SOLAR ENERGY IN DISTRIBUTED GENERATION AND GRID-CONNECTED PROBLEM

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Energy System

THESIS

Khoa Điện-Điện Tử 2002 – 2007

SOLAR ENERGY IN DISTRIBUTED

GENERATION AND GRID-CONNECTED

PROBLEM

Student: Vo Nguyen Qui Tu

CHƯƠNG TRÌNH ĐÀO TẠO KỸ SƯ CHẤT LƯỢNG CAO VIỆT-PHÁP PFIEV

Main parts

Solar Energy

1

Control single-phase inverter

2

TMS320F2812 DSP

3

Conclusions and Future Works

5

Experimental results

4

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Khoa Điện-Điện Tử 2002 – 2007.

1 Solar Energy

How solar cell work

N‐type silicon

P‐type silicon

+ + + + + + + + + + + + + + +

‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐ ‐

+

P‐N junction

(‐)

(+)

DC current

‐

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Characteristics of a solar cell

sc

I ≈ 20 mA cm → 40 mA cm

V oc = 0.6V → 0.7V

( V ,I mpp mpp )

: Maximum Power Point

(I-V) and (P-V) characteristics for a solar cell

Effects of temperature and insolation

levels on silicons solar cell

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• One silicon solar cell produces 0.5 volt

• 36 cell connected together have enough voltage to charge 12

volt batteries and runs pump and motors

• Can connect modules togethers to get any power configuration

Photovoltaic cells, modules, panels and arrays.

Grid-connected PV system

electric utility grid

Converts the DC power produced by the PV array into AC power consistent with

the voltage and power quality requirements of the utility grid

Automatically stops supplying power to the grid when the utility grid is not

energized

Diagram of grid-connected photovoltaic system.

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Grid-connected PV system

output circuits and the electric utility network

Either supply on-site electrical loads, or to back-feed the grid when the PV system

output is greater than the on-site load demand

When the electrical loads are greater than the PV system output, the loads is

received from the electric utility

Stand-alone PV system

loads

Direct-coupled PV system.

Diagram of stand-alone PV system with battery storage powering DC and AC loads.

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2

Control single-phase PV

inverter

Inverter

with conventional utility-powered appliances

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Inverter control schemes

Sinusoidal PWM

Space Vector Modulation (SVPWM)

To control inverter output frequency (fundamental)

To control inverter output voltage (fundamental)

To minimize harmonic distortion

Single-phase inverter output voltage

Space Vector Modulation

s

v = Ve ω = Ve α

Reference vector

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1

0 2

2

3 sin( 3 )

2

DC

DC s

V

V V

V

π α

⎧

⎪

⎨

⎪

⎪ = − −

⎪

⎪⎩

Total number of switchings: 4

Switching sequence

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Control single-phase inverter by

3

larger amplitude than phase voltage

leading corresponding phase voltage by 30 degrees

Simulation results in Matlab

Single-phase inverter output voltage waveform

Fourier analysis (50 Hz)

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LC Filter

Second-order LC Filter Magnitude Bode plot for second order LC Filter

2

1 1 1 1

o

i

L L

V

L

Z

ω ω

+ ⎜ + ⎟

Voltage ratio Cut-off frequency

3 TMS320F2812 DSP

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flexible, control specific designs

High-performance DSP controller allows most efficient control techniques

Most Powerful Control

TMS320F2812 DSP

• 32-bit DSP Core

150 MIPS performance

32x32 bit MAC

Fast interrupt service time

• Control Peripherals

Up to 16 independent PWM channels

16-channel ADC 12-bit

GPIO

Up to 2 SCIs

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TMS320F2812 DSP

SVPWM Block

Symmetric SVPWM Waveforms (sector I)

(SVRDIR=0)

TMS320F2812 DSP

Symmetric SVPWM Waveforms (sector VI)

(SVRDIR=1)

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Code Composer Studio v3.1

Editor window

Project

files

Message

window

Program code is C language and/or Assembly

Program flowchart

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System control of single-phase inverter

Interface control system

output

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4 Experimental Results

Experimental Results

Buffer circuit

Single-phase inveter

Optocoupler

isolation

MOSFET gate

driver

sources

Rectifier

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System is running

TMS320F2812

DSP

Control circuit

High-frequency

Load voltage

12.6 Ratio of transformer

L=0.59 mH C=3.3 uF

LC Filter

110 V RMS Load Voltage

R = 1.25 kΩ

L = 0.13 H Load (lamp + inductor)

24 V

DC Voltage

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f pwm = 5kHz

f pwm =10kHz

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f pwm =15kHz

5 Conclusions and Future

Works

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systems structure

harmonic magnitude of single-phase inverter output

voltage

Future research works

closed-loop control with estimated and monitored fast and

accurated enough grid voltage and frequency, and

synchronized the current with the grid voltage.

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Tiêu đề	Solar Energy In Distributed Generation And Grid-connected Problem
Tác giả	Vo Nguyen Qui Tu
Người hướng dẫn	Prof. Assoc. Nguyen Huu Phuc
Trường học	PFIEV
Chuyên ngành	Khoa Điện-Điện Tử
Thể loại	Luận văn
Năm xuất bản	2002 – 2007
Thành phố	Việt Nam

Định dạng
Số trang	20
Dung lượng	1,14 MB