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UNITROLUNITROL ® ® 50005000

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Refresher:Refresher:

Excitation SystemsExcitation Systems

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UNITROL ® 5000

AVR

Automatic VoltageRegulator

Excitation Transformer

Thyristor

Converter Crowbar

Field Breaker

Excitation System Main ComponentsExcitation System Main Components

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UNITROL ® 5000

Providing variable DC current with

short time overload capability Controlling terminal voltage with

suitable accuracy

Ensure stable operation withnetwork and / or other machines

Keep machine within permissibleoperating range

Contribution to transient stabilitysubsequent to a fault.

Communicate with the power plantcontrol system

AVR

Excitation System Duties

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UNITROL ® 5000

Max. field current limiter Max. field current limiter

Min. field current limiter Min. field current limiter

Stator current limiter Stator current limiter

Under excitation P,Q limiter Under excitation P,Q limiter

P

+Q-Q 1/Xd

Power Chart with Opreation Limits

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UNITROL ® 5000 Excitation Transformer

•Galvanic insulation between power

source and rotor winding

•Limitation of DC short circuit current

•Adaptation of supply voltage to reach the

required ceiling voltage

•Air cooled or oil immersed

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UNITROL ® 5000 Thyristor Converter

•Rectification of AC voltage

•Fast control of DC current

•Inversion of DC voltage

•Short-time overcurrent capability

•Withstand certain overvoltages on

AC side

•Limitation of commutation

overvoltages

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UNITROL ® 5000 Field Discharge Circuits

•Field Breaker on AC-side of the converter

•Opening of field circuit under fault conditions

•Fast absorption of field energy

•Field overvoltage protection

•Allow machine to slip

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UNITROL ® 5000 AVR Automatic Voltage Regulator

•Control terminal voltage on preset value with required accuracy

•Ensure stable operation with network and / or other machines

•Keep machine within permissible operating range

•Generate thyristor triggering pulses even under possible fault conditions

•Communicate with the power plant control system

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UNITROL ® 5000 Basic Characteristics

•Excitation Current up to 10’000 amps

•Input frequency range from 16 Hz to 400 Hz

•Adaptable to different redundancy requirements for controls and converters

•State of the art man machine interface

•Compatibility with most applied power plant control systems

•Remote diagnostics

•Comfortable commissioning tools

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UNITROL ® 5000 Operational Application

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UNITROL ® 5000

R a n g e o f A

p p l i c a t i o n

Generator Power/Excitation current

Excitation with

rotating machinesStatic Excitation Systems

UNITROL ® 5000

UNITROL ® F

UN 1000

15A 500 A >10’000 AIfn

Product RangeProduct RangeUNITROL ®

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UNITROL ® 5000

UNITROL 5000UNITROL 5000 UNITROLF

REDUNDANCY- Control Current control back up or Full redundancy

full redundancy

- converter Twin or N-1 Twin

HARDWARE- No. of digital I/O‘s >32 32- Current measurement 3-phase 1-phase

BUS COMMUNICATION AF100 30 words AF100 6 Words

CONVERTOR SUPPLY 16…400 Hz (unlim. Current) DC 25 A16…400 Hz max

300 A

Delimitation Against UNF

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UNITROL ® 5000

UNITROL 5000UNITROL 5000 UNITROL

CONTROL FUNCTIONS Adaptive Power SystenStabilizer

CONVERTER Negative excitation current

(4 quadrant)Automatic equalizing ofbridge current

FAULT HANDLING Real time stamp sequence offaults

Delimitation Against UNF

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Main Standard Software FunctionsMain Standard Software Functions

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UNITROL ® 5000

M e

a s u r i n g

Protection

Monitoring

AVR + FCR

Logic Control

Fieldbreaker

Field flashing

Field suppression

AVR 1 AVR 2

Converter

Control

CONVERTER 1

CONVERTER 2

CONVERTER 3

AVR = Autom. Voltage Reg.

FCR = Field Current Reg.

Systems Overview

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UNITROL ® 5000 Standard Program Functions

CLOSEDCLOSED--LOOP CONTROLLOOP CONTROL (AVR, Limiters, Other controllers)

• Voltage regulator with adjustable PID filter circuit

• Soft-start (gradual voltage increase)

• Reactive and active current droop• Individually adjustable limiters

- overexcited (max. field current, stator current)

- underexcited (-Q = f (P) * U2, stator current, min. field current)

- Volt per Hertz

• Superimposed controllers- Power Factor

- MVAr

- Soft-stop (MVAr unload)

• Power System Stabilizer (add. Hardware required)

• Field current regulator with adjustable PI filter

• Follow-up control between AUTO / MAN mode

A

U T O M A T I C

M A N U A L

IARV / UNF10 E

CHIND / 612

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UNITROL ® 5000

Max. field current limiter Max. field current limiter

Min. field current limiter Min. field current limiter Stator current limiter Stator current limiter

Under excitation P,Q limiter Under excitation P,Q limiter

P

+Q-Q 1/Xd

Power Chart with Operation Limits

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UNITROL ® 5000

+P[MW]

+Q[MVAR]-Q

Q = 0.2 p.u

+P [MW]

+Q [MVAR]

-P

-Q

Cos φ = 0.8

a) POWER FACTOR Control b) REACTIVE POWER Control

Superimposed RegulatorsSuperimposed Regulators

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UNITROL ® 5000 Standard Program Functions

MONITORING AND PROTECTIONMONITORING AND PROTECTION

• Thyristor conduction monitoring• Thyristor heatsink temperature

• DC short-circuit

• Field flashing time

• Loss of actual value (PT failure)

• Overcurrent• Volts per Hertz

• Loss of excitation

• Rotor temperature

• Rotating diode failure (add. hardware required)

IARV / UNF11 E

CHIND / 612

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UNITROL ® 5000

•Rotor thermal overload stage 1

•Rotor over temperature stage 1

•Loss of p.t.

•SW supervision per channel

•HW supervision per channel

•supply monitoring

HW /SW

monitoring

•Thyristor

monitoring

•Air flow

monitoring

Monitoring Concept

(use of redundancy)

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UNITROL ® 5000

•Overflux V/Hz

•Over temperatrure

•Over load

•Rotor earth fault

•Rotor short circuit

•Rotor thermal overload stage 2

•Rotor over Temperature stage 2

•Rotor overvoltage

•SW supervision

•HW supervision

•internal supply

•internal short

circuit

•converter overload

Protection Concept (shut down)

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UNITROL ® 5000

Current versus time characteristic of converter and settings of protectionfunctions for a 48 MVA generator

1 p.u. = 1'315 A

0.1 0.2 10

1

1.6

2

3

t (s)

I(p.u.)

f

n bridges

(n = 3)

n-1 bridges(n = 2)

Change over

to manual

Rotor

If limiter

Trip

Induced field current

3ph SC gen. terminals

Induced field current

3ph SC HV side block transf.

Overcurrent Capability and

Protection Setting

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UNITROL ® 5000

+

_

+

_Σ

Σ

Σ Σ

AVR Setpoint-V/Hz limiter

- Soft start

- IQ Compensation

- IP Compensation

Underexcit. limiter -Q=F(P,U,UG)

-Stator current lead

-Min. field current

Overexcit. limiter -Max field current

-Stator current lag

Power System

Stabilizer PSS

Man setpoint

M e a s u r i n g a n d A / D

c o n v e r s i o n

M i n .

/ m a

x . v a l u e p r i o r i t y

PID

PI

To pulse

generation

UG, IG, If

UG, IG

UG

UG, IG, If

UG, IG

If

AVR’s Main Functions

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UNITROL ® 5000

Low

value

gate

PID

Σ

PSS

High

value

gate

Σ

UG

AVR set point

Parameter set 2

IG OEL

IG UEL

P(Q) UEL

Parameter set 3Ie max lim OEL

Ie min lim UEL

Under excitation

limiter

UEL

Over excitation

limiter

OEL

Parameter set 1 AVR

Parameter set

1,2,3

Intervention in the AVR

OEL and UEL Limiters

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UNITROL ® 5000

t

UG

If

Field FlashingReference value ramp up

Normal operation

Intervention in the AVR’s

Set Point Soft Start

Inter ention in the AVR’s Set Point

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UNITROL ® 5000

+ Q- Q

UG

Uref

droop

compensation

Reactive Power Droop+ P

UG

Uref

droop

compensation

Active Power Droop

Intervention in the AVR’s Set Point

Reactive and Active Power Droop

I t ti i th AVR’

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UNITROL ® 5000

f

UG set point

UG nominal

f nominal

UG min set point

UG max setpoint

Setting range V/Hz

Allowed range of operation

Intervention in the AVR’s

Set Point V/Hz-Limiter

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UNITROL ® 5000

Power factor control

MVAr control

MVAr unload control

MUB

QBUS

QGEN

PFGEN

PFBUS

Q controlDischarge

P.F control

BUS 1)

Generator

Σ

Power

factor

Reactive

Power

Dis-charge

(0)

set point

⌠

⌡

AVR

set point

1) mainly used in

industrial plants

Super-Imposed Controllers

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UNITROL ® 5000

Uf [p.u.]

Generator voltage [p.u.]

Generator ReactivePower [p.u.]

1

1+sTR

HV

Gate

LV

Gate 1+sTB2

1+sTC2

UPKR

TBTC

11

UP

KR

TB

TC

−

1

1

1+sTB1

1+sTC1

UP

KR

UP

KR

−

KR1

1+sTs

Up+ UT–Kc

If

Up-

UT

from under-excitation

Limiters UEL

from over-excitation

Limiters OEL

UT -

UT setpoint

[p.u.]

Σ

+

1

1+sTR

1

1+sTR

KIR

KIA

QT

PT

+

+

+

UST

Stabilizing

signal from PSS

Generator ActivePower [p.u.]

+

Σ

Σ

+ Parameter Description Unit RangeTR Measuring filter time constant s 0.020

Ts Gate control unit and converter time constant s 0.004

KIR Reactive power compensation factor p.u. -0.20...+0.20

KIA active power compensation factor p.u. -0.20...+0.20

KR Steady state gain p.u. 10...1000

Kc Voltage drop due to commutation p.u. Acc. Transf.

TB1 Controller first lag time constant s TB1≥TB2

TB2 Controller second lag time constant s 0<TB2≤TC2

TC1 Controller first lead time constant s 0.01...10

TC2 Controller second lead time constant s 0.01...2

Up+ AVR output positive ceiling value p.u. Fixed

Up- AVR output negative ceiling value p.u. Fixed

Acc. to IEEE 421-5 Type ST1A Potential Source Exciter

Transfer Function

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UNITROL ® 5000

s.TW3

1 + s.TW3

Ks2

1 + s.T7

s.TW4

1 + s.TW4

Ks3

V2

UST

+

s.TW1

1 + s.TW1

s.TW2

1 + s.TW2

( )

( )

1 8

1 9

⋅

⋅

⎡

⎣

⎤

⎦

s T

s T M

N ++

-

1+s.T1

1+s.T2Ks1

1+s.T3

1+s.T4

USTmax USTmax

USTmin USTmin

V1

Σ

Parameter Description Unit Range

TW1,TW2 Measuring filter time constant s 0.1...30

TW3,TW4 Gate control unit and converter timeconstant

s 0.1...30

Ks1 PSS gain factor p.u. 0.1...50

Ks2 Compensation factor for calculationof integral of electric power p.u. 0.01...5

Ks3 Signal matching factor p.u. 0.01...5

T1,T3 Lead time constants of conditioningnetwork

s 0.00...2.50

T2,T4 Lag time constants of conditioningnetwork

s 0.00..2.50

Parameter Description Unit Range

T7 Time constant for integral of electricpower calculation

s 3...30

T8 Ramp tracking filter time constant s 0.00...2.50

T9 Ramp tracking filter time constant s 0.00...2.50

M Ramp tracking filter degree - 2...5

N Ramp tracking filter degree - 1...4

USTmax Upper limit of stabilizing signal p.u. 0.000...3.277

USTmin Lower limit for stabilizing signal p.u -0.000...-3.277

Transfer Function

Acc. to IEEE PSS 2A

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RedundancityRedundancity conceptconcept

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UNITROL ® 5000

IARV / SES38 E

CHIND / 805

Redundancy

Every converter bridge is supplied with its own ventilator and pulse

amplifier.

(n-1) Redundancy• Several converter bridges operating in parallel at the same

time (3 x 50 %, 4 x 33.3 %, etc.)

• In case of failure of one bridge, this one is blocked.Operation continues without restrictions.

(1+1) Redundancy (Twin)

• Two bridges: one in operation, the other blocked (2 x 100 %)• In case of failure of the active bridge, there is a switch-over

to the standby bridge.

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UNITROL ® 5000

AVR

FCR

UG

IG

IF

AVR = Automatic Voltage Regulator

FCR = Field Current Regulator

Single Channel AVRSingle Channel AVR

Automatic channel with change over to manual control

Type S5E

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UNITROL ® 5000

AVR

FCR

IF

AVR = Automatic Voltage Regulator FCR = Field Current Regulator

BFCR = Backup Field Regulator

BFCR

Block

Backup Regulator follows the

main control and takes over

automatically in case of failure

of the main control but not vice

versa

Backup Regulator follows the

main control and takes over

automatically in case of failureof the main control but not vice

versa

Single Channel and back up FCR

Type D5E

UG

IG

IF

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UNITROL ® 5000

AVR

FCR

Block

IF BFCR

Block

AVR = Automatic Voltage Regulator FCR = Field Current Regulator BFCR = Backup Field Regulator


With Redundant Twin Converters(cold standby, 100% redundancity)

Type D5T

UG

IG

IF

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UNITROL ® 5000

AVR

FCR

1

2

n

IF BFCR

Block

AVR = Automatic Voltage Regulator FCR = Field Current Regulator BFCR = Backup Field Regulator


With redundant n-1 Converters(Redundancity: 3 x 50%, 4 x 33%, 5 x 25% etc )

Type D5S

UGIG

IF

Dynamic Current Distribution among

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UNITROL ® 5000

Σ

t

Σ

t

Σ

t

Current equalizing line

Thyristor firing pulses from AVR

+

-

1 2 n

Dynamic Current Distribution among

Parallel Converters

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UNITROL ® 5000



AVR

FCR

AVR

FCR

Block

Two Channel Control

With Single Converter

Type A5E

UG

IG

IF

UG

IG

IF

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UNITROL ® 5000

Regulation

Logic Control

Regulation

Monitoring

Protection

Logic Control

•Voltage regulator (AUTO)

•Field current regulator (MAN)

•Power System Stabilizer

•

Limiter functions•Overriding controllers (P.F., VAr)

• Actual voltage value (P.F. failure)

• Actual field current value

•CPU

•Rotor temperature

•Field overcurrent

•V/Hz

•Rotating diodes

• Actual values

•Trip signals

•Status of system

•Follow-up

• Actual voltagevalue

• Actual field current value

•CPU

•Field overcurrent

•V/Hz

•Rotating diodes

Monitoring

Protection

STAND BY OPERATING

Redundancy Concept of A5..Types

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UNITROL ® 5000



AVR

FCR

AVR

FCR

BlockBlock

Two Channel control

Type A5T

With Redundant Twin Converters(cold standby, 100% redundancity)

UG

IG

IF

UG

IG

IF

®

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UNITROL ® 5000



AVR

FCR

1

2

n

AVR

FCR

Block

Two Channel control

With redundant n-1 Converters(Redundancity: 3 x 50%, 4 x 33%, 5 x 25% etc )

Type A5S

UG

IG

IF

UG

IG

IF

®

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UNITROL ® 5000

BFCRIF

IF BFCR

AVR

FCR

1

2

n

AVR

FCR

Two Channel control with Back up FCR

Type Q5S With redundant n-1 Converters(Redundancity: 3 x 50%, 4 x 33%, 5 x 25% etc )

UG

IG

IF

UG

IG

IF

UNITROL® 5000 S ti l f R d d

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UNITROL ® 5000

TRIP

Functionality AVRFull Prot.

Full Monit

Full Control

FCRFull Prot.

Full Monit

Full Control

BFCRBack up

Prot.

Minimum

Control

AVRFull Prot.

Full Monit

Full Control

FCRFull Prot.

Full Monit

Full Control

BFCRBack up

Prot.

Minimum

Control

Possible

Failure

Failure

in AVR

Failure

in Hardware

Failure in

back upcontrol

Failure

in AVR

Failure in

Hardware

Failure in

back upcontrol

D5..

A5..

A5.. with BFCR

CHANNEL 1 CHANNEL 2

Sequentional use of Redundancy

UNITROL® 5000

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UNITROL ® 5000

The reference values of all controllers that are on standby orswitched off are always adjusted so that bumpless change over isassured.

• Automatic Voltage Regulator AVR set point

• Field Current Regulator FCR set point

• Back up Field Current Regulator BFCR set point

• Superimposed Q-control set point (optional)

• Superimposed Power Factor control set point (optional)

Follow up Control

Documents

abb avr