International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072

Proposed Method to Control Load Frequency in Single Area Power

System
Sunil Kumar Sharma1, Anupam Agarwal2, Atul Kulshrestha3

1Student, Dept. of Electrical Engineering Jagannath University Jaipur

2lifetime member, ISRD
3Assistant Professor, Dept. of Electrical Engineering JECRC Jaipur

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Abstract: In order to supply reliable electric power of instability problem. In electric power generation, system,
good quality Load Frequency Control (LFC) in power system disturbances caused by load fluctuations result in changes
is very important. In industries, the speed of the machines to the desired frequency value. Load Frequency Control
depends on the frequency. Any Fluctuation in the frequency (LFC) is a very important issue in power system operation
may lead to fault of system. The load-frequency control is and control for supplying sufficient and both good quality
used to create the balance between load and generation of and reliable power [3].Changes that happens in load of
each control area by means of speed control. So load power system, can affect the frequency and in addition it
frequency control is the key problem in the power system. In will make the power quality crisis on the customers’ super
this paper frequency deviation problem associated with load sensitive equipment’s. To avoid this frequency must be
frequency control is evaluated by integral controller and regulating inside the limit. In the power system the load
proportional integral controller for one area power system. changes are arbitrary without control and there is
The results of two controllers are compared using unbalance in real and reactive power. For controlling
MATLAB/Simulink software package. Comparison results of frequency in power system a load frequency control (LFC)
Integral Controller and PI controller System are presented is needed and it plays an essential role in power system
hereunder. control [4,7].The conventional controllers such as
proportional integral and integral controller are utilized
Keywords: Single area Load Frequency Control, for Load Frequency Control. However, these methods have
Integral Controller, PI Controller, Area Control Error the capacity to control the single area, perform well under
load variation, and good robustness. It also has some crisis
such as damping oscillation, long settling time and
I. INTRODUCTION maximum overshoot of frequency. As the load varies
constantly the control is actually difficult due to the gain
The modern power systems with industrial and value of the controller is fixed of these controller. The
commercial loads required to operate at fixed Frequency results of the two controllers are compared using
with reliable power. Load Frequency Control (LFC) is a MATLAB/Simulink software package. Comparison results
very important issue in power System operation and of Integral Controller and PI controller System are
control for supplying sufficient and reliable electric power presented.
of good quality. The main objective of the LFC is to
maintain zero steady state errors for frequency deviation
and good tracking load demands in a multi-area
II. SINGLE AREA LOAD FREQUENCY CONTROL
restructured power system [1]. Load frequency control is MODEL
the basis of many advanced concepts. The dynamic
behavior of many industrial Plants is heavily influenced by The goal of LFC is to maintain real(active) power balance
disturbances and, in particular, by changes in the in the system through control of system frequency.
operating point. This is typically the case for power Whenever the active power demand changes, a frequency
systems [2].Frequency is an explanation of stability change occurs. This frequency error is amplified, mixed
criterion in power systems. To provide the stability, active and changed to a command signal which is sent to turbine
power balance and steady frequency are must. If any governor. The governor operates to restore the balance
change occurs in active power demand/generation in between the input and output by changing the turbine
power systems, frequency cannot be hold in its rated output. This method is also known as Power frequency
value. So oscillations increase in both power and control [5,6]. One generating unit or bunch of generating
frequency. Thus, system is subjected to a serious units placed in close vicinity to distribute the electricity in

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 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072

the same area is called single area system. More than one
control area power systems with a single control zone is
actually a combination of power systems and the problems
of each region, combining a control structure. Figure 1 is a
single zone with a power system block diagrams. Here a
regulator, balance the speed of synchronous generator and
the load is comprised. Only the generating unit present in
that area is responsible to balance the desired frequency in
normal and abnormal conditions.
Fig 3: PI controller

The proportional plus integral (PI) controller produces an

output signal consisting of two terms-one proportional to
error signal and the other proportional to the integral of
error signal. An advantage of the PI control technique is to
reduce the steady-state error to zero by feeding the errors
in the past forward to the plant .P-I controller is mainly
used to remove the steady state error resulting from
Fig1: Single-zone power system block diagram Integral controller. However, in terms of the speed of the
response and overall stability of the system, it has a
III. DESIGN OF CONVENTIONAL CONTROLLER negative impact. This controller is mostly used in areas
where speed of the system is not an issue. Since P-I
controller has no ability to forecast the future errors of the
A. Integral Controller: The integral controller used system it cannot decrease the rise time and eliminate the
for the purpose of LFC is comprised of a frequency sensor oscillations.
and an integrator. The work of frequency sensor is to
sense the frequency error (Δf) of the system due to load
IV. SIMULATION RESULTS
change or fault condition. This frequency error signal is
then fed to the integrator. This frequency error which is
given as the input to integrator is known as “Area Control The MATLAB simulation has been organize in MATLAB
Error”. So we can say that ACE is the frequency change of (R2010a) for single area power system with Integral
an area which is given to integral control action loop to Controller and PI controller is design for Power plant
bring the system in steady state and keep frequency error model using MATLAB Simulink.
as zero.
Case 1 (uncontrolled load frequency control)

DPd (s)

1 1 120
DPc (s)
0.08 s+1 0.3s+1 20 s+1
Speed Governor Turbine Generator Scope

simout

To Workspace

Fig 2: Integral controller 1/2.4

1/R

B. PI Controller: PI controllers are very often used in

industry, especially when speed of the response is not an Fig 4: MATLAB Diagram of Uncontrolled model of
issue. Out of various methods of load frequency controller, single Area Load Frequency Control
the PI controllers are mostly used in speed-governing
system for LFC scheme.

© 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1593
 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072

0
Case3 (Load frequency control with using P I
controller)
-0.005

-0.01

-0.015
Delta f (pu)

-0.02

-0.025

-0.03

-0.035
0 5 10 15 20 25 30
Time (s)

Fig 8: MATLAB Diagram of PI Controller for single Area

Fig 5: Frequency response of Uncontrolled model of Load Frequency Control
single Area Load Frequency Control

Case 2 (Load frequency control with using integral

controller)

DPd(s)=0.01
Integral Controller

1 1 1 120
-0.671
s 0.08s+1 0.3s+1 20s+1
Integrator Governor Turbine Generator Scope
Ki

simout
b 1/R
0.425 To Workspace
1/2.4
Fig 9: Frequency response of PI controller

V. CONCLUSION
Fig 6: MATLAB Diagram of Integral Controller for
single Area Load Frequency Control In this paper, the above results show that we can stabilize
the frequency by using integral controller and PI controller
0.005
for single area power system. Simulation results show that
Integral controller is frequency deviations of power
0
system has a better performance than the PI controller,
-0.005
because of reduced the settling time and minimize
overshoot.
-0.01
Delta f (pu)

-0.015 REFERENCES
-0.02

[1] Prasanth, B.V. and Kumar, S.V.J “ New Control Strategy

-0.025 for Load Frequency Problem of a Single Area Power
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-0.03
0 5 10 15 20 25 30
Time (s)

Fig 7: Frequency response of Integral controller [2] DeMello, F.P., Mills, R.J. and B’Rells, W.F. Automatic
Generation Control: Part I. Process Modeling, Paper T72
598-1, 1972 IEEE-PES

© 2017, IRJET | Impact Factor value: 6.171 | ISO 9001:2008 Certified Journal | Page 1594
 International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 04 Issue: 10 | Oct -2017 www.irjet.net p-ISSN: 2395-0072

Summer Meeting, San Francisco, CA, July 19972.

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