Page 1
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 17
FACULTY OF ENGINEERING MANIPAL UNIVERSITY JAIPUR
SCHOOL OF ELECTRICAL ELECTRONICS amp COMMUNICATION (SEEC) ENGINEERING
Department of Electrical And Electronics Engineering
Home Assignment-1Subject Power System Analysis (PSA) (EE1505)
Prepared By Dr Amit Saraswat
Date of Submission 29-09-2014
Q (1) Obtain the per unit impedance (reactance) diagram of the power system as shown in Fig1 Let choose
100 MVA as a common base value of power for the power system The power system data is given as
Gen G1 35 MVA 105 KV Xrsquorsquo=16 Ω
Gen G2 25 MVA 66 KV Xrsquorsquo=12 Ω
Gen G3 20 MVA 66 KV Xrsquorsquo=056 Ω
Trans T1 15 MVA 1133 KV X=152 Ω phase on HT side
Trans T2 15 MVA 3362 KV X=16 Ω phase on HT side
Trans Line TL 205Ω phase
Load A 15 MW 11 KV 09 Lagging PF
Load B 40 MW 66 KV 085 Lagging PF
Load C 20 MW 322 KV 09 lagging PF
Bus 1 Bus 2
T1 T2G1
G2
G3
AB
Bus 3
C
Fig 1 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 27
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983090
Q (2) The single line diagram of a radial transmission system is given as shown in Fig2 The ratings and the
reactances of various components are shown therein A load of 60 MW at 09 power factor (lagging) is
tapped from the 66 KV substation which is to be maintained at 60 KV Calculate the terminal voltage
of sysnchronous machine Represent the transmission line and transformers by series reactances only
Fig 2 Single Line Diagram of Power Systems
Q (3) Draw the per unit impedance diagram for the power system shown in Fig3 Neglect resistance and
use a base of 100 MVA 220 KV in 50 Ω transmission line The ratings of the generator motors and
transformers are given as
Gen G 40 MVA 25 KV Xrsquorsquo= 20
Motor M1 25 MVA 11 KV Xrsquorsquo= 30
Motor M2 25 MVA 11 KV Xrsquorsquo= 30 Trans T1 40 MVA 33220 KV X=15
Trans T2 30 MVA 22011 KV X=15
Trans Line TL 50Ω phase
Fig 3 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 37
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983091
Q (4) The one-line diagram of a three-phase power system is shown in Fig4 Select a common base of 100
MVA and 22 KV on the generator side Draw an impedance diagram with all impedances including
the load impedance marked in per-unit The manufacturerrsquos data for each device is given as follows
Gen G 90 MVA 22 KV Xrsquorsquo=18
Trans T1 50 MVA 22220 KV X=10
Trans T2 40 MVA 22011 KV X=6
Trans T3 40 MVA 22110 KV X=64
Trans T4 40 MVA 11011 KV X=8
Trans Line TL1 220 KV 484 Ω phase
Trans Line TL2 110 KV 6543 Ω phase
Motor M 665 MVA 1045 KV X=185
Load A 17 MVA 09 pf (lagging) at 214 KV
Load B 57 MVA 06 pf (lagging) at 1045 KV
Fig 4 Single Line Diagram of Power Systems
Q (5) The one-line diagram of a three-phase system is as shown in Fig5 The transformer reactance is 20
percent on a base of 100 MVA 23115 KV and the line impedance is Z = j 66125 Ω The load at bus
2 is S2= 1848 MW + j66 MVAr and at bus 3 is S3= 0 MW + j20 MVAr It is required to hold the
voltage at bus 3 at 0115 0ang KV Working in per-unit determine the voltage at bus 2 and 1
Fig 5 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 47
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983092
Q (5) Two generators rated 15 MVA 11 KV having 15 sub-transient reactance are connected through
transformers and a 120 Km long line as shown in Fig6 The reactance of the line is 012 Ω Km The
transformers near the generators are rated 30 MVA 1166 KV with leakage reactance of 10 each A
symmetrical three-phase fault occurs at a distance of 30 Km from one end of the line when the system
is on no-load but at rated voltage Determine the fault current and the fault MVA
Bus 1 Bus 2
(60 KV)
T1 T2G1
V1 V2
1166 KV
30 MVA
X = 10
6611 KV
30 MVA
X = 10
Transmission Line
66 KV
15 MVA11 KV
Xdrdquo = 15
G2
15 MVA11 KV
Xdrdquo = 15
Fault
120 Km
30 Km
Fig 6 Single Line Diagram of Power Systems
Q (6) Two 11 KV generators G1 and G2 are connected in parallel to a bus-bar A 66 KV feeder is connected
to the bus-bar through a 1166 KV transformer Calculate fault MVA for three-phase symmetrical
fault (a) at the high-voltage terminals of the transformer and (b) at the load end of the feeder Find
the fault current shared by G1 and G2 in each case The ratings of the equipments are as follows
Generator G1 60 MVA 11 KV Xrsquorsquo= 15
Generator G2 25 MVA 11 KV Xrsquorsquo= 12
Transformer T 75 MVA 1166 KV X=10
Feeder 66 KV XF = 25 Ω phase
Q (7) A 100 MVA 132 KV generator is connected to a 100 MVA 132132 KV transformer The
generatorrsquos reactances are
d X = 015 pu
d X = 025 pud X = 125 pu on a 100 MVA base while
the transformer reactance is 01 pu on the same base The system is operating on no-load at a rated
voltage when a three-phase symmetrical fault occurs at the HT terminals of the transformer
Determine the following
(a) The sub-transient transient and steady state symmetrical fault currents in pu and in amperes
(b) The maximum possible dc components
(c) Maximum value of instantaneous current
(d) Maximum RMS value of the symmetrical fault current
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 57
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983093
Q (8) A 25 MVA 11 KV generator with
d X = 20 is connected through a transformer to a bus that supplies
four identical motors as shown in Fig7 Each motor has
d X = 25 and
d X = 30 on a base of 5
MVA 66 KV The three-phase rating of step-up transformer is 25 MVA 1166 KV with leakagereactance of 10 and that of the step-down transformer is 25 MVA 66 KV with leakage reactance
of 10 The bus voltage at the motors is 66 KV when a three-phase fault occurs at the point F as
shown in Fig7 The reactance of line is 30 Ω Assume that system is operating on no-load when the
fault occurs For the specified fault calculate the sub-transient current in the fault
Fig 7 Single Line Diagram of Power Systems
Q (9) A synchronous generator and a synchronous motor each rated 50 MVA 11KV having 20 sub-
transient reactance are connected through transformers and a transmission line as shown in Fig8 The
transformers are rated 50 MVA 1166 KV and 6611 KV with leakage reactance of 10 each The
line has reactance of 10 on base of 50 MVA The motor is drawing 40 MW at 08 pf (leading) at
terminal voltage of 105 KV when a symmetrical three-phase fault occurs at the motor terminals
Determine the sub-transient current in the generator motor and fault
Fig 8 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 67
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 2
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 27
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983090
Q (2) The single line diagram of a radial transmission system is given as shown in Fig2 The ratings and the
reactances of various components are shown therein A load of 60 MW at 09 power factor (lagging) is
tapped from the 66 KV substation which is to be maintained at 60 KV Calculate the terminal voltage
of sysnchronous machine Represent the transmission line and transformers by series reactances only
Fig 2 Single Line Diagram of Power Systems
Q (3) Draw the per unit impedance diagram for the power system shown in Fig3 Neglect resistance and
use a base of 100 MVA 220 KV in 50 Ω transmission line The ratings of the generator motors and
transformers are given as
Gen G 40 MVA 25 KV Xrsquorsquo= 20
Motor M1 25 MVA 11 KV Xrsquorsquo= 30
Motor M2 25 MVA 11 KV Xrsquorsquo= 30 Trans T1 40 MVA 33220 KV X=15
Trans T2 30 MVA 22011 KV X=15
Trans Line TL 50Ω phase
Fig 3 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 37
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983091
Q (4) The one-line diagram of a three-phase power system is shown in Fig4 Select a common base of 100
MVA and 22 KV on the generator side Draw an impedance diagram with all impedances including
the load impedance marked in per-unit The manufacturerrsquos data for each device is given as follows
Gen G 90 MVA 22 KV Xrsquorsquo=18
Trans T1 50 MVA 22220 KV X=10
Trans T2 40 MVA 22011 KV X=6
Trans T3 40 MVA 22110 KV X=64
Trans T4 40 MVA 11011 KV X=8
Trans Line TL1 220 KV 484 Ω phase
Trans Line TL2 110 KV 6543 Ω phase
Motor M 665 MVA 1045 KV X=185
Load A 17 MVA 09 pf (lagging) at 214 KV
Load B 57 MVA 06 pf (lagging) at 1045 KV
Fig 4 Single Line Diagram of Power Systems
Q (5) The one-line diagram of a three-phase system is as shown in Fig5 The transformer reactance is 20
percent on a base of 100 MVA 23115 KV and the line impedance is Z = j 66125 Ω The load at bus
2 is S2= 1848 MW + j66 MVAr and at bus 3 is S3= 0 MW + j20 MVAr It is required to hold the
voltage at bus 3 at 0115 0ang KV Working in per-unit determine the voltage at bus 2 and 1
Fig 5 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 47
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983092
Q (5) Two generators rated 15 MVA 11 KV having 15 sub-transient reactance are connected through
transformers and a 120 Km long line as shown in Fig6 The reactance of the line is 012 Ω Km The
transformers near the generators are rated 30 MVA 1166 KV with leakage reactance of 10 each A
symmetrical three-phase fault occurs at a distance of 30 Km from one end of the line when the system
is on no-load but at rated voltage Determine the fault current and the fault MVA
Bus 1 Bus 2
(60 KV)
T1 T2G1
V1 V2
1166 KV
30 MVA
X = 10
6611 KV
30 MVA
X = 10
Transmission Line
66 KV
15 MVA11 KV
Xdrdquo = 15
G2
15 MVA11 KV
Xdrdquo = 15
Fault
120 Km
30 Km
Fig 6 Single Line Diagram of Power Systems
Q (6) Two 11 KV generators G1 and G2 are connected in parallel to a bus-bar A 66 KV feeder is connected
to the bus-bar through a 1166 KV transformer Calculate fault MVA for three-phase symmetrical
fault (a) at the high-voltage terminals of the transformer and (b) at the load end of the feeder Find
the fault current shared by G1 and G2 in each case The ratings of the equipments are as follows
Generator G1 60 MVA 11 KV Xrsquorsquo= 15
Generator G2 25 MVA 11 KV Xrsquorsquo= 12
Transformer T 75 MVA 1166 KV X=10
Feeder 66 KV XF = 25 Ω phase
Q (7) A 100 MVA 132 KV generator is connected to a 100 MVA 132132 KV transformer The
generatorrsquos reactances are
d X = 015 pu
d X = 025 pud X = 125 pu on a 100 MVA base while
the transformer reactance is 01 pu on the same base The system is operating on no-load at a rated
voltage when a three-phase symmetrical fault occurs at the HT terminals of the transformer
Determine the following
(a) The sub-transient transient and steady state symmetrical fault currents in pu and in amperes
(b) The maximum possible dc components
(c) Maximum value of instantaneous current
(d) Maximum RMS value of the symmetrical fault current
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 57
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983093
Q (8) A 25 MVA 11 KV generator with
d X = 20 is connected through a transformer to a bus that supplies
four identical motors as shown in Fig7 Each motor has
d X = 25 and
d X = 30 on a base of 5
MVA 66 KV The three-phase rating of step-up transformer is 25 MVA 1166 KV with leakagereactance of 10 and that of the step-down transformer is 25 MVA 66 KV with leakage reactance
of 10 The bus voltage at the motors is 66 KV when a three-phase fault occurs at the point F as
shown in Fig7 The reactance of line is 30 Ω Assume that system is operating on no-load when the
fault occurs For the specified fault calculate the sub-transient current in the fault
Fig 7 Single Line Diagram of Power Systems
Q (9) A synchronous generator and a synchronous motor each rated 50 MVA 11KV having 20 sub-
transient reactance are connected through transformers and a transmission line as shown in Fig8 The
transformers are rated 50 MVA 1166 KV and 6611 KV with leakage reactance of 10 each The
line has reactance of 10 on base of 50 MVA The motor is drawing 40 MW at 08 pf (leading) at
terminal voltage of 105 KV when a symmetrical three-phase fault occurs at the motor terminals
Determine the sub-transient current in the generator motor and fault
Fig 8 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 67
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 3
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 37
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983091
Q (4) The one-line diagram of a three-phase power system is shown in Fig4 Select a common base of 100
MVA and 22 KV on the generator side Draw an impedance diagram with all impedances including
the load impedance marked in per-unit The manufacturerrsquos data for each device is given as follows
Gen G 90 MVA 22 KV Xrsquorsquo=18
Trans T1 50 MVA 22220 KV X=10
Trans T2 40 MVA 22011 KV X=6
Trans T3 40 MVA 22110 KV X=64
Trans T4 40 MVA 11011 KV X=8
Trans Line TL1 220 KV 484 Ω phase
Trans Line TL2 110 KV 6543 Ω phase
Motor M 665 MVA 1045 KV X=185
Load A 17 MVA 09 pf (lagging) at 214 KV
Load B 57 MVA 06 pf (lagging) at 1045 KV
Fig 4 Single Line Diagram of Power Systems
Q (5) The one-line diagram of a three-phase system is as shown in Fig5 The transformer reactance is 20
percent on a base of 100 MVA 23115 KV and the line impedance is Z = j 66125 Ω The load at bus
2 is S2= 1848 MW + j66 MVAr and at bus 3 is S3= 0 MW + j20 MVAr It is required to hold the
voltage at bus 3 at 0115 0ang KV Working in per-unit determine the voltage at bus 2 and 1
Fig 5 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 47
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983092
Q (5) Two generators rated 15 MVA 11 KV having 15 sub-transient reactance are connected through
transformers and a 120 Km long line as shown in Fig6 The reactance of the line is 012 Ω Km The
transformers near the generators are rated 30 MVA 1166 KV with leakage reactance of 10 each A
symmetrical three-phase fault occurs at a distance of 30 Km from one end of the line when the system
is on no-load but at rated voltage Determine the fault current and the fault MVA
Bus 1 Bus 2
(60 KV)
T1 T2G1
V1 V2
1166 KV
30 MVA
X = 10
6611 KV
30 MVA
X = 10
Transmission Line
66 KV
15 MVA11 KV
Xdrdquo = 15
G2
15 MVA11 KV
Xdrdquo = 15
Fault
120 Km
30 Km
Fig 6 Single Line Diagram of Power Systems
Q (6) Two 11 KV generators G1 and G2 are connected in parallel to a bus-bar A 66 KV feeder is connected
to the bus-bar through a 1166 KV transformer Calculate fault MVA for three-phase symmetrical
fault (a) at the high-voltage terminals of the transformer and (b) at the load end of the feeder Find
the fault current shared by G1 and G2 in each case The ratings of the equipments are as follows
Generator G1 60 MVA 11 KV Xrsquorsquo= 15
Generator G2 25 MVA 11 KV Xrsquorsquo= 12
Transformer T 75 MVA 1166 KV X=10
Feeder 66 KV XF = 25 Ω phase
Q (7) A 100 MVA 132 KV generator is connected to a 100 MVA 132132 KV transformer The
generatorrsquos reactances are
d X = 015 pu
d X = 025 pud X = 125 pu on a 100 MVA base while
the transformer reactance is 01 pu on the same base The system is operating on no-load at a rated
voltage when a three-phase symmetrical fault occurs at the HT terminals of the transformer
Determine the following
(a) The sub-transient transient and steady state symmetrical fault currents in pu and in amperes
(b) The maximum possible dc components
(c) Maximum value of instantaneous current
(d) Maximum RMS value of the symmetrical fault current
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 57
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983093
Q (8) A 25 MVA 11 KV generator with
d X = 20 is connected through a transformer to a bus that supplies
four identical motors as shown in Fig7 Each motor has
d X = 25 and
d X = 30 on a base of 5
MVA 66 KV The three-phase rating of step-up transformer is 25 MVA 1166 KV with leakagereactance of 10 and that of the step-down transformer is 25 MVA 66 KV with leakage reactance
of 10 The bus voltage at the motors is 66 KV when a three-phase fault occurs at the point F as
shown in Fig7 The reactance of line is 30 Ω Assume that system is operating on no-load when the
fault occurs For the specified fault calculate the sub-transient current in the fault
Fig 7 Single Line Diagram of Power Systems
Q (9) A synchronous generator and a synchronous motor each rated 50 MVA 11KV having 20 sub-
transient reactance are connected through transformers and a transmission line as shown in Fig8 The
transformers are rated 50 MVA 1166 KV and 6611 KV with leakage reactance of 10 each The
line has reactance of 10 on base of 50 MVA The motor is drawing 40 MW at 08 pf (leading) at
terminal voltage of 105 KV when a symmetrical three-phase fault occurs at the motor terminals
Determine the sub-transient current in the generator motor and fault
Fig 8 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 67
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 4
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 47
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983092
Q (5) Two generators rated 15 MVA 11 KV having 15 sub-transient reactance are connected through
transformers and a 120 Km long line as shown in Fig6 The reactance of the line is 012 Ω Km The
transformers near the generators are rated 30 MVA 1166 KV with leakage reactance of 10 each A
symmetrical three-phase fault occurs at a distance of 30 Km from one end of the line when the system
is on no-load but at rated voltage Determine the fault current and the fault MVA
Bus 1 Bus 2
(60 KV)
T1 T2G1
V1 V2
1166 KV
30 MVA
X = 10
6611 KV
30 MVA
X = 10
Transmission Line
66 KV
15 MVA11 KV
Xdrdquo = 15
G2
15 MVA11 KV
Xdrdquo = 15
Fault
120 Km
30 Km
Fig 6 Single Line Diagram of Power Systems
Q (6) Two 11 KV generators G1 and G2 are connected in parallel to a bus-bar A 66 KV feeder is connected
to the bus-bar through a 1166 KV transformer Calculate fault MVA for three-phase symmetrical
fault (a) at the high-voltage terminals of the transformer and (b) at the load end of the feeder Find
the fault current shared by G1 and G2 in each case The ratings of the equipments are as follows
Generator G1 60 MVA 11 KV Xrsquorsquo= 15
Generator G2 25 MVA 11 KV Xrsquorsquo= 12
Transformer T 75 MVA 1166 KV X=10
Feeder 66 KV XF = 25 Ω phase
Q (7) A 100 MVA 132 KV generator is connected to a 100 MVA 132132 KV transformer The
generatorrsquos reactances are
d X = 015 pu
d X = 025 pud X = 125 pu on a 100 MVA base while
the transformer reactance is 01 pu on the same base The system is operating on no-load at a rated
voltage when a three-phase symmetrical fault occurs at the HT terminals of the transformer
Determine the following
(a) The sub-transient transient and steady state symmetrical fault currents in pu and in amperes
(b) The maximum possible dc components
(c) Maximum value of instantaneous current
(d) Maximum RMS value of the symmetrical fault current
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
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EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983093
Q (8) A 25 MVA 11 KV generator with
d X = 20 is connected through a transformer to a bus that supplies
four identical motors as shown in Fig7 Each motor has
d X = 25 and
d X = 30 on a base of 5
MVA 66 KV The three-phase rating of step-up transformer is 25 MVA 1166 KV with leakagereactance of 10 and that of the step-down transformer is 25 MVA 66 KV with leakage reactance
of 10 The bus voltage at the motors is 66 KV when a three-phase fault occurs at the point F as
shown in Fig7 The reactance of line is 30 Ω Assume that system is operating on no-load when the
fault occurs For the specified fault calculate the sub-transient current in the fault
Fig 7 Single Line Diagram of Power Systems
Q (9) A synchronous generator and a synchronous motor each rated 50 MVA 11KV having 20 sub-
transient reactance are connected through transformers and a transmission line as shown in Fig8 The
transformers are rated 50 MVA 1166 KV and 6611 KV with leakage reactance of 10 each The
line has reactance of 10 on base of 50 MVA The motor is drawing 40 MW at 08 pf (leading) at
terminal voltage of 105 KV when a symmetrical three-phase fault occurs at the motor terminals
Determine the sub-transient current in the generator motor and fault
Fig 8 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
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EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 5
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 57
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983093
Q (8) A 25 MVA 11 KV generator with
d X = 20 is connected through a transformer to a bus that supplies
four identical motors as shown in Fig7 Each motor has
d X = 25 and
d X = 30 on a base of 5
MVA 66 KV The three-phase rating of step-up transformer is 25 MVA 1166 KV with leakagereactance of 10 and that of the step-down transformer is 25 MVA 66 KV with leakage reactance
of 10 The bus voltage at the motors is 66 KV when a three-phase fault occurs at the point F as
shown in Fig7 The reactance of line is 30 Ω Assume that system is operating on no-load when the
fault occurs For the specified fault calculate the sub-transient current in the fault
Fig 7 Single Line Diagram of Power Systems
Q (9) A synchronous generator and a synchronous motor each rated 50 MVA 11KV having 20 sub-
transient reactance are connected through transformers and a transmission line as shown in Fig8 The
transformers are rated 50 MVA 1166 KV and 6611 KV with leakage reactance of 10 each The
line has reactance of 10 on base of 50 MVA The motor is drawing 40 MW at 08 pf (leading) at
terminal voltage of 105 KV when a symmetrical three-phase fault occurs at the motor terminals
Determine the sub-transient current in the generator motor and fault
Fig 8 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 67
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 6
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 67
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983094
Q (10) A generating station has four identical generators G1 G2 G3 and G4 each of 20 MVA 11 KV having
20 reactance as shown in Fig9 They are connected to a bus-bar which has a bus-bar reactor of
25 reactance of on 20 MVA base inserted between G2 and G3 A 66 KV feeder is taken off from
the bus-bar through a 15 MVA transformer having 8 reactance A symmetrical 3-phase fault occurs
at the high voltage terminals of the transformer Calculate the current fed into the fault
Fig 9 Single Line Diagram of Power Systems
Q (11) The one-line diagram of a power system is as shown in Fig10 Draw positive negative and zero
sequence networks of the given power system The power system data is given as below
Generator G1 30 MVA 11 KV X1= 020 pu X2= 020 pu X0= 005 pu
Generator G2 50 MVA 11 KV X1= X2= 025 pu X0= 006 pu
Transformer T1 30 MVA 11220 KV X1= X2= X0= 007 pu
Transformer T2 50 MVA 11220 KV X1= X2= X0= 008 pu
Transmission Line X1= X2= 150 Ω phase X0= 500 Ω phase
Fig 10 Single Line Diagram of Power Systems
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
Page 7
8102019 MUJ PSA Assignment-I Power System Analysis (EEE1505)
httpslidepdfcomreaderfullmuj-psa-assignment-i-power-system-analysis-eee1505 77
EE1505 Power System Analysis (PSA)
Dr Amit Saraswat Dept of Electrical amp Electronics Engg Manipal University Jaipur (MUJ) India 983095
Q (12) A 30 MVA 138 KV 3-phase generator has a sub-transient reactance of 15 It supplies two motors
over a transmission line having transformers at both ends as shown in the one-line diagram of Fig11
The motors are rated 15 MVA and 10 MVA both 125 KV with a sub-transient reactance of 20
The transformers are both rated 50 MVA 132132 KV with a reactance of 10 The series reactance
of the line is 90 Ω phase The negative sequence reactance of each machine is equal to sub-transient
reactance The zero sequence reactance of line is 300 Ω phase Current limiting reactor connected in
neutrals of generator and motor M1 are 2 Ω phase Draw the positive negative and zero sequence
networks of the given power system
Fig 11 Single Line Diagram of Power Systems
