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NEUTRAL FLOATING PROBLEM ELIMINATION IN THREE PHASE FOUR LINE
POWER DISTRIBUTION SYSTEM USING GROUNDING THE NEUTRAL
TRANSFORMER LINE
Article · April 2019
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International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
NEUTRAL FLOATING PROBLEM ELIMINATION IN THREE PHASE
FOUR LINE POWER DISTRIBUTION SYSTEM USING GROUNDING
THE NEUTRAL TRANSFORMER LINE
1
MOHD H.S AL-RASHDAN, 2ABED-ALRAHMAN M.S AL-SHARQI
1
Electrical Engineering Department, Engineering Faculty Al-Hussein Bin Talal University, Ma’an, Jordan.
2
Power engineering department, Hijjawi facultyYarmouk university Irbid, Jordan.
E-mail: 1alsharqi619@gmail.com, 2moh.alrashdan@ahu.edu.jo
Abstract - Neutral floating problem is common problem in three phase four-line power distribution system, its happen when
the neutral line breakdown due to human mistakes or due to environmental conditions. Sometimes, it's very dangerous and
led to totally system damage including the transmission line and final residential customer’s loads. This paper discusses the
neutral floating conditions and proposed a simple solution by grounding the transformer neutral line. Matlab simulation is
carried out for three phase –four-line power distribution system with different load impedances including Symmetrical
Resistive Load, Unsymmetrical Resistive Load, Symmetrical Resistive Inductive Load and Unsymmetrical Resistive
Inductive Load. Furthermore, experimental procedure for residential customers is take place for two days with step time of
ten minutes for this type of power distribution system. Matlab simulation and the experimental results shows phase
overvoltage's problem in case of floating neutral without grounding the transformer line, this paper overcome the neutral
floating and the associated overvoltage's problem by grounding the transformer neutral line. Again, the Matlab simulation
and the experimental results shows stable peak phase voltage around 230 V with very small variations in the real experiment
which not affect the load and phase voltage.
Keywords - Neutral Floating, Grounding The Transformer Neutral Line, Matlab, Real Experimental Procedure, Residential
Customers.
faults is the “incipient” fault, in which begin as very
small faults and increasing with a time to become a
solid fault [9]. Passive faults related to the electrical
Distribution Systems conditions more than real faults
[10]. Such as Overloading problem associate with
insulation overheating, thus reduced electrical
Distribution Systems life time and system total failure
can occur. Other problems relating to passive faults
including Overvoltage, Under Frequency and Power
swings. So, the reducing in passive faults by
Protection the system against abnormal conditions are
of greatest priority, it leads to reduce the possibility of
having active faults.
In healthy three phase four wire power distribution
system, Power entering from one Phase and leaving
from the neutral line or return path. on the other hand,
the neutral line retune path broken which is known as
neutral floating as shown in figure 1 below, the power
will flow in different unwanted paths, the power will
flow from one phase and retune through the other
phases in absence of neutral ground, and cause
overvoltage's problem for some of the residential
customers.
The float neutral is common problem in power
distribution system and it may occur at several
locations, random time period, and due to many
reasons. It may occur at The Three Phase Distribution
Transformer [11], or due to Broken Overhead Neutral
conductor in LV Line [12], Broken of Service Neutral
Conductor [13], High Earthen Resistance of Neutral at
Distribution Transformer [14], Over Loading and
Load Unbalancing [15], Shared neutrals and Poor
workmanship and Maintenance.
I. INTRODUCTION
There are various types of fault can occur on electrical
Distribution Systems, where the voltages and currents
deviate from reference values [1], its occur at random
locations and random times [2], due to the nature of
electrical Distribution Systems itself, loads, and
interments conditions such as temperature, moisture
and wind speed. Many researcher tries to locate the
electrical Distribution Systems faults and eliminate it
using automated fault algorithm [2], smart meters [3],
fault current limiter Bridge-Type structure [4] and
sparse
measurements
[5].
Designing
and
implementation of electrical equipment or networks
without any possibility of failure is impossible due to
environmental issues. On the other hands, there are
two main areas where faults occur and can be
classified into two main categories “Active” and
“Passive” [6].
The “Active” fault occurs as a results of flowing
currents from one phase to another instead of from
one phase to earth. More precisely, the “Active” fault
can be divides into two main categories known as
solid fault and the incipient fault [7]. Solid fault
Occurs as a results of totally and suddenly insulator
breakdown. electrical explosion related to very high
fault current may occurs due to incidents including
underground cable, a pick struck and bridging
conductors [8]. Solid fault can be very danger to
residential customers, totally damage the fault location
and increasing the possibilities of spreading earth
faults to the other phases. The other type of active
Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
1
International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
Fig.1. three phase- four-line power distribution system with Floating Neutral
In this paper, we focus on reducing the passive faults
overvoltage problem associated with Floating Neutral
Condition in three phase four wire distribution system,
using Grounding the transformer Neutral line for real
residential customers.
order to covers most loads combinations in the labs
and real residential customers. The peak voltage is
measured for the all lines A-B, B-C, and C-A. It’s also
measured for all loads A, B, C and for all three phases.
The system is simulated again using Matlab with
grounding the transformer line as shown in figure 2.
Comparison between three phase four-line power
distribution system with and without grounding the
transformer line is take place.
II. METHODOLOGY
In this paper, three phase four-line power distribution
system studied when the neutral line transformer is
grounded and compared with ungrounded one using
Matlab software and in real case residential customers
in Jordan.
Initially three phase four-line power distribution
system is simulated using Matlab without grounding
the transformer line, the load impedance is changed to
validate the system in several loads situations, the
three loads named A, B and C. The system is
simulated using Matlab for four load combinations
including
Symmetrical
Resistive
Load,
Unsymmetrical Resistive Load, Symmetrical Resistive
Inductive Load and Unsymmetrical Resistive
Inductive Load. This impedance chosen in this way in
Verifying grounding the transformer neutral line
protection method is tested again by studding a real
case for a real residential customer in Jordan. Where
the real testing is continuing for two days with ten
minutes' step time. The total number of reading is 288.
The real testing is repeated two times, one experiment
carried out for three phase – four-line power
distribution system with loose junction contact due to
poor maintenance without grounding the transformer
neutral line, the other experiment is carried out for the
same system and same customers with transformer
neutral line connected to the ground.
Fig.2. Matlab block diagram of three phase four-line power distribution system.
Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
2
International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
115 V peak value mean that a one loads is
disconnected. The disconnected load voltage is zero
volte and other load voltages are 200 V beak value,
the lowering in connected voltage is due to the access
current flow in the disconnected phase (between line
to phase) this leads to overvoltage problem up to
345V peak value in disconnected phase. when the NG voltage peak value is 230 V mean that a two loads
are disconnected, in this case the overvoltage of 400 V
peak value occur in each disconnected phase while the
disconnected load voltage peak vale is 200 V and the
connected load is zero volte, this due to access current
flow inside between the two disconnected load itself.
III. RESULTS AND DISCUSSIONS
Table 1 below shows the Matlab results for three
phase four-line protection method without grounding
the transformer neutral line in case of symmetrical
resistive load (each load equal 1KW). the line voltage
equal to 400V and the source voltage is 11KV. based
on this results; the neutral to ground voltage (N-G) is
zero when the system is healthy, all load is connected
in proper way and all phase and load voltages are 230
V peak value which is due to due to it loads
symmetrical value used of 1KW. on the other hand,
when the N-G voltage peak value is not zero V,
indicate that there is at least one load disconnected
from the system. when the N-G voltage peak value is
ON load
A,B,C
A, B
B, C
C, A
A
B
C
OFF load
-----
C
A
B
B,C
A,C
A,B
Voltage Load A
230
200
0
200
0
200
200
Voltage Load B
230
200
200
0
200
0
200
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
230
230
230
230
0
0
200
200
345
115
200
345
200
200
115
200
200
345
200
115
200
0
400
400
230
200
400
0
400
230
0
400
400
0
230
Table I : ymmetrical Resistive Load Without Grounding the Neutral Line Transformer.
Table 2 below shows the Matlab results for three phase four-line protection method with grounding the
transformer neutral line in case of symmetrical resistive load (each load equal 1KW). It's clear that the phase not
suffering overvoltage problem anymore. When a load is disconnected, the return current path is completed along
with neutral line. This improve that the system itself is not affected due to load disconnection, the damage will
affect the load itself only.
ON load
A,B,C
A, B
B, C
C, A
A
B
C
OFF load
-----
C
A
B
B,C
A,C
A,B
Voltage Load A
230
230
0
230
230
200
200
Voltage Load B
230
230
230
0
200
230
200
Voltage Load C
230
0
230
230
200
200
230
Voltage A-N
230
230
230
230
230
230
230
Voltage B-N
230
230
230
230
230
230
230
Voltage C-N
230
230
230
230
230
230
230
Voltage N-G
0
0
0
0
0
0
0
TABLE II. Symmetrical Resistive Load With Ground Neutral transformer.
Tables 3&4 below shows the Matlab results for unsymmetrical impedances load with pure resistance, where load
A is chosen to absorb 1 kW of real average power, while load B absorb 2 kW and load C absorbs 3 kW and the
line voltage is used to be 400 V peak value.
Table 3 show that a phase overvoltage problem happens when one or two loads are disconnected, this cause
system burn or damage in disconnected area. On the other hands, table 4 shows stable phase voltages when the
transformer neutral line is connected to the ground. The variation in phase voltage in case of ungrounded system
is due to unsymmetrical load nature.
Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
3
International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----290
240
175
290
240
175
66
A, B
C
265
133
0
265
133
352
133
B, C
A
0
240
160
350
240
160
122
C, A
B
300
0
100
300
360
100
153
A
B,C
0
240
160
0
400
400
230
B
A,C
300
0
100
400
0
400
230
C
A,B
266
133
0
400
400
0
230
Table III. .Unsymmetrical Resistive Load Without Grounding the Neutral Line Transformer
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----230
230
230
230
230
230
0
A, B
C
230
230
0
230
230
230
0
B, C
A
0
230
230
230
230
230
0
C, A
B
230
0
230
230
230
230
0
A
B,C
230
240
160
230
230
230
0
B
A,C
300
230
100
230
230
230
0
C
A,B
265
130
230
230
230
230
0
Table IV. Unsymmetrical Resistive Load With Grounding the Neutral Line Transformer
Table 5 and table 6 below shows the Matlab results for symmetrical impedances load consists of a combination of
resistive and inductive load, where all load A, B and C is chosen to absorb
1 KW + 0.4 KVAR, and the line
voltage is used to be 400 V peak value. The phase voltage again in no grounded neutral line transformer suffer
overvoltage's problem when some loads are disconnected as shown in table 5, while this problem disappear again
when the transformer neutral line grounded as shown in table 6.
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----230
230
230
230
230
230
0
A, B
C
200
200
0
200
200
345
115
B, C
A
0
200
200
345
200
200
115
C, A
B
200
0
200
200
345
200
115
A
B,C
0
200
200
0
400
400
230
B
A,C
200
0
200
400
0
400
230
C
A,B
200
200
0
400
400
0
230
Table V. symmetrical Resistive Inductive Load Without Grounding the Neutral Line Transformer
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----230
230
230
230
230
230
0
A, B
C
230
230
0
230
230
230
0
B, C
A
0
230
230
230
230
230
0
C, A
B
230
0
230
230
230
230
0
A
B,C
230
240
160
230
230
230
0
B
A,C
300
230
100
230
230
230
0
C
A,B
265
130
230
230
230
230
0
Table VI.symmetrical Resistive Inductive Load With Grounding the Neutral Line Transformer
Table 7 and table 8 below shows the Matlab results for unsymmetrical resistive inductive load, where load A is
chosen to absorb 1 KW + 0.4 KVAR, while load B absorb 2 KW + 0.4 KVAR and load C absorbs 3 KW + 0.4
KVAR and the line voltage is used to be 400 V. this tables confirms the previous results and shows that the
grounding of transformer line method solves the phase peak overvoltage problem in three phase-four line power
distribution system when some of the loads are disconnected from the system . The variations in the phase
voltage and load voltages in ungrounded transformer line shown in table 7 is due to the values of load
impedances.
Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
4
International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----290
240
175
290
240
175
66
A, B
C
265
133
0
265
133
352
133
B, C
A
0
240
160
350
240
160
122
C, A
B
300
0
100
300
360
100
153
A
B,C
0
240
160
0
400
400
230
B
A,C
300
0
100
400
0
400
230
C
A,B
266
133
0
400
400
0
230
Table VII. Unsymmetrical Resistive Inductive Load Without Grounding the Neutral Line Transformer
ON load
OFF load
Voltage Load A
Voltage Load B
Voltage Load C
Voltage A-N
Voltage B-N
Voltage C-N
Voltage N-G
A,B,C
----230
230
230
230
230
230
0
A, B
C
230
230
0
230
230
230
0
B, C
A
0
230
230
230
230
230
0
C, A
B
230
0
230
230
230
230
0
A
B,C
230
240
160
230
230
230
0
B
A,C
300
230
100
230
230
230
0
C
A,B
265
130
230
230
230
230
0
Table VIII.Unsymmetrical Resistive Inductive Load With Grounding the Neutral Line Transformer
Figures 3, 4 and 5. Shows each phase voltages of three
phase- four-line power distribution system in Jordan
without grounding the neutral in comparison with
same system using ground the neutral line. It's clear
that, the system used ground the neutral shows
approximately stable phase voltage with small
variation due to real environment conditions about
230 V peak voltage. While the system doesn't
implement the ground shows fluctuation in phase
voltage in case of pore maintenance, which cause
overvoltage problems and damage the residential
customer’s electric equipment's.
Fig. 5. Phase C to line voltage with and without ground neutral
transformer.
IV. CONCLUSION
This paper highlighted the floating transformer neutral
problems and types of faults can cause. The passive
faults due to poor maintenance or environments
condition starts as small faults and increasing along
with time to completely damage the power
distribution system and cause severe difficulties to
final customers.
Fig. 3. Phase A to line voltage with and without ground neutral
transformer.
This paper is conducted to provide a real example of
importance the ground in three phase – four-line
power distribution systems, along with Matlab
simulation for such systems for different load
impedance.
The grounding neutral line method shows a good
solution to neutral floating problems in power
distribution systems, its reduce the overvoltage's
problems in case of residential customers and shows
very simple and direct way of protection against this
type of problems specially in developing region.
Fig. 4. Phase B to line voltage with and without ground neutral
transformer.
Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
5
International Journal of Industrial Electronics and Electrical Engineering, ISSN(p): 2347-6982, ISSN(e): 2349-204X
Volume-7, Issue-7, Jul.-2019, http://ijieee.org.in
[7] IDC Technologies, “Faults Types & Effect.” IDC
ACKNOWLEDGMENT
Technologies Tech Briefs (Electrical),2000.
[8] Stefania Conti, Analysis of distribution network protection
The authors would like to thanks all staff in electrical
issues in presence of dispersed generation, In Electric Power
engineering department – Al- Hussien Bin Talal
Systems Research, Volume 79, Issue 1, 2009, Pages 49-56,
ISSN 0378-7796.
University ,Ma’an , Jordan for their supports .
[9] S. Ebron, D. L. Lubkeman and M. White, "A neural network
approach to the detection of incipient faults on power
REFERENCES
distribution feeders," in IEEE Transactions on Power
Delivery, vol. 5, no. 2, pp. 905-914, Apr 1990.
[1] D. Thukaram, H. P. Khincha and H. P. Vijaynarasimha,
[10] D. Chen, L. Xu and J. Yu, "Adaptive DC Stabilizer With
"Artificial neural network and support vector Machine
Reduced DC Fault Current for Active Distribution Power
approach for locating faults in radial distribution systems,"
System Application," in IEEE Transactions on Power
in IEEE Transactions on Power Delivery, vol. 20, no. 2, pp.
Systems, vol. 32, no. 2, pp. 1430-1439, March 2017.
710-721, April 2005.
[2] Jun Zhu, D. L. Lubkeman and A. A. Girgis, "Automated fault
[11] T.-H Chen, W.-C Yang, T.-Y Guo, G.-C Pu, Modelling and
location and diagnosis on electric power distribution feeders,"
analysis of asymmetrical three-phase distribution transformer
in IEEE Transactions on Power Delivery, vol. 12, no. 2, pp.
banks with mid-tap connected to the secondary neutral
801-809, Apr 1997.
conductor, In Electric Power Systems Research, Volume 54,
[3] Sadegh Jamali, Alireza Bahmanyar, Ettore Bompard, Fault
Issue 2, 2000, Pages 83-89, ISSN 0378-7796,
location method for distribution networks using smart meters,
[12] Puneet Chawla , Rajni Bala. "Existence of Electrical
In Measurement, Volume 102, 2017, Pages 150-157, ISSN
Pollution" International Journal of Electronics, Electrical and
0263-2241.
Computational System IJEECS ISSN 2348-117X Volume 4,
[4] M. Abdolkarimzadeh, M. Nazari-Heris, M. Abapour and M.
Special Issue May 2015.
Sabahi, "A Bridge-Type Fault Current Limiter for Energy
[13] Babrauskas V. (2016) Electrical Fires. In: Hurley M.J. et al.
Management of AC/DC Microgrids," in IEEE Transactions
(eds) SFPE Handbook of Fire Protection Engineering.
on Power Electronics, vol. 32, no. 12, pp. 9043-9050, Dec.
Springer, New York, NY.
2017.
[14] P. Stepien and R. Griffiths, "History of earthing and the
[5] S. Jamali, A. Bahmanyar, A new fault location method for
impact on coal mining," 2016 Down to Earth Conference
distribution networks using sparse measurements, In
(DTEC), Hunter Valley, NSW, 2016, pp. 1-6.
International Journal of Electrical Power & Energy Systems,
[15] O. V. Kulkarni and M. K. Mishra, "Power quality
Volume 81, 2016, Pages 459-468, ISSN 0142-0615.
improvement using Zig-Zag transformer and DSTATCOM in
[6] M. K. Hasan and F. Hossain, "Earth Fault Currents in Three
three phase power distribution system," 2013 Annual IEEE
Phase systems," Blekinge Institute of Technology,
India Conference (INDICON), Mumbai, 2013, pp. 1-6.
Karlskrona, 2015.
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Neutral Floating Problem Elimination in Three Phase Four Line Power Distribution System using Grounding the Neutral Transformer Line
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