AIM OF PROJECT Battery Monitoring System Efficient usage of Battery Integrating solar panel real time data with building computer Storage of data Like EGAUGE METHODS OF S.O.C MEASUREMENT Voltage Measurement Specific Gravity Method Quantum Magnetism Integrated Current Method PROBLEMS ASSOCIATED : Better S.O.C Measurement : Capacity changes : Temperature Depth Of Discharge Effect Charge / Discharge cycles Self Discharge Charge Rate (C-Rate) dependence HOW TO INCORPORATE THESE FACTORS ? Piece Wise Linearization : Temperature effect C-Factor effect Depth Of Discharge effect Number Of Cycles effect Incorporate these factors through feed back control into Simulink Model

1. REMOTE SOLAR MONITORING
SYSTEM
Mamoon Ismail Khalid
Mohammad Ahsan Azim
Mohammad Hamza Khawaja

2. • Battery Performance is not reliable.
State Of Charge is not accurately known.
• Unawareness of Load / Consumption data by consumer.
PROBLEM STATEMENT

3. Storage is the most expensive of all expenditures in Solar PV :
• 100 AH Gel Regulated sealed Batteries: 28,000 RS/-
• 3 Batteries usually used
• We worked with 45 AH --- Cost 9200 Rs.

4. AIM OF PROJECT
• Battery Monitoring System
• Efficient usage of Battery
• Integrating solar panel real time data with building computer
• Storage of data
• Like EGAUGE

6. METHODS OF S.O.C MEASUREMENT
• Voltage Measurement
• Specific Gravity Method
• Quantum Magnetism
• Integrated Current Method

7. PROBLEMS ASSOCIATED :
Better S.O.C Measurement :
• Capacity changes :
1) Temperature
2) Depth Of Discharge Effect
3) Charge / Discharge cycles
4) Self Discharge
• Charge Rate (C-Rate) dependence

8. HOW TO INCORPORATE THESE FACTORS ?
• Piece Wise Linearization :
Temperature effect
C-Factor effect
Depth Of Discharge effect
Number Of Cycles effect
• Incorporate these factors through feed back control into Simulink Model

9. TEMPERATURE EFFECT & C-RATE
PIECE WISE LINEAR APPROXIMATION
0.05c
0.1c
0.2c
1c
2c

10. CHARGE/DISCHARGE CYCLES & D.O.D
For 30%
D.O.D

11. EFFICIENCY ALGORITHM
Set a 30% Depth Of Discharge floor!
• Use Parallel Battery Banks
• Connected through Power MOSFETS
• If Battery 1 S.O.C == 70 % ; Discharge Battery 2
• If Battery 2 S.O.C == 70% ; Discharge Battery 1 again
• Continue repeatedly

12. BATTERY COST FEASIBILITY :
If 1 cycle = 1 day (assumption)
50 % D.O.D :
Approximately 650 Cycles
30 % D.O.D:
Approximately 1700 cycles
After 1700 days :
Cost 1 = (1700/650)* 3 *30000 = ~ 235000 Rs
Cost 2 = 3(30000) = 90,000 Rs!!

13. SIMULINK MODEL
CHARGE
INTERGRATOR
No Of
Charge
Cycles Of
CYCLES RELAY Battery
SWITCHING
Charge Cycles
Capacity
Temperature Effect and FINAL
CAPACITY

14. EXPLANATION OF INDIVIDUAL BLOCKS

15. SOURCE
• Charging = 8Amp Discharging = 9Amp
• C-rate = 0.2

16. • function inst_charge2 = fcn(current2,storedCharge2)
•
• if (current2>0)
•
• inst_charge2=storedCharge2+current2*0.001;
•
• if(inst_charge2>=1620)
• inst_charge2=storedCharge2;%protect from over charging
• end
•
•
• elseif(current2<0)
•
•
• inst_charge2=storedCharge2+current2*0.001;
•
• else
• inst_charge2=storedCharge2;
•
• end
• end
• Stored Charge is the Charge that is previously
stored in the battery.
• Ceiling of 1620 – Prevents Overcharge
• If CURRENT + ve : INCREASE the charge
stored in the battery using q=it
• vice versa for discharging.
• If CURRENT = 0 : Charge kept constant.
• 0.001 is the sampling time.
CHARGE INTEGRATOR
COULOMB COUNTING/STATE OF CHARGE

17. Stored Charge on the battery.
STATE OF THE CHARGE vs Time

18. RELAY
• Decision of which battery to discharge.
• 30% D.O.D floor - to maximize the life of a battery.
• After 30% discharge – RELAY will shift the load to the
other battery!

19. Shifting Between two batteries
Y=0; load on battery 1.
Y=1; load on batter 2.

20. Calculating number of
discharge cycles
No_Cycles=fcn(previous_storedCharge,next_storedCharge,
inst_capacity,u3)
• if(next_storedCharge/inst_capacity <= 0.7 &&
previous_storedCharge/inst_capacity > 0.7 )
• No_dischargeCycles=u3+1;
• else
• No_dischargeCycles=u3;
• end
• end
If the state of charge is 70% we
count that as a complete
discharge cycle.
Hence if the state of charge
decays to 70% we know that
one cycle has been traversed.
CHARE CYCLE COUNT

21. Number of
discharge cycles
• Discharge cycle number
progressively increases
• due to continuous
discharging and charging of
the battery

22. Number of cycles
and Capacity
function y=fcn(capacity_feedback,no_cycles,initial_capacity)
• if(capacity_feedback<=0)
• y=0;
• elseif(no_cycles<=4)
• y=initial_capacity;
• elseif(no_cycles>4 && no_cycles<=6)
• y=initial_capacity*(-.025*no_cycles*100+110)/100;
•
• elseif(no_cycles>6 && no_cycles<=8)
• y=initial_capacity*(-.0375*no_cycles*100+117.5)/100;
• elseif(no_cycles>8 && no_cycles<=10)
• y=initial_capacity*(-.05*no_cycles*100+127.5)/100;
• else
• y=initial_capacity*(-.0875*no_cycles*100+165)/100;
• end
• < 400 discharge cycles :
• capacity ~ UNCHANGED
• 400 -600
• 600 – 800
• 800-1000
• >1000
linear piecewise
approximation

23. Decrease in
capacity with
number of cycles
Governed by Piece-Wise Linear
Transformation

24. Dependence of
capacity on c-rate
and temperature
• function y = fcn(y1,temp,capacity,rated_capacity_ah,c_rate,c,rated_capacity,
current,capacity_charging)
• rated_capacity=1620;
• rated_capacity_ah=45;
• temp=45;
•
• if(current>0)
• y=capacity_charging;
•
• else
•
• c_rate=(-1*current)/rated_capacity_ah;
• if(c_rate>= 0 && c_rate<=.2)
• c=-.75*c_rate+.85;
•
• elseif(c_rate>= 0.2 && c_rate<=1)
• c=-.50*c_rate+.80;
• elseif(c_rate>= 1)
• c=-.05*c_rate+.35;
•
• end
• y=c;
• c=100*c;
• y1 = 0.72 * temp + c;
•
•
C-rate has an inverse relationship
with the capacity of battery.
Standard testing condition at 25o C
Capacity increases as temperature
changes from 25o C to 40o C
Capacity decreases as temperature
decreases from 25o C .

25. Calculating the final resulting capacity of the
battery
y=rated_capacity-(1-y1)*(rated_capacity)-
(rated_capacity-capacity);
• End
•
• if(capacity<=0)
• y=0;
Output final capacity =y
Final capacity incorporates the change
due to :
•No. of Cycles
•Temperature
•C-rate
This final capacity is then fed
back into the starting blocks as
our capacity is now altered !!

26. SIMULATION WORKING AND RESULTS

27. Charge Capacity
State Of the Charge
No of Cycles
Charge
Capacity
State Of The Charge
No Of Cycles
CHARGE CAPACITY
OF BATTERY
STATE OF CHARGE
CHARGE CYCLES