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NTG
MULTIFUNCTON GENERATOR PROTECTION
RELAY
NTG-Slide-03-2008
1
NTG
Digital protection relay that integrates a number of functions required for the protection of
generators. It is used in power stations from gas, steam, hydraulic turbine, or diesel driven
generators, operating in parallel with the public network and/or in island and with any
neutral state and network layout.
NTG-Slide-03-2008
2
EMERGENCY GENERATORS
100 kVA … 2 MVA, in BT e MT
 powered by diesel motors or small gas turbines
DISPERSED GENERATORS
1 MVA … 10MVA, in MT
 powered by diesel motors or small gas turbines, wind, solar
 Industial plants
COGENERATION
1 MVA a 50 MVA, in MT
 Cogeneration power plants (Gas&oil, chemical..)
POWER STATION
 Powered by Hidro, Gas, Steam, Gas turbines
NTG-Slide-03-2008
from 10 MVA to several hundreds MVA
Applications
3
B
C
D
E
F
G
H
I
MMI
A
NTG-Slide-03-2008
A
19” rack (h=3U, p=300 mm)
B
Power supply LED
C
8 free assignable LEDs
D
8 free assignable LEDs (optional)
E
RS232 local communication interface
F
DSP and CPU LEDs
G
1 LED (ON service)
+
7 free assignable LEDs
H
LCD display
I
keyboard
Front view
4
B
C-D
E
F
G-H
L-M
N
I/O with connectorized terminals
A
R
T
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A
Current inputs
B
Voltage inputs
C-D
RTD inputs (optional)
E
8 binary inputs
F
8 binary inputs (optional)
G-H
8 output relays (optional)
L-M
8 output relays
N
Power supply
R
Remote interface
RS485+RJ45 or Fiber optic (MODBUS TCP/IP)
T
earth terminal
Rear view
5
A
B
C
C
D
D
E
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L
G
F
H
A
Power supply module
B
Rotor earth fault module
C
8 output relays module
D
8 binary inputs + 8 LEDs module
E
PT100 module
F
CPU module
G
DSP module
H
CT/VT module
L
Communication module
Layout
6
COMMUNICATION INTERFACE


MEASURING INPUTS





3 phase currents
1 residual current
3 phase voltages
1 residual voltage
1 rotor earth fault
40MHz DSP



local (RS232)
remote RS485 + Ethernet (F.O./RJ45)
SPI SERIAL BUS
control&
communication
(2Mbyte)
(8Mbyte)
66 MHz CPU
FLASH
SDRAM
16 channels 10 bit ADC
measure&protection
(DFT 16 samples/period)
PARALLEL BUS
I/O
MMI
NTG-Slide-03-2008
Hardware structure
7
NTG-Slide-03-2008
Selection table
8
3 IL (hw setting 1A-5A)
IE (hw setting 1A-5A)
3 UL (UN sw programmable)
UE (UEN sw programmable)
8 output relays (optional)
8 output relays
8 binary inputs
8 binary inputs (optional)
16 LEDs
UAUX on request:
48…110 Vac/dc
24 Vac/dc
230 Vac (DAC200)
8 LEDs (optional)
RS485 Port
RJ45 Ethernet Port (optional)
8 Inputs PT100 (optional)
Optical Ethernet Port (optional)
RS232 port
64 Earth fault (optional)
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Keyboard
Input/Output
9
21-51V
Underimpedance (21) or voltage-controlled overcurrent protection (51V)
X
coordination with distance protective devices
t
R
t<
t<<
Z<<
Z<
Z
G
21
MT
AT
Z<
Z<<
21
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Protection elements
10
21-51V
Underimpedance (21) or voltage-controlled overcurrent protection (51V)
Overcurrent protections coordination
50-51
G
50-51
MT
51V
G
MT
MT
voltage controlled 51V element
50-51
51V voltage restrained 51V element
U
a) Generator with step up transformer
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U
b) Directly connected generator
Protection elements
11
24
Generator limits
t
Thermal Protection with RTD’s probes (PT100)
26
Overflux V/Hz
Stator windings
bearings
transformer limits
GEN
TUR
TR
rotor
shaft
IEC A-B-C
stator
PT100
26 (up to 8 RTD probes)
1 alarm pickup + 1 trip for each probe:
U/f
t
q
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Protection elements
12
t
27
Undervoltage
U
t
59
Overvoltage
U
t
46
Generator limit
Negative sequence overcurrent
I22t=K
I2
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Protection elements
13
27H – 59H
100% Stator earth fault protection with 3° harmonic
measurement on star point
27H
100%

No earth faults
G
0%
27H
59N
third harmonic
Voltage level
measurement from broken delta VT


Earth faults at the
star point
Earth faults at the
terminals
NTG-Slide-03-2008
G
100%
0%
100%
0%
59H
59N
59H
0%
100%
90%
T
70%
27H-59H
N
59N (stator earth fault 90%)
Protection elements
14
32
Q
Active directional overpower
32R
37P
32
P
32 R
Active reverse power


37 P
Active underpower
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Faults in prime
mover
Sequential
tripping logic

Sequential
tripping
logic


Load shedding
Network
separation
Protection elements
15
40
A
Loss of field
first threshold (fast)
X
Loss of field with heavy load initial condition
R
B
second threshold (delayed)
A
C
Loss of field with light load
initial condition
Loss of field with low load
initial condition
alarm
B
C
NTG-Slide-03-2008
Protection elements
16
49
Thermal image
t
50/51
Overcurrent
I2t=cost
IEC A-B-C
I2t=cost
50G/51G
87N
Earth fault (50G/51G) or restricted earth
fault (87N) (90% stator earth fault)
59N
Neutral overvoltage
(90% stator stator earth fault)
64F
Rotor earth fault
50+27
I
Inadvertent energization
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Protection elements
17
50+27
Inadvertent energization
IL1  I>
IL2  I>
1
IL3  I>
1. VT at GEN side
UL1  U<
&
UL2  U<
&
&
UL3  U<
TRIP
50+27
2. VT at GRID
side
1
t1
2
TRIP
74TV
CB OPEN
&
t2
1
NTG-Slide-03-2008
Protection elements
18
81>
81<
Overfrequency
Underfrequency
Coordination example between four stage pickups underfrequency protection and turbine limits (Load Shedding)
grid

Cut load C4 (10 MW)

Cut load C3 (30 MW)

Cut load C2 (40 MW)

Cut load C1 (50 MW)
t
Forbidden area
50 MW
Q
( turbine demage)
130 MW
80 MW
C1
C2
C3
C4
40 MW
30 MW
10 MW
T
50 MW
G
fN
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f

Q open:
C1+C2+C3+C4 (130MW)
powered by G (80MW)
Protection elements
19
BF
Breaker Failure
IL1  I>
A. CT at line side
B. CT at star side
IL2  I>
1
IL3  I>
IE  IE>
CB CLOSED
B
TRIP INTERNAL PROTECTIONS
1
1
&
A
tBF
TRIP BF
TRIP EXTERNAL
PROTECTIONS
BF BLOCK
NOTA: with CTs at the line side, the current measures and the CB status make reliable the breaker failure function even if the currents are not present
(ie. trip 32R, 24, 27, 59) or when an auxiliary contacts discrepancy is detected (52a and 52b).
NTG-Slide-03-2008
Protection elements
20
74VT
VT monitoring



74CT
Fail of the voltage transformer and secondary connections are detected
Alarm and block of protective elements affected by loss of voltage (21-51V, 40, 27, 50+27, 37P)
Following measuring are employed:
• three phase currents
• three phase voltages
• CB state
CT monitoring



Fail of the current transformer and secondary connections are detected
Alarm and block of protective elements affected by loss of current (37P, 46,…).
Following parameters are employed:
• residual current
• residual voltage
NTG-Slide-03-2008
CT/VT monitoring
21
MMI
Within the 20…80 Hz range, NTG change the sampling frequency to keep 16
samples per cycle

I, U
fN=50 Hz
t
I, U
fN=20 Hz
t
I, U
fN=80 Hz

t
Measuring accuracy is assured during the start and stop of the generator
NTG-Slide-03-2008
Frequency tracking
22
MMI
8 binary inputs (standard) + 8 binary inputs (optional), freely assignable with the following preset:

Ext reset
Two profile switching (BANK A, BANK B)
synchronization
Logic selectivity
Logic block of protection functions

Trip Circuit Supervision

CB monitoring (operations, SI, SI2t, trip time)

Breaker failure (BF)

Thermal image reset
Reset counters
Reset CB diagnostic, (SI, SI2t, trip time)
Reset timer 46
Sequential tripping








74CTS
BF
NTG-Slide-03-2008
Binary input
allocations
23
MMI
SEQUENTIAL TRIPPING
It is a stop procedure, planned or following delayed trip command, intended to avoid overspeeding
TRIP 32R (P>>)
TRIP 37P
&
MAIN AND FIELD CB OPEN
TURBINE VALVE CLOSED
STEAM
VALVE
T
P
G
CB
NTG-Slide-03-2008
The circuit breakers must be open after the turbine valve
has been closed,
When the power of the residual steam has been exhausted
(and the active power is absorbed to drag the turbine).
Binary input
allocations
24
MMI
8 output relays (normal) + 8 output relays (optional) with one change-over contact.
The function of each relay is programmable with a matrix structure
Max flexibility for setting of the tripping ways
Example 1
C
B
A
C
talarm
FUEL
B
Operator
command
VALE
G
SEQ
TRIP.
T
SEQ.
TRIP
NTG-Slide-03-2008
A
talarm
FUEL
VALVE
T
Type
A
A
B
B
B
B
B
C
C
Example 2
Function
87N
27H
46
51V
32R
40
27
26
64F
G
A
B
C
very urgent protections
little urgent protections
not urgent protections
Output relays allocation
25
Low power diesel emergency generator (< 1 MVA)
transformer-generator parallel grid connect (> 1 MVA, <
10 MVA)
27
27
32R
59
46
Diesel
G
49
50/51
51G
NTG-Slide-03-2008
81>
81<
40
T
G
59
46
81>
49
81<
51V
59N
Application examples
26
MMI
Parallel generators on the same bus (>10 MVA)
Transformer-generator (>10 MVA)
26
G
G
59H
32
27
59N
37P
59
26
32R
81>
32R
40
81<
46
50+27
51V
74VT
64F
74CT
87N
59N
NTG-Slide-03-2008
alternative
27
G
59
81>
40
81<
46
21
64F
27H
BF
59N
24
74VT
74CT
BF
Application examples
27
Setting & monitoring sw

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




Display, modify and print of settings
Event recorder reading and print
Parameters reading and store
Logical states visualization
Off-line setting files
Download and upload
Reset commands
User friendly
RS232 (RJ10)
PC
NTG-Slide-03-2008
ThySetter
28
MMI
Read










Frequency f
Phase currents IL1, IL2, IL3 (RMS)
Residual current IE (RMS)
Negative and positive sequence currents I1, I2
Thermal image Dq
Phase voltages UL1, UL2, UL3, line-to line voltages
U12, U23, U31 (RMS), negative sequence voltage U2
Residual voltage UE
Third harmonic residual voltage UE3H
Real and reactive power (RMS)
Apparent Power
NTG-Slide-03-2008











Phase power factor
Impedance Z, resistance R and reactance X (40)
Z power factor cosfZ
Insulation Resistance (64F)
Temperature through thermal probesRTD1…8
Trip counters, start, blocks, CB operations, SI, SI2t
Binary inputs state DIG-IN1...16
Output relays state K1...K16
Logical block state
Logic selectivity I/O state
Element state
ThySetter
29
MMI
Event recorder








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

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NTG-Slide-03-2008
date, time
cause
frequency
phase currents IL1,IL2,IL3
residual current IE
phase voltage UL1,UL2,UL3
residual voltage UE
third harmonic component of residual voltage UE3H
total active power P
flux
insulation resistance (64F)
temperature pt100
impedance Z (40)
Z resistive component R
Z reactive component X
Z power factor cosfZ
binary inputs state DIG-IN1...16
output relays state K1...K16
ThySetter
30
MMI
Ethernet connections with Modbus TCP/IP protocol
NTG-Slide-03-2008
Communication
31
MMI
Modbus TCP/IP features








Modbus protocol implementation on Ethernet networks
same protocol and available for a lot of devices
baud rate increase from 19.2 kBps to 10 or 100 MBps
mixed systems can be built with TCP/IP and RS485 devices by means of gateways
multimaster networks
unlimited Ethernet network (Internet)
the Modbus TCP/IP protocol make use of Modbus messages for the application layer and the TCP/IP protocols for
the Ethernet transfers
the NTG is a generic element of the network equipped with an IP address like a common PC
NTG-Slide-03-2008
Modbus TCP/IP
32