1. Optimal Over current relay co-ordination using Firefly Algorithm in Electrical Network: A nature inspired approach
A presentation on
Prepared by:
Snehal V Purani Nishant S Gandhi
Assistant Professor PG Student
Electrical Department Electrical Department
VIER University of Windsor
ICEEOT- 2016
3/5/2016

2. Flow of Presentation Relay constants and characteristics
Firefly Algorithm
Pseudo code of Algorithm
Analogy with Algorithm
Linear Programming method
Implementation Part
Result comparison and conclusion
References
ICEEOT- 2016
3/5/2016

3. Relay constants & Characteristics
Electromechanical Relay
Relay Characteristics A B C
Normal Inverse
0.92
0.02
0.149
Very Inverse
18.92 2
0.492
Extremely Inverse
28.08
0.13
Inverse Definite Minimum Time
0.14
0.0
ICEEOT- 2016
3/5/2016

4. Firefly Algorithm
Like particle swarm optimization and Meta heuristic in nature
All metaheuristic algorithms use randomization and local search.
Inspired from the behavior of fireflies developed by Dr. Xin She Yang in late
2007 & 2008.
Firefly algorithm is based on flashing pattern & light intensity emitted by fireflies.
Based on assumptions & hence nearby optimal solution for multi dimensional
non linear problem is achieved.
It may provide a sufficiently good solution to an optimization problem, especially
with incomplete or imperfect information or limited computational capacity.
The goal is to find the near optimal solutions and they are not problem specific.
These algorithms are approximate and usually non deterministic because there may
be some assumptions taken in the (solution) problem solving approach
ICEEOT- 2016
3/5/2016

5. Pseudo code OF FIREFLY ALGORITHM
Objective function f(x), where x=(x1,x2……..xd)T Generate initial population of fireflies xi (i= 1 , 2 , …..,n) Light intensity Ii at xi is determined by f(xi) Define light absorption co-efficient ϒ While (t<Max Generation) for I = 1:n all n fireflies for j = 1:I all n fireflies if ( Ij > Ii), Move firefly I towards j in d-dimension ; end if Attractiveness varies with distance r via exp [ -ϒr ] Evaluate new solution and update light intensity end for j end for i Rank the fireflies and find the current best end while Postprocess result and visualization
J firefly
I firefly
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6. Analogy of application
All fireflies are unisex so that they attract to other fireflies regardless of their sex , analogous to that all relays which are going to be coordinated have same characteristic.
Attractiveness is proportional to brightness & inversely proportional to distance , analogous to that Time of Operation is inversely proportional to fault magnitude & proportional to the time setting.
Brightness is determined by its objective function analogous to that time of operation is determined by relay setting parameters.
ICEEOT- 2016
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7. Linear Programming method
The relays are configured by adjusting time dial setting(TDS) of function properly in normal and fault conditions. The TDS adjustment is performed by using linear programming.
The said method is simple and easily implemented to solve the relay co-ordination problem.
In Linear Programming technique, the relationship between variables is linear which performance under the constraints to select the appropriate alternative between minimum or maximum value.
In this relay co-ordination problem , Time of operation is in a linear relationship with Time Dial Setting. The other terms which are included in the equation is considered as a linear function in their relationship.
The general linear programming problem can be expressed as a constrained optimization problem as follows:
A. X ≤ b , inequality constraints
Aeq.X = beq , equality constraints
Lower bound ≤ X ≤ Upper bound , bounded constraints
ICEEOT- 2016
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8. Implementation part
The radial feeder system is shown in the figure. The maximum fault current just beyond the bus are shown in the diagram 5000A, 4000 A and 3000 A respectively. The CT ratios are 1000:1 for all CT’s connected. Assume the plug setting of each relay is 1(100%). Initial time setting is 0.1s & minimum coordination time interval (MCT) is 0.25s. Assume IDMT Characteristics.
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9. calculation PSM for relay C ; (PSM)c = 3000/100 =30
Top = (0.14/((30) )) * 0.1 ; according to equation = 0.2s
If relay C will not operate in that case relay B will provide back up protection. This relay will operate after a time delay which is equal to minimum co-ordination Time interval.
Hence Top for relay B ; Top = = 0.45s
PSM for relay B ;
(PSM)b = 3000/300 =10
Top = (0.14/((10) )) * TDS
0.45 = (0.14/((10) )) * TDS hence , TDS = s
As the setting available is in the step of 0.1s . So the TDS is taken as 0.2s.
Now, Top by this TDS is calculated & it is,
Top = (0.14/((10) )) * TDS , Top = (0.14/((10) )) * 0.2 = s =0.6s
And with the same calculation for Relay A, TDS is 0.3 s.
ICEEOT- 2016
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10. Firefly Algorithm (FA) inputs
Objective Function: S=4.279*x(1)+4.979*x(2) *x(3)
In equality constraints g(1)= *x(1) *x(2)+0.3
g(2)= *x(2) *x(3)+0.3
Number of flies: 40
Iteration counts: 500
Alpha: 0.5
Betamin: 0.2
Gamma: 1
Dimensions: 3 (no. of relays)
Lower Bounds = [ ] ; (found by lower limit/constraints specified)
Upper Bounds= [ ] ; (found by upper limit/constraints specified)
ICEEOT- 2016
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11. Results comparison & conclusion
Time of operation is compared with Linear Programming & Firefly Algorithm and minimum time of operation is achieved using firefly algorithm.
The time of operation of the relay depends on the current settings , time dial settings , relay characteristics , type of relay & co-ordination interval.
As the result produced is near about optimal and because of its random nature the best result is obtained with large number of iterations.
Relay
TMS LP FA RA x1
0.127
0.126 RB x2
0.079 RC x3
0.032
0.031
ICEEOT- 2016
3/5/2016

12. References
X.S. Yang, Nature Inspired Meta-heuristic Algorithms, Luniver Press, Beckington, 2010.
S. S. Gokhale, Dr. V. S. Kale, “Application of the Firefly Algorithm to Optimal Over-Current Relay Coordination”, IEEE Conference on Optimization of Electrical & Electronic Equipment, Bran, 2014
Bhavesh Bhalja, R.P.Maheshwari, Nilesh G. Chothani, Protection and Switchgear, Oxford University Press, 2011.
IS-3842 , Indian Standards , Application Guide for electrical relays for electrical systems, 1966
The Math Works Inc., Optimization Toolbox, 2013.
Xin She Yang, Mehmet Kuramanoglu, Xingshi He, “Multi-Objective Flower Algorithm for Optimization”, ICCS 2013, Elsevier.
Indrajit N. Trivedi, Snehal V. Purani, Pradeep K. Jangir, “Optimized Over-Current Relay Coordination Using Flower Pollination Algorithm”, IEEE Conference on Advance Computing, Banglore, 2015.
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13. THANK YOU !!!
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