IPFC,It's FACTS device for controlling the power flow in the lines and improving the voltage profile and security of the lines.

1. By
NITISH KUMA
NIT CALICUT

2.  It is a combination of series controllers or a unified controller.
 Unified means that DC terminal of controller converters are connected
together for real power exchange
 The objective of introducing this controller is to address the problem of
compensating a number of transmission lines connected at a substation

3. The Interline Power Flow Controller (IPFC) provides, in addition to the facility
for independently controllable reactive (series) compensation of each individual
line, a capability to directly transfer or exchange real power between the
compensated lines.
Fig 1 Structure of IPFC

4. UPFC:
Capable of controlling the real and the reactive power flow in the line
independently
Injects a fully controllable voltage in series with the line and support
the resulting generalized real and reactive power compensation by
supplying the real power required by the series converter through the
shunt-connected converter from the ac bus
IPFC:
 Equalize both real and reactive power flow between the lines; reduce
the burden of overloaded lines by real power transfer; compensate
against resistive line voltage drops and the corresponding reactive
power demand; and increase the effectiveness of the overall
compensating system for dynamic disturbances.

5. * Converter can be controlled to supply real power to the common
dc link from its own transmission line apart from the series
reactive compensation
*Overall surplus power can be made available from the under
utilized lines which then can be used by other lines for real power
compensation
*Some of the converters, compensating overloaded lines or lines
with a heavy burden of reactive power flow can be equipped with
full two-dimensional, reactive and real power control capability

6. Fig 2 Basic two-converter Interline Power Flow Controller scheme
V1s = V2s = V1r=V2r= 1 p.u.
δ1 = δ2 = 30º
V1pqmax = V2pqmax
X1 = X2 = 0.5 p.u.

7. Fig 3 IPFC "prime" converter and
corresponding phasor diagram

8. Fig 4 Variation of receiving-end real and reactive power as a function of the injected
compensating voltage in Line 1

9. Fig 5 Illustration of the operation of a two-converter IPFC by coordinated phasor diagrams
and P - Q plots

10. Fig 6 Illustration of the operation of a two-converter IPFC by coordinated phasor diagrams
and P - Q plots

11. Fig 7 Illustration of the operation of a two-converter IPFC by coordinated phasor diagrams
and P - Q plots

12. Fig 8 Illustration of the basic relationships governing the operation of a two converter IPFC

13. Fig 9 Relationship between transmission angle δ1 and the compensation region in the P-Q
plane for a two-converter IPFC

14. Fig 10 Basic control scheme for a two-converter IPFC