A Novel Design of Sustainable Solar Home Power ...

Dr S.N. Singh et al. / International Journal of Engineering Science and Technology (IJEST)

A Novel Design of Sustainable Solar Home Power Lighting: A Case Study with Indian Restaurant Dr S.N. SINGH Electronics & Communication Engineering National Institute of Technology, Jamshedpur(India) - 831014

NISHA KUMARI Electronics & Communication Engineering National Institute of Technology, Jamshedpur (India) – 831014 Abstract: Indian restaurant popularly known as eatery house /dhabas uses grid assisted, battery backed up inverter for continuous supply for lighting. In case of prolonged grid cut off, battery do not get charged to its full strength and seizes to function before time. In this study, a novel design of solar inverter has been proposed which eliminate the grid dependability and provide 24 hour power to these dhabas which are pollution free and utilizes solar radiation as fuel which is abundantly available. The PWM technology is used to charge the battery of inverter in sharing mode with grid supply, due to varying PV energy throughout the day(sun hour), and use of dual battery used for continuous supply as well as storing charge alternatively are unique features to maintain sustainability. The impact study carried out have resulted satisfactory performance. The implementation of solar power lighting technology against conventional k- oil lamp increases sale figure resulted in uplifting socioeconomic status of restaurant owners also. Keywords: Solar inverter, PWM charger, Fuzzy control, MATLAB, Grid etc 1. INTRODUCTION Electricity reaches only a limited portion of the world’s population. More than 1.6 billion people worldwide lack connection to an electrical network. Candles and kerosene / oil lamps are still some of the most common basic options for lightning, with dry cells and automotive batteries used to power radios, televisions and small apliances.These sources are low quality, cumbersome expensive and often dangerous, but they are the only available option to rural families, resturarents small farmers, business, offices and institutions. The solar home lighting system, a wireless solar power system originally designed for rural and pen-urban customer in India, enables families to improve their productivities generating activities in the evening while their children can have better light for studying. Many standalone and hybrid power supply system have been developed by many authors in the past but sustainability and cost effectiveness have not been considered and thought much. In the proposed scheme, sustained power supply using PV energy as a primary source have been modeled and developed. Its impact study has been carried out as a case study in Indian restaurant popularly known as ‘ Eatery house/Dhabas’ located in almost all common places like parks, offices courts, industries, cinema halls, markets, bus/railway stations, colony etc. These dhabas, owned by potential youth of village or town, serve food items to customers throughout day and late hours of night. 2. SYSTEM MODEL DESCRIPTION The solar home light model consists of the following units as shown in Figure (1) namely:  Solar PV module  Battery charger  Battery bank  Intelligent control unit

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Figure 1: Block Diagram of Proposed Solar (PV) Power Supply Scheme

2.1. Solar Photovoltaic module A solar photovoltaic module is the basic element of each photovoltaic system. It converts solar energy into DC electricity when sunlight falls on its surface. This DC signal is converted to AC by inverter to meet AC load requirement of houses. 2.2. Solar inverter cum charge controller with intelligent logic control Solar Inverter converts DC power from battery, charged from PV source, to AC power compatible with the utility and AC loads. This unit consists of solar inverter cum charge controller with intelligent logic which controls the charging of battery from solar or mains or both with solar as priority in sharing mode. This system monitors the battery charging status and accordingly decides to charge the battery either from solar or from mains or both in sharing mode. 2.3. Battery A device that converts the chemical energy contains in its active material directly into electrical energy by means of an electrochemical reaction. Low maintenance tubular type batteries are provided with the system. Battery deep discharge, over charge protections are incorporated inside the solar converter. The battery charge is controlled through constant charging regulator module using PWM technology. Design incorporate auxiliary source i.e. grid which charges the battery in sharing mode with solar (PV) as first priority to charge battery attaining full voltage i.e, 13.4V. 3. WORKING PRINCIPLE Design incorporates PV module which charges battery in sharing mode with switch S3 and S4 with solar as first priority and feed power to load through inverter. The circuit model is shown in Figure (2).The use of dual battery 2x80Ah (i.e., B1 and B2) ensures the power delivery to load(s) i.e. Lighting and Fan(s) for 24 hours. One of battery (say B1/B2) gets charge through S1 while other switch S2 deliver power to load. The inverter takes input from 12V battery source (B1 and B2) and converts 220V, 50, Hz supply compatible to grid and ac load. Transistors (T1 and T2) are turned on alternatively for 10 ms duration controlled through frequency generator logic circuit producing 50 Hz output with step up voltage of 220V. Diodes (D1 and D2) are surge protecting devices to transistors T1 and T2 and acts as a freewheeling action. Under no load condition switch S5 is automatically become de-active and thus losses are minimized under ideal condition. In case of Low battery condition (10.4V) due to cloudy season or no insolution , Power is drawn from grid through S6 till battery get its charge from bidirectional inverter through diodes D3 and D4 making T1 and T2 off . Loads while fed from battery source are priotorised to accommodate peak loads or excess loads. The Transistors T1 and T2 are MOSFET devices (IRF540) rated for sharing 300W peak load.

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Figure 2: Circuit Model of Solar Inverter (PV =75Wp, Battery = 80Ah, Load = CFL 20W)

4. DESIGN OF SYSTEM MODULE The system module design includes PV module, Charging unit and Inverter etc. 4.1. PV Module design: The PV module design has been computed on the basis of load consumption of an eatery house/dhabas .The data acquired is tabulated and shown in Table 1. Table 1: Load Profile Load Profile (Watt x Hour x Number) 10 W CFL * 4 Hr * 2(No) 40 W Fan * 4 Hr * 3(No)

S. No 1 2 3

Peak Consumption (Wh) 80 480

Electrical Appliance(s) Total

1040 2100

The PV design is based on 50% sharing with grid supply (Equation (1) and Equation (2)) PV Rating (50% Sharing) T

P

W

.

Where, 1.5 = Safety Factor, 6.2 = Sun Hour (hr), ½ = 50 % sharing PV R No. of module

W

.

=112.9 Wh

.

S

(1)

=2(approx.) (2)

4.2. Battery Capacity The battery capacity is designed (Equation.3 and Equation.4) to feed the load requirement of house. Battery Capacity

T B

L

W V

=175Ah = 180Ah (2x80Ah) (3)

4.3. Inverter design Inverter capacity = Load requirement at a time=300 W (peak Load)

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Dr S.N. Singh et al. / International Journal of Engineering Science and Technology (IJEST) (4) 4.4. Control Strategy: Fuzzy algorithm for sharing of source current for charging Fuzzy logic control has been used to charge the battery on getting its inputs sun radiation and current battery status. The output variable of this controller is the adaptive duty cycle i.e. sharing time interval of grid/DG or turn-on time period of the battery. Since these input parameters represented by membership function are to be fuzzified, equation (5), the max-min method of fuzzification, is used to set the fuzzy rules of the controller. μ = (α1 μ1) (α2 μ2) (5) Where, μ1 and μ2 are membership functions α1 and α2 are variables Fuzzy algorithm has been changed back by using the method of defuzzification. Subsequently, the approximate centre of gravity (COG) method, supposed to be the most accurate method to get a crisp value i.e. sharing time, is used for the defuzzification, as shown in equation (6). COG

∑

µ ∑

µ

(6) Where, μi = action of the ith rule would dictate μ(i) = truth of rule Input Variable: 1) Battery Critical s: trimf (0 20 30) Base: trimf (25 40 70) Peak: trimf (65 80 100) 2) Sun Radiation Low: trimf (0 20 30) Medium: trimf (25 40 70) High : trimf (65 80 100) 3) Output variable: Grid Low: trapmf (0 30 75) Grid High: trapmf (30 75 100) A CASE STUDY: Actual Calculation for operational time in % for the given battery status (28%) and sun radiation (66.8%) has been given below: Rules fired are 2, 3, 5 and 6 Strength of rule 1

:

[L (0.165)  M(0.165)]

=

0.165

Strength of rule 2 Strength of rule 3 Strength of rule 4

: : :

[L (0.165)  H(0.245)] [L (0.165)  H(0.245)] [M (0.245)  H(0.245)]

= = =

0.165 0.165 0.245

Where, L: Critical (Low), M: Base (Medium), H: Peak (High) Output Variable using CENTROID Method (Equation 6): 75 0.165

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30 0.165 0.165 0.165

75 0.165 30 0.245 0.165 0.245

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Dr S.N. Singh et al. / International Journal of Engineering Science and Technology (IJEST) = 50.067 5.

RESULTS AND DISCUSSION

5.1. Validation of Control strategy with MATLAB software The computed data has been validated with MATLAB software as shown in Figure (3),(4),(5) and (6)

Figure 3: Fuzzy Rules used in Simulation

Figure 4: Membership function for Sun Energy and Grid

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Figure 5: Rule Viewer

6. Performance Evaluation of System The prototype unit developed for 300W has been tested in laboratory and the following tests has been carried out 6.1. Charging of Battery The charging current of Battery (80Ah) has been monitored for an autonomy period of one day(10hr) and depicted in graph as shown in Figure 6. 6.2. Power Sustainability The power sustainability has been maintained by assigning priority loads. Critical loads were assigned top priority and other loads in descending order of their use. Power monitoring data throughout day (24 Hour) for Battery status 10.4 -13.8V has been observed.

Figure 6: Battery charging voltage

6.3. Sensitivity Analysis 6.3.1. PV power delivery and saving in electricity The system has been tested under varying climatic condition throughout the year. The power delivered by PV system, as monitored, has been depicted in graph (Fig. 8). 6.3.2. Efficiency Load variation and its impact on efficiency has been monitored and shown in graph in Figure (7).

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Figure 7: Graph showing variation (%) in Saving and variation of load efficiency

6.3.3. Comparative study A comparative study has been carried out between the proposed system and conventional systems like PV stand alone, PV-grid and Grid Battery and results were recorded. 6.3.4. Working Economy The cost of the system for 750VA/300 Watt is computed and cost of system has been computed (Table 2). 7. IMPACT OF SOLAR INVERTER SYSTEM: A CASE STUDY A solar powered dhaba (Figure 10) located in the mid city of Jamshedpur was adopted to study the impact of design model of power supply to provide light during evening. Petromax and Kerosene oil lamps were being used in these dhaba during grid failures (load shedding) which were causing inconvenience to customers and owner during evening hours. The conventional inverter was used to attract the customer but frequent failure of grid could not charge the battery to its fullest strength and thus sustainability of power could not be maintained. This could become possible with the use of solar inverter only. During investigation it was observed that most of customers were leaving the place due to inadequate light and safety. The impact of solar inverter could be able to bring benefits like: a) Pollution free atmosphere b) Saving in budget towards the cost of fuel(kerosene oil) To maximum value of around Rs 300 per month. c) Reduction in medical expenses d) Food quality improved e) Services hour increased up to late hour f) Safety etc. Table 2: Cost Calculation of proposed system Cost S. Rating Item(s) (Rs) No 1 PV Module 2*75 WP Rs 15,000 2 Battery 150 Ah Rs 10,000 3 SOLAR Inverter 750 VA Rs 5,000 4 Maintenance per year Rs 1,000 Total Rs 41,000

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Fig.8: Solar dhaba

8. CONCLUSION AND FUTURE WORK In this project study, the design of a novel scheme of solar inverter has been developed with an objective to save grid power and creating a pollution free environment. The performance characteristic has been carried out and found to be well suited to these dhabhas. The technology used in this project may bring a green revolution in electrification of remote houses running dhabhas or charging station. The cost effectiveness of inverter and related accessories will attract more potential youths to adapt and run their own shops. REFERENCES [1] [2] [3] [4] [5]

J.S.R. Jang, C.T. Sun, E. Mizutani, “Neuro-Fuzzy and Soft-Computing: A computational approach to learning and machine intelligence”, Prentice Hall of India pp 13-63 (1997). Shehu, S and George Vachtsevanos,”Robust Stability of Fuzzy Logic Control Systems”. American Control Conference (.1995). Tanaka, K and Ugeno,”Stability Analysis and Design of Fuzzy Controller”. Fuzzy sets and systems (1992). Juang, C.F, Lin C.T,”A Recurrent Self-Organizing Neural Fuzzy Inference Network”, IEEE Trans. Neural Networks 10, pp. 828-845(1999). S.N.Singh, et al, “Sustainable Solar Power Generation”, Journal of ieema Dec pp 128-131 (2010).

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