Exciter Basics Be

Exciter Basics

DCExctr

DCExctr

SYNMach

AutomaticControl

MOT

PilotExciter

ForcingDown

ForcingUp

MainExciter

CTPTS

FixedResistor

QL QR

NL NR

ExciterField

Rheostat(ManualControl)

AC VoltageAdjuster

Notes: (1) NL, NR - Close for small errorQL, QR - Close for large error

DC Generator-Commutator Exciter Separately Excitedwith Noncontinuously Acting Rheostatic Regulator

DCExctr

SYNMach

CTPTS

AutomaticControl

AC VoltageAdjuster

PMG

RotatingAmplifier

RegulatorTransfer

Exciter FieldRheostat(Manual Control)

MOT Station Auxiliary Power

DC Generator-Commutator Exciter with Rotating Amplifier

AutomaticControl

DCExctr

SYNMach

CTPTS

RegulatorTransfer

Exciter FieldRheostat(Manual Control)

StationAuxiliaryPower

MOT AC VoltageAdjuster

PMG

DC Generator-Commutator Exciter with Continuously Acting Regulator Employing Static Amplifiers

StatorACExc GEN

RotorPMG

Perm.Mag.

Power Amp

Stator

ShuntDC

41

AC

+ -

DCIsolation

Transducer LimitingAnd

Protection

AC Reg.

FiringCircuit

Voltage Adjuster

ACIsolation

CT

PT

-+

Pulses

PMGAC

ExctrArm.

NS

PMSYNMach

ExciterField

CT

PTS

AutomaticControl

GateControl

RegulatorTransfer

AC VoltageAdjuster

BaseVoltageAdjuster(ManualControl)

Alternator-Rectifier Exciter Employing RotatingNoncontrolled Rectifiers (Brushless)

FeedbackInputs

Tur

bine

To Set UpTransformer

Generator

ControlledRectifier

ReferenceInputs

PermanentMagnet

Generator(PMG)

Exciter

Rotating Elements• Generator field• diode wheel with fuses• exciter armature• PMG field

ALTERNATOR EXCITERBrushless Type

SYNMach CT

PTS

GateControl

ManualControl

AutomaticControl

Start-UpPower

PowerPT

AC VoltageAdjuster

RegulatorTransfer

DC VoltageAdjuster

Potential Source-Rectifier Exciter Employing Controlled Rectifiers

GEN

AC IsolationTransducer

PT’s CT

120 VAC 4 VAC

TO DCADJ

REGTRIP

UNITTRIP

OXP

Damping

MEL

V/HZ

MXL

VED

AC Adj.

+/-10v

+/-10v

+/-10v

+/-10v

SIGMIX

+/-10v

BALMeter

DC Adj.

To AllModules

Auto

1pu=5v

Power AMP

15 VDCSupply

TransMOD

StartRES

Shunt

CurrentTransducer

WTA-300 STATIC

4:1 1pu=5v

DC Reg

Main

+/-10v

Firing Ckt

Power FromStation Service

Or Power FromPower PotentialTransformer41

To FiringCKT Phase

Back

VoltageTransducer

Feedback Control - Limiters

• Auto and Manual Operation

• Minimum Excitation Limiter

• Maximum Excitation Limiter OEL

• Volts/Hertz Limiter

• Overvoltage Limiter

• Instantaneous Current Limiter

Minimum Excitation Limiter• Generator Capability Curve -UEL

– Time Delay Curve and Gain– Adjustable 100%-130%– On Line-Off Line– Dynamic Pickup based on Pressure/Temperature

• Steady State Stability Limit - MEL– Varies Proportional -

• Square of Generator Terminal Voltage

Maximum Excitation Limiter OEL

• Limits Generator Field Current or Voltage• Adjustable Pickup Point

– On Line setting 100% -130%– Off Line setting 100% -200%

• Adjustable Time Delay • Dynamic Pickup based on Pressure/Temperature

Instantaneous Current Limiter

• Adjustable Pickup Point – 100%- 150% Field Current or– 100% - 300% Full Load Voltage

• Maintain Output – Within +/- 2% of Pickup Point

Volts/Hertz Limiter

• Adjustable Pickup Point 100%-120%• Adjustable Time Delays 0 - 1000 seconds• Inverse V/HZ Curve - ANSI C37.102

Overvoltage Limiter

• Limits Generator Voltage• Adjustable Pickup Points 100% - 130%• Adjustable Time Delay 0 - 10 sec.

Protection• Overexcitation Protection

• Volts/Hertz Protection

• Overvoltage Protection

• Minimum Excitation Protection

• Loss of Field Protection

• Loss of Sensing

Overexcitation Protection

• Configurable to Field Current or Field Voltage• On Line - Off Line Adjustable Settings• On Line - 100%-170% Full Load Value• Off Line 100% to 130% No Load Value• Dynamic Pickup based on Pressure/Temperature

Volts/Hertz Protection

• Adjustable Pickup Point 100% -120%• Adjustable Time Delay 0 - 1000 Seconds• Inverse Volts/Hertz Curve Per ANSI C37.102• Alarm On Pickup - Trip after Time Delay

Overvoltage Protection

• Adjustable Pickup 100-200% Generator voltage• Adjustable Time Delay• Alarm on Pickup• Trip After Time Delay

Minimum Excitation Protection

• Based upon Generator Capability Curve• Operating Curves approximated via:

– Five straight line segments

• Adjustable Time Delay on Trip• Dynamic Pickup based on Pressure/Temperature

Loss of Field Protection

• Based upon Steady State Stability Limit• Operating Curves approximated via:

– Five straight line segments

• Adjustable Time Delay on Trip• Varies Proportional

– Square of Generator Terminal Voltage

Loss of Sensing• Detects complete/partial Loss of Voltage Intelligence• Transfer based upon Adjustable Comparison• Comparison Configurable to:

– PT Secondary Voltage

• Configurable To Transfer to– Backup Metering PT’s (If existing)– Manual Control

GEN

AC IsolationTransducer

PT’s CT

120 VAC 4 VAC

TO DCADJ

REGTRIP

UNITTRIP

OXP

Damping

MEL

V/HZ

MXL

VED

AC Adj.

+/-10v

+/-10v

+/-10v

+/-10v

SIGMIX

+/-10v

BALMeter

DC Adj.

To AllModules

Auto

1pu=5v

Power AMP

15 VDCSupply

TransMOD

StartRES

Shunt

CurrentTransducer

WTA-300 STATIC

4:1 1pu=5v

DC Reg

Main

+/-10v

Firing Ckt

Power FromStation Service

Or Power FromPower PotentialTransformer41

To FiringCKT Phase

Back

VoltageTransducer

Two Basic Purposes of Firing Circuit1. To provide proper firing pulses at the right time to the thyristors

in power amplifier(s), such that –

2. The DC output from the power amplifier(s) is a Linear function of the DC control input to the firing circuit.

Power Amp.

Bridge

FieldDCOut

PowerACIn

+

-

FiringCircuit

DCControl

In

3Ph AC Timing (Same Ph. As AC Power)

Thyristor

Anode

GateCathode

+

-

I-

+

I

+

VGT

VDRM

- +-

VDRM

(Forward Blocking Voltage600 to 12KV.

IT(AV)

(Average Forward Current)100 to 5000 A.

VGT

(Gate Trigger Voltage)1 to 5 V.

IGT

(Gate Trigger Current)100 ma. To 500 ma.

1 2 1 2

Anode-Cathode Voltage

1

Thyristor Current in a resistive load

1 IAV.

2

IAV.

2

Thyristor Current in a resistive load

DC Output

AC Input

VDC

IDC

+

+

-

-

VDC

IDC

+

+

-

-DC Output

AC Input

One-Quadrant Converter

Two-Quadrant Converter

X1 Y1 Z1

X2 Y2 Z2

+R

L(>>R)

-

123

3-Phase6 PulseConverter

0o Delay

I

3-Phase6 PulseConverter

30o Delay

X1 Y1 Z1

X2 Y2 Z2

+R

L(>>R)

-

123 I

3-Phase6 PulseConverter

60o Delay

X1 Y1 Z1

X2 Y2 Z2

+R

L(>>R)

-

123 I

3-Phase6 PulseConverter

90o Delay

X1 Y1 Z1

X2 Y2 Z2

+R

L(>>R)

-

123 I

3-Phase6 PulseConverter

120o Delay(Transiently Only)

X1 Y1 Z1

X2 Y2 Z2

+R

L(>>R)

-

123 I

-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Universal Relationship between the DC output terminal voltage and the firing angle, for all 2-quadrant phase-controlled converters (with smooth DC current).

D-C

Te

rmin

al V

olta

ge

in P

.U.

Firing Angle

0o

60o

180o

PowerAmp.

Firing Angle

DCOut

0o

60o

180o

DCIn

FiringCircuit

The key is to make the firing circuit like this

FiringDCIn

AmpDCOut

So thatRESULTSare this!!!