Wind Diesel Hybrid Power Systems

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Wind Diesel Hybrid Power Systems
Ranjith J. Nair
Department of Electrical Engineering,
PVG’s College Of Engineering And Technology,
Pune, Maharashtra State, India-411009
[email protected]
Mobile: +919421028336,+918087778819
Abstract--The population explosion that has taken place in
recent times has led to an outburst in the demand of
electricity. The current eco-fad of trying to produce an ever
greater percentage of electricity from sources like wind has
some consequences on land use that are poorly thought out
.In addition to this, the velocity and direction of wind and also
its availability affects the production of electricity from wind.
This gave rise to the idea of hybrid power systems.
The hybrid system presented in this paper comprises
of a Wind Plant acting as the renewable source of energy and
a Diesel Generation System serving as the conventional
source of energy. The problems faced in conventional wind
power system are coped-up to a greater extent in case of the
hybrid power generation system of wind i.e. THE WIND
DIESEL HYBRID POWER SYSTEM. The following article
enlightens the principle of integration of wind energy with
diesel generating sets relying on complex controls to ensure
correct sharing of intermittent wind energy and controllable
diesel generation to meet the demand of the usually variable
load. It is used for larger systems with demands over ~ 100 kW
peak load up to many MW. Batteries, if used, store power to
cover short lulls in wind power. Because an existing diesel
plant frequently represents a substantial investment, it often
appears more cost-effective to retrofit wind turbines, system
controls, and any other required ancillary components to the
existing power system. Hence wind-diesel hybrid power system
is economically viable for developing countries like India
since the cost of setting up a new power plant altogether from
ground zero can be reduced.
Index Terms—Hybrid Power Systems, Penetration, Power
Systems, CHP technology

diesel power generation, but diesel power generation is very
inefficient when the load is a small percentage of the rated
power of the engine. The fact that every time there is a need
for power, the engine has to operate, makes it very
inconvenient and reduces the efficiency and lifetime of the
power generation system.Hence, the role of hybrid power
system comes into focus.
A wind-diesel hybrid power system combines diesel
generators and wind turbines, usually alongside ancillary
equipment such as energy storage devices, power converters,
and various control components, to generate electricity. They
are designed to increase capacity and reduce the cost and
environmental impact of electrical generation in remote
communities and facilities that are not linked to a power grid.
Wind-diesel hybrid systems reduce reliance on diesel fuel,
which creates pollution and is costly to transport. These
systems offer different penetration levels, with a large choice
of technical solutions.
II. CHALLENGES BEHIND THE WIND DIESEL HYBRID POWER
SYSTEM.
By their nature renewable energy is stochastic and it varies
with the resource. We prefer a constant power supply for our
household utilization. Turning the variable energy in the wind
into constant, consistent energy we can use can be a difficult
task–the more energy from the wind, the more complex the
task would be.
III. CLASSIFICATION OF WIND DIESEL HYBRID POWER
SYSTEMS.

.
I.INTRODUCTION
Generation of electricity from wind energy is
consumer and environment friendly, it requires shorter
construction time compared to thermal, nuclear generation and
is cost competitive. It becomes one of the most competitive
sources of renewable energy. However, wind power has some
disadvantages. For example, wind power is considered an
intermittent power supply because wind does not blow 100%
of the time. The cost of grid connection in the rural areas is
very high due to a low density of population; therefore various
organizations have turned to explore alternative solutions. One
of the most economical and reliable alternatives is to use

Wind/Diesel system can be classified according to
different levels of wind penetration.
(Where penetration [2] can be defined as follows):
Instantaneous Penetration =

Wind Power Output (kW)
Primary Load (kW)

– Voltage and frequency control.
– Reactive power.
Average Annual Penetration =

Wind Power Output (kWh)
Primary Load (kWh)

1

A. Diesel Generators:

– Total energy savings.
– Loading on the diesel engines.
– Spinning reserve losses/efficiencies.

The generators that can be turned on with short notice are
usually used. They usually require a lot of maintenance. Their
role depends on system .They must have a wide range of
control.

TABLE I [5]
SYSTEM PENETRATION

Peak
Instantaneous
Annual
Average
Commercial
status

Low
<50%

Medium
50 – 100%

High
100–400%

<20

20 – 50%

50– 150 %

Fully
utilized

Well proven
Fully
commercial
Multiple use

System
prototype
Operating

In low wind penetration, the diesel generator will run
at full time with the wind power reducing the net load on the
diesel generator. All the wind energy generated will be
supplying the primary load. Due to the simplicity of this
configuration and fuel savings, low wind penetration does not
require complex technology.
In medium wind penetration, the diesel generator will
operate at full time. During high wind power levels, the
secondary loads will be dispatched to ensure sufficient diesel
loading.
In high wind penetration, the diesel generator can be
shut down during high wind availability and auxiliary
components are required so as to regulate voltage and
frequency. When the wind generator output is sufficient to
supply the load demand, it is impractical to keep the diesel
generator on-line as spinning reserve to cover short-term
deficits in wind generator output.
IV. CONSTRUCTION

B. Wind Turbine Model.
In the designing of a wind turbine model, a couple of factors
that are important are the availability of the wind and the
power curve of the wind turbine itself. The kinetic energy (E)
per unit volume of moving air is expressed as [3] :
Energy = 0.5 * ρ * u2 Joules/m3

…(1)

As for the power that the wind turbines blades can extract
from the wind is given by the following expression.[5]
Power = 0.5 * e * k * A* ρ * u3 Watts.

…(2)

C. System Controller.
One of the principal technical objectives of this project is to
develop a system that is as reliable and robust and is
consistent with the requirements of high wind penetration and
maximum fuel savings. The heart of the control system is a
standard industrial PLC controller outfitted with the I/O
modules necessary to monitor and control the system. The
control system is also equipped with a telephone interface to
facilitate remote performance monitoring and fault diagnosis.
D. Synchronous Condenser [7] :
It helps to control voltage and balance active and reactive
power needs on the grid. It is primarily used when all diesel
engines have been shut off. It is made of a controlled AC
generator running on the AC bus. It consumes reactive power
as it rotates.
E. Batteries.
They are generally of two types
1) Lead Acid.
2) NiCad.
It requires periodic replacement. It is sensitive to use and
environment. It is used to store energy over a longer time
period or to store power over a shorter period of time.
F. Remote Access and Telecom.
Remote access allows oversight of system performance. It
enables real time system interrogation and troubleshooting
even when off site. The cell phone technology can be used as
it is inexpensive with a reasonable coverage.

FIGURE I: CONSTRUCTION OF A STANDALONE WIND DIESEL
HYBRID POWER SYSTEM

2

V. DESIGN OF A STANDALONE COST EFFECTIVE WIND DIESEL
HYBRID POWER SYSTEM.
The World Academy Of Science, Engineering And

Technology carried out a case study about setting up this
hybrid system in an isolated island Sandwip, Bangladesh.
They proposed the following steps to design a cost-effective
system based upon their study and research of the area.
A. Analysis of Electric Demand.
Through necessary survey, an electrical system for a single
home in the concerned region is to be initially carried out. An
example is shown Table II:

D. Wind Turbine.
Wind Turbine Average wind velocity at 45 metres height is 6.15
m/s in Sandwip. But at winter, wind velocity goes below the
average wind velocity. Cut-in speed of high capacity wind
turbines is more than 4 m/s. Enercon E33 wind turbine is a
suitable choice for low wind speed. The irregularity of wind
speed can be fixed by gear system. It has a rated capacity of 335
kW and cut-in speed of 2.5m/s .The installation cost for Enercon
E33 (50 m height tower) is $ 500000.
E. Cost of Other Equipments.
The cost of other equipments like battery, converter,
micro turbine etc. is also to be considered.

TABLE II
A TYPICAL ELECTRIC LOADING FOR A SINGLE
HOME.
Appliance

Quantity

Unit
(Watts)

Electric Bulb

2

100

Fluorescent Tubes

3

20

Fan
TV

2
1
Total

80
100
520 Watts

capacity

TABLE III
COST OF ACCESSORIES.

Cost ($)

Equipment
Battery
Converter
Micro-turbine

900/ String
1350/ MW
1000000/MW

VI. SIMULATION RESULTS AND ANALYSIS

A. Economic Analysis.
B. Thermal Load.

The area may have a number of industries within its
limits where a large amount of heat is required for a variety of
industrial processes. Thermal load also occurs in agricultural
loads. In the harvesting season, huge amount of electricity and
thermal load is required for boiling and breaking paddy to
rice. Processing of agricultural crops also require huge amount
of thermal load. Moreover, dehumidification equipment and
drying process also require a large amount of heat. Water
pump, rice mill, granary can also be run with the help of low
power steam generated by CHP Plants.
CHP (Combined Heat and Power) is the use of a heat
engine or a power station to simultaneously generate both
electricity and useful heat. With the recent trend towards the
decentralization of power supply, CHP systems have become
important. A new algorithm for economic dispatch of CHP is
reported in. CHP technology can be utilized for the design
purpose of off-grid wind-diesel hybrid system.
C. Diesel Generator.

In this hybrid system, diesel generators operate in
parallel with the wind turbine to increase the maintenance
flexibility, efficiency and distribute the electric load more
optimally. Cost of per MW of diesel generator can be
considered to be around $ 200000.

Simulation software can be used to design and simulate
the wind-diesel hybrid power system. It analyses the system
according to the COE of the system. Other factors which influence
the analysis are capital cost, operating cost, renewable energy
factor, total NPC (Net present cost) and diesel consumption rate.
There are some sensitive operative factors like diesel price
factor, surface roughness length, minimum load ratio etc.
After introducing CHP technology to the system, the
total efficiency increases. Because of the increased efficiency of
generator, the fuel cost decreases by 5%-25 % depending on the
generator output per month. The simulation results depict that the
production cost of electricity per kW may vary from $ 0.12 to
0.23 depending on wind velocity.
A cost comparison between wind and solar PV
system is shown in Table IV.
TABLE IV
COST COMPARISON OF WIND AND SOLAR PV
SYSTEM: [4]
Energy
System

Fuel
Cost
($/kWh)

Initial
investment
cost
($/kWh)

Transmission
and
distribution
cost ($/kWh)

Total
cost
($/kWh)

Wind
Solar
PV

0

0.08

0.023

0.103

0

1.05

0.02

1.07

3

The simulation results clearly reveal that wind-diesel
hybrid system using CHP technology is the most cost effective
off-grid power system for Sandwip.

A. Peculiarities of the Project:

B. Environmental Effect



The annual amount of reduction of gas emission is
presented in Table V. Wind-diesel hybrid system with CHP
technology reduces gas emission by a significant amount due
to reduced fuel consumption.





TABLE V
REDUCTION OF GAS EMISSION

Carbon dioxide

33,053,228

Carbon monoxide

81,587

Unburned hydrocarbons



Reduction of emission
( kg/year)

Gas (Pollutant)

Uses standard asynchronous wind generators with
diesel generators.
Under normal circumstances these generators require
a utility grid in order to operate and in this
configuration the grid will only allow a maximum of
20% - 30% wind power before becoming unstable.
Modified Diesel Generators achieve the frequency
and load control. Once the Wind generators are
operational, the Diesel Generators are running at
reduced load.
Allows considerable fuel savings.

9,037

Particulate matter

6,150

Sulphur dioxide

66,377

Nitrogen oxides

728,009

VII. WIND DIESEL HYBRID POWER TECHNOLOGY IN INDIA
Fully integrated Wind Diesel Technology was first
demonstrated in India in 2002 at the Sagar Island Wind Diesel
Project at Sagar Island in West Bengal. The West Bengal
Renewable Energy Development Agency (WBREDA) is
operating a Wind-Diesel Hybrid Power Projects having 10
AWS 15/50 WEG, 2 x 180 KVA DG Sets at this project. The
project has been funded by MNRE, Govt. of India; ICEF &
the West Bengal State Government. The Project was
conceived as a Technology Demonstration Project. A brief
statement of the power plant is furnished below:
TABLE VI
SPECIFICATIONS OF THE SAGAR ISLAND WIND
DIESEL POWER PROJECT [6]

FIGURE II: SAGAR ISLAND WIND TURBINE

B. Consumption of the Generated Power
1.
2.
3.
4.

Lighting.
Domestic Use.
Educational Centers.
Power Supply to small industries.

Thus the plant contributes to improve the socio-economic
conditions on the island.
VIII. ADVANTAGES

No.
of
Consumers

Average
Revenue

Duration of
Power Supply
per day

Distribution
line

Villages
Covered





700

Rs. 1.50
Lakhs
per
month

5-6 Hrs.

12 km LT
12 km HT


6



Wind is a totally clean indigenous energy source.
Wind power is the least cost of all renewables (except for
large hydro).
With the right equipment, wind turbines are relatively
easy to install.
Since the objective is to use the generator as little as
possible, it’s minimizes running cost.
The wind power allows a reduction of the diesel
generator rating.

4

IX. PROBLEMS FACED IN IMPLEMENTING WIND/DIESEL
PROJECTS AND THEIR REMEDIES
Problem:
1. High cost: Power in rural areas is always expensive,
but many elements drive up the cost of wind in rural
areas.
2. Size of the turbine: Turbine Size is likely be dictated
by site conditions.
Remedy: Use smaller turbines that will produce the power
equivalent to the single large turbine. It also has certain
advantages like reduction in shipment and installation charges
and requirement of smaller maintenance operations and
facilities.
Problem:
3. Chances of fluctuations in supply frequency.
Remedy: Reduce the distance between the wind turbine and
diesel generators. This will reduce consumption of reactive
power thus reducing the losses and thereby stabilising supply
frequency.
X. CONCLUSION
In the 21st century human life directly depends on
electricity. The energy crisis is severe in developing countries
like India which is a threat to their economic development. In
regions where grid connection is not feasible, alternate electric
sources like wind and Solar PV can be the potential solutions.
But the Solar PV system is at least 4 to 5 times more expensive
than wind power system. On the other hand only the wind
power system cannot satisfy the whole demand of electricity.
In this situation, a wind-diesel hybrid systems incorporating
CHP technology can be a cost effective solution for the isolated
islands. Moreover CHP technology reduces the emission of
gases and help to trim down the environmental pollution.

Preprint I.Baring-Gould National Renewable Energy
Laboratory, USA May 4 – 7, 2009
[2] Wind Power Systems-E. Ian Baring, National Renewable
Energy Laboratory, USA.
[3] Performance Analysis of Wind-Diesel Hybrid Power
System-L.H. Tay, W.W.L Keerthipala and L.J. Borle, School
of Electrical and Computer Engineering, Curtin University of
Technology, Perth, Australia
[4] Design of a Cost Effective Off-Grid Wind-Diesel Hybrid
Power System in an Island of Bangladesh- World Academy of
Science, Engineering and Technology 2011.
[5] Basics of Wind Diesel Power Systems, Ian Baring-Gould,
NREL, USA., September 28th, 2004
[6]. Website of West Bengal Renewable Energy Development
Agency (WBREDA): http://www.wbreda.org/wind-energy/
[7]Wikipediahttp://en.wikipedia.org/wiki/Synchronous_condenser

XIII. APPENDIX
Notations
1)
2)
3)
4)

ρ = Density of Air (normally 1.225 kg/m3at 15oC)
u = The Average Linear Wind Velocity (m/sec)
e = Efficiency Of The Blades (%)
k = Conversion Factor For Units{usually 0.6125 for
converting Area (m2) and Velocity (m/sec) to Power (W)}

XI. ACKNOWLEDGEMENT
Apart from the efforts of oneself, the successful
completion of any paper depends upon the encouragement of
the guide. So, I take this opportunity to thank my guide
Prof.Mrs.P.R.Khatri for her timely guidance in the preparation of
my paper. Without her assistance preparing this paper would have
been far from reality.
I am also thankful to all the faculty members who have
directly or indirectly helped me. Last but not the least; I once
would like to thank all my colleagues who have helped me in
this work.
XII. REFERENCES
[1] Technology, Performance, and Market Report of WindDiesel Applications for Remote and Island Communities

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