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- Open Access
- Total Downloads : 1703
- Authors : Ashish Dhanowa, Vijay Kumar Garg
- Paper ID : IJERTV4IS060964
- Volume & Issue : Volume 04, Issue 06 (June 2015)
- DOI : http://dx.doi.org/10.17577/IJERTV4IS060964
- Published (First Online): 25-06-2015
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Modeling and Simulation of an off Grid PV system for with Battery Backup for Remote and Rural Area Network
Ashish Dhanowa M.tech-EE Dept., UIET, KUK
Vijay Kumar Garg Asst. Prof., EE-Dept., UIET, KUK
Abstract – Solar PV systems are now popular everywhere in world. These systems generates electricity to meet the demands along with conventional resources but also electrifying the rural areas where grid facility not available. In this paper an off grid PV system for a domestic load (a house load) modelled and simulated in matlab.
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INTRODUCTION
Solar off grid PV system so called because there is no grid connection available and PV system work independently. For a house load an off grid PV system have components like modules, battery (if battery backup), controller converter and inverter (as most of appliances are running on AC). For whole system design it is necessary to estimate the load and then each component is selected as per ratings.
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Load Estimation
In a house following appliances are common and table 1 shows appliances with their rating and load estimations.
Table 1 Load estimations
LOAD
W AT TS
Q U A N T I
T Y
HO UR
/D AY
TOTAL WATTS
TOTAL WATTS- HOUR/DAY
TV
15
0
1
6
150
900
CFL
20
4
10
80
800
REFRIG ERATO
R
50
0
1
12
500
6000
FAN
40
3
8
120
720
COMPU
TER
15
0
1
2
150
300
TOTAL
960
1000
8720
8800
So a house load is = 1 kW or 8800 Wh/day
For 1 kW load following PV components are required as shown in table 2.
Table 2 PV Components and their ratings
COMPONENT
DESCRIPTION
RESULT
Load
Estimated
1 kW
PV array
Size
2.5 kW
Total panels
10
In series
2
In parallel
5
Panel power
295 Wp
Charge controller
Capacity
52
Number of controller
3
Inverter
Size
1.25 kVA
The PV panel or module has following specifications:
Table 3 PV module specifications
Parameter
Value
Peak power
295 watts
Module Efficiency
14.7%
Peak power voltage
36.51 volts
Peak power current
8.08 amps
Open circuit voltage
44.78 volts
Short circuit current
8.30 amps
Number of cells
72 cells
Max. System voltage
1000 volts DC
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PV ARRAY MODELING
PV array in matlab Simulink is a mathematical model which uses the equations of equivalent circuit model of solar cell. This PV array configure according to requirement of model. Figure shows a PV array:
Figure 1 PV array subsystem
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BUCK CONVERTER MODELING
A buck converter with fixed duty cycle is modeled to give constant output DC of 48V. The circuit and Simulink model of buck converter shown in figure below:
Figure 2 Buck converter subsystem
Figure 3 Buck converter model
Here values of inductor (L), capacitor (C), duty cycle (D) and PWM switching frequency () are:
> 0.0056 = 1.567
D = 0.42 and = 10000
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INVERTER MODELING
Here all the appliances need AC power for their working so the inverter is necessary in the system which gives AC output with desired level (120V/230V). Inverter in this model build by using PWM technique. Sine wave and triangular wave is compared to generate PWM which used to switching on/off semiconductor switches and DC input is converted in to AC. A transformer for step up of converted AC is used to get desire AC voltage level (230V here). Below figure shows inverter model in matlab.
Figure 4 Inverter subsystem
Figure 5 Inverter model
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OFF GRID PV SYSTEM MODEL WITH NO LOAD The models of PV array, Buck converter and Inverter is connected to make an off grid PV system model. Figure below shows the PV system in Matlab Simulink without load.
Figure 6 PV system Simulink model without load
At no load and standard operating conditions (1kW/2 irradiance and 25 operating temperature) following results are obtained.
Figure 7 Output Power & Voltage of PV array
Figure 8 PV array current & Buck converter output
Figure 9 Inverter Output
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OFF GRID PV SYSTEM WITH LOAD
Now model is connected to 1 kW load which is estimated in table 1. Figure shows the model with load and results obtained from simulation. These results are taken at standard operating conditions (1 kW/2 Irradiance and 25 operating temperature of array).
Figure 10 PV system with load
Figure 11 Output Power, Voltage & current of PV array
Figure 12 Buck converter & inverter (across load) output
8 BATTERY OPERATION
Battery in the off-grid system is for supplying load when there is no sun irradiance on the solar panels. Battery charged from array when load is less and excess power is generated by array and battery discharge through load when there is no power from the array. To prevent the under discharging of battery state of charge is monitored and when it less than 25% battery disconnected form the load by breaker. Below figure shows the battery in the PV system simulation.
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CONCLUSION
This study presents a simple but efficient off-grid photovoltaic system for a domestic load that can meet the daily load demands. The results show that the average daily load requirement of a house of 8800 Wh/day. In order to meet this load demand, an array of 10 solar panels required. Modeling and simulation of system shows the results for load and no load conditions at standard operating conditions.
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REFERENCES
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Design of an off grid photovoltaic system: A case study of government technical collage, wudil, kano state by Ishaq M, Ibrahim U Haruna and Abubakar Harnua from Bayero University, Kano, Nigeria. IJSTR volume 2, issue 12, dec- 2013.
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Appliance ratings from website – http://www.absak.com/library/power-consumption-table
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Simulation of grid connected photovoltaic system by Jingzhe Song (js4153).
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Circuit Simulation for Solar Power Maximum Power Point Tracking with Different Buck-Boost Converter Topologies by Jaw-Kuen Shiau *, Min-Yi Lee , Yu-Chen Wei, and Bo- Chih hen, Department of Aerospace Engineering, Tamkang University, Tamsui, New Taipei City, 25137, Taiwan.
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A PDF of Design Calculations for Buck-Boost Converters Application Report SLVA535A August 2012 Revised September 2012, by Texas Instruments.
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Inverter explanation and techniques https://www.wpi.edu/Pubs/E-project/Available/E-project- 042711-190851/unrestricted/PWM_Techniques_final.pdf
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Solar Panel Mathematical Modeling Using Simulink by Chandani Sharma (Research Scholar) Anamika Jain (HOD), Electronics & Communication Engg. Graphic Era University, Dehradun Uttrakhand, India published in Int. Journal of Engineering Research and Applications ISSN : 2248-9622, Vol. 4, Issue 5( Version 4), May 2014, pp.67-72.
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Using small-scale solar power plant to supply rural homes with electricity in the Ngan-ha locality (Cameroon) by Thang Dieudonné (Global Village Cameoon, Cameroon) and Fongnzossie Evariste (University of Douala, Advanced School for Technical Teachers Training, Douala).
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Website – www.pveducation.com
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Website –
http://www.openelectrical.org/wiki/index.php?title=Solar_Sy stem_Sizing