a design of utility/dg interfaced adaptive solar (pv) home...
TRANSCRIPT
A design of utility/DG interfaced adaptive solar (pv) home green power
generator and socio-economic impact in Indian rural society
Keywords: Off-grid power supply, Solar Hybrid System, Single Pulse Width Modulation (SPWM), State of Charge (SOC), Diesel Generator (DG).
ABSTRACT: In the present study an intelligent, adaptive solar (PV) power supply system has been proposed to minimize the use of DG source being used as an standby source during grid off period in a weak area of grid connected rural house. The design aspect of components of PV system such as PV sizing, Battery and Converter (Inverter) etc has been designed for varying load shading energy requirement. The prototype unit has been developed for a rural house against max anticipated load shading for energy requirement of 2400Wh per day. Simulation study with MATLAB software has been carried out to analyze the quality of power performance of system has been carried out to verify design objective and optimal operational feature of the system.
001-006 | JREN | 2012 | Vol 1 | No 1
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Journal of Research in
Energy An International Open Access
Online Research Journal
Authors:
Singh SN and Jha RK.
Institution:
1. Department of Electronics
Engineering,
National Institute of
Technology, Jamshedpur
(India).
2. Department of
Electronics Engineering,
National Institute of
Technology, Jamshedpur
(India).
Corresponding author:
Singh SN
Email:
Web Address: http://ficuspublishers.com/
documents/EN0002.pdf.
Dates: Received: 02 Jan 2012 /Accepted: 05 Jan 2012 /Published: 23 Jan 2012
Article Citation: Singh SN and Jha RK. A design of utility/DG interfaced adaptive solar (pv) home green power generator and socio-economic impact in Indian rural society. Journal of Research in Energy(2012) 1: 001-006
An International Online Open Access
Publication group Original Research Paper
Journal of Research in Energy
Jou
rn
al of R
esearch
in
En
ergy
INTRODUCTION
With the rapid growth of population, the energy
demand is increasing day by day where as resources of
grid supply are diminishing. As a result, further
expansion specially in remote rural sectors of the
country have become almost standstill. Load shading
has become a common feature of grid supply system. DG
sets are being used as an alternative source in pace of
the grid power supply but due to heavy expenditure on
the fuel consumption, maintenance and pollution of
environment, need has been felt to use green low cost
power supply sources like solar, wind electricity etc to
supplement the grid power. Many effort have been made
to integrate the solar power supply with grid as reported
by many authors [Baharuddin Ali, 2009; Sopitpan, 2000;
Saha; Lindgrin, 2002] but control features like
intelligent, adaptive load power control to minimize the
operational time of DG has not been thought much.
In the present study, a modular 300W solar
power system incorporating intelligent, adaptive load
power controlled features have been proposed to achieve
the above objective.
System configuration and -operation
The PV system (Fig. 1) consists of the
following :PV module
Battery
Bidirectional Converter
Controller unit
Grid and DG power source
The primary source of supply to rural houses is
the grid power. Load power is managed either by grid or
alternatively by a DG source. The proposed system
works as substitute of DG set Power converter unit of the
PV system takes the low 12V DC voltage input from PV
source, stored in battery, as shown in Fig. 2 and convert
it into usable 220VAC output with the help of a centre
tapped transformer (Tr) based push-pull configured
MOSFET inverter circuit. The controller circuit generate
PWM pulses with the help of IC 4047 to activate
transistors (2N3055) T1 and T2 alternatively producing
AC voltage across the load. The intelligent, adaptive
control action of the controller perform load power
management with PV source during grid off period and
thus monitor and manage to deliver continues power to
load. DG set is connected to load only when the PV
battery while supply power to load reaches a discharge
level of 10.8V observed during prolonged grid off period
and remain on till the grid supply is restored or battery
become fully /sufficiently recharged a level of 12.8V-
13.8V. The charging operation is performed by PV
system and /or converter (rectifier) circuit comprising of
diodes D1 and D2 through S1, S2/S3 switch while
transistors T1 and T2 remain off.
Optimal design of pv and battery sizing of
components of system [Singh, 2008; Rashid, 2004;]
PV Sizing
The empirical formula based on energy balance
equation has been used to compute the optimal size of
PV module for critical load as stated below :
PV Cell Rating (PPV) = (PTL * S.F) / Sun hour [watt] (1)
002 Journal of Research in Energy (2012) 1: 001-006
Singh et al.,2012
Fig.1 Block schematic of a Grid assisted solar power
converter with a standby DG Set
Fig.2 : PV system integrated with Grid supply and DG
as a standby source
Where,
Sun hour = 6.2 for adopted area; Safety Factor
(S.F) = 1.5 for cloudy weather; PTL is total load energy in
watt- hours (i.e total load power over a period of 24 hours
assuming hourly load power (PL) as constant.)
24h
PTL (Wh) = Σ (PL) Watt-Hours (2)
0hr
The optimal number of PV module = PPV / Standard PV
module rating (3)
The design of components of solar (PV) system
for PV is computed using Eq.1 – Eq.3 for different
varying daily load power i.e energy requirement of rural
houses as depicted in Table 1.
Battery Sizing
The battery (Deep Cycle ) stores the energy to a
maximum value as per average load power requirement.
Battery capacity (Ah) = PTL/(12V*SOC (4)
Where,
SOC (State of Charge) = 80%
The design of Battery sizing is computed using
Eq.4 for different varying daily load power i.e energy
requirement of rural houses as depicted in Table (2 )
respectively.
Technical Specifications Of Prototype System
Module
The prototype system has been designed based
on the load energy sharing by grid and DG observed
during investigation in a literacy house.
Data acquired from the field during
investigation has been depicted in Table 3.
From the Table 3, it is apparent that an average
load energy sharing by DG varying from 630-900 Wh.
Accordingly the PV system has been developed with the
following specifications to meet this energy requirement
to reduce the use of DG.
Performance of system
A prototype system was installed in small
vocational literacy house of adopted village in the
outskirt of Jamshedpur (India). Performance of the
system is considered in terms of the Technical
parameters as well as socio -economic impact in rural
society as follows:
Journal of Research in Energy (2012) 1: 001-006 003
Singh et al.,2012
Table 1 : Number of PV module
Load Energy
(Watt-Hours )
No. of 75 Wp
PV module
300 1
500 2
1000 3
2000 6
Month DG
Wh
Grid
(Wh) Month
DG
(Wh)
Grid
(Wh)
Jan 630 1700 July 800 1600
Feb 800 1500 Aug 710 1600
Mar 750 1550 Sept 740 1660
Apr 900 1500 Oct 800 1200
May 900 1500 Nov 700 1700
Jun 700 1700 Dec 800 1500
Table (3) Power sharing between grid and DG
During period of one year 2009-10
Load Energy
(Watt-hour)
Battery Capacity
(Ah)
300 - 500 80 Ah
1200 150 Ah
2000 300 Ah
Table (2): Battery capacity
Load Energy = 2000 - 2400 watt-hours over
24 hours in a day
PV size = 2*75 Wp, 12 V @STP
Power shared = Grid (1200-1700 Wh) supple-
mented by PV system Module
(approx 900Wh max),
Battery Size = 2 * 80Ah, 12 V low self dis-
charge inverter grade tubular
lead acid battery
Load = CFL lamps , Fans, Pump and
Electrical equipment
Converter
Mobility
=
300 /750VA, 12VDC ~ 220 V
SPWM AC , 50Hz
Portable
Technical:
Quality Of Power
The output waveform of the inverter was
recorded in the oscilloscope as shown in Fig. 3. The
wave form were simulated by the MATLAB program
also and the qualitative analysis of the waveform has
resulted in a low Total Harmonic Distortion (THD) (<
5%) sin wave.
Cost Saving In The Use Of Dg
The use of PV integrated with Grid-DG network
was monitored over a period of one month in the month
of June 2011during which a maximum reduction of 80%
in DG operational time was observed resulting in large
saving in the cost of diesel fuel.
Efficiency of system :
The efficiency of the inverter system was found
to be almost constant value in the range of 97% or more
under varying load conditions as shown in Fig. 4 leading
to an indication of low power loss and maximum
utilization of energy resources.
Sensitivity Analysis On Load Variation
PV system load sensitive analysis were carried
out under three different environmental configurations
and the consistency in output power supply was
observed . The response time to step change in load is
also 3ms or less .
DISCUSSIONS
The proposed PV system reflect the following
superiority over conventional system :
Grid quality power has been obtained due to PWM
technology having THD value less than 5% as
compared to 10-15% as achieved in the
conventional system.
The efficiency of the proposed model using
MOSFET devices is high due to low loss and remain
almost constant in the range of 96% as compared to
85-90% of BJT based conventional inverter system
The response i.e settling time of the system on load
variation is within 3 ms which is the desired limit for
an uninterrupted power supply. Hence system can
be used for computerized audio visual equipment
used in literacy claases without interruption. The
conventional system lack in this feature due to high
switchover time generally found in the range of 1
second or more.
Impact Study Of Solar Powered Literacy Houses
In Rural Society [Annual Report Jan Shikhan Sansthan
2011]
A solar powered rural vocational literacy house
(Fig. 5) located in the outskirt of the Jamshedpur city in
the state of Jharkhand (India) was adopted to study the
impact of design model of sustainable PV power supply
made available to literacy house. The study [Annual
Report Jan Shikhan Sansthan 2011] revealed that
although the house is connected with grid supply source
but during its frequent failure or load shedding period,
petromax and kerosene oil lamps or DG set were being
used for lighting and other related work in these training
004 Journal of Research in Energy (2012) 1: 001-006
Singh et al.,2012
Fig 3 : Control PWM pulses(Left) and Output
waveform of converter(Right) Fig 4: Normalized load (300W) Vs Efficiency
Normalized Load
Eff
icie
ncy
centers which were causing inconvenience to potential
youth and women clientele group trainee/ learners..
During investigation, it was observed that most of
learners were leaving the house due to inadequate light
and costly affair due to DG causing inconvenience in
continuing their study/training leading to unsafe
environment. This could become possible with the use of
proposed sustainable solar powered converter after
replacing the conventional lighting system and
integration of PV system with grid/DG unit only. The
impact of solar inverter and its use could be able to bring
many benefits and upliftment in rural society such as :
a) Approximately 30-40% potential youth were trained
in income generating vocational skill formation/or
up-gradation trades like electrician, plumbing, dress
designing, carpentry, domestic electrical and
mechanical appliances, pump operation, two
wheeler repairing etc and become self/wage
employed.
b. Female illiterate and neo-literate beneficiary
specially belonging to socially and economically
backward society were trained in cottage industry
products (candle, agarbatti, masala, pickle, jam-jelly
and papad making etc), agro-based products like
vermi compost and mushroom, garment/bag
making, jute product items, handicraft items, photo
frames, interior home decorative items, toy making
etc. They could be able to start small scale
production units at individual level or through self
help group(s) and thus supplementing the income of
their poor family.
c. School dropout children, along with their mother
started going to literacy schools in evening hour and
thus literacy rate would be increased from 30% to
60%.
d. Increase in intake of potential youth, undergoing
training in vocational literacy classes, took place due
to availability of ample light and safety.
e. Pollution free atmosphere could be maintained
inside and outside literacy house.
f. Saving in budget took place towards the cost of fuel
(kerosene oil) to an average value of around Rs 300
- 400 per month.
g. Reduction in medical expenses, due to pollution free
Journal of Research in Energy (2012) 1: 001-005 006
Singh et al.,2012
Fig 5: A visit to solar powered vocational literacy training centre
and clean environment, could be possible in each
family visiting literacy rural house.
h. Service hour of profession resource persons in
taking classes increased up to late hours in the
evening due to availability of 24 x 7 days power
supply.
Technical Benefits
Apart from the socio economic impact, The
following benefits can further be added:
Sustained green pollution free power output
Grid power saving to an extend of 40% or more.
CONCLUSIONS
Solar (PV) - grid hybrid system has a great
potential in future especially in rural sector as one of
renewable energy technologies. The hybrid technology,
integrating PV with grid , offers solution to local power
generation in terms of providing uninterrupted (i.e 24x7
days) reliable qualitative and high efficient supply
without /with minimum use of standby DG at an
effective cost. More number of PV modules with higher
capacity of battery, if cascaded in parallel, may make the
system independent of use of the grid as well as DG
standby source.
The easy installation and maintenance free
operational feature of the PV system has gained more
popularity among the rural masses. The successful
implementation of hybrid PV-Grid/DG system has
following outcomes :
Generating green electricity and meeting increasing
household load demand of a rural house with
minimum use of DG sets as well as preserving the
nature.
Minimum use of DG set reducing the maintenance
and operation cost of the system Cost
Effective i.e the minimum running hours also
reduces the maintenance cost of a diesel generator.
REFERENCES
Baharuddin Ali. 2009. “Hybrid photovoltaic diesel
system in a cable car resort facility” European journal of
scientific research 26(1):13-19.
Sopitpan S. 2000. “ PV System with / without GRID
Backup for Housing Applications”, IEEE 1687-1690.
Saha. “Grid interfaced Urban Domestic Power pack”
Proceeding of 29th IEEE photovoltaic specialist May 19-
24 Neworlians Louiana. 1625-1629.
Singh SN, Singh AK. 2008. “Modeling and dynamics of
a PWM sinusoidal Inverter for water pumping system
for use in agriculture and household application”, Journal
of ieema Jan 114-122.
Lindgrin 2002. “A 110W inverter for photovoltaic
application”, Published in International Journal of
Renewable Energy Engineering, April.
Rashid MH. 2004. Power Electronics: Circuits, devices
and applications, Pearson Education.
Annual Report Jan Shikhan Sansthan. 2011.
006 Journal of Research in Energy (2012) 1: 001-006
Singh et al.,2012
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