This document provides an overview of reactive power compensation. It defines reactive power compensation as any device connected in series or parallel with a load to supply the reactive power demanded. There are two main types of compensation: shunt compensation using parallel capacitors to improve power factor and boost voltage, and series compensation using series capacitors to boost receiving end voltage and transmission capacity. Fixed compensation uses breaker controlled capacitors for constant loads, while dynamic compensation uses thyristor controlled capacitors for fluctuating loads. Benefits include better efficiency, improved voltage, reduced losses and higher load capability. Capacitors are used as they generate reactive power to supply loads.

1. A SEMINAR REPORT
ON
REACTIVE POWER
COMPENSATION
By
PRAJNYA PRIYADARSINI MISHRA
Regd.0901106020

2. REACTIVE POWER
COMPENSATION
INTROUDUCTION .
Major industrial loads ,for example,
transformers, furnaces, induction motors etc
need reactive power for sustaining magnetic
field.

3. DEFINATION
 Any device which is connected in series or
parallel with load and which is capable of
supplying reactive power demanded by load is
called reactive power compensation device.

4. Power factor
 Power factor is the cosine of angle determined by
the inverse tangent ratio of reactive power and
real power.
 The closer this angle is zero ,the lesser is the
requirement of reactive power.
 Power factor below 0.85 is regarded as low
power factor

5. REAL, REACTIVE, AND APPARENT
POWERS
 Reactive power is not delivered as effective
mechanical power output unlike real power which
is effectively converted as mechanical power
output.
 The portion of power averaged over a complete
AC waveform, is the real power; that is, energy
that can be used to do work (for example
overcome friction in a motor, or heat an element).
 On the other hand, the portion of power flow that
is temporarily stored in the form of magnetic or
electric fields, due to inductive and capacitive
network elements, and then returned to source, is
known as reactive power.

6.  The figure shows the relationship between the reactive
power,active power, and apparent power on a power
factor angle .
 The load is uncompensated.If the conductor is fully
loaded,the arc of the circle represents the maximum
power output.
 The less the power factor angle of the circuit, higher the
apparent power,higher the losses,for the same amount of
real power.
CosQ=p/s
SinQ=Q/S
 Uncompensated Load
S
Q
Q
P

7. Compensated load
Qc=P (tanQ-tanQ1)
Qc
S
Q
S1
Q
p

8. THERE ARE TWO MAJOR WAYS OF
REACTIVE COMPENSATION
Shunt compensation:
Shunt capacitors are connected in parallel in the
system and are used mainly for power factor
improvement and in harmonic filters. It also boosts
the voltage of the bus. This also known as load
compensation.

9. SHUNT COMPENSATION
V-1 X R V2
source Load
Vr JX
P V2
Q Q R

10. Shunt compensation with current
source
Source V V2
X R Load
Z
Q
V JX
P $
V2 R
P Q
Q

11. Series compensation
 Series capacitor are connected in series in the
lines and are used mainly for boosting the
receiving end voltage, increase in transmission
capacity and reduction in losses in the lines.
 It also improve power factor at the sending end of
the line.
 Unlike shunt capacitor whose output depends on
the voltage, the voltage improvement by series
capacitors increase with increase in load current.
 In other word the series capacitor is a self
regulating type. Series compensation is also
known as live compensation.

12. SERIES COMPENSATION
Source
V1 V2
X R Load
v JX
V2 Ip
Ic R
Q

13. SERIES COMPENSATION WITH
VOLTAGE SOURCE
sourc v1
R V2 V2’
X load
e
Vcomp
V2’ Vcomp
v1 JX
v2 R
If

14. FIXED COMPENSATION VS
DYNAMIC COMPENSATION
 FIXED COMPENSATION:-Here the reactive
power fed by the capacitors to the system is
fixed. These are basically breaker controlled
capacitors and are used in system which has
constant load having a set pattern of operation.
 DYNAMIC COMPENSATION:-Here the reactive
power fed by the capacitors to the system is
dynamic. This is done using thyristor controlled
capacitors. These are used in systems where the
loads are fluctuating in nature like arc furnace
loads.

15. BENEFITS OF REACTIVE POWER
COMPENSATION
 Better efficiency of power generation,
transmission and distribution
 Improvement in voltage
 Reduced KVA demand
 Higher load capability.
 Reduced system losses.

16. Conclusion
 why capacitors are used as reactive power
compensation device?
 A capacitor is said to be generator of reactive power.
When a capacitor is connected across a load, it
provides reactive power to the load.
 Dielectric materials make it possible to increase the
output per unit and to reduce losses, thus making
the compensation by means of capacitor more
profitable.

17. Thanks