the inertia constants of two machines are respectively 30and
42 MJ per MVA.when the change in frequency due to change in
load in first machine is 12 Hz,the change in second machine
frequency will be?
Answer Posted / 7anoter4
If the change in load will be the same Pa1=Pa2 and the
rated frequency fo1=fo2
for the same time interval dt1=dt2
IF Pa=H*MVA/180/fo*d2R/dt2 [See IEEE-399 ch. 8.6.2 How
stability programs work]
and d2R/dt2=2*pi()*df/dt
then (df/dt)1=Pa/2/pi()*180*fo/MVA1/H1 and
(df/dt)2=Pa/2/pi()*180*fo/MVA2/H2
(df/dt)2/(df/dt)1=MVA1*H1/MVA2*H2
If MVA1=MVA2 then (df/dt)2=(df/dt)1*H1/H2
df2=12*30/42=8.57 Hz
Is This Answer Correct ? | 0 Yes | 7 No |
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