Power factor correction (PFC) is a process of negotiating the unwanted effects of electric loads that create a power factor less than one. Power factor correction may be applied either by an electrical power transmission utility to enhance the efficiency of transmission network. In this paper three transformers of different ratings have been used which acts as inductive load each of which produce different power factor variation. The power factor of the supply line is directly monitored by the Power Meter which is connected in parallel to the supply line. The value of the capacitance (capacitor bank) required for correcting the power factor variation due to each transformer and their combination is found out separately. Capacitor bank for the respective load is triggered by using PLC, which connects the capacitor bank parallel to the load and thereby bringing the power factor near to unity. This paper represents the most effective automatic power factor improvement and monitoring by using static capacitors which will be controlled by a PLC with very low cost although many existing systems are present which are expensive and difficult to manufacture. In this study, many small rating capacitors are connected in parallel and a reference power factor is set as standard value into the PLC. Suitable number of static capacitors is automatically connected according to the instruction of the PLC to improve the power factor close to unity. Some tricks such as using resistors instead of potential transformer and using one of the most low cost PLC SIEMENS S7-200 CPU215 DC/DC/DC which also reduce programming complexity that make it most economical system than any other controlling system.

1. Department of Electrical and Electronic Engineering
Port City International University

2. NAME OF THE PROJECT
Automatic Power Factor Improvement by Using PLC &
SCADA

3. Supervisor
Professor Ahmad Hossain
Co-ordinator, Department of CSIT, ECE & EEE.
PCIU.
Co-Supervisor
Abrar Hussain
Lecturer, Department of EEE.
PCIU.

4. Project Submitted by
Md.
ID: 008-07-16
Md.
ID: 008-07-04
Department of EEE.
PCIU.

5. Low power factor occurs large copper losses, poor voltage regulation and reduce handling capacity of the system.
At low power factor KVA rating of the equipment has to be made more, making the equipment larger and
expensive [1]. Power factor improvement is important because at high, medium and low power factor the current
distortion levels tends to fall into lowTHDI≤20%,medium(20%<THDI≤50%)and high(THDI
>50%)respectively[2].For the low power quality high financial loss per incident occurs that are given below.
INTRODUCTION

6. This paper represents the most effective automatic power factor improvement by using static capacitors which will
be controlled by a PLC with very low cost although many existing systems are present which are expensive and
difficult to manufacture. In this study, many small rating capacitors are connected in parallel and a reference power
factor is set as standard value into the PLC. Suitable number of static capacitors is automatically connected
according to the instruction of the PLC to improve the power factor close to unity. Some tricks such as using
resistors instead of potential transformer and using one of the most low cost PLC SIEMENS S7-200 CPU215
DC/DC/DC which also reduce programming complexity that make it most economical system than any other
controlling system.
Keywords : PLC SIEMENS S7-200 CPU215 DC/DC/DC, current transformer, comparator, relay, capacitor,
Software Micro win v4.0 SP9, Win CC Flexible ( SCADA).
.
Abstract

7. The low power factor is mainly due to the fact that most of the power loads are inductive and therefore, take
lagging currents. So capacitors are connected parallel with the load for leading power. It draws current Ic which
leads the supply voltage by 900 .The resulting line current I1 is the phasor sum of I and IC and it angle of lag is ᴓ2
as shown in Fig1(c).It is clear that ᴓ2 is less than ᴓ1 from phasor diagram. So that cosᴓ2 is greater than cosᴓ1 .So
that power factor of the load is improved
POWER FACTOR IMPROVEMENT THEORY
Power factor improvement circuit and phasor diagramFig1(c)

8. Benefits of Power Factor Correction. There are numerous benefits to be gained through power factor
correction. These benefits range from reduced demand charges on your power system to increased load carrying
capabilities in your existing circuits and overall reduced power system loses.
1. Avoid Power Factor Penalties
2. Reduced Demand Charges
3. Increased Load Carrying Capabilities in Existing Circuits
4. Improved Voltage
5. Reduced Power System Losses

9. OBJECTIVES
To develop an automatic Power system protection and control this system
using PLC and SCADA.
To increase the efficiency of an industrial plant by incorporating the
automation system which replaces the manual Protection of Power system
protection unit system.

10. EQUIPMENTS
PLC SIEMENS S7 200 (CPU 215 DC/DC/DC)
Programming Cable MPI cable
Software Micro win v4.0 SP9
Software USB to RS 232 driver v110.
Win CC Flexible ( SCADA)
Electromechanical Relay.
Cable.
Power supply (24 volts dc).
Fan
TC-K Type
PR-4116( Universal Transmitter)
CT
Weidmuller WAS1 CMA 1/5/10A ac
EM-235
Laurel TA210RMV5
PC

11. SCADA
PLC S7 200 CPU 215 DC/DC/DC
MPI
EM 235
Analog Input
Device
Digital Input
Device
Digital Out put Device
Inductive
Load
Capacitor
Bank
Block Diagram

12. Start Condition
Recipe download?
Temperature <80°C?
Voltage 1Ø<250?
Voltage 1Ø>120?
Operator Start command ?
Temperatu
re >40°C?
FFFan Start
Temperatur
e <35°C?
Over voltage
>250V?
FFAlarm & Full system stop
Under voltage
<100V?
Over Current
>7A?
FFAlarm & Full system stop
PF =.96
& A=1?
FFCapacitor Bank 1 Start
Current
>5A
FFLoad shading Start
PF =.98 &
A=10?
Load shading
time over
Flowchart
FFFF FFAlarm & Full system stopFan Stop Capacitor Bank 2 Start FFAlarm & Full system stop
Temperature
>48°C?
FFAlarm & Full system stop

13. FFFF FFAlarm & Full system
stop
Fan Stop Capacitor Bank 2 Start
Temperat
ure
>48°C?
FFAlarm & Full system
stop
FF
Alarm & Full system
stop

14. 1M 1L+ 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 2M 2L+ 1.0 1.1 M L+
1M 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 2M 1.0 1.1 1.2 1.3 1.4 1.5 M L+
CPU 214 EM 235
AI 3*12Bits
AQ 1*12Bits
RA A+ A- RB B+ B- RC C+ C- Vo Io L+ M
AC to DC
Pr4116
PR 4116
Input Supply Output
PR4116
14 11
UH
230 V AC
UA
+ -
CT
RS 485
SCADA
Voltage
MPI
Circuit Diagram
CT
TC K Type DC 24V EM 235 EM 235 EM 235

15. M
N

16. 1 In our project, we have used only one level indicator but in future it will be more suitable in industrial
application if we use two level indicator and sensors of higher specifications. We also used this only single
phase but in future we will develop this project for three phase line.
2 Siemens S7 200 CPU 215 PLC & WinCC Flexible2008 we have used in our project but in future
3 we can develop our project with Advance PLC S7 1200 & S7 1500 PLC & SCADA TIA Portal system
which will be very useful in industrial application and others utility services like water supply gas supply
and power sector etc.
Future work

17. This paper shows an efficient technique to improve the power factor of a power system by an economical way.
Static capacitors are invariably used for power factor improvement in factories or distribution line. But this
paper presents a system that uses capacitors only when power factor is low otherwise they are cut off from line.
Thus it not only improves the power
CONCLUSION