Icpe Actel - Presentation of Sratn

7/30/2019 Icpe Actel - Presentation of Sratn

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STATIC EXCITATION EQUIPMENT

SRATN

made by S.C. ICPE ACTEL S.A., ROMANIA, Bucharest

(Research Institute for Electrical Engineering - Electric Drives)

CATEGORY CODE

SRATNIEN/UENUPL - 1/2 - 3

S = systemR = regulationA = automatic

T = voltageN = digitalIEN = Excitation system rated current (Adc) - direct current at the excitation output

terminals which the excitation system can supply under defined conditions of

operation (taking in account the most demanding excitation requirements ofthe machine);

UEN = Excitation system rated voltage (Vdc) - direct voltage at the excitation outputterminals which the excitation system can provide when delivering excitation

rated field current;UP = Excitation ceiling voltage (Vdc) - The maximum direct voltage which the

excitation system is able to provide from its terminals under defined

conditions;1 = one rectifying bridge (without redundancy in the power circuit)

2 = two rectifying bridges (100% redundancy)3 = excitation transformer (installed in cubicle), for excitation current over 50ADC.


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STATIC EXCITATION EQUIPMENTSRATN ICPE-ACTEL SA

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The parametrization range offered by ICPE ACTEL for Static ExcitationEquipment is:

Three-phase supply voltage (Usupply) +10%, -15%: 3x400Vac or another

voltage, by means of a transformer.

Rated power (PN). Generator: 3...330MW; Motor: 100kW...8MW.

Maximum rated excitation current (IEN max). Generator: 3200Adc; Motor:

1600Adc.

Rated excitation voltage (UEN): related to synchronous machine excitation

parameters.

Control accuracy: 0,5%.Maximum forcing coefficient for current and voltage: 2.

Based on the support of its highly qualified specialists, ICPE ACTEL has focused

its activities on offering not only products, but also complete solutions, custom

made to meet the clients requirements, for normal and extreme climate.

Our products are always accompanied by technical assistance and additionalservices throughout their entire lifespan, from drawing-up of then application

up to the client training.

SRATN is found in almost all hydro and steam power plants in Romania. ICPE

ACTEL has also exported such equipment in: France, Turkey, India, Republic of

Moldavia, Kenya, Thailand and Vietnam.

Concerning the applications ofSRATN for synchronous motors, some references

are as follows: Iraq, Republic of Moldavia, Arcelor Mittal- Galati, Romgaz

Medias, Hidroelectrica and SNCF (Railway National Society) in Romania.

ICPE ACTEL is a reliable long-term partner.


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Static excitation equipment provides supply, control and protection ofsynchronous machine excitation: generators in hydro and steam power plants and

synchronous motors for various applications.

They ensure a stable and safe operation of synchronous machines, especially

relevant when these machines are connected to the public mains, characterized by alot of perturbations due to connecting and disconnecting of important loads, short-

circuit, etc.

Common applications are:

- supply of the generator's field windings in hydro and steam power plants,connected to a public mains;

- supply of synchronous motor's field windings for applications such as fans,air compressors, debit pumps, water feed pumps.

The excitation system provides the dc power supply required by the

synchronous machine field circuit to meet the specified ratings and operating ranges

of the generator/motor for all operating condition.

The excitation system is a static type. Its main power device consists in 3-

phase full wave thyristor rectifier bridges supplied from the ac terminals of the

synchronous generator/ motor or from an independent power supply.

The excitation system has a microproccesor based digital type automaticvoltage regulator and rectifier control that brings the suitable operating stability for

the synchronous generator/motor.

ADVANTAGES

Static excitation equipment, fitted with a digital control solution, ensures:

- higher stability of parameters related to electromagnetically perturbations andenvironmental condition variations;

- user friendly interface, with many settings and diagnosis options;- strict monitoring of internal and external failures, that lead to equipment

tripping;

- possibility of complete remote control;- enhanced reliability;


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WHY ICPE ACTEL?

- Higher safety of the operating process, due to digital control and significantsubassembly redundancy;

- Enhanced availability and competence in custom-made equipment (functions,special environment conditions, new design alternatives on demand);

- Possibility of intervention, software programming and license granting for theoperating mode parameter setting;

- Enhanced efficiency;- Higher availability through additional preset options;- Advanced diagnostic capabilities for failure analysis;- Cost saving and oriented solution in accordance with the clients budget;- Technical assistance throughout the entire product lifespan from mounting to

post guarantee service.


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FUNCTIONAL DESCRIPTION

Static excitation equipment, especially in hydro and steam power plants

represents a complex type of product, meant to provide the control and protection of

synchronous machine excitation in a large range of perturbations and in compliance

with the requirements of electric generators correct running.The technology of public mains is, by itself, a complex process, which has to face

several specific perturbations, such as the connecting and disconnecting of

important inductive loads, local and remote short-circuits, sudden unloading,

automatic turn-on of stand-by equipment.

The power supply systems, with static excitation equipment as their core,have to operate very stably and safety, in the event of such perturbations.

Static excitation equipment is meant to preserve generator set-points with high

accuracy, in strict respect of its stability diagrams (synchronous machine limit

values, cross current criterion, line drop compensation criterion, etc.) and provide avery accurate dynamic regime.


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SRATNBloc Diagram (example)

3x...kV/3x...V

TTA...kVA

3x...kV/....V

3x...kV/3x...V

10VA

I

=........A

x

ne

U

=......V

nex

Pn=.....MW

Un=.....kV

In=........A

cos

=......

+Ex

Fieldflash

voltagedc/ac

Digitalinput

signals

SRATNEXCITATION

SYSTEM

10VA

GeneratorCircuitBreaker

BRIDGE1

BRIDGE2

DCGN=Digitalfiringpulsesboard

DCGN

PLC

AVR1

Measuring

Board

PLC

AVR2

BRIDGE1,BRIDGE2-fullwaveth

yristorrectifiers

AVR1,AVR2-PLCwithAutomaticV

oltageRegulator

MAN1,MAN2-PLCwithFieldCurrentRegulator

FFC-FieldFlashCircuit

FDC-FieldDischargeCircuit

......A/....A

DCGN

DCGN

PLC

MAN1

Operating

panel

Measuring

Board

Measuring

Board

PLC

MAN2

Measuring

Board

Optionaldevices

FFC

FDC+

Crowbar

DCGN

TTA...kVA

3x...V/....V

Auxilia

ry

power

supply

dc/ac

Digitaloutput

signals

Analogoutput

signals

Comunication

forSCADA

RS232

RS485

RJ45


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Rectifier power supply voltage : Max 3 x 750V AC. +20% , -20%

Power supply frequency: 50Hz 5%

Field flash power supply: - from the power plant battery

- from the auxiliary ac power supply

Control electronics power supply

voltage

- 3 x 400V/ 230 (Vac)// max 10A

- power plant battery 24/ 110/ 200 (Vdc) // max10AMaximum output voltage: Minimum 1,2*U supply

Forcing in current: Minimum 1.8*In excitation for 30 sec

Forcing in voltage: Minimum 1.8*Un excitation

Control Modes: AVRVOLTAGE REGULATOR

POWER FACTOR REGULATOR

REACTIVE POWER REGULATOR

MANUAL:

CURRENT REGULATOR (FCR)

VOLTAGE REGULATOR (AVR)

mode has the following control

loops:

- control for machine voltage

- maximum field current limitation with inverse time

delay characteristic;

- stator current limitation with inverse time delay

characteristic for leading or lagging working of the

machine;

- lead or lag reactive power working limitation,

according to the real power;

- V/Hz limiter

- load (cross) current compensation;- soft start;

- power system stabilizer - PSS1A/ PSS2A;

POWER FACTOR REGULATOR

(APFC) mode has the following

control loops:

- control for (cos)





machine;

- limitation of the minimum and maximum generator

voltage;

REACTIVE POWER

REGULATOR (kVAR) mode has

the following control loops:

- control for reactive power





machine;

- limitation of the minimum and maximum generator

voltage;

CURRENT REGULATOR (FCR)

mode mode has the following

control loops:

- control for field current

- limitation of the regulator output


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Starting sequence in case of field

flash

After the generator reaches 90% of its rated speed the

start command is followed by the following actions:

- the field is supplied from an auxiliary powersupply until the generator voltage reaches over

50% of the rated value then the excitation

equipment is supplied from the excitationtransformer connected to generator terminals.

Starting sequence of synchronous

motors

- Asynchronous mode start on a starting resistor with

adjustable final level of sliding.

Field discharging - During operational shut-down the field is discharged

by inverter operation of the thyristor converter;

- In case of excitation or machine fault, the synchronous

machine will be de-energized using the field discharge

circuit.Protections

by bimetallic switch Field discharge breaker fault (field discharge resistor

over-temperature)

by PLC Generator over-voltage

Excitation over-current

Loss of field excitation current

by Earth Fault Relay Generator field ground protection

by Overcurrent Relays Transformer over-current

Cooling Natural/ 2 fans for each rectifier.


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A. The Power circuit contains (depending of the synchronous machine type):

1. Excitation transformerThe excitation transformer can be fed from the synchronous machine terminals or

from another power supply. The excitation transformer equipment can be fitted with

protection devices and/or switching devices.

2. Full wave thyristor rectifier bridge (1 or more);The rectifier equipment includes the following:

- Rectifier firing circuits;

- High speed over-current fuses to protect the thyristors in the event of short-circuit;- Transient voltage surge protection on the rectifier (resistor-capacitance circuit);

- Cooling equipment (if applicable);

- Optional: disconnecting switches on the input and output of the rectifiers;

3. Field discharge circuit.The field discharge circuit includes the following:- Static breaker for field discharging and crowbar for dc voltage surge protection;

- Field discharge resistor connected across the field to de-energize the generator as

fast as possible.

- Optional: DC circuit breaker one-pole or two-poles with field discharge contact.

4.

Field flashing circuit.The field discharge circuit can be feed from the power plant battery or from an AC

auxiliary power supply. The circuit consists in:

- Transformer and rectifier (AC power supply type field flash circuit);

- DC contactor;

- Blocking diode;

- Field flashing current limiting resistor;

5. Synchronous motor starting circuit.- Starting resistor;

- Short circuiting contactor for the starting resistor;- Synchronism sensing device;


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B. The Control circuits are divided in:- Internal power supply circuits

- Regulating circuits (inside PLC): set points circuits; control loops and limitation

circuits in AUTOMATIC mode: AVR/APFC/kVAR; control loop and limitation

circuits in MANUAL mode- Measurement circuits

- Thyristors firing pulses generation circuits

- Protection circuits for the rectifier and control devices (by protection relays and

PLC)

- Internal power supplies circuitsThe supply of the PLC and the other control devices is made with the constant

voltage: +24V.

This voltage is obtained from 230VAC (auxiliary power supply) and from 110 (220)Vdc (battery supply), using switch mode power supplies. The switch mode power

supplies output are connected in parallel separated through diodes (common

cathode).

- Regulating circuits (inside PLC)set points circuits

Set point value in the AUTOMATIC or MANUAL mode is computed inside the

PLC. Every regulator has a register in the PLC that represents the set point value.

The range of the set point is between a minimum and a maximum value. Thesevalues can be set from the PLCs operating panel (HMI).

The variation speed of the set point between minimum and maximum value, on the

increase or decrease command, can be set from the PLCs operating panel (HMI).

control loops and limiting functions in AUTOMATIC mode

- control of the machine voltage regulator (AVR with load/ cross current correction

of the voltage set point)- control of the machine reactive powerQ regulator

- control of the machine power angle (factor)

(cos ) regulator

- time limitation of the maximum field current - field current limitation is activated

when field current is higher than a threshold value (usually 1.15Iex rated) . PLC

begins to compute the diagram (I2t) and when the time exceeds the calculated time,

the regulator output is modified so that the field current will be lowered to the rated

value. The threshold current value, the ceiling current definite time and the time

break after a forcing can be set as parameters.

- instantaneous limitation of the maximum field current (for synchronous

generators) - field current limitation is activated when the generator is connected to

the grid and the generator voltage in lower than the grid voltage in case of a near

short-circuit (at generator terminals or generator transformer).


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- time limitation of the maximum stator current - stator current limitation is

activated when the stator current is higher than a threshold value (between 0.8 ...

1.5Is rated). PLC begins to compute the diagram (I2t) and when the time exceeds the

calculated time, the regulator output is modified trying to lower down the stator

current below the rated value. The threshold current value, the ceiling currentdefinite time and the time break after a forcing can be set as parameters.

- limitation of the reactive power (only in AVR mode)- the reactive power value can

be compute with the following formula:

QM - Qm

Q* = QM - P -------------- ,

Pn

Qm = the reactive power value at rated active

power;QM - the reactive power value at active power= 0.

These values can be set from HMI for both leading and lagging working.

If the reactive power is higher (in lagging working) or lower (in leading working)

than Q* value, the PLC modifies the regulator output, so that the reactive power tochange to the Q* value.

- voltage matching (for synchronous generators) in order to start the

synchronization and the paralleling process the excitation system can performed the

voltage matching between the generator and line voltages.

- V/HZ limiter (for synchronous generators) to cause the regulated voltage to

decrease in proportion with the ferquency reduction, if frequency falls below a

predetermined value.

control loop and limiting in MANUAL mode

- control of the field current - excitation current regulator

tracking and switching between functioning (control) modes(AUTO-MANUAL)

The tracking between the 2 control modes is made thus:

- if the equipment functioning mode is MANUAL, in the AUTOmatic

regulator (AVR, Q, cos ) set point register is written all time the feedback motor

voltage value (Q or cos ). This value is the set point for the AUTOC regulator that

is not in function. When the switching command is received from MANUAL to

AUTO mode, it is done with a special care for the AUTO regulator output to be the

same with MANUAL set point register.

- if the equipment functioning mode is AUTO mode, in the MANUAL setpoint register is written all time the feedback field current. The switch to MANUAL

mode can be done any time without any cautions.


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At switching command, the HMI displays the selected mode and enables or disablesthe corresponding control loops of the chosen mode.

If the excitation equipment is ON, a fault in the feedbacks measurement circuit (U,

Is or cos ) doesn't allow the equipment to function in the AUTOMATIC control

mode. The control mode will be switched to MANUAL mode or the switch to

AUTO mode will not be allowed

- Measurement circuitsIn order to obtain the feed-back for UM, IM, Q, P, f, the equipment receives from the

machine the following signals:

-3x100 (110) Vac - UM (star or V connection diagram);-3x5(1) Aac - IM (star or V connection diagram);

The excitation system has processor based devices that adjust and compute the

electric feedback measures needed for the control loops of the AVR and FCR.

- Thyristors firing pulses generation circuitsUsually the excitation equipment has 2 thyristor firing pulses generating devices.The equipment automatically switches on the channel 2 if channel 1 is in fault.

The thyristors firing pulses are generated to be synchronous with the power supply

voltage. The firing pulses are moving in accordance with the command voltage U .

The thyristor firing pulse generating devices are equipped with a processor that

supervises thyristors firing pulses (their presence), the synchronization voltages andthe presence of the power supply.

- Protections circuitsThe PLC receives signals from different devices that supervise the high speed fuses,

the fans, the rectifier and transformer temperature, the field discharging circuit and

the field flashing circuit, etc.

Machine protections

a. Stator overvoltageb. Excitation overvoltage (59F)c. Excitation overcurrent (overexcitation 40)d. Loss of field excitation current (40)

Synchronous motor protections

e. Elapsing synchronism time (stall time)f. Asynchronous working protection (pull out)g. Restarting protectionh. AVR feedback measurement loss protection with switching on the MANUAL

control mode (field current regulator)


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C. Sundries features- Local commands (increase, decrease, functioning modes selections, test

functions) and Local signalizations are performed using a HMI key-pad or touch

screen operating panel and/or push buttons and pilot lights.

On the HMI there are also displayed the fault log, the parameters set, the electric

measurements.

HMI screens example

- The discrete input and output signals for remote control are isolated by control

relays.

- On the Excitation System the following Internal Tests can be performed with

equipment switched off.

- Static Breaker Test (indicates if static breaker is healthy)

- Rectifier Test (indicates weather the rectifier bridges and the thyristors firing pulse

generation boards are healthy).

- Communication facilities:Ports: RS232/ RS485, RJ45

Communication protocols: ModbusRTU, Profibus, Ethernet TCP/IP, DF1.


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CONSTRUCTIVE DESCRIPTION

The equipment is usually manufactured as a metal cabinet with front and back

doors. The colour, dimmensions and protection degree are depending of the

custommer requirements.

OVERALL DIMENSIONS

The overall dimensions depend on the rated field current of the synchronous

machine and the requested custom design.

For standard types, the dimensions (L x l x H) are:- for current up to 50Amps 800x800x(17002300)mm- for current over 50Amps with 100% redundancy in rectifying bridges

2400x800x2100mm

ENVIRONMENTAL CONDITIONS

operating temperature range: -100C...+40

0C

storage temperature range: -250C...+55

0C

maximum relative humidity: 80% (at 300C)

maximum altitude: 1000m above sea level (over 1000m, the current decreases

by 0,5% at each extra 100m)

PROTECTION DEGREE

The protection degree is: IP20IP54

ELECTRIC and ELECTRONIC DEVICES

The control circuits are developed using the resources of the PLC's

(Micrologix made by Allen Bradley or 313C made by Siemens)The thyristor bridge is designed and built at our company using Semikron

thyristors.

Inside the equipment it can be found several PCB's designed and planted at

our plant facilities.

Also it can be found electric devices as transducers, different protectionrelays, synchronization relay, relays, switch breakers, circuit breakers made by

Phoenix Contact, Deif, ABB, Schneider Electrique, Aeton, Siemens, Microelettrica

Scientifica, Bender, etc.

The HMI can be a key-button or/and touchscreen type, a color, grayscale, or

monochrome display, available in 315 in. size.


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QUALITY ASSURANCE

Static excitation equipment operates in compliance with "SR EN ISO 9001:2001"

quality management system, concerning the design, development, production,

installation and servicing.

The company is also certified for SR EN ISO 14001:2005 environmental

management system and OHSAS 18001:2004 occupational health and safetymanagement system.

SERVICE

consulting for application definition;

custom solution design;

technical assistance at mounting and commissioning;

service within and post guarantee;

customer personnel training;

OPTIONALS

stand-by equipment, as presented in the functional description;

firing circuit, as presented in the functional description;

exciter transformer, powered from generator terminals;

rotor earth fault relay;

stand-by rectifying bridges;

AC and DC disconnecting switches for each rectifying bridge (in additional

cubicle);

Current balancing coils for two rectifier bridges power circuit;

Communication circuit optical fiber for SCADA compatibility.


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FUNCTIONAL CHARACTERISTICS OF THE EXCITATION SYSTEM - SRATN

1. Resolution for measures acquisition 14bits2. Regulation accuracy


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INTERNAL FAULT SIGNALS MESSAGES DISPLAYED ON THE HMI

1. Power supply missing or synchronisation voltages missing2. Thyristors firing fault3. High speed fuse fault4. Static breaker fault or overtemperature on the field discharge resistor5. Thyristors over temperature6. Fans power supply fault7. Measuring circuit fault8. Auxiliary power supply missing9. Excitation transformer overcurrent10. Fault on the AUTOMATIC control channel and switch on

the MANUAL control channel

ELECTRIC MEASURES DISPLAYED

1. Field current2. Field voltage3. Stator voltage4. Stator current5. Power factor6. Active power7. Reactive power

MINIMUM DIGITAL INPUTS

1. Main Circuit Breaker position2. START commandlocal or remote3. STOP commandlocal or remote4. EMERGENCY STOP command from machine protections5. INCREASE SETPOINTlocal or remote6. DECREASE SETPOINTlocal or remote

SUPPLEMENTARY for SYNCHRONOUS GENERATOR

7. GENERATOR SPEED >90%

MINIMUM DIGITAL OUTPUTS

1. EXCITATION ON2. EXCITATION OFF3. INTERNAL FAULT4. INTERNAL WARNING5. Limitation functions activated

OPTIONAL for SYNCHRONOUS MOTOR

MCB SWITCH ON command

MCB SWITCH OFF command(MCBmotor circuit breaker)


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STATIC EXCITATION EQUIPMENTSRATN ICPE-ACTEL SAREFERENCE LIST:

Excitation equipments for synchronous generators - export

Someshwara - India - 3 pcs. SRAT-N 13A/48V 2004

Ranganatha - India3 pcs. SRAT-N 11A/23V 2005Ambuthirtha - India2 pcs. SRAT-N 17A/36V 2005

Middle Kollab - India2 pcs. SRAT-N 862A/85V 2006

Varahi - India2 pcs. SRAT-N 862A/85V 2007

Gezende - Turkey - 1pc. SRAT-N 883A/110V 2008

Somanamaradi - India - 1pc. SRAT-N 16.8A/39V 2008

Kang Krachan - Thailand - 1pc. SRAT-N 1000A/ 186V 2009

Tana Kenya2 pcs.2 pcs.

SRAT-N 17A/31VSRAT-N 20A/40V

2009

Motz France2 pcs. SRAT-N 16A/30V 2010

Nam La - Vietnam - 3 pcs. SRAT-N 15A/30V 2011

Om Power - India - 2 pcs. SRAT-N 15A/30V 2011

Song Giang - Vietnam - 2 pcs. SRAT-N 871A/93V 2011

Icpe Actel - Presentation of Sratn

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