Download higher harmonics analize in led diode lamps used to illumination

ELEKTRYKA
Zeszyt 1 (217)
2011
Rok LVII
Łukasz PUTZ, Ryszard NAWROWSKI
Instytut Elektrotechniki i Elektroniki Przemysłowej. Politechnika Poznańska
HIGHER HARMONICS ANALIZE IN LED DIODE LAMPS USED
TO ILLUMINATION SCENERY
Summary. The paper presents the use of electroluminescence diodes (LED). The
structure and principles of operation of the diodes are presented. The paper shows
positive and negative aspects of LED diode operation. Main part of the paper includes
presentation of preliminary study of electroluminescent light sources taking into account
generation of the higher harmonics. The results provided the plots of the voltage and
current harmonics contents in the phase and neutral conductors. The characteristics
obtained this way have been thoroughly analyzed.
Keywords: higher harmonics, LED diodes LED lamps, operation of diodes, THD ratio
ANALIZA WYŻSZYCH HARMONICZNYCH W LAMPACH LED
UŻYWANYCH DO OŚWIETLENIA DEKORACYJNEGO
Streszczenie. W artykule zaprezentowano zastosowania diod elektroluminescencyjnych (LED). Przedstawiono budowę oraz zasadę działania takich diod.
Artykuł prezentuje także pozytywne i negatywne aspekty pracy diod LED. Część główną
publikacji stanowi zaprezentowanie wstępnych badań na elektroluminescencyjnych
źródłach światła w zakresie generacji wyższych harmonicznych. Na podstawie wyników
pomiarów zostały sporządzone wykresy zawartości harmonicznych napięcia i prądu.
Następnie dokonano szerokiej analizy uzyskanych charakterystyk.
Słowa kluczowe: diody LED, działanie diod, lampy LED, współczynnik THD, wyższe harmoniczne
1. INTRODUCTION
The electroluminescence diodes (i.e. LED – Light Emitting Diodes) are modern light
sources widely introduced to lighting industry. They replace traditional bulbs, halogens and
fluorescent light sources for lighting homes. They are also used at outer illumination of
buildings. The present automotive vehicles are as well provided with lighting diodes,
inclusive of lighting the vehicle interior and the outer road lights. At present the
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Ł. Putz, R. Nawrowski
electroluminescent light sources are used in lighting of streets, replacing to growing degree
the low and high pressure gas discharge lamps [7].
2. THE LED DIODES – DESIGN AND OPERATION
The electroluminescent diodes are made in the form of a p-n junction composed of
semiconductors of two types: the electron excess (N-egative) and electron defect (P-ositive)
ones. The current flowing through the junction causes recombination of electrons that transit
from the higher to basic energetic state. While passing to lower energetic state the energy
excess is transformed into the electromagnetic radiation quanta that is observed as a light of
the colour depending on the type of semiconductor used for the purpose. The design and
operation of electroluminescent diodes are shown in Fig. 1 [1, 10].
Fig. 1. Design and operation of LED diodes [10]
Rys. 1. Budowa i działanie diod LED [10]
The diodes of cold colours (white, blue, green) are obtained by proper doping of four
components: aluminum, gallium, indium, and nitrogen. The warm colours (red, orange,
yellow) may be obtained similarly, replacing nitrogen with phosphor. Colour of the diodes
affects the pattern of its voltage-current characteristics in the conduction direction, that
approximates a silicon rectifying diode. Current conduction begins at various voltage values
(Fig. 2) [1, 9]:
 0.5 – 0.7V – a silicon rectifying diode,
 1.3 – 1.5V – red diode,
 1.8 –2.0V – yellow diode,
 2.0 – 2.2V – green diode.
Higher harmonics analize…
101
Fig. 2. Voltage-current characteristics of LED diodes [9]
Rys. 2. Charakterystyki napięciowo-prądowe diod LED [9]
3. INTRODUCTION FEEDING SYSTEMS OF LED LAMPS
For proper operation of diode light sources an appropriate feeder is required. At present
such feeders are based on specialized integrated systems. An example of a control – feeding
system based on the SP7600 integrated system from EXAR is presented in Fig. 3. Such
controllers significantly improve the operation parameters of diode lamps, growing power
efficiency and power factor. Simultaneously such a feedings have a better resistance to
electromagnetic interference [3].
Fig. 3. LED feeder with Exar SP7600 integrated circuit [2]
Rys. 3. Zasilacz LED z układem scalonym Exar SP7600 [2]
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Ł. Putz, R. Nawrowski
4. THE CONCEPT OF HIGHER HARMONICS
The term higher harmonics is assigned to sinusoidal voltage or current patterns the
frequencies of which exceed the basic frequency (50Hz). The patterns superpose together
resulting in distorting the basic sinusoidal shape. The k-th voltage (current) harmonics is
defined as the ratio of multiplicity of the frequency of considered pattern to the basic
sinusoidal frequency [7]:
where:
fk – harmonic frequency,
f1 – basic mains frequency.
Connection of nonlinear receivers to the power network results in distortion of the current
pattern. On the other hand, the voltage drop occurring at the network impedance causes
voltage distortion in the receiver connection point. The distorted voltage (current)
disadvantageously affects other receivers connected to the same network, that, in
consequence, is conducive to [4]:
 increase in active power loss in transformers and motors;
 perturbations in operation of power-electric security systems;
 wrong operation of electric power meters;
 overload of capacitor batteries;
 difficulties in electric arc extinction in case of earth shorting;
 additional heat loss in the supplying line.
The distorted patterns of T period caused by the higher harmonics may be presented in
the form of Fourier series expansion [6]:
or
where:
Higher harmonics analize…
103
In order to appraise the degree of the pattern deformation the synthetic indexes are used,
referred to as the distortion factors of the voltage or current harmonic distortion THDU and
THDI (Total Harmonic Distortion), respectively [4]:
where:
U1 – rms value of the basic voltage harmonic component,
Uk – rms value of further voltage harmonic components,
I1 – rms value of the basic current intensity harmonic component,
Ik – rms value of further current intensity harmonic components.
5. THE INVESTIGATE POSITION
In order to find the level of higher harmonics generation emitted by the diode light
sources used in housekeeping the LED diode from APOLLO Lighting has been tested. The
tested diode is marked by manufacturer as LED-E27A12-WHT. It is a diode with a E27
screw-cap, supplied with alternate voltage 230V 50Hz and 1.2W power, white light emitting.
The tests have been carried out in the Theoretical Electrical Engineering Laboratory of
the Institute of Electrical Engineering and Industrial Electronics of Poznan University of
Technology. For the measurement purposes a high class FLUKE 434/PWR Power Quality
Analyzer of harmonic contents has been used (Fig. 4). It is a complete three-phase
troubleshooting tool that measures virtually every power system parameter: voltage, current,
frequency, power, energy consumption or power factor (cos φ), unbalance, and harmonics and
inter-harmonics [8].
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Ł. Putz, R. Nawrowski
Fig. 4. The measurement diagram with Fluke 434 meter
Rys. 4. Schemat pomiaru miernikiem Fluke 434
One can use Fluke 434/PWR meter to conduct energy consumption studies and electrical
load analysis, and to perform power quality logging and analysis according to PN-EN 50160.
From most important advantages of power quality meter it is possible to feature [8]:
 Captures events like dips and swells, interruptions and rapid voltage changes, based upon
½ cycle rms values;
 Auto Trend function gives a fast insight into changes over time;
 System Monitor function gives you an overview of power system performance. It also
checks that incoming power complies to norm PN-EN 50160 limits or to user own custom
specifications;
 Detailed, user-configurable long-term recording gives the MIN, MAX and AVG readings
of different parameters on all phases. Averaging time can be selected down to 0.5 seconds
(or 1 minute for 1 day’s recording, 10 minutes for 1 week, 30 minutes for 1 month or more;
 Two groups of four channels: simultaneously measure voltage and current on all three
phases and neutral;
 Auto Scaling function: easier trend analysis with automatic scaling of the vertical axis – so
user will always view the waveforms on a full display;
 Meets the stringent 600 V CAT IV, 1000 V CAT III safety standard required for
measurements at service entrance;
 Extensive data analysis: cursors and zoom can be used ‘live’ while taking the
measurements, or ‘offline’ on stored measurement data;
 The stored measurements can also be transferred to Power Log software on the computer
by the infrared port (safety connecting between computer and meter) and then widely
analyzed.
The meter enables measuring percent contents of particular harmonic components H
(until the 50th one), the harmonic contents THD factor and voltage or current direct
Higher harmonics analize…
105
component (DC). Accuracy available in case of the FLUKE 434 analyzer reaches ±2.5 per
cent in the measurement range 0÷100% (for THD, DC, H1..H50) [8].
According to the norm PN-EN 50160, for the lighting equipment, total harmonic
distortion factor for voltage (THDU) can’t exceed 8 percent. Instead for current total harmonic
distortion THDI isn’t clearly precise – there are given acceptable levels each harmonics:
second harmonic – 2 percent, third harmonic – 30×φ (power factor) percent, fifth – 10
percent, seventh – 7 percent, ninth – 5 percent, eleventh to thirty ninth – 3 percent [5].
6. FINDINGS
The measurement has been made for higher harmonics range. Other parameters of
electric power have not been measured. The harmonics arising in the phase and neutral
conductors have been separately recorded. Afterwards, the results obtained this way have
been averaged in order to minimize the errors (Table 1) and, consequently, served for making
the plots of percent contents of higher voltage and current harmonics, shown in Fig. 5 (the
phase conductor) and Fig. 6. (neutral conductor).
Analysis of the plots allows observing clear predomination of odd harmonics, both in
case of voltage and current. The THDU factor is similar both for the phase and neutral
conductors, being equal to 3.7 and 3.3%, respectively. It might be said that it is a satisfying
value – the pattern of actual voltage value is only slightly distorted as compared to the
sinusoidal shape. The contents of constant component in the voltage pattern is quite
insignificant (0.1 percent).
The bigger attention turns the plots of harmonic contents of current intensity. Same as in
case of voltage becomes visible the domination of odd harmonics. However the basic
harmonic of the phase conductor is no longer dominating, because amounts 57,5 percent (for
voltage it was 99,9 percent). In effect we have a large total harmonic distortion factor of
current – THDI = 59,3 percent. In the neutral conductor we can see the phenomenon of the
current rectification. The curve of current intensity is widely deformed from the sinusoid
(THDI = 90,3%), became straight – the content of constant component amount 95,9 percent.
One can declare that the stabilizing structure inside the LED lamp realize his role very well.
However it influence wrong on the energetic network by the generating higher harmonics of
current intensity and deform the current curve.
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Ł. Putz, R. Nawrowski
Table 1
The higher harmonics contents measuring results
Percent contents of THD factor, constant component DC
and each harmonics (1…50) [%]
Component
THD
DC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Phase conductor L1
Neutral conductor N
Voltage U
Current I
Voltage U
Current I
3,7
0,1
99,9
0,1
2,5
0
2,5
0
0,9
0
0,5
0
0,2
0
0,4
0
0,5
0
0,1
0
0,2
0
0,2
0
0
0
0,1
0
0,1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
59,3
23,7
57,5
16,3
22,2
6,4
13,3
5,3
7,9
3,9
6,1
4,9
6,8
4,8
6,4
4,2
6,1
4,5
6,2
3,8
4,7
4,1
4,9
4,1
4,2
3,9
4
4,2
4,3
4,3
4,1
4,5
3,6
4,6
4,2
4,6
4,3
3,8
4,2
3,9
4,4
4,1
3,9
4
3,9
3,9
4,1
3,6
3,6
3,7
4,2
3,3
3,3
0,1
99,9
0,3
2,2
0,1
2,1
0
0,9
0,1
0,3
0
0,2
0
0,3
0
0,3
0
0
0
0,1
0
0,1
0
0
0
0,1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
90,3
95,9
4,8
1,8
1,9
1,6
2
1,8
1,5
1,7
1,6
1,4
1,7
1,6
1,6
1,7
1,8
1,4
1,8
1,9
1,5
1,7
1,7
1,7
1,7
1,7
1,8
1,8
1,6
1,6
1,5
1,5
1,6
1,6
1,7
1,7
1,6
1,6
1,7
1,6
1,6
1,5
1,7
1,5
1,6
1,6
1,5
1,5
1,5
1,5
1,7
1,1
Higher harmonics analize…
Fig. 5. Percent harmonics contents in the phase conductor
Rys. 5. Procentowa zawartość harmonicznych w przewodzie fazowym
Fig. 6. Percent harmonics contents in the neutral conductor
Rys. 6. Procentowa zawartość harmonicznych w przewodzie zerowym
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Ł. Putz, R. Nawrowski
7. SUMMARY
The use of electronic systems with a view to stabilizing operation of the lighting diodes,
apart from its many advantages has one important fault – it generates higher harmonic
component. The systems of diode lamps emit higher order harmonics to the network, giving
rise to important hazard. This phenomenon would not be very significant without the fact that
the electroluminescent lighting is more and more commonly used and may become soon a
basic light source. In effect the distortion of voltage and current introduced to energetic
network are more and more greater, causing increasing of the THD factor in points of the
electrical energy distribution. It is necessary to use the special devices to reducing higher
harmonics. It is also possible that using nonlinear elements, like LED lamps, will force the
legislators to introduction of changes in the present norm PN-EN 50160.
The tests referred to in the present paper only depict the scope of the knowledge on
generation of higher harmonics by the electroluminescent light sources. The subject is very
wide and requires further experiences and studies with the use of various types of the LED
lamps [6].
BIBLIOGRAPHY
1. Collective Work: Technika świetlna ’09. Poradnik – Informator. Polish Lighting
Committee of SEP. Warsaw 2009.
2. Datasheet of EXAR SP7600 Integrated Circuit.
3. Gondek J., Kordowiak S.: Cyfrowe sterowniki hybrydowe LED. Materials of XIII
Scientific Conference Computer Applications in Electrical Engineering. Poznan 2008.
4. Lubierski K., Nawrowski R.: Badanie harmonicznych generowanych przez wyładowcze
źródła światła. Materials of Conference Polish-Ukrainian School-Seminar. Jawor-Solina
2000.
5. Polish – European Norm PN-EN 50160.
6. Putz Ł.: Generating higher harmonics in LED diode lamps used in housekeeping.
Materials of XI International Conference Computational Problems of Electrical
Engineering. Lazne Kynzvart 2010.
7. Putz Ł.: Oświetlenie elektroluminescencyjne a emisja wyższych harmonicznych.
Materials of XV Scientific Conference Computer Applications in Electrical Engineering.
Poznan 2010.
8. User Manual of FLUKE 434/PWR Power Quality Analyzer.
9. www.elektroda.pl (2011.02.01.).
10. www.en.wikipedia.org (2011.02.01.).
Higher harmonics analize…
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Recenzent: Prof. dr hab. inż. Marian Pasko
Wpłynęło do Redakcji dnia 20 września 2011 r.
Omówienie
W artykule zaprezentowano zastosowania diod elektroluminescencyjnych (LED).
Przedstawiono budowę oraz zasadę działania diod oraz pokazano przykład układu
stabilizująco – zasilającego dla lampy LED. Artykuł prezentuje także pozytywne i negatywne
aspekty pracy diod LED. W artykule przedstawiono także podstawy teorii wyższych
harmonicznych oraz skutki ich działania. Część główną publikacji stanowi zaprezentowanie
wstępnych badań na elektroluminescencyjnych źródłach światła w zakresie generacji
wyższych harmonicznych. Do pomiarów użyto analizatora jakości energii Fluke 434/PWR.
Źródłem światła, które wykorzystano do badań, była lampa LED firmy Apollo Lighting LEDE27-A12-WHT. Na podstawie wyników pomiarów zostały sporządzone wykresy zawartości
harmonicznych napięcia i prądu. Następnie dokonano analizy uzyskanych charakterystyk.