Post on 02-Jun-2018
8/11/2019 Thyristor Voltage Controller Cwrk
1/16
Calculations
1.
Single phase half wave controller
a. Load Voltage waveform with diode b. Load Voltage waveform without diode
c. Anode to Cathode Voltage of SR1 d. Anode to Cathode Voltage of SR1
(With diode) (Without diode)
e. Gate voltage
8/11/2019 Thyristor Voltage Controller Cwrk
2/16
Sample Calculation
For Delay angle =
Output Voltage ( )
() Resistance() Er (V) Ec (V) VL(theoretical)
(V) (theoretical)
(degrees)
0 19 12 12.96 115.45
1 18.6 12 13.36 114.34
2 18.2 12 13.78 113.20
3 17.6 12.5 15.24 109.23
4 17 13 16.78 105.19
5 16 13.5 18.91 99.69
6 14.4 14 22.10 91.61
7 13.2 14.5 24.86 84.63
8 9.8 16 33.06 62.97
9 4.4 17.5 42.76 28.22
10 0 18 45.47 0
8/11/2019 Thyristor Voltage Controller Cwrk
3/16
Resistance () VL(practical)(V)
VL(theoretical)(V)
(theoretical)(degrees)
0 14 12.96 115.45
1 15 13.36 114.34
2 16 13.78 113.20
3 18 15.24 109.23
4 20 16.78 105.19
5 22 18.91 99.696 25 22.10 91.61
7 28 24.86 84.63
8 33 33.06 62.97
9 40 42.76 28.22
10 43 45.47 0
8/11/2019 Thyristor Voltage Controller Cwrk
4/16
0
5
10
15
20
25
30
35
40
45
50
0 20 40 60 80 100 120 140
OutputVoltage(V)
Delay angle (degrees)
Output voltages vs Delay angle
VL(practical) (V) VL(theoretical) (V)
8/11/2019 Thyristor Voltage Controller Cwrk
5/16
2. Single phase full wave controller
a. Load Voltage waveform
b. Anode to Cathode Voltage of SR1 c. Anode to Cathode Voltage of SR2
d. Gate voltage
8/11/2019 Thyristor Voltage Controller Cwrk
6/16
Sample Calculations
For Delay angle =
Output Voltage ( )
()
Resistance() Er (V) Ec (V) VL(theoretical)
(V)
(theoretical)
(degrees)
0 17.5 11.5 27.15 113.38
1 17 12 29.94 109.56
2 17 12.5 31.60 107.35
3 16.5 13 34.48 103.53
4 15.5 14 40.45 95.82
5 14.5 15 46.54 88.06
6 13.5 16.5 53.93 78.58
7 12 18 62.33 67.38
8 10 20 72.02 53.13
9 5 23 85.97 24.53
10 1.4 24 89.73 6.68
8/11/2019 Thyristor Voltage Controller Cwrk
7/16
Resistance () VL(practical)(V)
VL(theoretical)(V)
(theoretical)(degrees)
0 12 27.15 113.38
1 13 29.94 109.56
2 15 31.60 107.35
3 17 34.48 103.53
4 19 40.45 95.82
5 22 46.54 88.06
6 33 53.93 78.58
7 43 62.33 67.38
8 57 72.02 53.13
9 78 85.97 24.53
10 86 89.73 6.68
8/11/2019 Thyristor Voltage Controller Cwrk
8/16
0
10
20
30
40
50
60
70
80
90
100
0 20 40 60 80 100 120
OutputVoltage(V)
Delay angle (degrees)
Output voltages vs Delay angle
VL(practical) (V) VL(theoretical) (V)
8/11/2019 Thyristor Voltage Controller Cwrk
9/16
3. AC Voltage controller
a. Load Voltage waveform
b. Anode to Cathode Voltage of SR1 c. Anode to Cathode Voltage of SR2
8/11/2019 Thyristor Voltage Controller Cwrk
10/16
Sample Calculation
For Delay angle =
1.991 rad
Output Voltage
Resistance() Er (V) Ec (V) VL(theoretical)
(V)
(theoretical)
(degrees)0 18.5 12 50.78 114.06
1 18.5 12.5 52.81 111.91
2 18 12.5 54.19 110.44
3 17.5 13.5 59.49 104.70
4 17 14.5 64.51 99.08
5 16 16 72.12 90
6 14.5 17.5 80.16 79.28
7 13 19 86.88 68.76
8 11 21.5 94.04 54.19
9 4.5 24.5 101.49 20.82
10 1 25 101.99 4.58
8/11/2019 Thyristor Voltage Controller Cwrk
11/16
Resistance () VL(practical)(V)
VL(theoretical)(V)
(theoretical)(degrees)
0 29 50.7776 114.0612
1 30 52.8137 111.90812 34 54.1887 110.4443
3 39 59.4892 104.7048
4 43 64.5104 99.0755
5 48 72.1249 90.0000
6 62 80.1620 79.2883
7 74 86.8784 68.7607
8 87 94.0378 54.1911
9 99 101.4933 20.8154
10 100 101.9945 4.5812
8/11/2019 Thyristor Voltage Controller Cwrk
12/16
0
20
40
60
80
100
120
0 20 40 60 80 100 120
OutputVoltage(V)
Delay angle (degrees)
Output voltages vs Delay angle
VL(practical) (V) VL(theoretical) (V)
8/11/2019 Thyristor Voltage Controller Cwrk
13/16
Discussion
1.
Give a short discussion on the application of the thyristor voltage control in practice
The basic use of the thyristor voltage controller is to adjust the output voltage to a certain load. The two main
methods used are on-off control and phase angle control. There are many applications of the controller, some are
listed below:
Thyristor dimmer:
By changing the firing angle, the voltage across the lamp can be varied. Thus, the mean power output to the lamp
will change and so will the brightness of the lamp. This switching method is fast and consumes low power. The
basic diagram is shown below:
Six SCR in-line controllers
As the name implies, this makes use of six SCRs to control power output to the load. The load power can be varie
from 0-100% by changing the thyristor firing angles. This configuration is an ideal configuration for inductive loa
applications, unbalanced resistive loads and transformer coupled loads.
Single phase/Three phase rectifiers
These are used to convert AC supply to DC supply. By changing the firing angle, we can adjust the magnitude of
the voltage appearing across the load. The main uses for the rectifier are in AC-DC power supplies required for
electronic components and largely used in HVDC substations for long distance transmission of electricity. Other
applications maybe; charging of battery banks and setting the field voltage in synchronous generators. Below is a
basic 3 phase full-wave bridge rectifier:
8/11/2019 Thyristor Voltage Controller Cwrk
14/16
DC Motor control
Control of dc motors can be achieved by regulating the armature voltage, armature resistance or flux. In armature
voltage control, it is common to use a single phase full wave converter.
Converter 1 on the left and converter 2 on the right
The circuit above consists of dual single phase converters, this mode allows for both a positive armature voltage
and negative armature voltage across the motor and so four quadrant operation is possible. Converter 1 provides
operation in first and fourth quadrants, and converter 2 provides operation in second and third quadrants and so
provides four modes of operation: forward powering, forward braking (regeneration), reverse powering, and rever
breaking (regeneration).
8/11/2019 Thyristor Voltage Controller Cwrk
15/16
Thyristor Controlled Series Capacitor (TCSC)
TCSC is technology that can be used with new capacitor banks as well as exisiting cacpacitor banks. Some uses of
the capacitor banks are:
Increased dynamic stability of power transmission systems
Improved voltage regulation and reactive power balance
Improved load sharing between parallel lines
In a TCSC, the whole capacitor bank or alternatively, a section of it, is provided with a parallel thyristor controlle
inductor which circulates current pulses that add in phase with the line current so as to boost the capacitive voltage
beyond the level that would be obtained by the line current alone. By controlling the additional voltage to be
proportional to the line current, the TCSC will be seen by the transmission system as having a virtually increased
reactance beyond the physical reactance of the capacitor.
2. What is the reason for the directional diode?
The thyristor will conduct in its current direction as long as the current through it is greater than zero, once a gate
pulse has been given. The only way to stop it from conducting is to reverse the voltage or drive the current to zero
In the case of inductive loads, the load current lags from the output voltage, as a result when the supply goes into a
negative half cycle there is a part of the current that is still positive and so the thyristor is still conducting. This is
undesirable, therefore there is diode that opposes negative half cycle, such that it will stop conducting as soon as it
is reverse biased. As a result if we short the diode during the experiment, we can see that the thyristor conducts for
a small portion of the negative half cycle as well.
8/11/2019 Thyristor Voltage Controller Cwrk
16/16
EE 4092 Laboratory Practice IV
THYRISTOR VOLTAGE CONTROLLER
Name : S. B. Nawarathne
Index No : 090594D
Group : G17
Date of Sub : 15/07/2013
Instructed By : Dr. Anjula de silva