design of mppt based hybrid wind and fuel-cell energy system

DESIGN OF MPPT BASED HYBRID WIND AND FUEL-CELL

ENERGY SYSTEM

Ch Rambabu, M Sunil Kumar and N Sri Harish Sri Vasavi Engineering College, Tadepalligudem, W.G.Dt., A.P.-534101

[email protected]

Abstract The wind energy conversion system can deliver the

maximum power when the load impedance matches with the source impedance under a given wind

speed. Since the load and wind speed are varying

dynamically, the maximum power point tracking

(MPPT) becomes more complex. A wind-generator

(WG) maximum-power-point tracking (MPPT)

system is presented in the present work, consisting

of a high efficiency buck-type dc/dc converter and a

control unit running the MPPT functions. The

advantages of the MPPT method are that no

knowledge of the WG optimal power characteristic

or measurement of the wind speed is required and

the WG operates at a variable speed. Thus, the system features higher reliability, lower complexity

and less mechanical stress of the WG.

A hybrid algorithm is used for tracking the

maximum power. In this method, on power

variation, the duty cycle is adjusted in according to

the variation in rectifier output voltage.

Key words: Maximum Power Point Tracking

(MPPT), Wind Energy Conversion System (WECS).

1. Introduction The worldwide concern about the environment has

led to increasing interest in technologies for

generation of renewable electrical energy. The

ever-increasing demand for conventional energy

sources has driven society towards the need for research and development of alternative energy

sources. Many such energy sources, such as wind

energy, fuel-cells and photovoltaic‟s are now well

developed, cost effective and they are widely used.

These sources offer the advantages of load shifting,

customer demand, production of power in

environmentally friendlier ways, and emergency

backup power[1]-[5]. These generation systems

allow utility companies to locate small energy

generating or storage units closer to the customer.

These sources face many hurdles, such as cost, grid

interface issues, power. Today more than ever, environmental concerns have taken a prominent

seat in the forefront of people's minds. The

coupling of this with rapid advancements in the

field of wind turbine generation has made this

mode of electricity production a realistic option on

the commercial scale. It has become more and

more possible to produce 'green' electricity at

reasonable rates, which translates into profit that

may become more significant[4]-[7].

Wind energy system consists of a turbine coupled to a generator and the turbine is rotated by means

of the wind energy. Most modern wind power is

generated in the form of electricity by converting

the rotation of turbine blades into electrical current

by means of an electrical generator. Wind

generators (WGs) have been widely used both in

autonomous systems for supplying power to remote

loads and in grid-connected applications. Although

WGs have a lower installation cost compared to

fuel cells, the overall system cost can be further

reduced using high-efficiency power converters,

controlled such that the optimal power is acquired according to the atmospheric conditions. In

windmills (a much older technology) wind energy

is used to turn mechanical machinery to do physical

work, like crushing grain or pumping water[17].

Wind power is used in large-scale wind farms for

national electrical grid as well as in small

individual turbines for providing electricity to rural

residences or grid-isolated locations. The countries

with the highest total installed capacity are

Germany (20,621 MW), Spain (11,615 MW), USA

(11,603 MW), India (6,270 MW) and Denmark (3,136 MW). Maximized electricity generation by

wind turbines is an interesting topic in electrical

engineering and many types of variable speed

generating systems have been researched to achieve

this goal. Use of a variable speed generating system

in wind power applications can increase the

captured wind energy by 10-15% annually [17].

This can yield a significant revenue increase over a

20 or 30 years life of operation. The designers of

small turbines (up to about 40 KW) stress

simplicity over complexity and the machines are designed for little or no maintenance. Integrated

horizontal axis wind-rotor designs, simplified to

reduce the number of moving parts have emerged

as the most successful general configuration. The

variability and intermittent character of renewable

resources requires the system to have back-up

generation capability and/or energy storage, the

latter usually a battery bank. A nominal battery

bank voltage of 120 or 240V is common. In battery

charging stations, batteries are connected in series

and in parallel and the whole battery bank is

charged through a wind turbine [12]-[17].

2. Wind Energy Conversion System Wind energy is transformed into mechanical energy

by means of a wind turbine that has one or several blades. The turbine is coupled to the generator

Ch Rambabu et al, International Journal of Computer Science & Communication Networks,Vol 1(3), 297-304

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system by means of a mechanical drive train. It

usually includes a gearbox that matches the turbine

low speed to the higher speed of the generator.

New wind turbine designs use multi pole, low

speed generators, usually synchronous with field

winding or permanent magnet excitation, in order to eliminate the gearbox. Some turbines include a

blade pitch angle control for controlling the amount

of power to be transformed. Stall controlled

turbines do not allow such control. Wind speed is

measured by means of an anemometer [5]. A

general scheme of Wind energy conversion system

is shown in Fig 1.

Fig.1Block diagram of wind energy conversion system

A wind turbine is a device for converting the

kinetic energy in wind into the mechanical energy

of a rotating shaft. Usually that rotating mechanical

energy is converted immediately by a generator

into electrical energy. In the large turbines, there is

generally a generator on top of the tower. The

generator is usually connected to the turbine shaft

through gears which turn the generator at a

different speed than the turbine shaft. Fancy power

electronic controls convert the electricity into the

correct frequency and voltage to feed into the

power grid (probably 50 Hertz depending on which country you live in).The electrical generator

transforms mechanical energy from the wind

turbine into electrical energy. The generator can be

synchronous or asynchronous. In the first case, an

excitation system is included or permanent magnets

are used. Variable speed systems require the

presence of a power electronic interface, which can

adapt to different configurations. The compensating

unit may include power factor correction devices

(active or passive) and filters [3].

The speed and direction of the wind impinging upon a wind turbine is constantly changing. Over

any given time interval, the wind speed will

fluctuate about some mean value. The degree of the

fluctuations is characterized by the standard

deviation of the wind speed during that time

interval. The power extracted by the wind turbine is

a function of the wind and, thus, it will have a

mean value during the time interval in

considerations and variations about that mean. A

"power curve" is typically used to define the

performance of a wind turbine [1].

It is the relationship between the average hub-

height wind speed and the average generator power during the averaging time interval, assuming

certain standard atmospheric conditions. Also, a

wind turbine will have a cut in wind speed at which

the turbine starts to generate power, a rated wind

speed, at which it starts to generate rated power,

and a cut-out wind speed at which it is shut down

for safety. The power obtained by the turbine is a

function of wind speed. This function may have a

shape such as shown in Fig.2. For variable speed

WECS the upper part of the curve between and can

be kept linear, equal to the reference power [10].

The following notations are used: Pr: reference power, maximum power that the

turbine can attain

Vr: reference power wind speed, wind speed for

which reference power isachieved.

Vci: cut-in wind speed, wind speed at which the

turbine starts to produce power

Vco: upper limit of the wind speed called cutout

wind speed, at which the turbine can operate.

Fig.2 Typical power curve of a wind turbine

The wind output Pw is a function of wind velocity

Vw such that:

Pw=Pr if Vci≤Vr≤Vco (1)

Pw=0 if 0<Vr<Vci or Vr>Vco (2) The wind speed can be found by using the formula:

)(m

rmw

H

HVV (m/s) (3)

Vm: measured wind speed at height Hm in m/s

Hr : rotor height in meters

: Ground surface friction coefficient (1/7) Pr : rated power of wind generator in kW

Wind energy conversion system consists of wind

turbine coupled with wind generators. Depending

on the application, there are different types of

generators and turbines available.

3. Mathematical Model of Wind Turbine A wind energy conversion system is basically

comprised of two main components, the

aerodynamic component and the electrical

component. The turbine forms a major constituent

of the aerodynamic system. The energy that could be captured from wind by a specific turbine

depends on its design particulars and operating

conditions. In this section all aspects related to the


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power conversion, from kinetic wind energy to

rotational energy, that are of relevance for the

stability model are explained.

The kinetic energy Ek of a mass of air m having the

speed Vw is given by:

2

2wK V

mE

(4)

The power associated to this moving air mass is the

derivative of the kinetic energy with respect to time

can be expressed as follows:

22 .2

1.

2

1ww

Ko qVV

t

m

t

EP

(5)

Where q represents the mass flow given by the

expression:

q=VW.A (6)

Where ρ: Air density.

A: Cross section of the air mass flow.

Ek: kinetic energy of the air.

Only a fraction of the total kinetic power can be

extracted by a wind turbine and converted into rotational power at the shaft. This fraction of power

(Pwind) depends on the wind speed, rotor speed and

blade position (for pitch and active stall control

turbines) and on the turbine design. The

aerodynamic efficiency Cp is defined as follows:

o

windP

P

PC

(7)

For a specific turbine design, the values of Cp(α, β) are usually presented as a function of the pitch

angle (β) and the tip speed ratio (α). The tip speed

ratio is given by:

w

tur

V

R

(8)

Where R : The radius of the turbine blades.

ωtur: The turbine angular speed.

Vw : Speed

The aerodynamic efficiency Cp(α, β) is usually

defined as a form of a two-dimensional lookup

characteristic (for different values of α and β) by

actual measurement. The variation of the power coefficient Cp with variation of the tip speed ratio is

shown in Fig 3.

Fig.3 Power coefficient versus tip speed ratio

A two dimensional, cubic line-interpolation method

is used for calculating points between measured values. The high accuracy of the interpolation

method avoids the need of entering a large number

of points. Alternatively, analytical approaches for

approximating the aerodynamic efficiency Cp(α, β)

characteristic could be used. Finally, the

mechanical power extracted from the wind is

calculated using:

22 ).,(.2

wPmech VCRP

(9)

The aerodynamic efficiency Cp(α, β) characteristic

can be calculated using special software for

aerodynamic designs that is usually based on blade-

iteration techniques or it can be obtained from

actual measurements. The power coefficient of wind turbine can be expressed by:

6432

1

5

)(),( ceccc

cC i

c

i

p

(10)

Where c1, c2, c3, c4, c5 and c6 are the constants they

depend on mechanical characteristics of the wind

turbine.

4. Modelling of Permanent Magnet

Synchronous Generator The wind turbine drives a permanent magnet

synchronous generator whose terminal voltage

equations can be described by the following set in a matrix form [7]

][]][[][ m

abcabcabcabc PiRV

(11)

Assuming that zero-sequence quantities are not

present and applying Park‟s transformation, equation may be rewritten in a rotor reference

frame as

mrdqrqqq iLipLRV )( (12)

qqrddd iLipLRV )(

(13)

Where R - Stator phase winding resistance,

Lq - Stator inductance in the quadrature axis,

Ld - Stator inductance in the direct axis,

ωr - Rotor angular velocity of the generator,

λm - Amplitude of the flux linkages

established by a permanent magnet as viewed from

the stator phase windings,

p - operator d/dt.

The expression for the electromagnetic torque in

the rotor reference frame is

qmdqqde iiiLLp

T

)(

22

3

(14)

Where P is a number of poles of the PM generator.

The relationship between the rotor angular velocity of the generator ωr, and the mechanical angular

velocity of the rotor ωm, may be expressed as

2r m

P (15)

The rotational speed and the torque may be related

as:

er TpP

JT

21

(16)

Where T1 = input torque to the machine.


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Let us assume that the output corresponds to the

torque developed by the wind turbine Tp, stator

voltages of the generator are sinusoidal so that:

rsa VV cos

(17)

)

3

2cos(

rsb VV

(18)

)3

2cos(

rsc VV

(19)

Expressing equations (17), (18), and (19) in a rotor

reference frame me may write:

sq VV

(20)

0dV

(21)

Where Vs: amplitude of the stator voltage.

For practical permanent magnet synchronous

machines Ld=Lq=L. Under this assumption,

substituting (20) and (21) into (12) the voltage

equation in q-axis may be written:

mrqr

q ipLR

LpLRV

222 )()(

(22)

If ωr2L2 is neglected, then the equation (22) is

linear. For this approximation to be valid, it is

required that Vq,ωr and Te, are to be equal to or

greater than zero. Thus with ωr2L2 being neglected,

Ld=Lq=L, and substituting (20), equation (17)

becomes:

rmqs ipLRV )(

(22)

The energy that a wind turbine will produce

depends on its wind speed power curve and the

wind speed frequency distribution at the installation

site. Electrical power generated by wind turbine is

given by: 3....5.0. wpgtw VACP

(23)

Vw : Wind speed at projected height in m/s

: Factor to account for air density (1.225 kg/m2 at sea level)

Cp : Power coefficient (0.35 for a good design)

A : Wind turbine rotor swept area in m2

t : Turbine efficiency

g : Generator efficiency

5. Fuel-Cells A fuel cell is an electrochemical cell that converts

chemical energy from a fuel into electric energy.

Electricity is generated from the reaction between a

fuel supply and an oxidizing agent [8]. The reactants flow into the cell, and the reaction

products flow out of it, while the electrolyte

remains within it. Fuel cells can operate

continuously as long as the necessary reactant and

oxidant flows are maintained [9].

Fig.4 Block Diagram of a Fuel Cell

Anode Reactions :2H2 => 4H+ + 4e-

Cathode Reactions: O2 + 4H+ + 4e- => 2 H2O

Overall Cell Reactions: 2H2 + O2 => 2 H2O

The output voltage of a single fuel cellis given by

(24)

ENernst = Thermodynamic potential of the cell.

Vact = Voltage drop due to the activation of anode and cathode.

Vohmic= Ohmic voltage drop resulting from the

resistances to the conduction of protons through the

solid electrolyte and the electrons through its path.

Vcon = Voltage drop resulting from the reduction in

concentration of the reactants gases.

The thermodynamic potential (ENernst) represents

the fuel cell open circuit voltage and the other three

voltages activation voltage drop (Vact), ohmic

voltage drop (Vohmic) and concentration voltage

drop (Vcon) represent reductions in this voltage to supply the useful voltage across the cell electrodes,

VFC, for a certain operation current [16].

Thermodynamic Potential/ Cell Reversible Voltage

(ENernst):

( )

* ( )

( )+ (25)

Where ∆G=change in the free Gibbs energy(J/mol)

F=Constant of Faraday (96.487 C)

∆S=Change of the entropy (J/mol) R= Universal constant of the gases (8.314 J/Kmol)

PH2=Partial pressures of hydrogen (atm)

PO2=Partial pressures of oxygen (atm)

T=Cell operation temperature (K)

Tref=Reference temperature (K)

( ) * ( )

( )+ (26)

Using the standard pressure and temperature (SPT)

values for change in G, change in S and Tref

equation can be simplified. The activation voltage

drop, which takes into account both the anode and

the cathode over-voltage is given by:

[ ( ) ( )] (27)

Where iFC=Cell operating current(A)

ξ's=Parametric coefficient of each cell model

CO2= Concentration of oxygen in the catalytic

interface of the cathode (mol/cm2)

Ohmic Voltage Drop (Vohmic) can be represented using Ohm‟s law as:

( ) Where Rc=Resistance to electron flow

RM=Resistance to the flow of protons

Concentration Voltage Drop (Vcon) is given by the

equation:


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http://en.wikipedia.org/wiki/File:Fuel_Cell_Block_Diagram.svg

(

) (28)

Where B=Parametric coefficient (V) J=Actual current density (A/cm2)

Jmax= Maximum current density (A/cm2)

Fuel Cell Power is the instantaneous electric power

of each fuel cell is given by:

(29)

Where iFC=Cell operating current(A)

VFC= Output voltage of the fuel cell (V)

PFC= Output power of each fuel cell (W)

The voltage-current (V-I) and power-current (P-I)

characteristics of the fuel cell system are shown in

fig 5

Fig.5 Voltage-Current (V-I) and Power-Current (P-

I) Characteristics of the fuel cell

6. Maximum Power Point Tracking The maximum power tracking from wind energy

initially by using the mechanical sensors was

explained by R.Chedid, F.Mrad, and M.Basma. But

the accurate mechanical sensors are required for

tracking the maximum power. Wang, Q., Chan, L

explained about maximum power point tracking by

the mechanical characteristics of wind turbine. But these Methods are very difficult to implement. But

now by the invention of power electronic devices

the power tracking using dc-dc converters are also

possible. The wind speed varies continuously and

the load also changes continuously. In order to

match the load with the wind energy conversion

system we require a power electronic interface

between the wind energy conversion system and

the load. The basic block diagram of the wind

energy conversion system is shown in fig 6.

Fig 6 Block Diagram of WECS

The power output varies with the load impedance

being connected. The load impedance is varying

continuously and the wind speed is also not

constant. So the system by itself cannot reside in

the region of maximum power operating region,

which is more desired. Thereby the importance and

complexity becomes increased for making the system to operate in the maximum power operating

point (MPOP). The technique by which a system is

maintained or made to operate in the MPOP is

called maximum power point tracking (MPPT). If a

maximum power point tracker is not incorporated

in the WEC system, the WECS will deliver a power

that is always lesser than the power that can be

delivered by it. Maximum power point tracking is

basically a software algorithm that is the heart of a

WECS. By the maximum power point tracking algorithm, the WECS is being operated at or

nearest to the maximum power point.

Fig.7 Block Diagram for maximum power point

tracking A maximum power point tracker is basically a

converter connected in between the WECS source

and the load. The duty cycle is continuously

changed and operated at a value such that the

maximum power is tracked from the source [2]. By

maximum power transfer theorem, a source will

deliver its maximum power when the source impedance matches the load impedance. The duty

cycle of the converter is maintained in such a way

that the effective impedance seen by the wind

energy conversion system source will be equal to

the internal source impedance and hence maximum

power is delivered. In order to extract the

maximum wind power, an analysis was provided to

understand the probable displacement of the

operating point in the two operating zones of wind

turbine. Fig.8, represents the typical curve of wind

power variation according to the operating voltage and it shows that there are two operating zones: the

first is located on the right side of the MPP where

dp/dΩ < 0 and the second on the left side of the

MPP where dp/dΩ > 0. For searching the maximum

wind power operating point and tracking this point,

in order to reduce the error between the operating

power and the maximum power, in the event of

change of the wind speed, the control of the boost

converter perturbs periodically the operating point

of the wind turbine. By acquiring the output

voltage and current of PMSG, the control uses this

information to increase or decrease the duty cycle of the boost converter to change the operating point

of the wind turbine [3].

Fig.8 Probable displacement of the operating point

MPPT process in wind energy conversion system is

based on directly adjusting the dc/dc converter duty

SOURCE

(WECS+

FUEL CELL)

DC-DC

CONVERTER

+

MPPT

Load


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cycle according to the result of the comparison of

successive WG-output-power measurements.

Although the wind speed varies highly with time,

the power absorbed by the WG varies relatively

slowly, because of the slow dynamic response of

the interconnected wind-turbine/generator system [9]. Thus, the problem of maximizing the WG

output power using the converter duty cycle as a

control variable can be effectively solved using the

steepest ascent method according to the following

control law:

1

1

11 .

k

k

kkD

PCDD

(30) where Dk and Dk-1 are the duty-cycle values at

iterations k and k - 1, respectively (0 < Dk< 1);

ΔPk-1/ΔDk-1 is the WG power gradient at step k-1;

and C1 is the step change. In order to ensure that this method results in

convergence to the Wind Generator maximum

power point at any wind-speed level, it is adequate

to prove that the function P(D), relating the WG

power P and the dc/dc converter duty cycle D, has

a single extreme point coinciding with the WG

MPPs. It is obvious that at the points of maximum

power production , where is the WG rotor speed.

Applying the chain rule, the above equation can be

written as

0..

d

d

d

dV

dV

dD

dD

dP

d

dP e

e

WG

WG (31)

Where VWG is the rectifier output voltage level and

Ωe is the generator-phase-voltage angular speed. In

case of a boost-type dc/dc converter, its input

voltage is related to the output (battery) voltage and the duty cycle as follows:

WGV

VD 0

0

12

O

WGWG

VVdV

dD

(32)

Where V0 is the battery voltage level. The wind-

turbine rotor speed is related to the generator speed

as follows:

.pe

0

p

d

d e

(33)

Where p is the number of generator pole pairs. The

rectifier output voltage VWG is proportional to the

generator phase voltage Vph. Considering Fig. 9, it

is concluded that

0e

ph

d

dV

0

e

WG

d

dV

00 dD

dP

d

dP (34)

Thus, the function P(D) has a single extreme point,

coinciding with the WG MPOP, and the dc/dc

converter duty-cycle adjustment according to the

control law ensures convergence to the WG MPOP

under any wind-speed condition. The power

maximization process is shown in Fig.9.

Since the duty-cycle adjustment follows the

direction of dP/dD, the duty-cycle value is

increased in the high-speed side of the WG

characteristic, resulting in a WG-rotor-speed

reduction and power increase, until the MPOP is

reached.

Fig.9 MPP tracking process

Similarly when the starting point is in the low-

speed side, following the direction of dP/dD results

in duty-cycle reduction and the subsequent

convergence at the MPOP, since the WG rotor

speed is progressively increased.

7. Boost Converter A boost converter (step-up converter) is a power

converter with an output DC voltage greater than

its input DC voltage. It is a class of switching-mode power supply (SMPS) containing at least two

semiconductor switches (a diode and a transistor)

and at least one energy storage element. Filters

made of capacitors (sometimes in combination with

inductors) are normally added to the output of the

converter to reduce output voltage ripple.

A boost converter is used as the voltage increase

mechanism in the circuit known as the 'Joule thief'.

This circuit topology is used with low power

battery applications, and is aimed at the ability of a

boost converter to 'steal' the remaining energy in a

battery. This energy would otherwise be wasted since the low voltage of a nearly depleted battery

makes it unusable for a normal load [18].

Fig.10 boost converter basic diagram

8. MPPT Algorithm

Fig.11 Flow chart for MPPT algorithm


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The wind energy conversion systems interface the

load by using power electronic converter .The

power electronic converter consisting of the boost

converter. The control of MPPT is done by using

boost converter .By varying the boost converter

duty ratio we can achieve maximum power tracking. Two different control variables are often

chosen to achieve the maximum power control,

Voltage feedback control and power feedback

control

In Voltage-Feedback Control the converter

terminal voltage is used as the control variable for

the system. The system keeps the wind energy

conversion system operating close to its maximum

power point by regulating the rectifier output

voltage and matches the voltage of the desired

voltage. However, this has drawbacks like the

effects of the wind speed are neglected. It cannot be widely applied to battery energy storage systems.

Power-Feedback Control Maximum power control

is achieved by forcing the derivative (dP/dV) to be

equal to zero under power feedback control. A

general approach to power feedback control is to

measure and maximize the power at the load

terminal. This has an advantage of unnecessarily

knowing wind energy characteristics. However,

this method maximizes power to the load not power

from the wind energy conversion systems.

Although a converter with MPPT offers high efficiency over a wide range of operating points,

but for a bad converter, the full power may not be

delivered to the load due to power loss.

Therefore, the design of a high performance

converter is a very important issue. In this present

work power feedback control is used to track the

maximum power from the system.

9. Simulation Results The wind energy conversion system is modeled in

MATLAB simulink simulation software. The

mathematical model of wind energy conversion

system is explained chapter two is used for

simulation. The MPPT algorithms were simulated

in the graphical simulation software Simulink for

which the graphical representation has been taken. The simulation is carried out using MATLAB

Simulink for 24 hours duration.The single line

diagram of the test system is shown in Fig.12 the

wind energy conversion system details

Fig.12 Single line diagram of the test system

For simulation purpose ER3100 model wind

turbine is used, for that turbine rated wind speed is 8.2m/s. At the rated wind speed turbine rotor

rotates at 270RPM. The turbine coupled to the

generator rotor by a tip speed ratio of 7.5 and the

generator rated speed is 3000RPM, at that speed

generator will produce the voltage of 400V. The

generator parameters taken for the simulation are

direct and quadrature axis inductance 8.5mH(Ld=Lq=8.5 mH). The source resistance of

conditions taken for the simulation first for the

constant load of 2000W and variable load of load

curve shown in the figure.

Fig.13 constant load curve for simulation (2000Watts)

When the load is directly connected to the wind

generator the output power fluctuates shown in fig.

This fluctuations may damage the load .To avoid

this condition the load is connected through the

power conditioner unit.

Without MPPT unit Maximum power is 12000W,

Average power is 10.25kW and energy taken from

the WECS on complete day.

Fig.14 power output without MPPT

Maximum power is 12000W

Average power is 10.25kW

When new method is used for the MPPT,

Maximum power is 12300W, Average power is

10.40kWand energy taken from the WECS on

complete day.

Fig.14 Power output using New MPPT Method

Maximum power is 12300W

Average power is 10.40kW

Table:1 comparison of Max. & avg. Power Power Without MPPT With MPPT

Max.Power 10100 10947

Average Power 9.17 9.87

%increase in

Max.Power

8.4%

% increase in average

power

7%


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From the above results it is clear that using the new

method, the power output is increased by 8.4% in

case of constant load condition.

From the above results it is clear that when the load

changes continuously and wind speed change

continuously, the new method will respond quickly. The energy output of wind turbine on a particular

day using the simulation methods are given in

table. Load value is 1000 ohms.

10. Conclusion In this work WG maximum power tracking

controls are presented, comprising of a high-

efficiency boost-type dc/dc converter and control

unit. The advantages of the MPPT methods are no

knowledge of the WG optimal power characteristic

or measurement of the wind speed is required and

the WG operates at variable speed and thus

suffering lower stress on the shafts and gears. The

MPPT methods do not depend on the WG wind and

rotor-speed ratings or the dc/dc converter power rating. In this project a new method is used for the

maximum power point tracking of the wind energy

conversion systems. In this thesis, a new algorithm

is presented to track the maximum power from the

wind energy conversion system eliminating the

drawbacks under rapidly changing atmospheric or

load conditions. The average output power is

increased by 7%. From the above results it is clear

that using the new method the power output is

increased in case of constant load condition.

11. References 1. Tafticht, T.; Agbossou, K.; Cheriti, A, “DC Bus

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