FACTS CONTROLLERS

PRESENTED BY:

NAME: DEBAYON SAHA

ROLL NO: 10300512028 (12/EI/28)

REG. NO: 121030110360

DEPT: AEIE

HALDIA INSTITUTE OF TECHNOLOGY

OUTLINE• What is FACTS

• FACTS Controllers

• Why FACTS Controllers

• Types of FACTS Controllers

• Voltage Source Converter (VSC)

• Static Variable Compensator (SVC)

• Static Synchronous Compensator (STATCOM)

• Thyristor Controlled Series Compensator (TCSC)

• Static Synchronous Series Compensator (SSSC)

• Unified Power Flow Controllers (UPFC)

• Others FACTS devices

• Benefits of FACTS

WHAT IS FACTS

• FACTS- ‘Flexible AC Transmission System’.• Flexible AC Transmission Systems (FACTS) are the name given to the

application of power electronics devices to control the power flows and other quantities in power systems.

• FACTS is defined by the IEEE as "a power electronic based system and other static equipment that provide control of one or more AC transmission system parameters to enhance controllability and increase power transfer capability."

• FACTS contains the design of the different schemes and configurations of FACTS devices is based on the combination of traditional power system components (such as transformers, reactors, switches, and capacitors) with power electronics elements (such as various types of transistors and thyristors).

FACTS CONTROLLERS

• The FACTS controller is defined as a power electronic based system and other static equipment that provide control of one or more AC transmission system parameters.

WHY FACTS CONTROLLERS

• Earlier days Mechanical Circuit Breakers like Relay, Contactors etcare used to control the power flow of the transmission systems.

• Mechanical Circuit Breakers was not very reliable and they can not compensate the power loss due to Reactive Power of the transmission systems.

TYPES OF FACTS CONTROLLERS

SHUNT

• Static Variable Compensator (SVC)

• Static Synchronous Compensator (STATCOM)

SERIES

• Thyristor Controlled Series Compensator (TCSC)

• Static Synchronous Series Compensator (SSSC)

HYBRID

• Unified Power Flow Controller (UPFC)

• Distributed Power Flow Controller (DPFC)

• Interline Power Flow Controller (IPFC)

TYPES OF FACTS CONTROLLERS

Depending on the power electronic devices used in the control, the

FACTS controllers can be classified as:

1. Variable Impedance Type: SVC & TCSC

2. Voltage Source Converter (VSC) Type: STATCOM, SSSC, UPFC

VOLTAGE SOURCE CONVERTER• Power Electronics based device

• In the figure, we have represented

ideal bi-directional switches. It

converts voltage and currents from

DC to AC while the exchange of power

can be in both directions

1.From AC to DC (rectifier mode)

2.From DC to AC (inverter mode).

• Using VSC devices we can control

The reactive power.

STATIC VARIABLE COMPENSATOR (SVC)• SVC is the First Generation FACTS Controller.

• SVC is a variable impedance device where the current through a reactor is controlled using back to back connected thyristor valves.

• The application of SVC is for load compensation of fast changing loads.

• SVC provide dynamic power factor improvement.

• SVC can Improve stability with fast acting voltage regulation.

• SVC can Control dynamic over voltages.

• A SVC has no inertia and can be extremely fast in response. This enables the fast control of reactive power in the control range.

• Ideally SVC should be located at the electrical centre of the system or midpoint of a transmission line.

CONTD..

STATIC SYNCHRONOUS COMPENSATOR (STATCOM)

• STATCOM is a ‘Voltage Source Converter’ based device.

• STATCOM is installed to support electricity networks that have a poor power factor and often poor voltage regulation.

• The voltage source is created from a DC capacitor and therefore a STATCOM has very little active power capability.

• If the terminal voltage of the VSC is higher than the AC voltage at the point of connection, the STATCOM generates reactive current.

• When the amplitude of the voltage source is lower than the AC voltage, it absorbs reactive power.

• The response time of a STATCOM is shorter than that of an SVC, mainly due to the fast switching times provided by the IGBTs of the voltage source converter.

CONTD..

• The strategy of STATCOM controller is to keep the DC capacitor voltage constant while controlling the modulation index to keep the voltage constant during the disturbance interval

THYRISTOR CONTROLLED SERIES COMPENSATOR (TCSC)

• TCSC is a series connected device.

• It is a variable impedance type device.

• It can affect active power flow.

• Its switching frequency is low compared to other FACTS devices.

• Insertion of a capacitive reactance in

• series with the line’s inherent inductive reactance lowers the total effective impedance of the line and thus both angular and voltage stability gets improved.

CONTD..

STATIC SYNCHRONOUS SERIES COMPENSATOR (SSSC)

• It is a VSC based device.

• It is a series connected device.

• Must have higher rated transformer and devices.

• Impacts active power flow.

• SSSC injects a reactive voltage (Vr) in series with the line.

• An SSSC comprises a voltage source inverter and a coupling transformer.

CONTD..

UNIFIED POWER FLOW CONTROLLER (UPFC)

• It is the combination of STATCOM and SSSC.

• It is a VSC type device.

• Control Voltage, Impedance, and Phase angle.

• Impacts both active and reactive power flow in transmission line.

• The shunt converter (STATCOM) is primarily used to provide active power demand of the series converter (SSSC) through a common DC link. STATCOM can also generate or absorb reactive power and thereby provide independent shunt reactive compensation for the line.

• SSSC provides the main function of the UPFC by injecting a voltage with controllable magnitude and phase angle in series with the line via an voltage source.

CONTD..

OTHERS FACTS DEVICES

• Thyristor Controlled Phase Shifting Transformer (TCPST)

• Interline Power Flow Controller (IPFC)

• Thyristor Controlled Braking Resistor (TCBR)

• Thyristor Controlled Voltage Limiter (TCVL)

• Thyristor Controlled Voltage Regulator (TCVR)

• Interphase Power Controller (IPC)

• Distributed Power Flow Controller (DPFC)

• NGH-SSR damping

Benefits of FACTS

• To increase the power transfer capability of transmission networks.

• To provide direct control of power flow over designated transmission routes.

• Increase the loading capability of lines to their thermal capabilities.

• Control of power flow as ordered so that it follows on the prescribed transmission corridors.

• To increase the reliability of transmission network.

• To compensate the power loss due to reactive power of transmission system.