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Abstract and Figures

Phase sequence is the order in which the rotated voltage or current generated by 3-phase system attain peak or maximum value. Each sequence voltage is 120 degree apart. Therefore, the maximum value achieved by each sequence is at the definite time interval. Based on this individual response time a new technique of phase detection system is discussed in this paper. An algorithm is developed in order to detect phase sequence. A micro-controller is used to incorporate the algorithm into it. The simulation result is illustrated here to verify the proposed algorithm. A prototype device was built to compare the practical and simulated result. Supporting codes available at: https://github.com/sifat62/papercodes
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Micro-controller Based 3-phase Sequence Indicator
Anwarul Islam Sifat∗†, Md. Nazmul Islam Sarkar, Md. Milon Uddin, Pias Biswas, Muhammad Navid Anjum Aadit
Institute of Energy, University of Dhaka
Bangladesh University of Engineering and Technology
Email: sifat62@gmail.com
Abstract—Phase sequence is the order in which the rotated
voltage or current generated by 3-phase system attain peak or
maximum value. Each sequence voltage is 120 degree apart.
Therefore, the maximum value achieved by each sequence is at
the definite time interval. Based on this individual response time a
new technique of phase detection system is discussed in this paper.
An algorithm is developed in order to detect phase sequence.
A micro-controller is used to incorporate the algorithm into it.
The simulation result is illustrated here to verify the proposed
algorithm. A prototype device was built to compare the practical
and simulated result.
Index TermsPhase Sequence Indicator, Phase Detection, 3-
phase Sequence, Micro-controller.
I. INTRODUCTION
The order in which the three phases attain their peak or
maximum value and the three generated electrical voltages or
currents rotate is called the phase sequence [1]. Each voltage is
separated from the next generated voltage by 120 degrees. The
3-phase has only two possible sequences ABC or ACB, posi-
tive and negative sequence respectively [2]. In normal balanced
condition, the 3-phase sequential order is positive i.e. ABC. In
unbalanced condition, this sequence changed and turned into
negative sequence. Unbalanced loads or asymmetric faults will
reduce the proportion of positive sequence current and will
produce negative sequence currents. This negative sequence
components results the sequential order to change [3].
At present, there are many phase sequence detection system.
They can be classified as computer code based sequence
detector, identify phase order by relative positioning of phase,
sequential logic to identify phase characteristic, phase angle
measurement, double dq synchronous reference frame, sim-
ulation method, quick phase detection method, correlation
analysis of phase sequence, and combination of zero crossing
and wave transformation method.
A phase sequence detector is a system that compares self-
generating code by hardware circuit with pre-defined specific
codes corresponding to positive and negative sequences for
successful match in each measuring cycle [4]. Utilization of
micro-controller and a simple sequence indication method will
be the general rule to find the proper phase sequence of any
balanced multi-phase system. For the unbalanced multi-phase
system, a relative position of various phases with respect to
reference is determined by measuring the phase angle of each
subsequent phase [5].
The sequential logic was implemented in a phase-angle
monitoring system, which can simultaneously measure the
phase-angle between two signals and identifies their lead-lag
characteristics once every cycle. It can also detect periodic and
aperiodic sequence of pulses once in each cycle [6].
An indicator based on double dq synchronous reference
frame, a novel three-phase magnitude-phase detection method
that can decouple the positive dq and negative dq-sequences
and detect the magnitudes or phases of fundamental positive-
sequence component and negative-sequence component of
three-phase voltages or currents has been proposed [6].
In addition, based on the calculating method of unbalance
factor, phase angle difference of positive and negative se-
quence component of three-phase voltage in the condition of
supply voltage unbalance can be attain. By measuring phase
angle, different positive and negative sequence could separate
[7].
In simulation method, the frequency is calculated based on
the time difference between signal of two circuits zero crossing
time. It transfers the time difference into voltage or current
to determine the frequency. This method requires specialized
hardware to detect phase sequence.
Another method is a quick phase detection method. Here
the sinusoidal pulses are converted into saw tooth waveform.
The phase sequence is detected by selecting the bipolarity of
the wave. This process mostly relies on the peak of input
sinusoidal voltage.
The correlation analysis method is based on analog to
digital conversion of the sinusoidal signal. The signals are
sampled at maximum point. As the sampling points increase,
the complexity of algorithm will simultaneously increase. It
requires sophisticated hardware to detect accurately the phase
sequence.
The combined system of zero crossing and wave trans-
formation method is operated by transforming the sinusoidal
signal into a square wave. The transformation is done by zero
crossing circuit. A test circuit was used here to obtain the
phase difference and pulse signals. The duty ratio of the signal
is the key to detecting the pulse. It is necessary to detect the
width of the high-level square wave to determine the duty ratio
[8].
II. METHODOLOGY
In this paper, a system is proposed for detecting negative
phase sequence based on the timing response of each phase. In
Fig. 1. 3-phase Negative Sequence.
a 3 phase supply each phase achieve its peak at different time
interval. A micro controller is used in this method to check
every phase in assigned time interval and to detect which peak
voltage responds first. An Algorithm was developed based
on the response of peak voltage i.e. A, B and C. In the
programing, conditional loop is applied to detect different
combination of positive and negative sequence.
III. MOTI VE OF NE GATIV E SEQUENCE
The negative sequence set is balanced with three equal
magnitudes of quantities at 120 degrees apart but with the
phase rotation or sequence reversed, i.e. a, c, b. If the positive
sequence is a, c, b as in some power systems, then negative
sequence will be a, b, c. For the negative sequence set, again
the sequence currents or sequence voltages always exist in
three’s, never alone or in pairs [9].
Unbalanced voltages usually occur due to variation of loads.
When the load of on one or more within the phases is different
from the other(s), unbalanced voltages will appear. This can
be due to different impedances, or type and value of loading
on each phase. Single phasing, which is the complete loss of a
phase, is the ultimate voltage unbalance condition for a three
phase circuit [10].
IV. PHA S E SEQUENCE DET EC T IO N SYST EM
The sequence detection system begins with build up a
voltage divider circuit. Then a dc power supply circuit is
build up for constant supply to micro-controller. An algorithm
is developed in order to sense the negative sequence of 3-
phase supply. The algorithm is customized as Micro-controller
requirement. The objective is to design & build a micro-
controller based (PIC18F452) digital phase sequence indicator
that can determine the phase sequence of 3-phase power
system and compatible with global utility grid frequencies
[11].
A. Design Procedure
From the national grid of Bangladesh, the supply voltage
is approximately 200 to 214V, the MCU or micro-controller
unit is not able to operate in such a high voltage. Therefore, it
has to be optimized to approx. 2V by a star connected 3-phase
resistor divider circuit. In summary, to set up the logic to detect
negative sequence, PIC18f452 ADC module must initialized.
As three consecutive rising voltages are there to detect so
Voltage Divider Circuit
Fig. 2. Design Block Diagram.
three analog pin assigned for ADC. The maximum voltage
or reference voltage is selected, in this case it is +1.3v -1v.
In the test sequence parameter, every rising voltage measured
after 5ms delay. The maximum sampling frequency is 50Hz,
so according to Nyquist criterion it becomes 250= 100Hz. The
phase sequence is tested by 3-phase function,
Phase12 (); Phase23 (); Phase31 ();
An appropriate flag is assigned to each phase. The test
sequence functions are executing under an infinite loop. LED
(Light Emitting Diode) is assigned according to flag output.
V. PROGRAMING LOGIC IMPLEMENTATION
To detect the phase sequence PIC18f452 micro-controller is
used; by using its ADC (Analog to Digital Converter) module,
Fig. 3. Flow Chart of Programing Logic Implementation.
(Input Voltage)
VAIN
VREF+
Reference
Voltage
VDD
PCFG<3:0>
CHS<2:0>
AN7*
AN6*
AN5*
AN4
AN3
AN2
AN1
AN0
111
110
101
100
011
010
001
000
10-bit
Converter
VREF-
VSS
A/D
Fig. 4. PIC18f452 Internal 10-bit ADC Module Block Diagram [12].
the 3-phase voltage is measured. Proper conditional logic is
given to micro-controller to detect the phase sequence from
measured voltage. In case of examining the 3-phase sequence
i.e. ABC or ACB, it is divided into,
Phase AB (); Phase BC (); Phase CA ();
In programing code, AB sequence is assigned to FLAG 1, BC
sequence is assigned to FLAG 2 and CA is sequence assigned
to FLAG 3. Similarly, in micro-controller, AB sequence is
assigned to port AN0 & AN1, BC sequence is assigned to
port AN1 & AN4 and CA sequence is assigned to port AN4
& AN0.
Fig. 5. Phase A and B Input Signal.
Fig. 6. Phase B and C Input Signal.
To check ABC sequence: For AB sequence, AN0 port has
the1st peak value, and then AN1 port has the second peak
value. let consider,
AN0 = FLAG1 = 1
AN1 = FLAG1 = 0
For BC sequence, AN0 port has the1st peak value, and then
AN1 has the second peak value. Consider,
AN1 = FLAG2 = 1
AN4 = FLAG2 = 0
For CA sequence, AN4 port has the1st peak value, and then
AN0 has the second peak value. Consider,
AN4 = FLAG3 = 1
AN0 = FLAG3 = 0
Fig. 7. Phase C and A Input Signal.
Now if we want to check ABC sequence the logic will be
implement as follows:
IF (Flag1==1&& Flag2==1&& Flag3==1)
OUTPUT ”Positive Sequence”
VI. SIMULATION AND RESU LT
Circuit components requirements are 3-phase supply, Re-
sistor 1M, 100K, 10K, Diodes D1N4002, LED RED (ACB);
GREEN (ABC). In figure 8, the schematic diagram of 3-phase
indicator circuit is illustrated.
Fig. 8. Schematic Diagram of 3-phase Sequence Detector.
The device divided into three major components. Star con-
nected 3-phase voltage divider circuit micro-controller unit and
indicator apparatus. The star connected voltage divider circuit
is consisted of three resistors in parallel and a diode connected
in series with a resistor. Same circuit arrangement is done
for remaining two phases. Let us consider the single-phase
equivalent circuit of three-phase voltage divider and at point
A, the voltage can be calculated as follows:
Here, Diode resistance = 0.655 M
Here, Requiv alent =100k×(0.655M+ 10k)
100k+ (0.655M+ 10k)= 86.93k
Therefore, at point C (Figure 10) the voltage would be
Fig. 9. Single-phase Equivalent Circuits of 3-phase Voltage Divider.
Fig. 10. Equivalent Circuit Diagram of Single-phase Circuit.
= 200 ×86.9k
86.9k+ 1M= 15.99V
Here C = A = 15.99
Voltage at point B:
= 15.99 ×10K
86.93k+ 10k= 1.64V
The output of voltage divider circuit: In micro-controller unit,
from the figure 11, the voltage is measured in a simulation
oscilloscope and we observed it to be 2.5V. The input analog
Fig. 11. Output Signal of Voltage Divider Circuit.
signal is fed to micro-controller on across of 10K resistor to
port AN0, AN1 and AN4, which are the input voltage node
as we can see from the block diagram (Figure 4) of internal
ADC module. Then we see that this AN0, AN1 and AN4 pins
are connected to the input channel of ADC, which is software
selectable.
In the indicator apparatus section, two LEDs were used.
They are Green and Red; both are connected to micro-
controller RD7 and RD6 analog pin respectively. According to
logic, this will show as well as indicate the phase sequence of
3-phase supply. In figure 8, a 3-phase supply is fed into micro-
controller and it successfully determines its phase sequence as
an indicator shows result as below:
IF (Flag1==1&& Flag2==1&& Flag3==1)
OUTPUT HIGH at Pin RD7 //Positive Sequence
ELSE IF (Flag1==0&& Flag2==1&& Flag3==1)
OUTPUT HIGH at Pin RD7 //Positive Sequence
IF (Flag1==1&& Flag2==0&& Flag3==1)
OUTPUT HIGH at Pin RD7 //Positive Sequence
ELSE OUTPUT HIGH at Pin RD6 //Negative Sequence
As the input voltage is of negative sequence, the output RED
LED indicates negative sequence.
From the experimental hardware implementation, it is ob-
served that the prototype can reliably detects phase sequence
of a 50 Hz 3-phase system with a voltage range of 6 to 220
V. Since this is, a micro-controller based embedded system
the program code can be reconfigured to make the working
frequency flexible for a range from one to 1400 Hz by
either increasing the sample size or by changing the program
to sample and analyze at the same time. In a simulation,
the detection system works on system clock of 32.768 kHz
where the prototype model works on 4MHz clock. For this
configuration the there were some anomaly in output was
observed.
VII. HAR DWAR E IMPLEMENTATION
The prototype hardware installation of 3-phase sequence
indicator has three major units (Figure 12):
A. 3-phase Voltage Divider Unit
It consists of resistor-diode divider network. It reduces the
supply of 220 volt to 2 volt approximately.
B. DC Power Supply Unit
The micro-controller runs on 5-volt DC supply. This unit
provides necessary DC volt for the operation of micro-
controller. It consists of 7805 IC (integrated Circuit), polar-
ized/ non-polarized capacitor, resistor and LED.
Fig. 12. Phase Sequence Indicator (prototype) Hardware Implementation.
C. Controlling and Indication Unit
This unit consists of micro-controller, an external clock
source and two indicator LEDs.
VIII. CONCLUSION
The purpose of this 3-phase negative phase sequence in-
dicator was to transform the protection system into smart
protection system. In existing power system protection, a
protective relay plays an important role. Most of the re-
lays are electromechanical. The phase sequence indicator
can implement by using a current transformer to sense the
faulty condition. For this purpose, a vast system arrangement
should be needed. Introducing a micro-controller can solve this
problem. It also reduces installation and maintenance budget.
Integrating the existing protection scheme with this system
will transform the protection system into a smart protection
system. In actual implementation the proposed system faces
some difficulty to detect the given phase sequence due to
heating, lose connection, variable supply voltage, and a system
clock. Future work will investigate to solve these issues.
ACK NO WL EDG MEN T
The authors would like to thank Institute of Energy and
Stamford University Bangladesh for allowing to use their
laboratory facilities.
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ResearchGate has not been able to resolve any citations for this publication.
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For achieving the compensation method which is used for balancing the three-phase unbalanced load by TCR, unbalance factor, phase angle difference of positive and negative sequence component of three-phase voltage should be detected. Accuracy and rapidity of detection is the key factors which affects three-phase unbalance compensation effect. This paper proposes a calculating method of unbalance factor, phase angle difference of positive and negative sequence component of three-phase voltage in the condition of supply voltage unbalance. The method can use dq transformation to achieve the relative parameters by delay sampling voltage to construct PLL signal. Simulation results show that the method can detect the parameters rapidly and accurately.
A new phase-angle monitor is presented in this paper which can simultaneously measure the phase-angle between two signals and identify their lead-lag characteristics once every cycle. A novel phase-sequence detector is also described which can detect periodic and aperiodic sequence of pulses once in each cycle. Sequential logic circuit designs for these have been synthesized and tested in the laboratory. The inherent simplicity of these circuits particularly using digital integrated circuits and their adaptability in power system instrumentation and control are the novel features of the paper.
An introduction to symmetrical components, system modeling and fault calculation
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S. Marx and D. Bender, "An introduction to symmetrical components, system modeling and fault calculation," 2013.
A micro-controller based 3-phase 600 v universal phase sequence tester
  • B Wright
  • J Wyatt
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  • C Clemens
  • R Lush
B. Wright, J. Wyatt, K. VandenBerge, C. Clemens, and R. Lush, "A micro-controller based 3-phase 600 v universal phase sequence tester."
A textbook of electrical technology vol ii
  • B Theraja
  • A Theraja
  • U Patel
  • S Uppal
  • J Panchal
  • B Oza
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  • R Patel
B. Theraja, A. Theraja, U. Patel, S. Uppal, J. Panchal, B. Oza, V. Thakar, M. Patel, and R. Patel, "A textbook of electrical technology vol ii," Chand & Co., New Delhi, 2005.
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  • M Wenchuan
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M. Wenchuan, Z. Shuo, S. Nan, W. Shuwen, B. Yu, and L. Shumin, "Detection methods of unbalance factor and phase angle difference of positive and negative sequence component of three-phase voltage," in Power and Energy Engineering Conference (APPEEC), 2012 Asia-Pacific. IEEE, 2012, pp. 1-4.