FLEXIBLE AC FLEXIBLE AC TRANSMISSION SYSTEMS TRANSMISSION SYSTEMS - - PowerPoint PPT Presentation

FLEXIBLE AC FLEXIBLE AC TRANSMISSION SYSTEMS TRANSMISSION SYSTEMS ( ) FACTS ( ) FACTS

WHAT IS FACTS ?

 IEEE definition : “AC transmission systems

incorporating power electronic based and other static controllers to enhance availability and to increase power transfer capabilities”

 

SERIES CONTROLLER

Variable impedance or

variable source

Injects voltage in series

with the line

More powerful controller For active power control Improve transient stability

• f power system

SHUNT CONTROLLERS

Injects current into a line  Variable impedance or

source connected to the line

 Improve dynamic stability



COMBINED SERIES COMBINED SERIES SHUNT CONTROLLER SHUNT CONTROLLER





Inline power flow

control

 

Unified power flow

controller

COMBINED COMBINED SERIES SERIES SERIES SERIES CONTROLLER CONTROLLER

(B) CLASSIFICATION BASED ON COMMUTATION

  Forced Commutation : GTO



Natural commutation : SCR





(C) CLASSIFICATION BASED ON SWITCHING FRQUENCY

  low frequency (50 – 60 Hz)  Medium frequency switching (100 – 500 Hz)  High frequency switching ( > 500 Hz)



(D) CLASSIFICATION BASED ON TYPE OF PE DEVCIE USED



VARIABLE IMPEDENCE TYPE(VIT) VOL

TAGE SOURCE CONVERTER(VSC)



Consists of impedances Supplies or absorbs reactive

 power

No voltage source

 Eg: SVC, TCSC, TCPST etc. 

Ø

C onsi sts of a vol tage source C om pact C an suppl y acti ve and reacti ve pow er : , , . Eg STATC O M SSSC U PFC etc

IMPORTANT FACTS CONTROLLERS

 SVC (Static var compensator)  STATCOM (Static Compensator)  SSSC (Static Synchronous Series Compensator)  UPFC (Unified Power Flow Controller) 

STATIC VAR COMPENSATOR (SVC)

Classification string: 1P-NC-LF-

ZES-NDC

 PF correction  Provides fast acting reactive

power

 Stabilization of bus bar voltage  Improve damping of dynamic

• scillation



STATIC VAR COMPENSATOR (SVC)

 Transformer Switchgear Reactor Thyristor valves Capacitor bank Cooling system Control and protection

STATIC SYNCHRONOUS COMPENSATOR(SSC) OR STATCOM

Classification string: 1P-FC-HF-

CES-DC

 For supplying reactive power  Active power control is

 possible

 Quick response  Less space

STATIC SYNCHRONOUS SERIES COMPENSATOR (SSSC)

Classification string: 1S-FC-HF-

CES-DC



Exchange both active and

reactive power

 Compensate drop due to

reactive and resistance losses

 Maintains constant X/R ratio

UNIFIED POWER FLOW CONTROLLER (UPFC)

Classification string: 2-FC-HF-

CES-DC

 Combination of STATCOM

and SSSC

Control both active and

reactive power

Provides high flexibility T

erminal voltage control

Phase angle regulation Series line compensation

ADVANTAGES OF FACTS

 Power transmission capability System stability Power quality Environmental impact Transmission losses Dynamic and reactive power support and voltage

control

Dynamic oscillation in power system 

CONCLUSION

FACTS is an application of power electronics in

transmission system

FACTS controllers makes a system ‘flexible’ FACTS controllers are classified based on

connection, commutation etc.

SVC, STATCOM, UPFC etchave a number of

applications in power systems

FACTS has an important role in active and reactive

power control

FACTS helps to improve the capacity of an existing

system

FACTS controllers improve the power quality and

stability



REFERENCES

W.N. Chang and C.J. Wu, “Developing static

reactive power compensator in a power system”, IEEE Trans. on Power Systems

K.R. Padiyar and R.K. Varma, “Damping torque

analysis of static VAR system controllers”, IEEE

• Trans. on Power Systems,

N.G.. Hingorani, “Flexible ac transmission”, IEEE

Spectrum, pp. 40–45

Power Semiconductor Devices and Circuits, Brown

Boveri symposia series, Baden Datettwil

  QUESTIONS?

QUESTIONS?



  THANK YOU

THANK YOU