Modeling and Simulation of Photovoltaic Components of a Solar Power - - PowerPoint PPT Presentation

Modeling and Simulation of Photovoltaic Components of a Solar Power System

Ajith Gopi

Parsons Brinckerhoff

• Parson Brinckerhoff

– >14,000 people – 150 offices – six continents

• PB Power Asia

– 500 people – Most major Asian cities – Asia-Pacific region since early 1990s – Engineering Support for solar and wind power development

Recent Solar PV Modeling Experiences

• LE’s Technical Advisor for

Multiple Solar PV Projects in China (25.5MW)

• Technical Due Diligence
• f PV Projects (20MW) in

Portugal for a client in Korea

• LE for 25 MW Solar PV

project in Gujarat in India

Contents

PV Cell Model

The output current from the PV cell can be found using the equation: I=Isc-Id

(Where Isc is the short-circuit current that is equal to the photon generated current, and Id is the current shunted through the diode)

The diode current is given by the Schottky diode equation: Id= I0* (eq*Vd/(k*T) -1)

(Where Isc is the reverse saturation current of the diode (A), q is the electron charge (1.602 x 10-19C), Vd is the voltage across the diode (V), k is the Boltzmann’s constant (1.381x10-23 J/K) and T is the junction temperature in Kelvin (K))

PV Cell Model (…continued)

Combining the diode current equation with the equation for the output current of the PV cell creates: I= Isc- I0* (eq*V/(k*T) -1) (Where V is the voltage across the PV cell, and I is the output current) We can solve for the reverse saturation current (I0) by setting I=0 (no

• utput current).

I0= Isc (eq*Vd/(k*T) -1)

More accurate model of a PV Cell

Taking into account the series Resistance, Shunt Resistance and Recombinations, the equation becomes: I= Isc – I01 * (eq*V+I*Rs /(k*T) -1) – I02* (eq*V+I*Rs /(2*k*T) -1)- (V+I*Rs)/Rp The two diodes can be combined to simplify the equation to: I= Isc – I0 * (eq*V+I*Rs /(n* k*T) -1) - (V+I*Rs)/Rp (Where n is known as the “ideality factor” and takes a value between one and two)

Model of a PV Cell

The effect of the shunt resistance is minimal for a small number of modules. Therefore, we can assume Rp=∞ ∞ ∞ ∞, simplifying the photon-generated current equation to: I= Isc – I0 * (eq*(V+I*Rs /(n*k*T)-1)

Simulink - PV Cell Model

PV Cell Model I-V and Power Characteristics

Simulink Implementation of PV Module

PV Modules are implemented as Masked Subsystems in Simulink in two Input modes

• Current Input PV

Module

• Voltage Input PV

Module

Model parameters for the Simulink Model

Model parameters, in both cases, are the standard PV module data-sheet parameters:

• Short-circuit current Isc
• Open-circuit voltage Voc
• Rated current Ir at maximum power

point (MPP)

• Rated voltage Vr at MPP

(Under standard test conditions of 1kW/m2, 1.5 AM, 25oC).

Simulink Implementation of a Current Input PV Module

Inputs:

• PV current Ipv [A]
• Insolation [W/m2]

Outputs:

• PV voltage Vpv [V]
• PV output power Ppv [W]

This model is well suited for the case when modules are connected in series and share the same current

Simulink PV Module Model

Simulink PV Module Model Sub System with Current Input (Ipv)

Simulink Implementation of a Current Input PV Module

Inputs:

• PV voltage Vpv [V]
• Insolation [W/m2]

Outputs:

• PV current Ipv [A]
• PV output power Ppv [W]

This model is well suited for the case when modules are connected in parallel and share the same voltage

PV Module Sub System with Voltage Input (Vpv) (Suitable for Parallel Connections)

Simulink PV Module Model as a Software Tool for Performance Analysis

PV Module Model – I-V and Power Characteristics

Performance Comparison two PV Modules

Data Sheet Parameters of Module A Isc 2.5 A Voc 21.8 V Imp 2.3 A Vmp 17.3 V Power at S.T.C 40 W Data Sheet Parameters of Module B Isc 2.5 A Voc 21 V Imp 2.18 A Vmp 17 V Power at S.T.C 40 W

I V Characteristics comparison and validating with PV Syst values

Fill Factor is more for Module A since the squareness of the curves is more for Module A. Hence Module A is more efficient than Module B

Power Characteristics Comparison odf Module A & B

Fill Factor is directly proportional to the Power output of the PV Module Hence it is evident that

• utput power of Module

A more compared to Module B

Simulink – PV Array Model

(WITH SOLAR MODULE MODEL SUBSYSTEM BLOCK WITH CURRENT (Ipv) INPUT)

Conclusions

• Photovoltaic components of a Solar Power System are

mathematically modelled and then simulated in Matlab/Simulink.

• Simulink models are implemented for:

Solar Cell, PV Module (Current Input Model and Voltage Input Model) & a typical Solar Array

• Development of a Software tool for the PV Module Performance

Evaluation from the Module Data Sheet Parameters.

Any Questions?

Thank you for your attention!

Further information please contact: Ajith Gopi Principal Engineer gopi.ajith@pbworld.com