Advanced Electrical Engineering - Lab Manual

EE 707

ADVANCED ELECTRICAL ENGINEERING LAB

2006 Scheme

December 1, 2012

ACKNOWLEDGEMENT

This manual is the result of contributions from the following staff members.

Mr. Anith KrishnanMr. Jijo BalakrishnanMr. Githin GopalMs. Mini M. B.Mr. Sreekumar

INTRODUCTION

EE 707 - Advanced Electrical Engineering Lab is a part of the course study of thestudents of Electrical Engineering registered under CUSAT. The lab aims in deliveringa better understanding of advanced concepts especially related to instrumentation andcontrol. The lab also introduces the student to various simulations softwares like MATLABand SPICE. The knowledge of simulation tools will empower the students with sufficientknowledge for the simplified analysis of control systems, power systems and electroniccircuits.

INSTRUCTIONS

• Discipline has to be maintained throughout the lab session.

• All students should wear shoes.

• Male students should tuck in their shirts.

• Students should not lean on the work bench or on the computer table.

• Do not switch on the supply before the circuit is verified by the concerned lab faculty.

• Shutdown the computer before leaving the lab.

• Use of mobile phone inside the laboratory is strictly prohibited.

• Entry will be allowed only to students who have their rough record and fair record(completed) in custody.

• Students should have their identity cards in custody inside the lab.

• Use of USB drives, CDs, DVDs or any other portable data storage device withoutthe permission of the lab in-charge is forbidden.

All the students are to strictly abide by the instructions given here and any additionalinstruction given during the lab session, failing to which he/she will have to face disciplinaryaction.

Contents

Strain Measurement 1

Synchro. 3

Speed control of Dc shunt control. 5

Measurement of temperature using RTD. 7

LVDT. 9

Speed control of ac servomotor. 11

Familiarization of MATLAB I. 13

Familiarization of MATLAB II. 15

Familiarization of MATLAB III. 17

Lag Compensator. 19

Lead Compensator. 20

Familiarization of SIMULINK. 22

Steady-State Stability Analysis. 25

Lab Manual: Advanced Electrical Engineering Lab (EE 707) 2006 Scheme

Experiment No.: 1

STRAIN MEASUREMENT

Aim:

To study the strain measurement kit and to use the kit to measure the strain.

Components Required:

Students are expected to write the components required before coming to the lab.

Theory:

Students are expected to complete this section before coming to the lab.

Procedure:

1. Check the connections made and switch on the instrument.

2. Allow the instrument to stay in on position for 10 minutes for intial warm up.

3. Select the full bridge configuration from the selector switch on the panel.

4. Adjust the ZERO potentiometer on the panel till the display reads zero.

5. Apply 1kg load on the cantilever beam and adjust the CAL potentiometer till thedisplay reads 377.

6. Remove the weights and check whether the display reads zero. If it is not zero, thenadjust ZERO potentiometer again until the diaplay shows zero. Now the instrumentis calibrated to read micro-strain.

7. Apply load on the sensor using the loading arrangement provided in steps of 100gupto 1kg. The instrument displays exact strain in micro-strain. Note down thereadings in the tabular column during each step.

8. Unload the sensor and switch off the supply.

Observation Table:

Sl. Indicated Reading Actual Reading LoadNo. (micro-strain) (micro-strain) (kg)12...10

Department of Electrical and Electronics Engineering,College of Engineering, Kidangoor

1


Equations and Calculations:

S =6PL

BT 2E

whereP is the load applied in kg.L is the effective length of the beam (22 cm).B is the width of the beam (2.8cm).T is the thickness of the beam (0.25cm).E is the Young’s modulus (2× 106).S is the strain.

Sample Graph:

I

n

d

i

c

a

t

e

d

r

e

a

d

i

n

g

(

i

n

m

i

c

r

o

‐

s

t

r

a

i

n

)

I

n

d

i

c

a

t

e

d

r

e

a

d

i

n

g

(

i

n

m

i

c

r

o

‐

s

t

r

a

i

n

)

Result:


2


Experiment No.: 2

SYNCHRO TRANSMITTER/RECEIVER

Aim:

To study the synchro transmitter/receiver kit and to obtain the following characteristics

1. stator output voltage vs. rotor position

2. error vs. stator position


Students are expected to write the components required before coming to the lab.

Theory:


Procedure:

1. Connect digital voltmeter across to any of the two stator terminals of synchro trans-mitter.

2. Connect synchro transmitter stator outputs to the corresponding stator terminals ofsynchro receiver.

3. Power ON all the switches.

4. Verify the state output voltage is 0V at 0◦, if it not 0V, then adjust the pointer ofthe transmitter to make it 0V.

5. Adjust the transmitter rotor position step by step by using the knob and note downthe voltage, rotor position of the transmitter and receiver in the observation table.

6. Switch off all the switches.

Observation Table:

Sl. Transmitter rotor position Stator Voltage Receiver rotor positionNo. (degree) (V) (degree)12....


3


Sample Graph:

S

t

a

t

o

r

o

u

t

p

u

t

(

V

)

Result:


4


Experiment No.: 3

SPEED CONTROL OF DC SHUNT MOTOR.

Aim:

To study the speed control of dc shunt motor by using single phase fully controlled con-verter.



Theory:


Procedure:

1. Initially SW1, SW3, SW4 and SW5 SPDT switches in OFF position.

2. Set the switch SW2 in INT mode.

3. Power on the switch SW1 and SW3.

4. Connect the voltmeter across the bana connectors P15 and P17.

5. Connect the pulse 1 connectors P5 to P9, pulse 2 connectors P6 to P14, pulse 3connectors P7 to P12 and pulse 4 connectors P8 to P11.

6. Motor armature winding is connected across the banana connectors P15 (A) and P17(AA).

7. Motor field winding is connected to banana connector P16.

8. Switch ON SW5 ans SW4.

9. Vary the pot in steps from minimum position to maximum position and note downthe output voltage and speed in each step.

10. Bring the pot to minimum position and switch off the supply.


5


Observation Table:

Sl. Armature Voltage SpeedNo. (V) (rpm)12....

Result:


6


Experiment No.: 4

MEASUREMENT OF TEMPERATURE USING RTD

Aim:

To analyse the working of RTD and to determine its characteristics.



Theory:


Procedure:

1. Connections are done as per the circuit diagram. Connect a voltmeter across theRTD terminals. Switch on the supply and keep the instrument in on condition for10 minutes for initial warm up.

2. Pour water to about 3/4th of the kettle and place the sensor and the thermometerinside it.

3. Note down the initial water temperature from the thermometer.

4. Adjust the initial set potentiometer in the front panel till the display shows the intialwater temperature.

5. Switch on the kettle and wait till the water boils. Note down the reading in thethermometer and adjust final set potentiometer till the display reads the boilingwater temperature.

6. Remove the sensor from the boiling water and immerse it in cold water. If thedisplay reading and the thermometer reading are not the same, then adjust the initalset potentiometer until they are equal.

7. Repeat the above process till the display reads the exact boiling and cold watertemperatures. If the correct value is displayed, it is inferred that the device has beencaliberated.

8. After caliberation, pour cold water into the kettle and adjust the thermostst settingin steps so that the water temperature increases. Note down the temperature andthe display reading during each step. Also note down the voltmeter reading. Thethermostat is varied until the water starts boiling.

9. Switch of the kettle and the supply.


7


Observation Table:

Sl. Thermometer reading Indicated reading VoltageNo. (◦C) (◦C) (V )12....

Result:


8


Experiment No.: 5

LVDT

Aim:

To calibrate the LVDT in the range ±10mm and to plot the characteristics.



Theory:


Procedure:

1. Switch on the instrument. The display glows to indicate that the instrument is on.Keep the instrument in the on position for ten minutes for initial warm-up.

2. Rotate the micrometer till it reads 20mm.

3. Adjust the CAL potentiometer so that the display reads 10.

4. Rotate the micrometer till it reads 10mm.

5. Adjust the ZERO potentiometer until the display shows 0 reading.

6. Rotate back the micrometer till it reads 20mm and adjust the CAL potentiometeruntil the display reads 10. Now the instrument is caliberated for ±10mm range.

7. Rotate the micrometer in steps pf 1 or 2 mm and tabulate the readings. The readingsto be noted down are: actual displacement, indicated displacement and the voltageacross the output terminals.

8. Switch off the supply.

Observation Table:

Sl. Actual reading Indicated reading VoltageNo. (mm) (mm) (V)12....


9


Sample Graph:

O

u

t

p

u

t

V

o

l

t

a

g

e

(

V

)

Result:


10


Experiment No.: 6

SPEED CONTROL OF AC SERVOMOTOR

Aim:

To control the speed of ac servo motor using open-loop and closed-loop PI controller.



Theory:


Procedure:

Circuit set-up

1. Connect G1K1 of pulse isolation output to G1K1 of SCR1.

2. Connect G2K2 of pulse isolation output to G2K2 of SCR1.

3. Set open-loop control mode using switch S1.

4. 9 pin D-connector (male) is connected from the motor setup to the D-socket (female).

5. Speed indicator switch is kept in CV mode.

Open-loop controller

1. Switch on the supply and the switch S2.

2. Set the motor speed using the CV pot and note down the set speed.

3. Switch the indicator switch to PV mode and note down the process speed.

4. Take around 5 readings for different positions of CV pot.

Closed-loop controller

1. Set closed-loop control mode using switch S1.

2. Switch on the supply and the switch S2.

3. Set the motor speed using the CV pot and note down the set speed.

4. Switch the indicator switch to PV mode and note down the process speed.

5. Take around 5 readings for different positions of CV pot.


11


Observation Table:

Sl. Mode Set speed Process SpeedNo. (CL or OL) (rpm) (rpm)12....

Result:


12


Experiment No.: 7

FAMILIARIZATION OF MATLAB I

Aim:

To familiarize with some basic commands in MATLAB.

Main Window:

Some Basic Commands:

• To store a row matrix A =[1 2 3

]>> A=[1 2 3]

• To store a column matrix, A =

123

>> A=[1;2;3]


13


• To store a square matrix, A =

1 2 34 5 67 8 9

>> A=[1 2 3;4 5 6;7 8 9]

• To find the inverse of matrix A

>> A=[1 2;3 4]

>> inv(A)

gives the answer

[−2 11.5 −0.5

]• To find the determinant of A

>> det(A)

gives the answer −2

• Multiplication two matrices, A =

[1 23 4

]and B =

[4 32 1

]>> A=[1 2;3 4]

>> B=[4 3;2 1]

>> A*B

gives the answer

[8 520 13

]

• Square of a matrix A2 =

[1 23 4

]2>> A=[1 2;3 4]

>> A^2

gives the answer

[7 1015 22

]Result:


14


Experiment No.: 8

FAMILIARIZATION OF MATLAB II

Aim:

To familiarize with some basic commands in MATLAB related to electrical engineering.

Commands and their usage:

• Realize a transfer function G(s) = 1s2 + 2s+ 5

>> num=[1] % coefficients of numerator

>> den=[1 2 5] % coefficients of denominator

>> G=tf(num,den)

The transfer function can also be realized directly as shown below

>> G=tf([1],[1 2 5])

• Multiplication of two transfer functions G1(s) = 1s2 + 2s+ 5

and G2(s) = 32s2 + 5

>> G1=tf([1],[1 2 5])

>> G2=tf([3],[2 0 5])

>> G1*G2

The answer will be a fourth order transfer function (as evident).

• To obtain the step response of the system G1(s) = 1s2 + 2s+ 5

>> G1=tf([1],[1 2 5])

>> step(G1)

0 1 2 3 4 5 60

0.05

0.1

0.15

0.2

0.25

Step Response

Time (sec)

Am

plitu

de


15


• To obtain the bode plot of the system G1(s) = 1s2 + 2s+ 5

>> G1=tf([1],[1 2 5])

>> bode(G1)

−80

−70

−60

−50

−40

−30

−20

−10

Mag

nitu

de (

dB)

10−1

100

101

102

−180

−135

−90

−45

0

Pha

se (

deg)

Bode Diagram

Frequency (rad/sec)

• To obtain the root locus of the system G1(s) = 1s3 + 3s2 + 5s+ 4

>> G1=tf([1],[1 3 5 4])

>> rlocus(G1)

−5 −4 −3 −2 −1 0 1−4

−3

−2

−1

0

1

2

3

4

Root Locus

Real Axis

Imag

inar

y A

xis

Result:


16


Experiment No.: 9

FAMILIARIZATION OF MATLAB III

Aim:

To familiarize the usage of m-file.

Procedure:

1. From the main window, choose to open a new Blank M-File from the File menu.

2. In the new window, the commands can be entered in the sequence in which they aremeant to be executed.

3. After all the necessary commands are entered, the file is saved using .m extension.

4. The file (all the commands in sequence) can be executed by clicking on the runbutton on the toolbar or by pressing F5.

5. The commands will be executed, if there was no error in the code. The commandprompt will display all the errors (if any).


17


Excercise:

Obtain the unit-impulse response of the following system:[x1

x2

]=

[0 1−1 −1

] [x1

x2

]+

[01

]u

y =[0 1

] [x1

x2

]+ [0]u

0 2 4 6 8 10 12−0.1

0

0.1

0.2

0.3

0.4

0.5

0.6

Unit Impulse Response

Time (sec)

Am

plitu

de

Result:


18


Experiment No.: 10

LAG COMPENSATOR

Aim:

To design a lag compensator for a system whose open-loop transfer function is given by

G(s) =5

s(s+ 2)

so that the static velocity error constant kv is 20s−1, the phase margin is atleast 55◦ andthe gain margin is atleast 12dB.

Theory:

Students are expected to complete this section by themselves.

Procedure:


Result:

G(s)Gc(s) =20(0.26s+ 1)

s(0.5s+ 1)(0.04s+ 1)


19


Experiment No.: 11

LEAD COMPENSATOR

Aim:

To design a lead compensator for a system whose open-loop transfer function is given by

G(s) =5

s(s+ 2)

so that the static velocity error constant kv is 20s−1, the phase margin is atleast 55◦ andthe gain margin is atleast 12dB.

Theory:


Procedure:


Result:

G(s)Gc(s) =20(8.7s+ 1)

(166.7s+ 1)s(0.5s+ 1)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Time (s)

Am

plitu

de

Ramp Response

InputUn−compensated SystemCompensated System


20


4.95 5 5.05 5.1 5.15 5.2 5.25 5.3 5.35 5.45

5.05

5.1

5.15

5.2

5.25

5.3

Time (s)

Am

plitu

de

Ramp Response

InputUn−compensated SystemCompensated System

0.05

−100

−50

0

50

100

150

Mag

nitu

de (

dB)

10−4

10−3

10−2

10−1

100

101

102

−180

−135

−90

Pha

se (

deg)

Bode Diagram of Compensated SystemGm = Inf dB (at Inf rad/sec) , Pm = 58.1 deg (at 0.95 rad/sec)

Frequency (rad/sec)


21


Experiment No.: 12

FAMILIARIZATION OF SIMULINK

Aim:

To familiarize with SIMULINK.

Introduction:

SIMULINK is a Graphical User’s Interface (GUI) software which works directly with theblock diagram of a control system (rather than differential equations, or transfer functions)to produce a simulation of the system’s response to arbitrary inputs and initial conditions.The basic entity in SIMULINK is a block, which can be selected from a library of commonlyused blocks. Alternatively, a user can device special blocks out of the common blocks, M-files, MEX files, C, or Java codes through the S-function facility.

Procedure:

1. To open the SIMULINK library browser, double click on the SIMULINK icon on theMATLAB toolbar, or issue the following command at the MATLAB prompt

>> simulink

2. Click on the create a new model icon on the SIMULINK toolbar. A window for thenew model will open.


22


3. Open the subsystem library in the general SIMULINK library browser by double-clicking on the appropriate icon. The subsystems are: Continuous, Discontinuous,Sinks, Sources etc.

4. Select the required blocks from the subsystems libraries and drag them individuallyto the open new model window.

5. Once the required blocks are dragged and placed in the new model window, the in-ports and out-ports of the adjacent blocks can be joined to create a block diagram asdesired. Double clicking on each block will open a dialog blox, in which the block’sparameters can be set.

6. Once the block diagram is ready, it is saved into a location on the hard disk drive.

7. In order to simulate the block diagram, click on the play button on the toolbar.If the model created was correct, the simulation will start and the results can beviewed using any of the sink blocks in the model. However, if there was an error,SIMULINK prompts with a diagnostics dialog box which describes what went wrongin the simulation and also what has to be modified in the model for a successfulsimulation.

8. The simulation can be further refined by adjusting the simulation parameters.SIMULINK provides several simulation parameters that can be adjusted to achieve adesired accuracy in a simulation. A user can select from a number of time-integrationschemes, such as Runge-Kutta, Euler, etc and as well as refine the tolerances and timestep sizes used for performing the simulation.


23


Excercise:

Realize the following block diagram using SIMULINK.

0 5 10 150

0.2

0.4

0.6

0.8

1

1.2

Time (s)

Am

plitu

de

Unit Step Response

Result:


24


Experiment No.: 13

STEADY-STATE STABILITY ANALYSIS

Aim:

To study the steady-state analysis of a power system using MATLAB.

System Description:

A 60Hz synchronous generator having inertia constantH = 9.94MJ/MV A and a transientreactance X ′

d = 0.3 per unit is connected to an infinite bus through a purely reactive circuitas shown in the figure. Reactances are marked on the diagram on a common system base.The generator is delivering real power of 0.6 per unit, 0.8 power factor lagging to aninfinite bus at a voltage of V = 1 per unit. Assume the per unit damping power coefficientis D = 0.138. The generator is operating in the steady state at δ0 = 16.79◦ when the inputpower is increased by a small amount ∆P = 0.2 per unit.

Modelling:

It is given that the input power is increased by a small amount ∆P . The linearized swingequation is thus

H

πf0

d2∆δ

dt2+D

d∆δ

dt+ Ps∆δ = ∆P

ord2∆δ

dt2+

πf0H

Dd∆δ

dt+

πf0H

Ps∆δ =πf0H

∆P

or in terms of the standard second-order differential equation,

d2∆δ

dt2+ 2ζωn

d∆δ

dt+ ω2

n∆δ = ∆u

where

∆u =πf0H

∆P

ωn =

√πf0H

Ps

ζ =D

2

√πf0HPs

The synchronizing coefficient Ps is given by

Ps = Pmax cos δ0


25


where Pmax (steady-state stability limit) is given by

Pmax =|E ′| |V |

X

X = 0.3 + 0.2 +0.3

2= 0.65

E ′ is computed fromE ′ = V + jXI

where current I is

I =S∗

V ∗ = 0.756 − 36.87◦

The per unit apparant power

S =0.6

0.86 cos−1 0.8 = 0.756 36.87◦

Transforming to the state variable form by taking x1 = ∆δ and x2 = ∆ω = ∆δ, thestate-space representation is given by[

x1

x2

]=

[0 1

−ω2n −2ζωn

] [x1

x2

]+

[01

]∆u

and

y(t) =

[1 00 1

] [x1

x2

]Matlab Code:

A=[0 1;-37.705 -2.617];

Du=3.79;

B=[0;1]*Du;

C=[1 0;0 1];

D=[0;0];

t=0:0.01:5;

[y,x]=step(A,B,C,D,1,t);

Dd=x(:,1);

Dw=x(:,2);

d=(d0+Dd)*180/pi;

f=f0+Dw/(2*pi);

subplot(2,1,1);

plot(t,d);

grid on;

subplot(2,1,2);

plot(t,f);

grid on;

where d0 is the initial δ and f0 is the steady state frequency.


26


Simulink Block Diagram:

Results:

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 515

20

25

30

δ 0 (de

g.)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 559.95

60

60.05

60.1

Time (s)

f (H

z)


27

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