International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391

Volume 6 Issue 3, March 2017

www.ijsr.net Licensed Under Creative Commons Attribution CC BY

Microcontroller Based Control Scheme for Solar PV

System under Asymmetrical Fault Condition

Mohini W. Badwaik1, Prashant P. Jagtap

2

1M.Tech. (IPS) Student, Department of Electrical Engineering, G. H. Raisoni college of Engg., Nagpur, India

2Assistant Professor, Department of Electrical Engineering, G. H. Raisoni college of Engg., Nagpur, India

Abstract: In the current situation there is a speedy growth in request of electrical energy and will be duple in upcoming days but still

the use of Non-conventional energy sources is relatively very low over conventional energy sources. But now the several awareness

programs of several societies results in to the growth in utilisation of Non-conventional energy sources like solar, geothermal, winds etc.

While getting the electrical energy from Non-conventional energy sources it is very difficult task to maintain the quality of power with

less interruptions to avoid the failure of grid, since there are various faults and problems occurs in the network. For example in the case

of solar power plant shadowing, short circuit, open circuit etc. This paper focuses on the occurrence of Asymmetrical fault and its

control schemes while deriving the Electrical energy from one of the largest and free of cost source of Non-conventional energy i.e.

Sunrays through the Solar panel. Asymmetrical fault is nothing but short circuit fault which is analysed and controlled by the voltage

support control method and positive sequence recovery with the help of microcontroller based inverter is to be discussed in this paper.

Keywords: Grid connected PV system, Pulse Width Modulated Inverter, Voltage Support Control, Positive Sequence Recovery

1. Introduction

As the improvement of technologies to get the desired output

results into the increase in some complications also similarly

while deriving the electrical energy from the sun through the

Solar Photo Voltaic Cell say solar connected grid to satisfy

the electrical energy demand and parallel reducing the harm

to nature, there are some conditions occur which are very

harmful to the network. One of them is Asymmetrical Fault.

It is very mandatory to dump the Asymmetrical fault; if not

then it will affect the network lot and leads the whole Grid

towards failure. The control over asymmetrical fault in the

network makes the grid connected solar PV system more

reliable and safest source of electrical energy in addition to

the cleanest and cheapest source of energy.

The credit for the invention of PV cell goes to the Greek

scientist Mr. Allesandro Volta who discovers the method of

converting solar energy into electrical energy through

radiations. But the obtained electrical energy is in the DC

form and therefore its uses were limited in early days. This

major problem is now eliminated with the help of inverter

which converts the DC Electrical energy from solar PV cell

into Alternating current source.

The main objective of the paper is to minimize the grid

failure due to asymmetrical faults in the grid connected solar

PV system with the help of microcontroller based control

schemes.

2. Grid Connected PV System

The grid Connected PV system is nothing but the Series-

Parallel connected Solar PV cells connected to the Load via

Bus through a proper components i.e. Inverter Filters etc.

Usually the output of a solar PV cells is 12 volts DC which is

then inverted to AC with the help of inverter and then its

voltage step-up to the bus voltage level with the help of

transformer and then connected to Grid.

Figure 1: Block diagram of main system

3. PWM Inverter

In this experiment we have used the three phase controlled

inverter, in which IGBT switches are used for controlling

purpose instead of MOSFET in the three legs of the inverter

circuit. Due to the inbuilt PWM module and low cost of

Microcontroller based inverter enhances it’s used in

photovoltaic application. In this the voltage level is

controlled by the Multilevel Inverter with Pulse Width

Modulation, for which the Microcontroller AT89C52 is used

to generate PWM pulses and to control the operation of three

phase inverter. The following figure shows the inverter

circuit with IGBTs connected with resistive load:

Figure 2: 3 phase inverter with resistive load

Paper ID: ART20172135 2312

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391

Volume 6 Issue 3, March 2017

www.ijsr.net Licensed Under Creative Commons Attribution CC BY

4. Microcontroller

The microcontroller AT89C52 used in this research is

manufactured by Atmel’s non-volatile Flash programmable

and erasable read only memory (PEROM) technology which

provides cost effective and highly flexible solution to

embedded control.

The proteus software is used to check the simulation

program or connections if any error detected then we can

resolve it.

The simplified diagram for microcontroller is shown below:

Figure 3(a): Simplified diagram of microcontroller 89c52

Port 0 is used for interfacing LCD Display which displays

the project title. It also displays the occurrence of fault on a

particular phase and its recovery.

Port 1 is used for getting PWM output which will feed to

Gate driver Circuit of inverter.

The microcontroller programming is done in C-code

programming language. The error codes are debugged by the

IDE before compiling it into binary code which can be

executed by the microcontroller the in-circuit serial

programmer is used to transfer these codes from PC to

Microcontroller of which typical diagram shown in

following figure.

Figure 3(b): Programming through RIDE software

Crystal oscillator(11.0592 MHz) along with two capacitors

(33pF) is added in the circuit to make the microcontroller

feasible to burn, first prepare the program in C-code with the

help of Ride software which is then converted into hex file

and programmed through programmer or burner, six pin of

microcontroller are connected with burner female pin.

Figure 3 (c): Required circuitry while program burning

5. Voltage Support Control

Voltage support control method is nothing but the method to

keep the output voltage level and power of PV cells within

limits when the system is in normal operation. The short

circuit in the grid tends to the reduction in the grid voltage as

well as the grid power at the same time if the output power

of the PV cell is constant then this imbalance of power

results into the rise in the DC link voltage. To maintain the

PV cells in the system during this low voltage condition it is

mandatory to reduce the output of the PV cells, this method

is known as DC Voltage Control and can be obtained by

using microcontroller just by regulating the Duty cycle same

as MPPT control strategy during normal operation. In

addition to this the PV generation also injects the certain

reactive power in the system for supporting recovery of grid

voltage.

6. Hardware Implementation

The Hardware model for microcontroller based Solar PV

system under asymmetrical fault condition is designed as

shown below:

Figure 4: Hardware

From above figure it is seen that three phase inverter with

IGBT, bridge rectifier, microcontroller are used along with

LCD display. The block diagram for hardware

implementation is shown below:

Paper ID: ART20172135 2313

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391

Volume 6 Issue 3, March 2017

www.ijsr.net Licensed Under Creative Commons Attribution CC BY

Figure 5: Block diagram

The 12 V DC is obtained from the output of step down

multistage transformer which is then rectified with the help

of rectifier followed by IC7812 and fed to the three phase 3

level PWM inverter. Here the pulse width modulation is

done through microcontroller which has LCD Display

interfaced at port 0 and Gate driver circuit interfaced at port

1.

The 5 V DC supply for the operation of microcontroller is

obtained from same step down multistage transformer

followed by IC7805. L-C filter is used to filter out the

harmonics so that the pure AC is available for the load. The

high resistive filament incandescent lamp is used as the load.

The Gate Driver circuit has TLP250 8 pin IC required to

drive the power transistors i.e. IGBTs in an inverter. The pin

configuration diagram is shown below:

Figure 6: Gate driver pin 8 pin configurations

In addition to the IGBT and microcontroller various

components and devices are used for hardware

implementation. The list of components and their ratings are

shown in the below:

Table 1: List of components Components Ratings

Microcontroller 89c52

Multistage

Transformer Step down 15v (1 no.)

IGBT (25N120 IC)

VCES = ±1200 V (6 no.) IC25 = 25 A

VCE(sat) typ. = 2.5 V Maximum

Capacitor 0.1 µf 15V, (4 no.)

Resistor 1k (7 no.), 10k (1no.), 100k (6 no.)

Cristal oscillator 11 kw (1 no.)

Voltage regulator

IC 7805(1 no.),

7815(4no.)

+5 v, supply,

+15 v. supply.

TLP250 Opto coupler Gate driver IC (6 no.)

Multistage

Transformer (1 no.) (0-15) volt step down transformer

LC Filter Connector 1 no.

Diode (16 no.) 4007

Capacitor 0.1 microfarad (16 no.), 1000 farad (1

no.), 10 microfarad (1 no.)

IC gate controller 4069

IC base 40 pin

Copper PCB 1*1

Solar panel 75 watt

7. Experimental Process And Results:

A 75 watt solar panel which generates DC power of up to 20

volts is connected to input side of inverter through charge

controller and battery which has two terminals i.e. positive

and negative terminals. The inverter converts DC voltage

into pure AC voltage with the help of L-C filter and is ready

to fed to the Resistive load, here high resistive Filament lamp

is used as a resistive load and it glows under normal

condition.

Now the L-G fault is created with the help of switches and

the waveforms under fault condition is shown below:

Figure 7(a): During fault condition

This fault is then cleared by controlling the PWM pulses of

inverter through microcontroller programming with the help

of gate driver circuit. The waveforms after fault clearing are

shown below:

Figure 7(b): After fault cleared condition

The fault created on particular phase and recovery of positive

sequence is shown in LCD display:

Paper ID: ART20172135 2314

International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064

Index Copernicus Value (2015): 78.96 | Impact Factor (2015): 6.391

Volume 6 Issue 3, March 2017

www.ijsr.net Licensed Under Creative Commons Attribution CC BY

Figure7(c): LCD display with phase sequence

8. Conclusions and Future Scopes

Thus a new idea of control schemes for solar PV system

under asymmetrical fault condition with the help of

microcontroller based PWM inverter in which voltage

support control is done by adjusting duty cycles and positive

sequence recovered with the help of microcontroller is

introduced in this paper. This will help to make the grid

connected solar PV system more reliable and ensures fast

recovery under asymmetrical fault condition to avoid the

failure of grid.

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[2] Md. Manirul Islam, Md.Masud Rana, Abu Farzan Mitul.

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[3] Kaiting LI, Junjie QIAN, Huaren WU, Tianran LI, Jianfei

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[5] Amol Sutar1, Satyawan Jagtap2,”Advanced Three Phase

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Author Profile

Mohini Waman Badwaik received the Degree in

Bachelor of Engineering in Electrical Engineering

from Priyadarshini Indira Gandhi College of

Engineering and Technology, Nagpur in 2014 and

pursuing Post Graduation in Masters in Technology in

Integrated Power System From G. H. Raisoni College of

Engineering, Nagpur.

Prashant P Jagtap received the Masters Degree in

Power System from Visvesvarya National Institute of

Technology, Nagpur in 2004 and working as a

Professor in Department of Electrical Engineering

(Integreted Power System) G. H. Rasisoni College of

Enginnering, Nagpur.

Paper ID: ART20172135 2315