1

REVIEW OF CFL AND ITS HARMONIC IMPACT ON ELECTRICAL DISTRIBUTION SYSTEM

Guide: Mr. Rijo Rajan, prepared by: Merin Lukose Lecturer, S7 EEE EEE department.

Seminar On

2

C O N T E N T S

• Introduction

•Why CFL preferred over incandescent?

•What is CFL and its working and ballast circuit.

•Harmonics, terms related and how csfl cause harmonics.

•Problems of harmonics and its effect on power factor.

•Harmonic components from a cfl and its effect.

•Methods to reduce harmonics.

•Classification of CFL

•Effects of wide spread adoption of CFL

•conclusion

3

Energy advantages of CFL has made it a common lighting device recently.

CFL comprises of electronic components which produces harmonics.

System gets polluted due to harmonics and it seriously affect the electrical equipments connected in the network.

INTRODUCTION

4

CFLs consume about 80% less power than conventional lamps.

Life span is 8-15 times that of incandescent.

Cost saving.

Shapes, styles and provide variety in light colors.

Produce 75% less heat.

Why CFL preferred over incandescent.

5

Most commonly used lighting device.

It consists of dc power supply and an ac inverter

Electronic device used in CFLs is the electronic ballast circuit.

Ballast circuit limits the ionizing current.

What is CFL and its working

6

ultraviolet rays are formed by the ionization of gases.

Fluorescent phosphor on glass tube surface convert ultraviolet rays to visible light.

Ionizing current generated is limited by the ballast circuit.

Working in detail

7

ELECTRONIC BALLAST CIRCUIT

8

1. Electromagnetic interference filter. Filter unwanted harmonic currents

consumed by the load.2. Bridge rectifier. Ac voltage is converted to dc which is

supplied to the high frequency oscillator3. High frequency oscillator. High frequency ac voltage to the output

circuit and fluorescent tube.

PARTS OF BALLAST CIRCUIT AND FUNCTIONS

9

Presence of multiples of fundamental frequency.

Measured in terms of THD, Total Harmonic Distortion.

Created by non-linear loads.

Amount of equipments generating harmonics has risen dramatically.

Disturbs the power quality

HARMONICS

10

Input wave with harmonic frequencies

Wave form showing harmonic distortion

Resultant wave

11

THD

• Measurement of the harmonic distortion in terms of rms voltage and current.

• THDV=√(V2²+V3²+V4²+…+Vn²)*100/v1.

IDF •Input Displacement Factor which refers to the cosine of the angle between input 50Hz voltage and current.

DF •Distortion factor shows the variation of the wave from the input sinusoidal wave.•DF=1/√(1+THD²), PF=IDF*DF

12

CFLs contain the electronic ballast within them.

The components of electronic ballast are non-linear in nature.

Non-linear components conduct during short bursts of the input sine wave.

Thus there forms cropped wave after the conduction of each component.

How CFL cause harmonics

13

There are different cropped waves of this type within the system.

Combines and forms higher order harmonic components.

Different harmonic voltages act together and there by disturbs the entire power quality.

How CFL cause harmonics

14

Harder to mitigate since CFLs are distributed across the network rather than in one location.

Why CFL harmonics exists?

15

Current wave and harmonic spectrum for CFL combinations.

Current wave for 2*11W+2*7W cfls

Harmonic spectrum for 2*11W+2*7W cfls

16

%of CFL load

total power factor

%of voltage distortion

%THD

1.5 0.84 0.3 1.7

4.1 0.82 0.7 4.5

9.4

0.76 1.5 9.8

26.3 0.65 4.4 23.5

50

0.58 5.4 55

Impact of CFL on 100kva building load.

17

5 Order

Harmonics(2.4%)

7Order

harmonics(0.69%)

Major harmonic components generated by a 15 W Compact Flourescent Lamp

3 OrderHarmonics (7.6%)

thrd

th

18

a. Effect of 3rd order harmonic ..Causes hysteresis loss

..Over heating of neutral conducts ..Causes no effect on IM

b. Effect of 5th order harmonic ..Counter electro motive force in large machines ..Counter torque in case of IM c Effect of 7th order harmonic .. causes excessive heating in the machine .. contributes to the machine torque.

Effect of 3rd,5th&7th order harmonics

19

Introduce neutral currents over 100% of the phase current.

Over heating of transformers.

Reduces the life expectancy of motors.

Over stressing of power factor correction capacitors.

Nuisance tripping of residual current circuit breakers.

Decreases equipment lifetime.

Problems caused by harmonics

20

Power factor in sinusoidal cases(linear loads)

V(t)=v1sin(ω0t+δ1)i(t)=i1sin(ω0t+θ1)

Pftrue=pfdisp=cos(δ1-θ1)

Power factor in non-sinusoidal cases(non-linear loads)

V(t)=Σ vnsin (nω0t+δn)i(t)=Σinsin(nω0t+θn)

Pf true=pfdisp*pfdist

Effect of harmonics on power factor

21

Reinforced distribution system

It is about 10 times cheaper to manufacture high power factor(0.9), low harmonic CFLs than correcting.

Harmonic filters. 1. active filters 2. passive filters

Isolation transformers

Methods to reduce harmonics

22

ACTIVE FILTERSUsed for low voltage

networks.Active filter reduction to

5%or less.Grouped as series,

parallel and hybrid filters.

Cancels multiple harmonic orders.

An array of capacitors, inductors and resistors.

Passive filter reduction to 15-25%.

Classified as series and parallel filters

Cancels only one harmonic order.

Reliable and economical

ACTIVE AND PASSIVE FILTERS

PASSIVE FILTERS

23

• High level of current distortion up to 140%.

• Low order harmonics are dominant.

High distortion electronic

ballast CFLs.

• Current harmonic distortion is 30%.

• Considerable drop in lower order harmonics reduction in THD.

Low distortion electronic

ballast CFLs.

• Harmonic distortion is below 20%.

• drop in lower order harmonics reduction in THD.

Magnetic ballast CFLs.

Classification of CFLs based on harmonic characteristics.

24

Use of some CFLs exhibit high level of harmonic distortions.

Generation and radiation of RF noise.

Low power factor and harmonic current distortion and its effect on distribution system.

There is about 0.5 grams of mercury in each CFL causes health hazards.

Effects of widespread adoption of CFL

25

CFL reduces power consumption on lighting load side.Injects harmonics and causes distortion.Ballast circuit causes the generation of harmonics.Damage the equipments connected and seriously affect

the power factorHarmonics has to be eliminated to improve the power

quality.But advancing power electronic sector further makes

the distribution system impure.

CONCLUSION