High-Speed Busbar Transfer

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SYNCHROTACT® HBT

High-Speed Busbar Transfer

M

HBT

M

~ ~



Main Features

High-speed busbar transfer

The high-speed busbar transfer system (HBT) is applied for thechangeover of feeding busbars from their normal to a backup sup-ply feeder and vice-versa. This function is usually needed in auxil-iary supply systems of power stations and industrial plants.

The changeover may be initiated by a manual command or a pro-cess signal, e.g. after synchronization of a generator. Opening andclosing operations of the corresponding circuit breakers are then

Application and features• Changeover of feeding bus systems

in power stations and industrialplants

• Coupling of asynchronous networks

• Two and three-breaker configurations• Customer-specific configurations• Combination with control and protec-

tion functions in the same hardwareunit

• Multiple configuration of the HBTfunction in a single device

Manual changeover• Changeover initiated by manual or

process command• Synchronism check with adjustable

parameters• Short supply interruption times• Make-before-break and make-after-

break operating mode

Automatic changeover• Surge-free synchronized changeover after loss of the consumer

feeder supply • Circuit breaker closing time taken into consideration• Reclosing up to an adjustable maximum phase angle prior to the

first phase coincidence• Reclosing at the first phase coincidence• Automatic changeover at low residual voltage• Automatic changeover after an adjustable time delay • Adjustable release limits for maximum amplitude and frequency

differences• Two breaker closing times, individually adjustable

Circuit breaker control• Control of two circuit breakers• Three-breaker configuration covered by two functions in the

same device

• Status supervision• Plausibility check• Breaker run-time supervision• Breaker closing and tripping commands

Application and functional description

performed almost simultaneously, providingthe feeder voltages are in phase.

After a sudden loss of the motor feeder sup-ply which may be caused by a primary faultin a superior circuit, the changeover to abackup feeder must be fast enough to en-sure continuous operation and must be

Fig 1:

Standard applications

of high-speed bus

transfer systems

(M: motor / consumer)

HBT HBTHBT

S1 S2 S1 S2

M M M MM M

Feeder A Feeder A Feeder B Feeder B

Two-breaker configuration Three-breaker configuration

Coupler

ABB



Fig. 2:

Block diagram of the

HBT function

AUT Automatic changeover

DRV Circuit breaker drive control logic

MAN Manual changeover

SEL Selection circuit

SUP Circuit breaker supervision logic

S1ON, ... Circuit breaker status signals

(double indication)

U1, U2 Supply feeder voltages

UM Motor busbar voltage

ϕ < ϕ L

Reclosing up to an adjustable angle

limit

ϕ = 0 Reclosing at first phase

coincidence

U< Changeover at residual voltage

T> Changeover after an adjustable

time delay

Functional description (cont.)

almost surge-free especially in order to limitstresses of the motor shafts. Depending onthe moment of inertia and the actual motorload, the slip increases more or less rapidly.Therefore the breaker closing time has to beconsidered when emitting the breaker clos-

ing command.

The motors can be reconnected to thebackup feeder at the first phase coincidenceor – at lower slip gradients – even before adefined maximum phase angle is reached.In case of a sudden loss of feeder supply,the signal to initiate the fast transfer is nor-mally derived from an application-specificlogic using protection trip signals and statusinformation from disconnectors and break-ers. This logic can be implemented in theSYNCHROTACT HBT by means of the func-tion plan programming tool FUPLA.

If for any reason a fast changeover is notpossible, a transfer can be performed afterdecay of the motor residual voltage below an adjustable value or after a certain timedelay. Before reclosing at residual voltage,selective load shedding can be programmed

by using an additional undervoltage function from theSYNCHROTACT HBT software library.Fig. 1 shows the most common applications of high-speed bustransfer systems.

Coupling of asynchronous networks

The HBT function can be used to couple two asynchronous networks by closing a circuit breaker at the exact phase coincidence of both voltages. The closing command may be manual or a processsignal transmitted to the coupling device via the network controlsystem. The operational range can be limited as regards to the am-plitude and frequency difference of the voltages.

The high-speed bus transfer (HBT) unit comprises all inputs, out-puts and function blocks for the application in a two-breaker con-figuration. Application-specific logic can be added by means of thefunction plan programming tool FUPLA.

The application-specific logic may generate the start signal for theHBT or may block or release certain function blocks depending onthe process status signals.

The HBT function contains the following function blocks (Fig. 2):• Manual changeover (MAN)• Automatic changeover (AUT)• Voltage selection (SEL)• Circuit breaker supervision and control (DRV)

ϕ<ϕL

T>

U<

MAN

AUT

DRV SUP

SEL

U1

U2

UM ϕ = 0

S1 ON

S1 OFF

S2 ON

S2 OFF

S1 CLOSE

S1 OPEN

S2 CLOSE

S2 OPEN

Settings

Start signals

Release signals

Measuring signals

Signalling

Make-after-break

Make-before-break

ABB




Fig. 3:

Two algorithms for the

automatic changeover

after loss of feeder

voltage, complementing

each other

Manual changeover

Upon a manual changeover command

which may be given from the substa-tion control system via the serial bus or via an opto-coupler input of theSYNCHROTACT HBT device, this func-tion block checks the synchronism be-tween the voltage at the busbar and thefeeder voltage to be transferred.

In case of synchronism, the changeoveris performed in two selectable modes:

• Make-after-break mode

• Make-before-break mode.

In the “make-after-break” mode, open-ing resp. closing commands are sentout to both circuit breakers at the sametime. The closing command can be de-layed by means of an adjustable timer.This mode ensures the shortest possibleinterruption times.

In the “make-before-break” mode, theclosing command is issued first andthen, after an adjustable time delay, the

other breaker is tripped.

Automatic changeover

This sub-function is used after a sudden loss of

the feeder voltage and may be triggered by aprotection trip signal, for example. But it canalso be started by a manual command. It con-tains two different algorithms complementingeach other (Fig. 3). The algorithms can beused in parallel.

The first algorithm allows a fast changeoverimmediately after the loss of the feeder voltageuntil a certain adjustable maximum phaseangle between the consumer voltage and thenew feeder voltage is reached. This function isapplicable in particular at a low rate of slip

changes and if new and old feeder voltages aresynchronous (Fig. 4, curve 1).

The second algorithm provides a changeoverat the first phase coincidence between the con-sumer voltage and the new feeder voltage.This algorithm works correctly in all cases: atsynchronism and asynchronism of old and new feeder voltage, irrespective of the motor fre-quency being lower or higher than the fre-quency of the new feeder, at highest rates of change of the motor frequency (tests with morethan 50 Hz per second have been conducted

successfully) and up to slip frequencies of 10 Hz.

Uref

ϕG

Uref

ϕCB CB)= f (s, ds/dt, tϕCB CB)= f (s, ds/dt, t

UBB

UBB

ϕv

ϕL

Close commandpermissible

Close commandto be given

Closing up to adefined angle limit

Closing at firstphase coincidence

U ref

voltage of the feeder to which the busbar will be connected

U BB voltage of the feeding busbar ϕ

v angle prior to loss of feeder voltage

ϕCB

angle corresponding to the circuit breaker closing time

ϕL

limit angle for breaker closing

s slip frequency

t CB

closing time of circuit breaker

ABB




Curve Slip before c.b. tripping (%) Rate of change of the slip (% per s)

1 0.5 6

2 2 6

3 0.5 25

4 2 25

Fig. 4:

Angle difference

between the voltage at

the feeding busbar and

the supply feeder

voltage versus time

after tripping of the

circuit breaker.

Fig. 4 shows how the angle difference be-tween motor voltage and supply voltage will develop over the time after tripping of the supply feeder, depending on the initialslip and the rate of slip change mirroringthe actual load conditions.

For both algorithms the breaker closing timeis taken into account. The correspondingphase angle is calculated considering theslip as well as the speed of the slip change.

Secondary changeover modes

These additional function blocks use sim-pler criteria because they do not check thesynchronism between the voltages. Twodifferent modes can be activated in parallel:

• Minimum voltage• Maximum time.

The “Minimum voltage” mode permits achangeover after the residual voltage at themotor bus decayed below an adjustable

threshold. A typical setting is 30 %.

The “Maximum time” mode provides achangeover after the adjustable time delay has expired, independent of the synchro-nism.

Voltage selection

The voltage of the feeding busbar is com-pared with a reference voltage to checksynchronism. In Fig. 1 this reference voltageis U2 (feeder 2) if feeder 1 is connected and

feeder 2 disconnected and vice versa. Theselection of the right voltage is performedaccording to the start signals for the manual,resp. automatic transfer.

Circuit breaker supervision andcontrol

The status signals of two circuit breakers arecollected and checked for plausibility. Anabnormal condition generates an alarm andblocks the changeover function. A breaker

run-time supervision is included.

360

320

280

240

200

160

120

80

40

0

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

1

34

2

Time (s)

Angle(Degrees)

ABB



Fig. 5 illustrates an automatic changeover ata 6 kV motor busbar. The record was madeby means of the internal event recorder of the SYNCHROTACT HBT. In this example,reclosing to the auxiliary feeder takes placeabout 320 ms after the main feeder breaker

opened. This time it takes up to the first phasecoincidence (360° angle) between the motor voltage (MotorBus) and the auxiliary feeder voltage (T29AUX). In this case, main andauxiliary feeder voltage were synchronous.

Example of a high-speed changeover

The cursor is put to 249.5 ms, the instant when the closing command was issued(Q19 Close). The measurands indicated onthe right apply for this instant. The com-mand was given at a frequency difference of 4 Hz, and a rate of change of the frequency

of 16.5 Hz per second. The HBT function was started about 10 ms after breakeropening (HBT Start). The internal measure-ment is active from the start signal up to theissue of the closing command.

Fig. 5:

Changeover occurrence

on a 6 kV motor busbar

(Description on page 5)

Integration into a substation control system

If integrated into a substation control system(SCS), the HBT function may operate in thefollowing manner:

The HBT can either be released or blockedfrom the operator’s control screen. Amanual changeover can also be initiated

from there. The status of the HBT – released

/ blocked/disturbed – is indicated on thescreen.

Status signals from disconnectors and circuitbreakers used to initiate the start signal forHBT operation can be transferred via theserial interbay bus of the substation control

system.

ABB



Technical data

Measuring range _________________________________________________________

Rated frequency f n 50 Hz or 60 Hz

Frequency range 0.8 to 1.04 f n

Rated input voltage Un 100 to 130 V or 200 to 260 V

Available hardware inputs/outputs_________________________________________

Voltage inputs 6 with input module K41

maximum 9 with customized input module

(preferably phase-to-phase measurement)

Control outputs maximum 8 for control of 4 circuit breakers

Optocoupler inputs maximum 32 with 4 × 316DB61

practically unlimited with RIO500 modules

Parameters ______________________________________________________________

S1, S2 closing time 0 to 150 ms in steps of 1 ms

Live line check 0.5 to 1.2 Un in steps of 0.1 Un

Circuit breaker runtime supervision 50 to 500 ms in steps of 10 ms Angle compensation

of input voltages U1, U2 –180 to +180 degrees in steps of 0.5 degree

Manual transfer

Maximum time to be operative

after start 0.02 to 60 s in steps of 0.02 s

Maximum voltage amplitude

difference for operation 0.00 to 1.00 Un in steps of 0.01 Un

Maximum absolute angle difference

for operation 0 to 90 degrees in steps of 5 degrees

Maximum frequency difference

for operation 0.05 to 0.4 Hz in steps of 0.05 Hz Time delay for closing command 0 to 200 ms in steps of 10 ms

Time delay for tripping command 0 to 200 ms in steps of 10 ms

Automatic transfer

Maximum time for synchronized

transfer to be operative after start,

release of non-synchronized

transfer (T>) 0.1 to 10 s in steps of 0.01 s

Maximum voltage amplitude

difference for operation 0.00 to 1.00 Un in steps of 0.01 Un

Limit angle for transfer before the

1st phase coincidence 0 to 90 degrees in steps of 5 degrees

Maximum frequency difference

for operation 0.05 to 10 Hz in steps of 0.05 Hz

Residual voltage for release of

non-synchronized transfer 0.1 to 1.0 Un in steps of 0.1 Un

Accuracy ________________________________________________________________

Typical values at sinusoidal voltage with constant amplitude and frequency

Angle measurement ± 1°

Frequency measurement ± 0.03 Hz

Voltage measurement ± 2 %

Reclosing at 10 % slip phase coincidence ± 10°

ABB



ABB Switzerland Ltd.

Static Excitation Systems, Voltage Regulators

and Synchronizing Equipment

CH-5300 Turgi / Switzerland

Telephone: +41 (0) 58 589 24 86

Fax: +41 (0) 58 589 23 33

Email: [email protected]

Internet: www.abb.com / synchrotact 3B

HT

490

196

R0201

PrintedinSwitzerland(0301-PDF)

We reserve the right to change in the interest of technical development.

Dimensional drawing

All measures in the graphics in mm

Panel cutout (W × H) 265 × 254 mm

5

8

7

6

3

4

1

2

13

16

15

14

11

12

9

10

16

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15

14

8

13

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9

5

7

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3

2

1

OUT

IN

SYNCHROTACT HBT ®

2 7 6

271

c a .

3 3 4

c a . 2

9 0

2 7 .

5

C

E

Mounting elements(2 on upper shape, 2 on lower)

Front view Rear view

View from top View of the device

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High-Speed Busbar Transfer

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