UNITROLUNITROL®® 50005000

Refresher:Refresher:

Excitation SystemsExcitation Systems

UNITROL® 5000

AVR

Automatic Voltage Regulator

Excitation Transformer

Thyristor Converter

Crowbar

Field Breaker

Excitation System Main ComponentsExcitation System Main Components

UNITROL® 5000

Providing variable DC current with short time overload capabilityControlling terminal voltage with suitable accuracyEnsure stable operation with network and / or other machinesKeep machine within permissible operating rangeContribution to transient stability subsequent to a fault.Communicate with the power plant control system

AVR

Excitation System Duties

UNITROL® 5000

Max. field current limiterMax. field current limiterMin. field current limiterMin. field current limiterStator current limiterStator current limiterUnder excitation P,Q limiterUnder excitation P,Q limiter

P

+Q-Q 1/Xd

Power Chart with Opreation Limits

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

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 commutationovervoltages

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

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

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

UNITROL® 5000 Operational Application

UNITROL® 5000

Ran

ge o

f App

licat

ion

Generator Power/Excitation current

Excitation withrotating machines Static Excitation Systems

UNITROL® 5000

UNITROL® F

UN 1000

15A 500 A >10’000 AIfn

Product RangeProduct RangeUNITROL®

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

UNITROL® 5000

UNITROL 5000UNITROL 5000 UNITROL

CONTROL FUNCTIONS Adaptive Power Systen Stabilizer

CONVERTER Negative excitation current(4 quadrant)Automatic equalizing of bridge current

FAULT HANDLING Real time stamp sequence of faults

Delimitation Against UNF

Main Standard Software FunctionsMain Standard Software Functions

UNITROL® 5000

Mea

surin

g Protection

Monitoring

AVR + FCR

Logic Control

Fieldbreaker

Field flashingField suppression

AVR 1AVR 2

ConverterControl

CONVERTER 1

CONVERTER 2

CONVERTER 3

AVR = Autom. Voltage Reg.FCR = Field Current Reg.

Systems Overview

UNITROL® 5000 Standard Program Functions

CLOSEDCLOSED--LOOP CONTROL LOOP 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

AU

TOM

ATI

CM

AN

UA

L

IARV / UNF10 ECHIND / 612

UNITROL® 5000

Max. field current limiterMax. field current limiterMin. field current limiterMin. field current limiterStator current limiterStator current limiterUnder excitation P,Q limiterUnder excitation P,Q limiter

P

+Q-Q 1/Xd

Power Chart with Operation Limits

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

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 ECHIND / 612

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

•Thyristormonitoring•Air flow monitoring

Monitoring Concept(use of redundancy)

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)

UNITROL® 5000

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

1 p.u. = 1'315 A

0.1 0.2 101

1.6

2

3

t (s)

I(p.u.)

f

n bridges(n = 3)

n-1 bridges(n = 2)

Change overto manual

Rotor

If limiter

Trip

Induced field current3ph SC gen. terminals

Induced field current3ph SC HV side block transf.

Overcurrent Capability andProtection Setting

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 SystemStabilizer PSS

Man setpoint

Mea

surin

g an

d A

/D c

onve

rsio

n

Min

. / m

ax. v

alue

prio

rity

PID

PI

To pulse generation

UG, IG, If

UG, IG

UG

UG, IG, If

UG, IG

If

AVR’s Main Functions

UNITROL® 5000

Lowvaluegate

PID

Σ

PSS

Highvaluegate

ΣUG

AVR set point

Parameter set 2 IG OELIG UELP(Q) UELParameter set 3Ie max lim OELIe min lim UEL

Under excitation limiter UEL

Over excitation limiter OEL

Parameter set 1 AVR

Parameter set 1,2,3

Intervention in the AVROEL and UEL Limiters

UNITROL® 5000

t

UGIf

Field FlashingReference value ramp upNormal operation

Intervention in the AVR’s Set Point Soft Start

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 PointReactive and Active Power Droop

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’sSet Point V/Hz-Limiter

UNITROL® 5000

Power factor controlMVAr controlMVAr unload control

MUB

QBUS

QGEN

PFGEN

PFBUS

Q controlDischarge

P.F control

BUS 1)

Generator

Σ

Powerfactor

ReactivePower

Dis-charge

(0)

set point

⌠⌡

AVRset point

1) mainly used in industrial plants

Super-Imposed Controllers

UNITROL® 5000

Uf [p.u.]

Generatorvoltage [p.u.]

GeneratorReactivePower [p.u.]

11+sTR

HVGate

LVGate 1+sTB2

1+sTC2

UPKR

TBTC

+ ∗ 11

UPKR

TBTC

− ∗ 11

1+sTB1

1+sTC1

UPKR

+

UPKR

−

KR1

1+sTs

Up+∗ UT–Kc∗ If

Up- ∗ UT

from under-excitationLimiters UEL

from over-excitationLimiters OEL

UT -

UT setpoint [p.u.]

Σ

+

1

1+sTR

1

1+sTR

KIR

KIA

QT

PT

+

+

+

USTStabilizingsignal from PSS

GeneratorActivePower [p.u.]

+

Σ

Σ

+ Parameter Description Unit RangeTR Measuring filter time constant s 0.020Ts Gate control unit and converter time constant s 0.004KIR Reactive power compensation factor p.u. -0.20...+0.20KIA active power compensation factor p.u. -0.20...+0.20KR Steady state gain p.u. 10...1000Kc Voltage drop due to commutation p.u. Acc. Transf.TB1 Controller first lag time constant s TB1≥TB2TB2 Controller second lag time constant s 0<TB2≤TC2TC1 Controller first lead time constant s 0.01...10TC2 Controller second lead time constant s 0.01...2Up+ AVR output positive ceiling value p.u. FixedUp- AVR output negative ceiling value p.u. Fixed

Acc. to IEEE 421-5 Type ST1A Potential Source ExciterTransfer Function

UNITROL® 5000

s.TW3

1 + s.TW3

Ks2

1 + s.T7

s.TW4

1 + s.TW4

Ks3

V2

USTΣ

+

s.TW1

1 + s.TW1

s.TW2

1 + s.TW2( )

( )1 8

1 9

+ ⋅

+ ⋅

⎡

⎣⎢

⎤

⎦⎥

s Ts T M

N ++

-

1+s.T1

1+s.T2Ks11+s.T3

1+s.T4

USTmax USTmax

USTmin USTmin

V1Σ

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 FunctionAcc. to IEEE PSS 2A

RedundancityRedundancity conceptconcept

UNITROL® 5000

IARV / SES38 ECHIND / 805

Redundancy

Every converter bridge is supplied with its own ventilator and pulseamplifier.

(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.

UNITROL® 5000

AVR

FCR

UGIG

IF

AVR = Automatic Voltage RegulatorFCR = Field Current Regulator

Single Channel AVRSingle Channel AVR

Automatic channel with change over to manual control

Type S5E

UNITROL® 5000

AVR

FCR

IF

AVR = Automatic Voltage RegulatorFCR = Field Current RegulatorBFCR = 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 failure of the main control but not vice versa

Single Channel and back up FCR

Type D5E

UGIG

IF

UNITROL® 5000

AVR

FCR

Block

IF BFCR

Block

AVR = Automatic Voltage RegulatorFCR = Field Current RegulatorBFCR = Backup Field Regulator

Single Channel and back up FCR

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

Type D5T

UGIG

IF

UNITROL® 5000

AVR

FCR1

2

n

IF BFCR

Block

AVR = Automatic Voltage RegulatorFCR = Field Current RegulatorBFCR = Backup Field Regulator

Single Channel and back up FCR

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

Type D5S

UGIG

IF

UNITROL® 5000

Σt

Σt

Σt

Current equalizing line

Thyristor firing pulses from AVR

+-

1 2 n

Dynamic Current Distribution amongParallel Converters

UNITROL® 5000

AVR = Autom. Voltage Reg.FCR = Field Current Reg.

AVR

FCR

AVR

FCR

Block

Two Channel Control

With Single ConverterType A5E

UGIG

IF

UGIG

IF

UNITROL® 5000

Regulation

Logic Control

RegulationMonitoringProtection

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 voltage value•Actual field current value•CPU

•Field overcurrent

•V/Hz•Rotating diodes

MonitoringProtection

STAND BY OPERATING

Redundancy Concept of A5..Types

UNITROL® 5000

AVR = Autom. Voltage Reg.FCR = Field Current Reg.

AVR

FCR

AVR

FCR

Block Block

Two Channel control

Type A5TWith Redundant Twin Converters

(cold standby, 100% redundancity)

UGIG

IF

UGIG

IF

UNITROL® 5000

AVR = Autom. Voltage Reg.FCR = Field Current Reg.

AVR

FCR1

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

UGIG

IF

UGIG

IF

UNITROL® 5000

BFCRIF

IF BFCR

AVR

FCR1

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 )

UGIG

IF

UGIG

IF

UNITROL® 5000

TRIPFunctionality AVR

Full Prot.Full MonitFull Control

FCRFull Prot.Full MonitFull Control

BFCRBack up Prot.Minimum Control

AVRFull Prot.Full MonitFull Control

FCRFull Prot.Full MonitFull Control

BFCRBack up Prot.Minimum Control

Possible Failure

Failure in AVR

Failure in Hardware

Failure in back up control

Failure in AVR

Failure in Hardware

Failure in back up control

D5..

A5..

A5.. with BFCR

CHANNEL 1 CHANNEL 2

Sequentional use of Redundancy

UNITROL® 5000

The reference values of all controllers that are on standby or switched 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