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7/28/2019 Unit I-FACTS
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CONTROL MECHANISMS
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CONVENTIONAL CONTROL MECHANISMS
Automatic Generation Control (AGC)
Excitation Control
Transformer Tap-Changer Control
Phase-Shifting Transformers
Passive Compensation
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Automatic Generation Control (AGC)
-Real Power Controller
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Excitation Control
-Reactive Power Controller
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Transformer Tap-Changer Control
On load Tap Changer
Off - load Tap Changer
-Voltage Controller-Q
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Phase-Shifting Transformers
Fig. Schematic diagram Fig. Phasor diagram
-Real Power Controller
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Series Compensation
Shunt Compensation
Passive Compensation
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Shunt Compensation
Shunt devices may be connected permanently or through a switch.
Shunt reactors compensate for the line capacitance, and because
they control over voltages at no loads and light loads, they are often
connected permanently to the line, not to the bus.
Shunt Capacitor may be connected in the bus.
Fig. Shunt reactors compensation
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Series Compensation
Series capacitors are used to partially offset the effects of the series
inductances of lines.
1. The voltage magnitude across the capacitor banks (insulation);
2. The fault currents at the terminals of a capacitor bank;
3. The placement of shunt reactors in relation to the series capacitors
(resonant overvoltages); and
4. The number of capacitor banks and their location on a long line
(voltage profile).
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Flexible AC Transmission
Systems
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What is FACTS?
Flexible AC Transmission System (FACTS):
Alternating current transmission systems incorporating power
electronic-based and other static controllers to enhance
controllability and increase power transfer capability.
FACTS Controller:
A power electronic-based system and other static equipment
that provide control of one or more AC transmission system
parameters.
General symbol of FACTS controller
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Basic types of FACTS Controllers
Based on the connection, generally FACTS controller can be classifiedas follows:
Series controllers
Shunt controllers
Combined series-series controllers
Combined series-shunt controllers
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Basic types of FACTS Controllers
Series controllers
The series controller could be a variable impedance or avariable source, both are power electronics based devices to serve
the desired needs. In principle, all series controllers inject voltage in
series with the line.
General symbol of Series controller
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Shunt controllers
The shunt controllers may be variable impedance, variable
sources or combination of these. In principle, all shunt Controllers inject
current into the system at the point of connection.As long as the injected
current is in phase quadrature with the line voltage, the shunt Controller only
supplies or consumes variable reactive power.
General symbol of Shunt controller
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Combined series-series controllers:
The combination could be separate series controllers or unified
series-series controller. Series Controllers provide independent series
reactive compensation for each line but also transfer real power among
the lines via the power link- Interline Power Flow Controller.
Symbol of Series- Series controller
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Combined series-shunt controllers:
The combination could be separated series and shunt
controllers or a unified power flow controller. In principle, combined
shunt and series Controllers inject current into the system with the
shunt part of the Controller and voltage in series in the line with the
series part of the Controller.
Symbol of Series- Shunt controller
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Brief Description and Definitions of FACTS
controllers
Shunt connected controllers
Series connected controllers
Combined shunt - series connected controllers
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Shunt connected controllers
Static Synchronous Generator (SSG)
Stat ic Syn ch rono us Compensator (STATCOM)
Battery EnergyStorage System (BESS)
Superconducting Magnetic EnergyStorage (SMES)
Static Var Compensator (SVC)
Thyristor Controlled Reactor (TCR)
Thyrlstor Swltched Reactor (TSR)
Thyristor Switched Capacitor (TSC)
Static Var Generator or Absorber (SVG)
Thyristor Controlled Braking Resistor (TCBR)
Static Voltage Ang le Regulator (TCVAR)
Types of shunt connected controllers available in the market
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Series connected controllers
Static Synchronous Series Compensator (SSSC)
Interline Power Flow Controller (IPFC)
Thyristor Controlled Series Capacitor (TCSC)
Thyristor-Switched Series Capacitor (TSSC)
Thyristor-Controlled Series Reactor (TCSR)
Thyristor-Switched Series Reactor (TSSR)
Types of series connected controllers available in the market
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Unified Power Flow Controller (UPFC)
Interphase Power Controller (IPC):
Combined shunt-series connected controllers
Types of shunt series connected controllers available in the market
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Control of power flow as ordered.
Increase the loading capability of lines to their thermal capabilities,
including short term and seasonal.
Increase the system security through raising the transient stability limit,
limiting short-circuit currents and overloads, managing cascading
blackouts and damping electromechanical oscillations of power systems
and machines. Provide secure tie line connections to neighboring utilities and regions
thereby decreasing overall generation reserve requirements on both sides.
Provide greater flexibility in siting new generation.
Reduce reactive power flows, thus allowing the lines to carry moreactive power.
Increase utilization of lowest cost generation.
BENEFITS FROM FACTS TECHNOLOGY
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In-phase Voltage injection
V 0V
V+ 0V
V- 0V
V
V
Here, reactive power control
through voltage adjustment
Quadrature Voltage injection
V 90V
V- 90V V+ 90V
Here, real power control through
phase angle adjustment
VV 0V
V