This Ppt gives a short but complete content about the losses occuring in electric drives, different methods to improve the losses occuring in drives and detail description about 3 methods for improving efficiency of drives
1. ENERGY CONSERVATION IN ELECTRIC
DRIVES
By
VIVEK KUMAR SHARMA-1RV13EE059
SATVIKA SAKET-1RV13EE064
2. Major portion of electric power in a plant is consumed
by Electric Drives.
With increasing energy demand need for electrical
power can only be met by conserving electrical
power.
To keep manufacturing cost of product minimum.
Attain competitive price of product in market.
Introduction (Why Energy Conservation)
3. Losses in Electric Drive System
Losses Causes
Electric Transmission losses Depend on drive p.f & harmonics
Conversion losses Losses in power modulator or
converters
Mechanical Losses in drives Bearings, gears, clutches & belts
due to mechanical friction
Losses in Load Classification of load friction torque
Losses in Electric motor Choice of motor, design, rating,
characteristics,
4. Copper Loss
Core Loss
Friction & windage Loss
Stray load loss
Losses due to varying load
For an efficient operation of an electric drive the drive &
driven machinery/load should operate efficiently.
This requires careful design of both electrical & mechanical
system
Losses in Electric Motor
5. Use of efficient Semiconductor converters
Use of energy efficient motors
Use of variable speed drives
Improvement of power factor
Use of motor of right rating
Improving quality of supply
1Φ to 3Φ semiconductor in rural application
Measures for Energy Conservation in Electric Drive
6. Motor terminal voltage vary in wide limit due to
inadequate reactive power compensation
Improvement of quality of supply
Problems Solution
Low voltage Substation transformers are set for high
voltages
Light load condition Over-voltage conditions are produced
Motor & transformer
saturation at high voltage
Designed in such a way to avoid saturation at
high voltages
Unbalanced supply voltage
7. EEM have :-
More copper in windings
Reduced fan losses
9-15% more efficient than standard motors
Usually motors are inefficient due to :-
Poor quality of laminations & insulation.
Use of less active material causing saturation
Poor mechanical design of bearing, clutches, gears etc.
Use of Energy Efficient Motor
10. Decreases copper loss in transformer, distribution cable,
transmission lines & other equipment's
Helps in stabilizing system voltage
Reduces load on transmission & distribution equipment's
Allows large power transmission
Reduces load on transformer
Full utilization of substation & generating unit
It also minimize penalty imposed on low p.f consumers by
the utilities
Why improve p.f ?
11. Power factor equation
Linear load
Real power = 3VI𝑐𝑜𝑠Φ
Apparent power = 3VI
Reactive power = 3VI𝑠𝑖𝑛Φ
P.f = 𝑐𝑜𝑠Φ
Non-linear load
Real power = 3VI𝑐𝑜𝑠Φ
Apparent power = 3V*Irms
Reactive power = 3VI𝑠𝑖𝑛Φ
P.f=𝑐𝑜𝑠Φ * (I/Irms) or
P.f = displacement factor * distortion factor
12. Improvement of p.f of linear load & displacement
factor of non-linear load can be done by :-
Overexcited synchronous motors
Capacitors
Static VAR Compensators
Improvement of distortion factor for non-linear load
Method to improve p.f
13. Used when speed control is not
required
Overexcited
Synchronous
Motors
A synchronous motor running at constant
speed draws leading p.f when overexcited.
Leading reactive power can be controlled
by machines field excitation control.
Controlling field excitation by closed loop
control leading reactive power.
This counters the lagging reactive power of
electric drives & loads
Overall p.f of the plant can be kept close to
unity
14. For drives operating at constant
average power but low p.f
Capacitors
Capacitor is installed across the
motor.
It draws leading power and counters
the lagging power of motor.
Choice of capacitor value should be
done carefully.
Error in selection can cause over-
excitation of motor.
This results in high transient
voltages, currents & torques
15. Used for compensation of load with variable reactive
power.
Preferred over synchronous condenser .
Advantages:-
Low cost
Lower loss
Fast response
Lower maintenance
Smooth & quite operation
Static VAR compensation
16. It can be improved by :-
Filtering out harmonics in input current & voltage
Ex-
Diode bridge rectifier with filters connected at its input
terminals to filter out harmonics
Line commutated thyristor with static var compensation
Displacement Factor