POWER POINT PRESENTATION ON FACTS DEVICES AND POWER SYSTEM STABILITY

1. State of art presentation
on
FACTS AND POWER SYSTEM STABILITY
Electrical and Electronics Engineering
Department
SITE,MEERUT
Supervisor:
Dr. Sanjiv Kumar
Coordinator (EEE)
Presented By:
Mamta Bagoria
Roll.No.
(160102492100001)

2. CONTENTS
 What is FACTs?
 Objectives of FACTs.
 Types of FACTS Controllers.
 Advantages of FACTS Controllers.
 Applications Of FACT .
 Power System Stability Overview.

3.  Power System Stability: A Proposed Definition.
 Need of Stability Classification.
 Classification of stability.
 Power System Stability Classification.
 Rotor Angle Stability.
 Voltage Stability.
 Frequency Stability.
 Rotor Angle Stability vs. Voltage Stability.
 Conclusions.

4. What is FACTs?
 Flexible AC Transmission System (Facts) is a new integrated
concept based on power electronic switching converters and
dynamic controllers to enhance the system utilization and power
transfer capacity as well as the stability, security, reliability and
power quality of AC system interconnections.
 FACTS uses solid state switching devices to control power flow
through a transmission network , So that the transmission
network is loaded to its full capacity.
 A line can be loaded up to its full thermal limit by FACTs.
 Power transfer can be increased through an old line by FACTs.

5. History Of FACTs
 Flexible AC Transmission Systems Technology (FACTS) was first
proposed by the Dr Narain G. Hingorani in 1988 of Electric Power
Research Institute ( EPRI ), USA .
 The first FACTS installation was at the C. J. Slatt Substation near
Arlington, Oregon.
 This is a 500 kV, 3-phase 60 Hz substation, and was developed by
EPRI, the Bonneville Power Administration and General Electric
Company.

6. OBJECTIVES OF FACTS
 To increase the power transfer capability of transmission systems.
 To keep power flow over designated routes.
 Secure loading of transmission lines nearer to their thermal limits.
 Prevention of cascading outages by contributing to emergency
control.
 Damping of oscillations that can threaten security or limit the
useable line capacity.

7. Basic Types Of FACTS
Compensation
FACTS compensation are classified as :-
1) Series Compensation.
2) Shunt Compensation.
3) Combined series-series compensation.
4) Combined series-shunt compensation.

8. Basic Types Of FACTS
Compensation

9. Basic Types Of FACTS
Compensation

10. Basic Types Of FACTS
Compensation
 Series Compensation :-
 It could be a variable impedance, such as capacitor, reactor, or a
power electronic based variable source of main frequency,
subsynchronous and harmonic frequencies to serve the desired
need.
 Inject a voltage in series with the line .
 If the voltage is in phase quadrature with the current, controller
supplies or consumes reactive power.
 Any other phase, involves control of both active and reactive
power.

11. Series Compensation
 These controllers could be variable impedance such as a reactor or
capacitor or a power electronic based variable source.
 Examples of the series controllers include SSSC, TCSR, IPFC,
TSSC and TCSC.

12. Thyristor Controlled Series
Compensation (TCSC)
 TCSC is a capacitive reactance compensator ,which consists of a
series capacitor bank shunted by a thyristor – controlled reactor in
order to provide a smoothly variable series capacitive reactance.

13. Benefits of TCSC
 Current control.
 Damping Oscillations.
 Transient and Dynamic stability.
 Voltage stability.
 Fault current limiting.

14. Basic Types Of FACTS
Compensation
 Shunt compensation :-
 It could be a variable impedance (capacitor ,reactor , etc.) or
a power electronic based variable source or combination of
both .
 Inject a current in the system.
 If the current is in phase quadrature with the voltage
controller supplies or consumes reactive power.
 Any other phase ,involves control of both active and reactive
power.

15. Types Of Shunt
Compensation
 Shunt compensation are of two types :-
 1) inductive shunt compensation
 2) capacitive shunt compensation
• inductive shunt compensation :-
 If Vr > Vs ; usually happens due to no load or less load or leading
load.
 capacitive shunt compensation :-
 If Vr < Vs ; usually happens due to high load or lagging load.

16. Types Of Shunt
Compensation

17. Shunt compensation
 Shunt controllers include STATCOM, TCR, TSR, TSC, and TCBR.

18. Shunt Vs Series Compensation

19. Advantages Of FACTS
 Increase of transfer of power without adding new transmission line.
 Transmission cost is minimized.
 Smooth steady state and dynamic control.
 Active damping of power oscillations.
 Increase of reliability.
 Improvement of system stability and voltage control.
 Provide greater flexibility in sitting new generation .
 Control of power flow in transmission corridors by controlling line
impedance ,angle and voltage.
 Optimum power flow for certain objectives .
 Increase the loading capability of lines to their thermal capabilities,
including short term and seasonal.

20. Applications Of FACT
 Steady state voltage stability
 Power flow control
 Damping of power system oscillations
 Reducing generation costs
 HVDC link application
 Deregulated power systems
 Interconnection of renewable, distributed generation and storages.

21. Power System Stability Overview
 Power system is defined as a network of one or more generating
units, loads and power transmission lines including the associated
equipments connected to it.
 The stability of a power system is its ability to develop restoring
forces equal to or greater than the disturbing forces to maintain the
state of equilibrium.
 Power system stability problem gets more pronounced in case of
interconnection of large power networks.

22. Power System Stability: A
Proposed
Definition
 Power system stability is the ability of an electric power
system, for a given initial operating condition, to regain a
state of operating equilibrium after being subjected to a
physical disturbance, with most system variables bounded so
that practically the entire system remains intact.

23. Need of Stability Classification
 Stability analysis is easier. Also it leads to proper and effective
understanding of different power system instabilities.
 Key factors that leads to instability can be easily identified.
 Methods can be devised for improving power system stability.

24. Classification of stability
 Classification is based on the following
considerations:-
 Physical nature of the resulting instability.
 Size of the disturbance considered.
 Processes and the time span involved.

25. Steady State Stability
 Ability to regain normal and stable operation after being subjected
to gradual or slow change in the load.
 Concerned with upper loading of machine before losing
synchronism.
 Load is assume to be applied at a rate which is slow.
 System is Analysed by the set of linear equation.
 Action of Voltage regulators and turbine governers are not
included.

26. Transient Stability
 Ability to regain normal and stable operation after being subjected
to sudden & large changes in the load.
 Losses-generator excitation, transmission, switching operations and
faults.
 Linearization of system equation is not permitted.
 Studied on the basis of swing.
 Action of Voltage regulators and turbine governer are not included.

27. Dynamic Stability
 Same as steady state stability.
 Included action of turbine governers and voltage regulators.
 Study time is 4-10 sec.

28. Power System Stability
Classification
 Rotor angle stability :-
 Small disturbance angle stability.
 Transient stability.
 Voltage stability :-
 Small disturbance voltage stability.
 Large disturbance voltage stability.
 Frequency stability :-
 Short term frequency stability.
 Long term frequency stability.

29. Stability Classification at a
Glance

30. Rotor Angle Stability
 Rotor angle stability refers to the ability of synchronous machines of
an interconnected power system to remain in synchronism after being
subjected to a disturbance.
 Rotor angle instability occurs due to angular swings of some
generators leading to their loss of synchronism with other generators.
 Depends on the ability to maintain/restore equilibrium between
electromagnetic torque and mechanical torque of each synchronous
machine.
 At equilibrium, Input mechanical torque equals output electromagnetic
torque of each generator. In case of any disturbance the above equality
doesn’t hold leading to acceleration/ deceleration of rotors of machines.

31. Rotor Angle Stability
Classification
 Small Disturbance Rotor Angle Stability:-
 It is the ability of the power system to maintain synchronism under
small disturbances.
 Disturbances are considered to be sufficiently small such that the
linearization of system equations is permissible for purposes of
analysis.
 The time frame of interest in small-disturbance stability studies is
of the order of 10 to 20 seconds following a disturbance.

32. Rotor Angle Stability
Classification
 Large Disturbance Rotor Angle Stability:-
 It is the ability of the power system to maintain synchronism under
a severe disturbance, such as a short circuit on a transmission line.
 Disturbances are large so that the linearization of system equations
is not permissible for purpose of analysis.
 The time frame of interest in transient stability studies is of the
order of 3 to 5 seconds following a disturbance.

33. Voltage Stability
 Voltage stability refers to the ability of a power system to maintain
steady voltages at all buses in the system after being subjected to a
disturbance from a given initial operating condition.
 A system is voltage instable if for atleast one bus in the system, the
voltage magnitude decreases as reactive power injection is increased.
 Voltage instability results in progressive fall or rise of voltages of some
buses.
 Large scale effect of voltage instability leads to Voltage collapse. It is a
process by which the sequence of events accompanying voltage
instability leads to a blackout or abnormally low voltages in a significant
part of the power system.

34. Frequency Stability
 Frequency stability refers to the ability of a power system to
maintain steady frequency following a severe system upset resulting
in a significant imbalance between generation and load.
 Frequency instability leads to tripping of generating units and/or
loads.
 Frequency stability may be a short-term phenomenon or a long-
term phenomenon.

35. Rotor Angle Stability Vs.
Voltage Stability
 Rotor angle stability is basically a generator stability while voltage
stability means load stability.
 Rotor angle stability is mainly interlinked to real power transfer
whereas voltage stability is mainly related to reactive power
transfer.

36. Conclusion
 The objective of this study was to reach an efficient control of an
electrical power system plus FACTS devices under several
perturbations.
 FACTS is an application of power electronics in power transmission
system.
 FACTS has an important role in real and reactive power control.
 FACTS makes a system stable.
 All the above aspects show the effectiveness of these devices to
suppress oscillations and stabilizing the power system.
 Power system is always required normal and stable operation at rated
operating condition & it’s also required improvement of stability .
 Stability of power system is improved by using shunt & series
capacitors, governing system and FACTS controllers.

37. Thank
You….