CameraIcon

SearchIcon

MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Addition & Subtraction of Errors

Given a singl...

Question

Given a single area with two generating units.

Unit Rating Speed drop R (per unit on unit base)

1 400 0.04

2 800 0.05

The units share a load of $P_{1} = 200 M W, P_{2} = 500 M W$ . The units are operating in parallel to share a load of 700 MW at 50 Hz frequency. The load is increased by 130 MW with B = 0, The value of new frequency caused by steady state frequency deviation is _______ Hz.
49.75

Open in App

Solution

The correct option is A 49.75
$Δ f = \frac{- Δ P}{\frac{1}{R_{1}} + \frac{1}{R_{2}} + B}$

On a common base of 1000 MVA

$R_{1} = (0.04) (\frac{1000}{400}) = 0.1$

$R_{2} = (0.05) (\frac{1000}{800}) = 0.0625$

$Δ f = \frac{- 130 / 1000}{\frac{1}{0.1} + \frac{1}{0.0625}} = - 5 \times 10^{- 3} p . u$

$Δ f_{(a c t u a l)} = 50 \times Δ f p . u = 50 \times - 5 \times 10^{- 3}$

$f = f_{o} + Δ f_{(a c t u a l)} = 50 \times - (5 \times 10^{- 3}) (50)$

$= 49.75 H z$

Suggest Corrections

thumbs-up

2

Similar questions

Q. Two generating units rated 300 MW and 400 MW have governor speed regulation of 6% and 4% respectively from no load to full load. Both the generating units are operating in parallel to share a load of 600 MW. Assuming free governor action the load shared by the larger unit is

Q. Two generators

G_{1}

G_{2}

rated as 200 MW and 400 MW respectively, are operating in parallel. The droop characteristics of their governors are 4% and 5% respectively from no load to full load. At no load, the generators are operating at a system frequency of 50 Hz. If total load of 600 MW is being shared by the generators, then generation in

G_{1}

G_{2}

are respectively

Q. Incremental fuel costs (in some appropriate unit) for a power plant consisting of three generating units are

I C_{1} = 20 + 0.3 P_{1}

I C_{2} = 30 + 0.4 P_{2}

I C_{3} = 30

_{i}

is the power in MW generated by units for i = 1, 2 and 3.

Assume that all the three units are operating all the time. Minimum and maximum loads on each units are 50 MW and 300 MW respecitvely. If the plant is operating on economic load dispatch to supply the total power demand of 700 MW, the power generated by each unit is

Q. Two 200 MVA alternators operate in parallel. The frequency drops in first machine from 50 Hz at no load to 48 Hz at full load, where as in case of other machine, the frequency drops from 50 Hz to 47 Hz under the same conditions. If the two machines has to share a total load of 300 MW, then the maximum load at unity p.f. which can be delivered by the two machines without overloading any of them is

Q. A 50 Hz alternator is rated 500 MVA, 20 kV, with X

_{d}

= 1.0 per unit and X

_{d}^{''}

= 0.2 per unit. It supplies a purely resistive load of 400 MW at 20 kV. The load is connected directly across the generator terminals when a symmetrical fault occurs at the load terminals. The initial rms current in the generator in per unit is

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Error and Uncertainty

PHYSICS

Watch in App

explore_more_icon

Explore more

Addition & Subtraction of Errors

Standard XII Physics

Join BYJU'S Learning Program

CrossIcon