Engineering, 2013, 5, 215-220
doi:10.4236/eng.2013.51b039 Published Online January 2013 (http://www.SciR
Copyright © 2013 SciRes. ENG
Harmonic Measurement and Analysis during Electric
Vehicle Char ging*
Mohd Zamri Che Wanik1, Mohd FadzilMohd Siam1, Afida Ayob2, Subiyanto2, Azah Mohamed2,
Abu HanifahAzit3, SaharuddinSulaiman3, Mohamed Azrin Mohamed Ali4,
Zahrul Faizi Hussein1, A h mad Kamil MatHussin1
1TNB Research Malaysia, Mala ysia
2Power System Research Grou p, Universi tiKebangsaan Malaysia, Malaysia
3TNB Distribution Malaysia, Malaysia
4Malaysian Green Technology Corporation, Bandar BaruBangi, Malaysia
Received 2013
This paper presentsand describes harmonic measurement and analysis of studying harmonic propagation during electric
vehicle (EV) charging. The measurement study is performed on a golf cart and two modern type of EVs. Harmonics
from a single EV charging and a group of EV charging was measured. The voltage and current waveform during the
charging was captured and analyzed to investigate the harmonic components that exist in the electrical system. Total
current har monic distortio n (THDi) and total volta ge harmo nic distortion (T HDi) were both calc ulated. Mod ern electric
vehiclesare found to release low THDi but higher THDv compared to a golf cart. On the measurement study during
charging of a group of EV, it is found that the summation of THD is not linear with a number of vehicle s. T he finding
of the study reveals that harmonic contamination from EV charging on electrical grid is not as critical as thought by
most of power system researchers and engineers.
Keywords: Electric Vehicle; Total Harmonic Distortion; Electric Vehicle Charging; Harmonic; Power Quality
1. Introduction
In l igh t o f hi gh e ner gy usa ge, e nvir on me ntal po llut io n a nd
rising fossil fuel prices, current dependence on internal
combustion engine (ICE) technology employed in vehicles
should be red uced and t he widespread use ofelectricvehic le
(EV) as the transportation of choice in 20 to 30 years
time should be increased. It is estimated that EV vehicle
penetration will increa se gradually where 35% is proj ected
at 2020 and will reach 50% by the year of 2024 [1-2].
The general effect on distribution systems caused by
the spread of EV will be substantial load increase and
large increment of system voltage and harmonic distor -
tion. Anot her is sue t hat s hould be co nsider ed is t he coi n-
cidence between the charging start time and the eventual
evening load peak period, which varies with customer
and c ountry.
For charging, EVbatteries need DC current so the grid
AC current will be converted to DC by battery charger.
The charger is basically the rectifier/inverter with con-
troller integrated with protection circuit. This is where
the concern rises because inverter/rectifier is known asa
harmonic source. So one of the concerns with electric
vehicle charging is the harmonic contamination to the
electrical grid .
The re is no agreeme nt howe ver on how muc h the to tal
harmonic distortion (THD) can be released to the net-
work during charging. In one of the published report,
total current harmonic distortion (THDi) is reported be-
tween 2.36% to 5.26% at the beginning of charging and
reaching up to 28% at the end of charging. However total
voltage harmonic distortion (THDv) is claimed only to
range between 1 and 2% with power factor close to unity.
For commercial chargers, THDi from measurement re-
cording values are between 60% to 70% [1,3-4].
The concern of the engineers and researchers are when
a large number of EVs charging simultaneously to the
power system grid. What is the sum of THD when EV
multiplies in numbers?Many believethat THD will in-
crease with the number of vehicles. It is however diffi-
cult to find a report that discusses this issue. Moreover
the values indicate in the previous paragraph was re-
ported [3-4] more than 10 years ago so the valuesdo not
TNB is an abbreviation for TenagaNasionalBerhad which is a main
electrical utility company in Malaysia. TNB research is a research arm
of TNB.
Copyright © 2013 SciRes. ENG
represent the actual amount ofharmonic generated from
state-of-the-art charger technologies that is used in mod-
ern electric vehicles.
The study re port ed in this p aper tries to investigate the
harmonic distortion from a single EV and a group of EVs.
The measurement was performed on an older type of EV
and two modern types of EV. The results of the study is
usef ul in und ersta nding t he ha rmonic d istor tion co ntri bu-
tion from EV connected to t he grid for charging.
This pap er is organized as follo w. First EV technolo gy
is briefly reviewed.The harmonic distortion limit then
highlighted. Harmonic measurement during a single ve-
hicle charging is then presented. Finally the harmonic
distortion during charging of a group of EV is discussed
and commented.
2. Electric Vehicle Technology
Electric vehicle that will be seen creating issues on the
power system gridwill be of two types. First type is plug
in hybrid where there is a combinat ion o f IC E a nd b atter y.
The second type will be all electric vehicle where this
vehicle depends solely on battery. For both types of EV,
electrical power is needed from the grid for charging.
Example of typical PHEV hardware arrangement is
depicted in Figure 1. This is for parallel type of PHEV.
There is also series type of PHEV but the focus of this
paper is on the grid connection issue so it is not impor-
tant if the EV is of parallel or series type. For all electric
vehicle, the components in the light green dash lines are
not needed and removed leaving only batteries, charger,
po wer electronic drive and propulsion electric motor.
When EV is charging, the only active compo nents are
charger and battery because EV is not moving. For grid
inter fac i n g st ud ies, the EV can be represented electrically
as depicted in Figure 2. Battery charger is basically a
rectifier which converts AC current from the grid to DC
current to charge the battery. The rectifier is normally of
active type where the power electronic devices are em-
ployed for switching devices. In this diagram power
electronic devices are IGBT.
Figure 1. PHEV typical layout [5].
Figure 2 . Battery charg er circ uit diagram [6].
EV charger is normally of conductive type eventhough
inductive type is available. Conductive chargers have
direct plug-in connection to the supply e.g. using an ex-
tension power cord to plug form the wall outlet into the
EV. Inductive charger on the other hand use magnetic
coupling as a mode of energy transfer. Comparing these
two types, conductive charger is simpler to design, hav-
ing higher efficiency and more popular.
3. Harmonics Distortion Limit
Harmonicsdistortion has detrimental effects on elec-
trical equipment inside power system.Severity of har-
monic is determined by the percentage of total harmonic
voltage distortion. Harmonic voltage is referred to as a
sinusoidal voltage having frequency equal to an integer
multiple of the fundamental frequency of 50/60 Hz
supply. Total harmonic distortion is calculated as fol-
40 2
40 2
In Ma la ysi a, t he ma in uti l it y co mpa n y, T enaga Na sional
Berhad, has set a limit on total harmonic voltage distor-
tion according to voltage level as tabulated in Table 1.
For current there is no distortion li mit set.
4. Harmonic Measurement
A few field measurement activities were conducted in-
vestigatethe har monic d uri ng E V cha rgi ng. T he mea sure -
ment is performed using Fluke power quality meter. The
picture of the meter is portrayed in Figure 3. The meter
has the ca pa bi lit y t o d ir ect ly d i spl a y th e vol ta ge a nd cur re nt
waveforms in real time. In addition, the measurement
Copyright © 2013 SciRes. ENG
data can be saved into the memory of the meter for
further a nalysis.
For individ ual har monic, thre e types of electric vehicle
is compared. The first type of EV is a commercial type of
modern EV ( EV1). Second type is modern EV prototype
(EV 2). Third type is a golf cart. Due to classified and
sensitive issues, the name of the manufacturers and the
brand of these EVs are not disclosed.
Table 1. THDv limit in TNB Distribution system [7].
Volta ge Lev el THDv
33 kV 3%
11 kV 4%
0.4 kV and bel ow 5%
Figure 3 . Fluke power quality met er.
Figure 4 . Modern EV 1 voltage and current waveform.
Figure 4 shows the voltage and current waveforms of
EV 1. Figure 5 and 6 show THDv and THDi for EV 1
respectively. THDv and THDi after analysis are 1.5%
and 11.6% respectively. For EV 2, the voltage and cur-
rent waveform are depicted in Figure 7. THDv and
THDi for EV 2 is 1.2% (Figure 8) and 9.2% (Figure 9)
respectively. Figure 10 shows the voltage and current
waveform for the golf cart. Figure 11 and 12 shows
THDv and THDi for the golf cart which are 1.1% and
34.4% respectively.
Figure 5. Total voltag e harmonic distortion from EV 1.
Figure 6 . Total current harmon ic distorti on from EV 1.
Copyright © 2013 SciRes. ENG
Figure 7 . Modern EV 2 voltage and current waveform.
Figure 8. Modern EV 2 total voltage harmonic distortion.
Figure 9. Modern EV 2 total voltage harmonic distortion.
Figure 1 0. Gol f cart voltage and current waveform.
The measurement results reveal that the THDi from
chargers is low for modern EV but for THDv, modern
EV is releasing higher distortion. The lower THDv fro m
golf cart can be explained due to lower current magni-
tude drawn during the charging. For modern EV, even
though THD i is lower, T HDv i s hig her than measured for
golf cart. This is due to higher current magnitude drawn
by modern EV.
5. Harmonic From a Group of EV
In the previous sectio n, THDv measured from a single
EV was presented. The value was recorded lower than
limit set b y utility. B ut the concern o n harmonic is when
a group of EVs connected to the grid simultaneously for
char ging. T here a re many eng ineer s who tho ught tha t the
summation of THD from a group of EVs is linear with
the sum of EV.To find out the answer, a measurement is
performed to measure THD from a group of EVs.
In Malaysia, modern EV is not yet commercialized so
the study cannot be performed on the commercial EVs.
But there are many golf carts available which can be
used i n the st udy. T he resul ts wil l not re prese nt the mod-
ern EV harmonic but the main objective is to investigate
the sum of THD from a single EV and a group of [EV].
Figure 11. Golf cart total voltage harmonic distortion.
Copyright © 2013 SciRes. ENG
Figure 12. Golf cart total current harmonic distortio n.
The measurement was performed at a golf club at
Universiti Kebangsaan Ma laysia. The measurement was
car ried out o n a worki ng day. O n that day, it was ra ining
from early morning until 10:00 am. But the golfing activi-
ties were active where all golf carts left the charging
point by 9.00 am. The first golf cart returned to charging
station after 11 am. The time, number of vehicle, and the
line where they are connected are detailed in Table 2.
The measured quant iti es ar e voltage a nd cur rent harmoni cs
distortion. The measurement data was recorded initially
every one hour interval until 6:00 pm. Starting at 7:00 pm,
the golf cart start to arrive more often so the measure-
ment was taken for every 15 minut es.
The data are visualized through a graph as shown in
Figure 14 for TH Dv a nd Fig ure 15 for THDi. Instead of
time, the number of vehicles is used for x-axis to facili-
tate the pattern of consumption from these EV. The line
where these golf carts are connected were also identified.
The consumption starts to increase substantially starting
from 6:30 pm (18:30 hrs) when golfers start to return the
golf cart to the pick-up point.
Figure 13. Golf Club distr ibution Circuit.
Table 2. Time, number of vehicl e and conne ction.
Tim e Number of Ve-
L1 L2 L3
11:00 0 0 0 0
12:00 1 1 0 0
13:00 1 1 0 0
14:00 1 1 0 0
15:00 1 1 0 0
16:00 2 2 0 0
17:00 3 3 0 0
18:00 0 0 0 0
18:30 6 4 2 0
18:45 12 4 4 4
19:00 16 8 4 4
19:15 18 8 6 4
19:30 20 8 8 4
19:45 22 8 8 6
Figure 14. Measure d THD v dur i ng moni t ori ng .
Figure 15. Measured THDi duri ng charging.
The T HD is also measur ed b oth for voltage a nd c urrent
as shown respectively in Figure 14 and Figure 15.
Event hough T HDv for e ach single vehicle was measured
1.1% but a PCC, the value is only 0.7% for onevehicle.
With the increaseof vehicles connected, the THDv stea-
dily increase. For eight vehicles on L1, the recorded
THDv is only 1.9%.
For THDi of one vehicle, THDi 34.4% is recorded but
at PCC, THDi is recorded 47.8%. With the increment of
golf cart charging the THDi value at PCC decrease to
16.6% for 3 vehicles but increase again for12 vehicles.
Surprisingly THDi do not increase much when vehicle
increase from 16 to 22 on L1.
6. Conclusion
In thi s paper, the harmonic measurement study and anal-
ysis during electric vehicle charging is presented. The
measurement is performed on golf carts and two modern
types of EV. T he meas ureme nt result shows t hat mod ern
EV release lower THDi compared to a golf cart which i s
expected. Unfortunately for THDv, modern EV cause
higher percentage of distortion. For a group of EV
char gin g, THD fo r both voltage and current are found not
Copyright © 2013 SciRes. ENG
to be the dir ect summation o f the TH D fro m a single ve-
hicle . The re sults o f the stud y areus eful in underst anding
the harmonic distortion contribution from EV connected
to the grid for charging.
7. Acknowledgements
Thi s inve s ti ga tio n st udy is part of a project jointl y carried
out by TNB Research Malaysia, UniversitiKebangsaan
Malaysia, TNB Distribution Malaysia and Malaysian
Gree n Tec hnolog y Corp orat ion. T he proj ect i s funded by
TNB Research Malaysia through funding TNBR/RD55/
2012 and partly supported by UniversitiKebangsaan Ma-
laysia via research grant GGPM-2011-071.
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