of blackout/grid failure now a days is due to
voltage instability phenomenon.

This is because Modern power system is very vast and
interconnected to form a grid network.Also generation is
not sufficient to meet the load demand which is incresing
rapidly, due to which load end voltage drops.To maintain
load end voltage and power factor within permissible limits
shunt capacitors are used extesively at almost all load bus
bars(Over compensation),which has detrimental effect on
voltage stability.
At the time of peak load(load increase),the voltage at the
load end decreased so reactive power supplied by shunt
capacitors also reduced.So when we have most need of
reactive power supply,the shunt capacitor prove less
capable.
That's why modern power system satbility problem shifts
towards voltage stability.

Author:arbelectbit@yahoo.com

Answer / arvind

in todays time also rotor angle as well as voltage
stability anlaysis are been in focused, if rotor angle is
not into consideration then why so much transient analysis
is into picture.

Answer / iamdon

Yes...Arvind.
Your proposition is right.
I had just made a relative analysis with two stabilities
involved.It does not means that the rotor angle is of no
importance today.It just establish the fact that now we
MORE FOCUSSED towards volyage stability.

Answer / dharmesh

actualy both are cosider in today's power system the difference is rotor angle is for protection of generator and voltage regulation is for load regulation.

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