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High-Phase-Order Induction Generators for Electric Ships
Tom McDermott, [email protected] Famouri, [email protected] Polter, [email protected]
ASNE Day 2015; March 4, 2015
1. Advantages – (no) permanent magnets, cost, reliability2. How it fits the integrated power system3. Analysis of voltage and frequency control4. Start-up performance in transient simulation5. Machine and controller design questions
ASNE Day 2015: HPO-IG 2
U. S. production of rare earths had been shut down, but went up to 4000 metric tons in 2013.
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Induction generators and six-phase transmission lines have been used and tested.
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High-phase-order induction generators work for both AC and DC power distribution systems.
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~~
PFC
DC BusHPOIG
AC Loads
DC Loads
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The DC system voltage has less ripple when supplied through an 18-pulse rectifier.
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ASNE Day 2015: HPO-IG 6
The self-excited induction generator operates in resonance, where the sum of impedances around the loop is zero.
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RL
j2pf
eLL
j2pfeL1
j2pfeL2
-j/2pfeCL
Lm
R2fe/(fe-fm)Vg=
2pfelg
IL
R1
VL
Load Generator
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The machine’s non-linear saturation characteristic determines the operating point.
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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
Vg/FIm*Xc
Stable Operating Point at No Load
Im [per-unit]
Vol
tage
[pe
r-un
it]
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Fine-grain control of the voltage and frequency is possible.
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When the prime mover runs at constant speed, the voltage and frequency both decrease with load.
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0 6 12 18 24 30 360.97
0.98
0.99
1
1.01
Load Voltage
MW Target
Per
-Uni
t
0 6 12 18 24 30 3659.6
59.8
60
FeFm
Electrical and Mechanical Frequency
MW Target
Hz
0 6 12 18 24 30 360.97
0.98
0.99
1
1.01
Load Voltage
MW Target
Per
-Uni
t
0 6 12 18 24 30 3659.6
59.8
60
FeFm
Electrical and Mechanical Frequency
MW Target
Hz
ASNE Day 2015: HPO-IG 10
Thyristor switched capacitors provide step-wise control without switching transients.
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One Phase
C 2C 4C
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TSC voltage results with 31 and 63 capacitor levels.
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0 6 12 18 24 30 36100
200
300
400
500
Total Capacitance
MW Target
uF
0 6 12 18 24 30 360.94
0.96
0.98
1
1.02
1.04
1.06
Load Voltage
MW Target
Per
-Uni
t
0 6 12 18 24 30 3660
60.2
60.4
FeFm
Electrical and Mechanical Frequency
MW Target
Hz
0 6 12 18 24 30 36100
200
300
400
500
Total Capacitance
MW Target
uF
0 6 12 18 24 30 360.98
0.99
1
1.01
1.02
1.03
Load Voltage
MW Target
Per
-Uni
t
0 6 12 18 24 30 3660
60.2
60.4
FeFm
Electrical and Mechanical Frequency
MW Target
Hz
5 steps,31 levels.
6 steps,63 levels.
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9-phase, saturable induction machine model in IEEE Std. VHDL-AMS language supports transient analysis.
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Generator starts with full-load capacitance value; 36-MW load switches on at 3 seconds.
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Conclusion – the HPO-IG offers advantages for naval applications, if some questions can be answered.
• Advantages– No permanent magnets– Multi-phase motors with better torque performance– Enhanced reliability after losing one or more phases
• Questions– How many phases?– Providing the initial flux for self-excitation– Reactive power controller– AC or DC architecture– Machine speed and saturation characteristic
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