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MODELLING OF UNIFIED

POWER FLOW CONTROLLER

By

PRAHARSH MISHRA

B.TECH. EE

IEC-CET

[0909020083]

SUBMITTED TO :

MR. ASHOK KUMAR

ELECTRICAL DEPT.

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FACTS DEVICES

What is FACTS?

FACTS is flexible ac transmission systems.

FACTS is a new technology, the principle role ofenhancing controllability & power transfer capability in

ac systems. With the increasing demand of power, the power system

networks are becoming more complex from the point ofview of operation & control. The existing networks aremostly mechanically controlled but these devices are slow

in operation & another problem is that control cannot beinitiated frequently. Thats why we use FACTS as controldevices.

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FACTS DEVICES

Based on power electronic switching

converters

Enhances -system utilization

-power transfer capacity

-stability, security, reliability

-power quality of AC system Complex power systems require new devices

for controlling power flow in transmission

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Uses of facts devices

Facts devices in ac lines

- power flow control.

- increase of transmissioncapability.

- voltage control.

- reactive power compensation.- stability improvement.

- power quality improvement

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upfc

o Combination of 3 compensators

-impedance

-voltage magnitude-phase angle

o Consists of two voltage source converters;

-series converter-shunt converter

o Converters are connected by a common

dc link.

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Upfc-schematic diagram

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Operating principle of upfc

Consists of two voltage source inverters

(VSIs) sharing a common dc storage

capacitor.

VSIs are connected to the power system

through coupling transformers.

One VSI is connected in shunt to the

transmission system via a shunt transformer.

The other one is connected in series through

a series transformer.

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Components

series inverter

It injects an AC voltage VPQ with

controllable magnitude and phase angle

(0 360) in series with the line.

The line current flowing exchanges the

real and reactive power between it and ac

system

The reactive power exchanged is internally

generated by the inverter.

The real power must be supplied to it.

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Shunt converter

It supplies the real power demanded by theseries device at the dc link.

It can also absorb or generate thecontrollable reactive power.

It is used for voltage regulation at the pointof connection injecting an opportunereactive power flow into the line.

Balances the real power flow exchangedbetween the series inverter and thetransmission line.

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DC LINK

A capacitor works as a dc link between the

two voltage source inverters.

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Control functions

1. Voltage regulation-

Achieved by injecting

a voltage V1, in phase

(or out of phase) with

VS

The magnitude of the

sending bus voltage

Vs is increased (or

decreased)

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Control functions2. Series reactive

compensation-

It is obtained by

injecting a voltage V2,

orthogonal to the line

current

The effective voltage

drop across the lineimpedance X is

decreased (or

increased)

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Control functions

3. Phase shift- A desired phase

shift is achieved

by injecting avoltage V3

Shifts VSby + or

- while keepingits magnitude

constant as

shown in Fig.

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Reference

https://www.google.co.in/

http://www.wikipedia.org/

https://ieeexplore.ieee.org/ ELECTRICAL POWER SYSTEMS

by ASHFAQ HUSAIN

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