Experiment No.

01
SYSTEM MODELING AND SIMULATION: ELECTRICAL NETWORKS

1. Objective(s):
This activity aims to
1. introduce the modeling and simulation tools of Scilab
2. equip the students with the skills and knowledge in using Scilab model and simulate systems;
and
3. equip the students with the skill to measure the major performance indicators of a control system
2. Intended Learning Outcomes (ILOs):
At the end of this activity, the student shall be able to
1. create Scilab program that will simulate electrical control systems; and
2. determine the effects of component values to the system’s time response parameters
3. Discussion
One of the steps involved in the design of a control system is to model the system itself from its
schematic. The system’s model is very important since it will provide information on the system’s various
parameters, such as time response, error and stability information. These parameters will then help the
designer to come up with a control system that would make the system perform at its desired state.
Thus, modeling and simulation is an important step in the design of control systems.

Scilab is an open source, cross-platform numerical computational package and a high-level, numerically
oriented programming language. It is similar in its capabilities to MATLAB. It has a good implementation
of many of the required control systems functions and has a dynamic model simulator called XCos that
makes it a good tool for use by control engineers.

.
4. Resources:
To perform this activity, a computer workstation with Scilab is required. The control systems toolbox is
needed.
5. Procedure:
Modeling and simulation of a series RLC electrical network.
1. Consider the simple series RLC circuit shown below. This circuit will be modeled in s-domain and
will be simulated using LabVIEW. Let L=1 H, C=1 F and R=1 Ω. For the questions to follow,
write the solutions onto separate sheets of paper.

Q1.1 For this circuit, find the transfer function G ( s )=V c ( s ) /V ( s ) .

Q1.2 For a step input, find an expression for the output capacitor voltage.
Q1.3 Using this expression, plot the output capacitor voltage and roughly sketch the plot below.

2. Scilab. The transfer function can be created in Scilab by creating a row vector matrix containing the
coefficients of the numerator and the denominator of the transfer function. For the transfer function
of the form
m m−1
N ( s ) a m s + am−1 s + …+a1 s +a 0
G ( s )= =
D ( s ) b n s n+ bn−1 s n−1+ …+b1 s+ b0

1
For example: Let say the transfer function is G(s) = 2 . This is created in the Scilab console by
10 s +0.1 s
the following:

num = 1; //Coefficient of the numerator

den = poly([0 0.1 10],'s','c'); // Polynomial Coefficients of the denominator, starting with the lower order of s
P = syslin('c',num,den) // Define the linear continuous transfer function

Another method that eventually yields the same P is shown below.

s = poly(0,'s'); // Begin by creating the Laplace variable s. Alternatively you can use s = %s.
P = 1/(10*s^2+0.1*s) // Form the polynomial
P = syslin('c',P) // Convert P to a continuous-time linear transfer function, by using the syslin() command

To plot the step response of the system

t=0:0.01:3; // Define a time range for the step test
plot2d(t, csim('step',t,P)); // csim applies the step test and plot2d produces the graphical output

Q2.1 Roughly sketch the plot of the transfer function of the above circuit. Use this graph to determine the
time response of the system.

Q2.2 Change some of the parameters of the RLC circuit and obtain a new transfer function. Simulate this
new transfer function using Scilab. Conduct at least ten trials and plot the step response of the system in
each trial. Comment on the effect of the values of the resistor, inductor and capacitor on the output
capacitor voltage.

3. Simulate the transfer function of the given network using Scilab and plot the response of the system.
Course: ECE 006 Experiment No.: 1
Group No.: Section: EC51FB1
Group Members: Date Performed: 05/15/2020
MONVILLE, CHRISTIAN B. Date Submitted: 05/15/2020
PARILLA, JAMES KARL G. Instructor:
TAVARES, KARL ANDREI A. ENGR. SHEILA VALONDO
6. Data and Results:
Q1.1 For this circuit, find the transfer function G ( s )=V c ( s ) /V ( s ) .

Q1.2 For a step input, find an expression for the output capacitor voltage.

Q1.3 Using this expression, plot the output capacitor voltage and roughly sketch the plot below.
Q2.1 Roughly sketch the plot of the transfer function of the above circuit. Use this graph to determine the
time response and error of the system.

Q2.2 Change some of the parameters of the RLC circuit and obtain a new transfer function. Simulate this
new transfer function using Scilab. Conduct at least ten trials and plot the step response of the system in
each trial. Comment on the effect of the values of the resistor, inductor and capacitor on the output
capacitor voltage.
 3. Simulate the transfer function of the given network using Scilab and plot the response of the
system.

7. Conclusion:
MONVILLE, CHRISTIAN B.
ECE 006 – EC51FB1
EXPERIMENT NO. 1: SYSTEM MODELING AND SIMULATION: ELECTRICAL
NETWORKS
CONCLUSION

In this experiment, we are challenged because we were not very familiar with the
programming language that must be used in order to command in scilab. We were more
familiar in using matlab and labview, but because this is a freeware and the other two needs
license, this is the only software we can use today. By using this software, we were able to
explore new things and get ourselves to be familiarize with an alternative to the other software
if in case they were not available. We were able to simulate electrical control systems using
this software and produced the transfer function plot of a given circuit. We were also able to
find an expression for the output capacitor voltage. And lastly, we were able to produce a plot
of the output capacitor voltage.

PARILLA, JAMES KARL G.

ECE 006 – EC51FB1
 EXPERIMENT NO. 1: SYSTEM MODELING AND SIMULATION: ELECTRICAL
NETWORKS
CONCLUSION

While doing this experiment it was challenging for us because we really don’t know what to
do at first, but just by following the procedure helps a lot and little by little there’s some
improvement. It was difficult because I don’t know what other commands I can use to do this
experiment, I search online and it helps a lot in using this simulator. By doing this experiment
it teaches me the skills and knowledge in using Scilab model and simulate systems, and to
measure the major performance indicators of a control system. I was able to create Scilab
program that will simulate electrical control systems and determine the effects of component
values to the system’s time response parameters.

I can therefore conclude that modelling of the system is very important since it will
provide information on the different parameters of the system, such as time response, error and
stability information. Then, these parameters will help the designer develop a control system
that would make the system perform at its desired condition.

TAVARES, KARL ANDREI A.

ECE 006 – EC51FB1
 EXPERIMENT NO. 1: SYSTEM MODELING AND SIMULATION: ELECTRICAL
NETWORKS
CONCLUSION

In this experiment control theory is concerned with system that has innovative and optimum
qualities. It consists of a trial and error approach and also provides a vital learning and
identifying concepts of physical systems is also a new way to interpret the noise and other
simple issues. Ideally the plotted time functions deals directly with continuous-time quantities
and sometimes there are no approximate conversion to discrete time.

Assessment rubric for the activity’s intended learning outcomes

 INTENDED
LEARNING 1 2 3 4 Points
OUTCOMES
The program returns
Create a A program for The program works
The program works, results that are
program that will electrical system was but the results are
the results are expected and with
simulate the created but does not doubtful or are
credible but the little or no variation
performance of work or results vary inconsistent when
interface is difficult to from reality and with
electrical system significantly from trials are repeatedly
use user friendly
(MP 1) reality done
interface.
Determine the
effect of
component The data gathered
An investigation was A sufficient amount The data gathered
values of was analyzed very
made but contains of data were was analyzed but
electrical system well and valid
insufficient data or gathered but was not does not support the
to the conclusions were
limited trials. synthesized properly. conclusions made.
performance of drawn.
the system
(MP 1)
Total Score
Mean Score = (Total Score /2)

Percentage Score = (Total Score / 8) x 100%

Assessment rubric for the conduct of laboratory experiments

Performance Indicators 1 2 3 Points

Members do not follow Members follow good Members follow good
Conduct experiments in good and safe and safe laboratory and safe laboratory
accordance with good and laboratory practice in practice most of the practice at all times in
safe laboratory practice. the conduct of time in the conduct of the conduct of
experiments. experiments. experiments.
Members are able to
Members are able to
Members are unable to operate the equipment
Operate equipment and operate equipment and
operate the equipment and instruments with
instruments with ease instrument with
and instruments. ease and with minimum
supervision.
supervision.
 Performance Indicators 1 2 3 Points
The group has
Analyze data, validate complete data,
The group has
experimental values against validates experimental
The group has complete data but has
theoretical values to determine values against
incomplete data. no analysis and valid
possible experimental errors, theoretical values, and
conclusion.
and provide valid conclusions. provides valid
conclusion.
Total Score
Mean Score = (Total Score /3)

Percentage Score = (Total Score / 9) x 100%