Download Short-Circuit Generator Set for AICHI ELECTRIC CO., LTD.

［ Power Source Products for Special Applications ］
Short-Circuit Generator Set for
AICHI ELECTRIC CO., LTD.
Keywords
Short-circuit generator, Static excitation system, Medium-voltage inverter
Abstract
A short-circuit generator system is used to supply heavy currents and large
power for the testing of circuit breakers, switchgears, insulators, and transformers
by driving a generator with a motor.
We recently received an order for a 330MVA (3Hz) short-circuit generator
system for the High Power Laboratory of AICHI ELECTRIC CO., LTD., and supplied the system on full-turn-key contact. Major products we supply are a
short-circuit generator system (motor and generator), reactors, medium-voltage
inverters, control panels, monitoring systems, closing switches, circuit breakers,
test sequencer, and measuring devices.
1 Preface
We supplied a short-circuit generator system
to AICHI ELECTRIC CO., LTD. Our scope of supply
includes the main part of the short-circuit generator
system and a control panel. Others include a closing switch, a test sequencer to control a closing
switch and closing phase, and measuring devices
for currents and voltages. This paper introduces the
items mainly supplied.
2 Short-Circuit Generator
2.1 Motor-Generator Set
The ratings of the short-circuit generator and
the motor to drive this generator are as specified
below.
( 1) Synchronous generator
330/275MVA (3Hz) – 60/50Hz – 2P – 3600/3000min−1
– 13200/11000V (Y)/7620/6350N (Δ)
( 2 ) Induction motor
1120/933kW – 6600/5500V – 60/50Hz – 2P – 3600/
3000min−1
Fig. 1 shows an equipment layout drawing. For
the generator, a 2-pole machine has been adopted
because of its high revolving speed and large inertial
energy. For the excitation system of the generator, a
static excitation system with high responsiveness is
adopted. Generator windings can be changed over
between y-connection and Δ-connection with the
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Noriyuki Koshizuka
MEIDEN REVIEW Series No.167 2016 No.2
aid of an external disconnecting switch. For the
y-connection at 60Hz, the rated voltage is 13,200V.
At 50Hz, the rated voltage is 11,000V. For the Δconnection, the rated voltage is 7620V at 60Hz and
6350V at 50Hz, respectively. The system capacity is
designed to carry a short-circuit current of more
than 20kA for the Δ-connection at 60Hz.
The adopted driving motor is a squirrel-cage
rotor type induction motor. A medium-voltage inverter
system is adopted for start-up operation and speed
control. Bearings for the generator and the driving
motor are of the plain sleeve bearing type. The lubricating system provides a lubricating oil from a forced
lubricating oil supply unit at the time of start-up and
stoppage. While the system is operated at the rated
revolving speed, however, a pump directly connected
with the motor-generator shaft feeds a lubricating oil
to bearings for saving energy.
2.2 Control Unit
Fig. 2 shows the switchgears and Fig. 3 shows
the single-line connection diagram of this short-circuit
generator system.
( 1) Medium-voltage inverter
The medium-voltage inverter consists of three
panels. The basic function is specified to control the
speed at 3600min−1 at 60Hz and 3000min−1 at 50Hz.
Its main feature is that the inrush current is small at
the time of start-up. In addition, restarting is possible even in the middle of a stopping sequence.
Stairs
Waiting room
Driving
power
supply
Feeder
panel 2
4765
Operation room
Auxiliary
panel
DC
supply
unit
Lubricating equipment
Incoming
feeder
panel 1
Monitoring control desk
Stairs
Stairs
Inverter panel
Closing switch
T
R
S
VCB for R S
protecT
tion
R
S
T
Through
bushing
Soundproof
room (Test bay)
Short-circuit generator
AVR
panel
15,235
Generator room
SCR
panel
Reactor R
DS
DS
DS
RL Phase R
(Existing)
RL Phase S
(Existing)
DS
DS
Electricity room
DS
DS
DS
Capacitors
(Existing)
DS
DS・CH
Circulating
pump
Fig. 1
RL Phase T
(Existing)
Cooler
piping
Stairs
DS
Reactor S
DS
CH
Reactor T
CH
Disconnecting
switch for
y-Δ conversion
DS
Low-voltage
high-current
transformer
(Existing)
DS
CH
Exciting
transformer
Emergency genset
11,000
12,000
Unit: mm
Equipment Layout Drawing
Major products are neatly organized. In so doing, we factored the reduction of the overall footprint in the generator room.
Fig. 2
Switchgears
The switchgears are allocated in the line beside the short-circuit
generator.
( 2 ) AVR panel
The AVR control range is 0 to 110%. Using a
touch panel mounted on the panel surface, the generator voltage can be regulated. Thyristors for rectifying field currents have enough capacity to carry
4000A in a short time.
( 3 ) Monitoring and operation panel
Fig. 4 shows the control room where a touch
panel is installed. Using this touch panel, various
operations are possible at the monitoring and operation desk in this room, from the operation and stop
of the auxiliary machines, to the run-stop of the main
machine set and startup operation for short-circuit
testing. Since indicator lamps and graphic panels
are installed, it is possible to look over the full view
of the testing system.
MEIDEN REVIEW Series No.167 2016 No.2
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MEIDEN REVIEW Series No.167 2016 No.2
IM
CLR
64B
51F2
AS
Single-Line Connection Diagram
EXT
Exciting
transformer
＊A
ZCT
2CT
VCB
7.2kV
A single-line connection diagram is shown.
Fig. 3
Driving motor
Wh
Feeder panel 2
A/TC
VS
＊A
A
27B
V/TD
67F2
AS
51R
＊A
AS
A
CT
M
W2
CT
U2
VT
U1
R
SG
V1
S
VT
Current
limiting
reactors
Current
limiting
reactors
Current
limiting
reactors
Current
limiting
reactors
LA
GCB
36kV
LA
LA
GCB
36kV
LA
W1
VT
Encoder
Current
limiting
reactors
T
3CT
F1
F2
3VT
T1
S1
Bus duct
connections
From
exciting
transformer
A
CT
K50
V/TD
N
From inverter panel
A
From Incoming/Feeder panel 1
From inverter panel
V
From Incoming/Feeder panel 1
To measuring devices
R4 S4 T4
Thyristor
unit
51EX
51G
VT K50
K60
59G
VS
Sh
AVR
V
R
R
DV/TD
DV/TD
HV SCR panel
F
V
AVR panel
From SCR panel
V
F
From SCR panel
A
T2
S2
R2
Low-voltage high-current transformer (Existing)
Monitoring and operation desk
R3 S3 T3
Short-circuit bars
Short-circuit bars
R1
Short-circuit bars
Short-circuit bars
Short-circuit bars
To measuring devices
Current
limiting
reactors
LA
VCB
15kV
GCB
36kV
LA
275/330MVA at 3-cycle-50/60Hz
Voltage: 6.35/7.62kV (Δ connection)
11.0/13.2kV (Y connection)
Synchronous generator
CT
V2
3PLBS
Auxiliary
panel
Bus duct
connections
To HV SCR
panel
A
V
Vo
Incoming/Feeder panel 1
67F1
51F1
A/TD
TR
VCB
7.2kV
EVT
933/1120kW-5.5/6.6kW-50.5/60.6Hz-120A
HCT
Inverter panel
Incoming
transformer
panel
ZCT
2CT
2CT
VCB
7.2kV
3φ-6.6kV-60Hz
Fig. 4
Control Room
Fig. 5
The control room is shown. Various operations can be carried
out from here.
Closing
GCB
An external view of reactors is shown.
Signal converter unit
BNC
female
VCB
for
protection
BNC
female
BNC
female
From short-circuit
generator
To suppliers
BNC
female
BNC
cable
BNC
female
BNC
cable
BNC
female
BNC
cable
Reactors
BNC
BNC
female female
BNC
BNC
male
male
10：1
Probe
BNC
BNC
male
male
10：1
Probe
BNC
BNC
male
male
10：1
Probe
BNC cable
BNC
BNC
female female
Sh
Sh
LC duplex
optical fiber
Receiver unit
LC duplex
optical fiber
Receiver unit
Transmitter
unit
BNC
female
BNC
male
LC duplex
optical fiber
Receiver unit
BNC
male
BNC
male
Transmitter
unit
BNC
female
BNC
male
BNC
male
Transmitter
unit
BNC
female
Coaxial cable
BNC
male
Transmitter
unit
Transmitter
unit
BNC
male
BNC
male
Transmitter
unit
Transmitter
unit
BNC
BNC
female female
Sh
Transmitter
unit
BNC
male
Transmitter
unit
Via touch panel
Memory
highcorder
Rack top
Electrical room
Fig. 6
Test bay
Operator console
Monitoring and control room
Measuring System Diagram
A measuring system diagram is shown. Optical fiber cables are adopted for insulation.
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( 4 ) Others
In the event of a power outage for this testing
system, the interruption of lubricant supply to bearings is a big concern. As such, an emergency generating system is used as a backup power for the
auxiliary power supply. At the same time, a DC
pump is installed. In this manner, this makes a
redundant lubrication oil supply system which is
intended to improve reliability.
3 Reactors
Fig. 5 shows a view of reactors. Two reactor
sets with different capacities are allocated to each
phase. Reactor 1 is served by seven combinations
of changeover switches, and four combinations of
changeover switches for Reactor 2. Twenty eight
(28) combinations of current adjustment are, therefore, possible.
4 Closing Switch
In short-circuit testing, a closing-phase control
function is required. The supplied test sequencer
assures a high performance of adjustments to a
testing condition of 1/10000s (0.1ms). Signals from
the test sequencer are controlled through high-speed
conversion performed by the Insulated Gate Bipolar
Transistor (IGBT) switches. For the closing switch, a
36kV gas-insulated circuit breaker is adopted, which
assures a closing accuracy of ±0.5ms.
5 Measuring Devices
Fig. 6 shows the measuring system diagram.
The current transformers that measure short-circuit
currents are installed in the test bay. These are special products rated 30,000/15A. They use the BNC
connections where a 1Ω resistor generates a 15V
voltage.
Optical fiber cables are used between the test
(
bay where equipment under test is placed) and the
monitoring and control room (where the measuring
devices are installed). This is an excellent measured
data transmission method because the optical fiber
cable can insulate the surge voltages caused by the
switching of short-circuit currents or high voltages.
6 Postscript
A short-circuit generator system is an important facility for the performance verification of circuit
breakers and switchgears. Customers who have
short-circuit generator systems are limited in number and regular orders cannot be expected. We
consider, however, our mission is to keep improving
technology for our customers.
Lastly, we would like to express our gratitude to
all project-related personnel for their helpful suggestions and guidance for the production and supply of this system.
・All product and company names mentioned in this paper are
the trademarks and/or service marks of their respective owners.
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