This document investigates load frequency control in a two area power system with multiple variable loads. It compares pole placement and optimal control techniques for load frequency control and finds that the optimal control technique provides better transient response. PID control is also applied and tuned using particle swarm optimization. Frequency response plots demonstrate the system response under different control approaches.

2. LOAD FREQUENCY CONTROL OF TWO AREA POWER
SYSTEM
BY
• ANIMESH SACHAN
• SHUBHAM PRAKASH SAHU
• BHAWANA MISHRA
• GEETANJALI GAUTAM
UNDER THE GUIDANCE
OF
MR. SAMEER BHAMBARI

3. ABSTRACT
INVESTIGATING THE LOAD FREQUENCY CONTROL
PROBLEM IN A POWER SYSTEM CONSISTING OF TWO
POWER GENERATION UNIT AND MULTIPLE VARIABLE
LOAD UNITS.

4. INTRODUCTION
• THE MAIN PURPOSE OF OPERATING THE LOAD FREQUENCY CONTROL IS TO
KEEP UNIFORM THE FREQUENCY CHANGES DURING THE LOAD CHANGES
• IN MULTI AREA SYSTEM A CHANGE OF POWER IN ONE AREA IS MET BY THE
INCREASE IN GENERATION IN ALL AREAS ASSOCIATED WITH A CHANGE IN THE
TIE-LINE POWER AND A REDUCTION IN FREQUENCY. IN THE NORMAL
OPERATING STATE THE POWER SYSTEM DEMANDS OF AREAS ARE SATISFIED
AT THE NOMINAL FREQUENCY

5. REASONS FOR THE NEED OF MAINTAINING CONSTANT
FREQUENCY
If the normal operating frequency is 50 Hz and the turbines run at speeds corresponding to
frequencies less than 47.5 Hz or above 52.5 Hz, then the blades of the turbines may get damaged.
47.5 Hz 50 Hz 52.5 Hz

6. REASONS FOR THE NEED OF MAINTAINING CONSTANT
FREQUENCY
• THE SPEED OF A.C. MOTORS ARE DIRECTLY RELATED TO THE FREQUENCY.
FREQUENCY SPEED

7. REASONS FOR THE NEED OF MAINTAINING CONSTANT
FREQUENCY
• THE OPERATION OF A TRANSFORMER BELOW THE RATED FREQUENCY IS NOT
DESIRABLE. WHEN FREQUENCY GOES BELOW RATED FREQUENCY AT CONSTANT
SYSTEM VOLTAGE THEN THE FLUX IN THE CORE INCREASES AND THEN THE
TRANSFORMER CORE GOES INTO THE SATURATION REGION.
FREQUENCY
DECREASES
FLUX IN CORE
INCREASES
TRANFORMER
SATURATES

8. LOAD FREQUENCY PROBLEMS
• IF THE SYSTEM IS CONNECTED TO NUMEROUS LOADS IN A POWER SYSTEM,
THEN THE SYSTEM FREQUENCY AND SPEED CHANGE WITH THE
CHARACTERISTICS OF THE GOVERNOR AS THE LOAD CHANGES.
LOAD FREQUENCY
&
SPEED
INCREASES
DECREASES

9. LOAD FREQUENCY PROBLEMS
• IF CONSTANT FREQUENCY IS REQUIRED THE OPERATOR CAN ADJUST THE
VELOCITY OF THE TURBINE BY CHANGING THE CHARACTERISTICS OF THE
GOVERNOR WHEN REQUIRED.
INCREASE
IN LOAD
INCREASE
IN
VELOCITY
OF
TURBINE
CONSTANT
FREQUENCY

10. GOVERNOR MODEL

11. SPEED REGULATION BY GOVERNOR

12. BLOCK DIAGRAM OF SINGLE SYSTEM CONSISTING
OF GENERATOR, LOAD, PRIME MOVER AND
GOVERNOR

13. TWO AREA SYSTEM WITH PRIMARY LOOP LFC

14. IMPLEMENTATION
POLE
PLACEMENT
TECHNIQUE
OPTIMAL
CONTROL
TECHNIQUE

15. POLE PLACEMENT TECHNIQUE

16. POLE PLACEMENT TECHNIQUE
• THIS IS ONE OF THE DESIGN METHODS. HERE WE ASSUME THAT ALL THE
STATE VARIABLES CAN BE MEASURED AND ARE AVAILABLE FOR FEEDBACK
• THE POLES OF THE CLOSED Ζ APPROPRIATE STATE FEEDBACK GAIN MATRIX
IF THE SYSTEM IS COMPLETELY STATE CONTROLLABLE
• IN THIS APPROACH, EFFECTS ON THE RESPONSES OF NON-DOMINANT
CLOSED LOOP ARE TO BE NEGLIGIBLE

17. OPTIMAL CONTROL TECHNIQUE
• THIS IS A TECHNIQUE THAT IS APPLIED IN THE CONTROL SYSTEM DESIGN
WHICH IS IMPLEMENTED BY MINIMIZING THE PERFORMANCE INDEX OF THE
SYSTEM VARIABLES
• THE AIM OF THE OPTIMAL REGULATOR DESIGN IS TO OBTAIN A CONTROL LAW
U*(X, T) WHICH CAN MOVE THE SYSTEM FROM ITS INITIAL STATE TO THE FINAL
STATE BY MINIMIZING THE PERFORMANCE INDEX.
• THE PERFORMANCE INDEX WHICH IS WIDELY USED IS THE QUADRATIC
PERFORMANCE INDEX.

18. FREQUENCY DEVIATION STEP RESPONSE OF LFC USING
OPTIMAL CONTROL DESIGN
WE SEE THAT THE TRANSIENT RESPONSE SETTLES TO A STEADY STATE OF -
0.0007 PU IN ABOUT 0.6SECONDS.

19. TWO AREA SYSTEM LFC WITH PID CONTROL ACTION
• THE INTEGRAL CONTROL BLOCK IS REPLACED BY PID CONTROLLER AND
STATE SPACE MODEL OF THE SYSTEM Ẋ = AX IS OBTAINED.
• PID1(S) = 𝐾𝑝1 + 𝐾𝐼1 𝑠 + 𝐾𝐷1𝑠
• PID2(S) = = 𝐾𝑝2 + 𝐾𝐼2 𝑠 + 𝐾𝐷2𝑠

20. BLOCK DIAGRAM OF TWO AREA SYSTEM LFC WITH PID
CONTROL ACTION

21. PARTICLE SWARM OPTIMIZATION
• THE PROCESS OF PSO ALGORITHM IN FINDING OPTIMAL VALUES FOLLOWS
THE WORK OF AN ANIMAL SOCIETY WHICH HAS NO LEADER.
• PARTICLE SWARM OPTIMIZATION CONSISTS OF A SWARM OF PARTICLES,
WHERE PARTICLE REPRESENT A POTENTIAL SOLUTION.
• PARTICLE WILL MOVE THROUGH A MULTIDIMENSIONAL SEARCH SPACE TO
FIND THE BEST POSITION IN THAT SPACE.

22. VARIANT OF PARTICLE SWARM
OPTIMIZATION

23. FLOW CHART

24. PI CONTROLLER
PI out = Kp ACEi + Ki ACEi
2 dt

25. PI APPLICATION TO POWER SYSTEMS
• PI WERE USED IN POWER SYSTEM APPLICATION SUCH AS STATE ESTIMATION,
LOAD FLOW AND OPTIMAL POWER FLOW, POWER SYSTEM IDENTIFICATION
AND CONTROL ETC.
• OTHER APPLICATIONS TO NON-LINEAR OPTIMIZATION PROBLEMS ARE
GENERATOR MAINTENANCE, GENERATOR CONTRIBUTION TO TRANSMISSION
SYSTEM AND SHORT TERM LOAD FORECASTING ETC.

26. FREQUENCY RESPONSE FOR AREA -1

27. FREQUENCY RESPONSE FOR AREA -2

28. FREQUENCY RESPONSE FOR AREA -1 AND AREA -2

29. CONCLUSION
• THE PROJECT PRESENTS A CASE STUDY OF DESIGNING A CONTROLLER THAT
CAN BEAR DESIRABLE RESULTS IN A TWO AREA POWER SYSTEM WHEN THE
INPUT PARAMETERS TO THE SYSTEM IS CHANGED.
• TWO METHODS OF LOAD FREQUENCY CONTROL WAS STUDIED TAKING AN
ISOLATED POWER SYSTEM INTO CONSIDERATION.
• IT WAS SEEN THAT THE OPTIMAL CONTROLLER DESIGN BORE BETTER
RESULTS AND ACHIEVED DESIRED RELIABILITY UNDER CHANGES IN THE INPUT
PARAMETER. HENCE AN ATTEMPT WAS MADE TO EXTEND THE OPTIMAL
CONTROL DESIGN TO A TWO AREA NETWORK.