Simulation of Incremental Conductance MPPT based ...

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mathematical model of PV module, interleaved boost Converter and MPPT ... tear, less maintenance and no waste is produced during generation and it is ...
Simulation ofIncremental Conductance MPPT based Two phase Interleaved Boost Converter using MATLABISimulink D. Devaraj

S. Sheik Mohammed

Kalasalingam University, Srivilliputhur, Tamilnadu, India [email protected]

Dhofar University, PB. No. 250, Salalah,

Sultanate of Oman [email protected]

Abstract - The Photovoltaic power generation systems are connected to

the

load

via DC-DC

converters.

The DC-DC

converter circuits are controlled by Maximum Power Point Tracking (MPPT) controllers to extract maximum power from the

source.

Modeling

and

simulation

of

Interleaved

Boost

converter (IBC) with Incremental Conductance (InC) MPPT algorithm for PV application is discussed in this paper.

The

mathematical model of PV module, interleaved boost Converter and MPPT controller are simulated using MATLAB/Simulink. The

PV

system

is

simulated

for

various

temperature

and

irradiation level and the results are obtained.

Keywords

-

Maximum

Power

Point

Tracking

(MPPT),

Incremental Conductance (InC) algorithm, Interleaved Boost Converter (IBC), MATLAB/Simulink, solar power.

1.

INTRODUCTION

Depletion of fossil fuel, rise of its cost and the environmental impact of using fossil fuels for power generation has forced industrialist, scientist and general public to tum into renewable energy sources such as wind power, bio-mass, hydro, thermal and solar power generation. Solar power generation has many advantages such as no wear and tear, less maintenance and no waste is produced during generation and it is completely environmental friendly. The European and western countries are leaders in solar power generation. Agua Caliente Solar Project in USA is known as the world's largest individual PV power generation plant. The capacity of this plant is 250 MW[ I]. The Charanka Solar Park in India with a capacity 214 MW is holding the second place in the list [1] and it is also the Asia's largest PV plant [2]. Germany is the world's top photovoltaic (PV) installer, with a solar PV capacity of 33,877 gigawatts (GW) at the end of May 2013[3]. In July 2013, a new world record for solar power production is set by Germany. 23.95 GW of power is produced at midday of 23 July 2013[4]. The DC-DC boost converters are connected between the PV Modules and load in order to regulate and boost the output voltage of the PV. The DC-DC boost converters produces high ripple in input current and output voltage [5]. These issues with the conventional DC-DC boost converters 978-1-4799-6085-9/15/$31.00 ©2015 IEEE

are overcome by interleaved boost converters due to current sharing between the elements. Compared to the conventional converter the cost of TEC is high due to paralleling of multiple converters. But, on the other hand the current sharing technique results in utilization of low power components and switches for the converter [6]. The MPPT algorithms are used to control the duty cycle of the converter or power conditioning circuit connected in between the PV and load to extract the maximum power from the source and to feed it into the load. The MPPT algorithms proposed in the literature are Perturb & Observe (P&O) , Incremental conductance (InC); Constant voltage and parasitic capacitance algorithm are discussed in [7]. The other algorithms are such as short current pulse [8], open circuit voltage [9] and short circuit current [9] algorithm. The P&O and InC algorithm are widely used algorithms among the MPPT algorithms. The P&O algorithm is simple and easy to implement. But, the algorithm oscillates around the maximum power point (MPP) at steady state [10]. Improvement of algorithm results in slower response i.e., tracking is improper under rapidly changing weather conditions and drags efficiency of algorithm down during cloudy days [7,11]. The InC MPPT algorithm tracks faster than the P&O algorithm and also it has better accuracy [7]. InC MPPT based PV system with two phase interleaved boost converter is presented and discussed in this paper. The complete PV system is simulated in MATLAB/Simulink. II. MATHEMATICAL MODEL OF PV MODULE The equivalent circuit for simplified model of PV cell consists of a current source (Tpy), a diode(D), and series resistor (Rs) connected as shown in Fig. I. \I�--+

t

v

1 Fig.l Equivalent Circuit of PY Cell

The output current (I) equation is derived by applying Kirchhoffs law in the equivalent circuit. The equation for output current is as follows

Ipv. Vpv

and (1)

{ (

Equation 1 can re-written as I

=

I pv - I, exr

;

Ak N,

J }

.

In the above equation, - --IS the lllstantaneous conductance

Mpv.

--IS

�Vpv

the incremental conductance. The PV output

power maximum or at MPP when I pv + Vpv

V + IR", - l

(2)

-M pv

�V pv

=

0.

The V-P characteristics curve of PV module with MPP is presented in Fig. 2.

where, I pv

1s

=

=

[l,c + Kj (Tc - T,. )]. G

. (J3 [( -- J] T,.. T,.

1rl -

exp

qEg

A"

1 1 --T" T,.

PV Power (ppv) (3) I1P � > O I1Vpv

(4)

(5)

PV Voltage (V pv)

o

Fig. 2 Voltage-Power Characteristics of PV Module

The general model of the PV cell has a parallel resistor (Rp) in the circuit which is connected across the diode. The value of parallel resistance is very high and thus it is generally neglected in modeling the PV celL Modeling and simulation of The PV is based on the mathematical equations is presented in many literatures [12-17]. Modeling and simulation of PV module using simple blocks is presented in [15]. This model is very primitive, and the user has to change to parameters inside the blocks of the model in order to analyze different PV modules. Therefore, the possibilities of error in feeding the data are high. The PV module model with the masked subsystem and a dialogue box is discussed in [17]. This model provides the user with front end dialog box which makes the model more user-friendly to analyze any commercial PV modules.

Start

o.lay V".(kJand 1".(kJfor an instant and get J"'(k-IJ.I".(k-IJ

Yes

Ill. INCREMENTAL CONDUCTANCE MPPT The InC MPPT works based on the change in the PV power (Mpv ) and the PV voltage (�Vpv) to compute MPP [18]. It utilizes the following equations

Fig. 3. Flowchart of InC MPPT Algorithm

(6) where, �I pvis the change in PV current.

From Fig.2, the following equations are derived, 111

I pv + Vpv �

/l..Vpv

1 pv+ Vpv

Mpv /l..Vpv

>

=

/1..1 1_ ))· 0 or __

/l..Vpv

--

=

0 at the MPP

0 or MIN >0 at the left side of MPP

L',Vpv

(7) (8)

1 pv + Vpv

I1l pv 11 Vpv


CL

20

� CL

PV Voltage V)

M SX60 PV Module

Fig. 8(a) V-P Characteristics of Solarex MSX60 PV

Vp'

V.

4 ������====�---.�

Tc=2SoC, G=� OOW/m2�: , _ ,_ ' X: 17.1 ,-- - . Y: Ii:' Tc=40"C, G=I\OOW/m2 3.501 'i:' f-------'L---...I--_ X 15.68 ----- -� 2 :re"'sPe,-G.�BWfm -. - '- - "-.2.832 : -=- '1=" "- =---o " - -=-""""''" 3 I;-:-""""'-'"'�.-- -=-""""' ==,--:-��-' .=

� is:

l· R

R l'

G N D""'"" L h �' _ '-_ C --, P ---C= B7 2

Jl �

R

X: 12.79

,

,

------r---- Y:2.112

o�----�------�----���-�� o 5 10 PV voltage(V) Fig. 8(b) V-I Characteristics of Solarex MSX60 PV



Vl oad

Fig. 7. Subsystem for PV Module and 2 phase lEC

Further, in case 3, at 200 msec the values are changed 2 to Tc=750C, G=600 Wlm and continues until 300 msec. The ranges of values are selected as given only to simulate the model under different irradiation and temperature levels. The V-P characteristics and V-I characteristics of Solarex MSX60 PV module for the given conditions are shown in Fig. 8(a) and 8(b).

The duty cycle of the converter generated by the InC MPPT block under different conditions is shown in Fig. 9,

OI J- - - � - - � Z.

5

0.4 0.2

I

o

-

I

: ---�

----

-

I

I

150

200

,

- - � --I

- - + - - - � - - - - :- - - - -: - - - + - - 50

100

Time(mSec)

250

300

Fig. 9. Dutycycle of Two phase lEC under different cases

This signal is used to generate the PWM pulses for the converter switches. The MPPT controller tracks and

adjusts the duty cycle whenever the changes occur in temperature and irradiation to extract the maximum possible power from the PY. The output power the converter for the given conditions is shwon in Fig. 10.

60r--;�-;�����-;---r � -r



40 20

:

r ----i- - - � - - - - � V I I

I

� ---�-

I

-

---

-

: :

VI. CONCLUSION Simulation of Incremental Conductance MPPT based Two phase Interleaved Boost converter with PV is presented in this paper. The model is simulated for various conditions and the results are obtained. The input current ripple and output voltage ripple of the TEC are close zero at 50% duty cycle. The converter circuit operates at the duty cycle close to 50% for all the selected conditions. The ripple of input current and output voltage are also analyzed and found very less. The overall efficiency of the system is around 95%.

--------

;

- - - � - -------

O �����L-������� --� o 0.05 0.1 0.15 0.2 0.25 0.3 Time(sec) Fig. 10. Output Power of 2 phase TEC

Fig. I I (a) and I I (b) shows the voltage and current wavefroms of PV module and the load. The PV module output power, the converter output power, input current and the output voltage ripple values obtained for the different test conditions are presented in table I.

40 r---�-----.--�--r---�--�

s;a>

20

E g 10

:

:

__________ py y

Qjt!!9.e__



_

-2

o



____ .. ____

�",,- JU"L

:

0.05

0.1

0.15

Time(sec)

0.2

0.25

0.3

Fig. 11(b) PV current and Output current of 2 Phase TEC TABLE 1. COMPARISION OF INPUT CURRENT RIPPLE AND OUTPUT VOLTAGE RIPPLE OF TWO PHASE TEC UNDER DIFFERENT CONDITIONS Test Conditions

PV Output Power

Converter Output Power

Efficiency

Case 1: T,=40oC, G=800 W/m2 Case 2: T,=25OC, G=lOOO W/m2 Case 3: T,=75°C, G=600 W/m'

44.44W

42.03

59.85W

27.01W

EEG-

[8] Noguchi T, Togashi S, NAkamoto R" "Short current pulse based Maximum power point tracking method for multiple photovoltaic and converter module system", IEEE Transactions on Industrial electronics, Vol. 49, Issue I, pp-217-223, August 2002.

I



sowie

[7] D. P. Hohm and M. E. Ropp, "Comparative Study of Maximum Power Point Tracking Algorithms" PROGRESS TN PHOTOVOL TAICS: RESEARCH AND APPLICAnONS, 2003; II:47-62

I Curr nt ----� ----� --- �---- ____ ..J ____ I I I I I I I I I I I I I I

1'tL�ad

Datenmeldungen

[6] X Wu; J Zhang; X Ye and Z Qin, " Analysis and Derivations for a Family ZVS Converter Based on a New Active Clamp ZVS Cell", IEEE Trans. Ind. Electron., Vo1.55, No.2, pp. 773-781, Feb. 2008

I I I

____

[2] "Gujarat's 214MW solar park named as Asia's largest single PV plant". PV Tech. 23 April 2012. Retrieved Apr-20l2.

[5] R. W. Erickson and D. Maksimovic, "Fundamentals of Power Electronics",2nd ed. Norwell, MA: Kluwer Academic Publishers, 2001.

I

Fig. 11 (a) PV Voltage and Output voltage of 2 Phase TEC I

[I]Denis Lenardic "Large-scale photovoltaic power plants ranking I - 50" PVresources.com, 2011.

[4] en.wikipedia.org/wiki/Solar_powecin_Germany

O �--���L---����--��� o 0.05 0.1 0.15 0.2 0.25 0.3 Time(sec)

4

REFERENCES

[3] Photovoltaikanlagen: VergUtungssatze (in German)

----r----

30

The duty cycle of the converter is close to 50% for all the selected conditions. The efficiency of the converter is around 95% , the input current ripple and the ripple in output voltage are very less.

Input current ripple

Output voltage ripple

94.57%

2.822%

0.5266%

57.13

95.45%

3.14%

0.755%

25.47

94.29%

2.822%

0.618%

[9] J. Surya Kumari, Ch. Sai Babu "Comparison of Maximum Power Point Tracking Algorithms For Photovoltaic System" International Journal of Advances in Engineering & Technology, Nov 2011. [10] Nicola Femia, Giovanni Petrone, Giovanni Spagnuolo, and Massimo Vitelli "Optimization of Perturb and Observe Maximum Power Point Tracking Method" IEEE Transactions on Power Electronics, VOL. 20, NO. 4, JULY 2005. pp-963-973. [II] I. Batarseh, T. Kasparis, K. Rustom, W. Qiu, N. Pongratananukul, and W.Wu, "DSP-based multiple peak power tracking for expandable power system," in Proc. 18th Annu. IEEE Applied Power Electronics Con! Expo, vol. 1, Feb. 2003, pp. 525530. [12] J.A.Gow, C.D.Manning, " Development of photovoltaic array model for the use in power electronic simulation studies," lEE Proceedings Electric power applications, Vol. 146, No.2, March,1999. [13] Jee-Hoon Jung, and S. Ahmed, "Model Construction of Single Crystalline Photovoltaic Panels for Real-time Simulation," lEEE Energy Conversion Congress & Expo, September 12-16, 2010, Atlanta, USA. [14] S. Sheik Mohammed, "Modeling and Simulation of Photovoltaic module using MATLAB/Simulink" International Journal of Chemical and Environmental Engineering, 20II

[15 ] Francisco M. Gonzalez-Longatt, "Model of Photovoltaic Module in MatlabTM" 2do congreso iberoamericano de estudiantes de ingenieria electrica, electr6nica y computaci6n (ii cibelec 2005). [16] Huan-Liang Tsai, Ci-Siang Tu, and Yi-Jie Su "Development of Generalized Photovoltaic Model Using MATLAB/SlMULlNK" WCECS 2008, October 22 - 24, 2008, San Francisco, USA. [17] S. Sheik Mohammed, D. Devaraj, "Simulation and Analysis of Stand-alone Photovoltaic System with Boost Converter using

MATLAB/Simulink" International Conference on Circuits, Power and Computing Technologies (lCCPCT-20l4 ), March 2014. [18] Mihnea Rosu Hamzescu, Sergiu Oprea" Practical Guide to Implementing Solar Panel MPPT Algorithms" Microchip Technology Inc., 2013. [19] Solarex MSX60/64 datasheet. Available online at: http://www.californiasolarcenter.org/newssh/pdfs/Solarex­ MSX64.pdf