ICEE024_Malathy .ppt

MALATHY N
PG SCHOLAR, ME- PED
R.M.K ENGINEERING COLLEGE
Modeling and CONTROL OF PV POWER MODULE
INCORPORATED WITH SEPIC CONVERTER
PROJECT GUIDE
Dr. S. ANITA Ph. D, M.E
ASSOCIATE PROFESSOR
DEPT OF EEE
R.M.K ENGINEERING COLLEGE

OBJECTIVE
The main objective of this paper are
Modeling the PV Cell in a masked form which can be used as PV
module, panel or array.
Design the Converter using MATLAB/ Simulink.
Implement the MPPT algorithms (P & O ) in Code Form.
Interfacing both along with the MPPT algorithm to obtain the
maximum power point operation would be of prime importance and
Controlling the PV Module using Voltage mode controller.

PV Cell - Equivalent circuit
Governing Equation :
IP = Iph –K1*IO – ISH

Where
IP = output pv current (amperes)
Iph = photo generated current (amperes)
IO = saturated current (amperes)
ISH = shunt current (amperes).
Iph=s*(Iscr+(ki*(T-298)))/1000
Io=Iph/(exp(voc/(ns*vt))-1)
k1=exp(((vp+Ip*rs)/(ns*vt))-1)
voc=vocs+(kv*(T-298))
vt=A*k*T/q
Ish=(vp+Ip*rs)/rp
With the help of governing equation involved in PV Module, I
have created EMBEDDED FUNCTION to simulate PV Module in
MATLAB/Simulink. The PV Module parameters are taken from the
manufacturer data sheet of SOLAREXM60.
MAXIMUM POWER PMAX=60 W
VOLTAGE AT PMAX=17.1 V
CURRENT AT PMAX=3.5 A

MAXIMUM POWER POINT TRACKING
The voltage at which PV module can produce maximum power is called
‘maximum power point’ (or peak power voltage).
Maximum power varies with environmental conditions such as solar
radiation, ambient temperature and solar cell temperature.
The major principle of MPPT is to extract the maximum available power
from PV module by making them operate at the most efficient voltage.
There are different techniques used to track the maximum power point.
Among the different techniques, most popular and simple technique is
Perturb and Observe Method ( P & O ).
The Perturb & Observe algorithm states that when the operating voltage of
the PV panel is perturbed by a small increment, if the resulting changes in
power ΔP is positive, then we are going in the direction of MPP and we
keep on perturbing in the same direction. If ΔP is negative, we are going
away from the direction of MPP and the sign of perturbation supplied has
to be changed .

Solar irradiance input for mppt

Pv voltage with mppt implementation

Advantages and limitation
Implementation of P & O algorithm is simple.
The time complexity of this algorithm is very less but on
reaching very close to the MPP it doesn’t stop at the MPP
and keeps on perturbing in both the directions.
It cannot determine when it has actually reached the MPP.
Instead, it oscillates the operating point around the MPP
after each cycle and slightly reduces PV efficiency
under the constant irradiance condition.

Why sepic converter
The task of the MPPT algorithm is just to calculate the reference
voltage V ref for DC/DC converter, towards which the PV operating
voltage should move next for obtaining maximum power output.
The simplest topology Buck Converter - input current is
discontinuous, thus good input filter design is essential.
The input current of the CUK and SEPIC topologies is continuous,
and they can draw a ripple free current from a PV array that is
important for efficient MPPT.
Cúk converter has a polarity of the output voltage reverse to the
input voltage.
The input and output of SEPIC converter have the same voltage
polarity.
Also it is preferred for battery charging systems because the diode
placed on the output stage works as a blocking diode preventing
an adverse current going to PV source from the battery.

single-ended primary-inductance converter
The single-ended primary-inductance converter (SEPIC) is
a DC/DC-converter topology [3] that provides a positive regulated
output voltage from an input voltage that varies from above to
below the output voltage.

Design of Sepic converter
Specification:
INPUT VOLTAGE (0 - 21.1) V
INPUT CURRENT (0 – 3.8) A
OUTPUT VOLTAGE 17.1 V
OUTPUT CURRENT 3.5 A
MAXIMUM OUTPUT POWER 60 W
SWITCHING FREQUENCY 25KHz
DUTY CYCLE (0.1 < D<0.6)
The parameters used in SEPIC is calculated from formulas
which is given in the paper [3] is shown below.
L1 (min) = L2 (min) = 245.63 H
Cs = 178  F
C OUT >= 416.39  F

Controller technique
The Voltage control loop of SEPIC [8] is the PI controller, which
controls the output voltage of the converter.
KP is taken to be 0.005 and KI is taken to be 4.223. The values of
KP and KI are chosen from tuning the SEPIC Voltage loop transfer
function [2] which is given below.

Error signal and control signal

I out & Vout (closed loop response)

OUTPUT RESPONSE FOR SUDDEN INPUT VARIATION

Output response for load variation

Performance analysis of closed loop response of
SEPIC converter
Rise time (sec) 0.0306
Settling time (sec) 0.0552
Overshoot (%) 0
Closed loop stability Stable

Conclusion
The study and design of Solar PV Module in this paper is simple
and also efficient.
It models each component and simulates the system with the help of
embedded function in MATLAB / Simulink.
The result shows that the PV model using the Governing equation of
Solar cell in moderate complexity provides good matching with the real
PV module.
Also this paper successfully implemented with Perturb and Observe
Algorithm for Maximum Power Point Tracking (MPPT) of PV
Module at different solar irradiance.
The controller used in this project is quite simple and its closed loop is
achieved as stable.

Reference paper
1. Chen Qi, Zhu Ming (2012): “Photovoltaic Module Simulink Model for a Stand-alone PV
System.”, physics procedia 24
2. Chiang.S.J, Hsin-JangShieh, Member,IEEE, and Ming- Chen: “Modeling and Control of PV
Charger System With SEPIC Converter”,IEEE Transactions On Industrial Electronics, Vol.56,
No.11, November 2009.
3. Datasheet of “Design a SEPIC Converter”, May-2006, National Semiconductor.
4. Gomathy.S, S.Saravanan, Dr. S. Thangavel, March 2012: “Design and implementation of
Maximum Power Point Tracking (MPPT) Algorithm for a Standalone PV
System”.International Journal of Scientific & Engineering Research, Vol. 3, Issue no.3.
5. Hiren Patel and Vivek Agarwal, Senior Member, IEEE, March2008: “MATLAB - Based Modeling to
Study the Effects of Partial Shading on PV Array Characteristics”, IEEE Transactions On
Energy Conversion, vol.23,no.1,.
6. Eftichios Koutroulis, Kostas Kalaitzakis, Member, IEEE, and Nicholas C. Voulgaris , January 2001 :
“Development of a Microcontroller-based, Photovoltaic Maximum Power Point Tracking
Control System”, IEEE Transactions On Power Electronics, Vol.16, no.1.
7. Moacyr A. G. de Brito, Luigi G. Jr., Leonardo P. Sampaio, Guilherme A. e Melo and Carlos A. Canesin,
Senior Member, IEEE, 2012 : “Evaluation of the Main MPPT Techniques for Photovoltaic
Applications”.
8. A.I.Pressman, “Switching Power Supply Design”, NewYork: Mcgraw-Hill.
9. Ms. Sangita S. Kondawar , U. B. Vaidya, Aug 2012: “ A Comparison of Two MPPT Techniques for
PV System in MATLAB Simulink”, Vol.2, no.7, PP.73-79.

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