AVR

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RET 54_

Application and Setting Guide

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Copyrights ...4

1. 1. Scope

Scope ...

...

...5

2. 2. Intro

Introducti

duction

on ...

...

...6

....6

3. 3. Oper

Operation

ation princ

principle

iple ...

...

...7

.7

3.1.

3.1. General General ... ... ... 77 3.2.

3.2. Tap-changeTap-changer r position position indication ...indication ... 88 3.3.

3.3. Line Line Drop Drop CompensatioCompensation n (LDC) ...(LDC) ... 1212 3.4.

3.4. Reduce Reduce Set Set Voltage Voltage (RSV) (RSV) ... ... 1313

4. 4. Regulation

Regulation of

of a

a single

single transformer

transformer ...

...

... 15

15

4.1.

4.1. Purpose Purpose and and connections connections ... 1515 4.2.

4.2. Settings Settings ... ... ... 1515 4.3.

4.3. Example Example 1: 1: Basic Basic parameters ...parameters ... ...16...16 4.4.

4.4. Example Example 2: 2: Line Line drop drop compensatiocompensation ...n ... ...18...18 4.5.

4.5. CommissionCommissioning ing and and troubleshootroubleshooting ...ting ... ...21...21

5. 5. Para

Parallel

llel oper

operation

ation ...

...

...23

..23

5.1.

5.1. Master Master / / Follower Follower (M/F) (M/F) mode ...mode ... ... 2424 5.1

5.1.1..1. PurPurpopose and cose and connennectictions ...ons ...24...24 5.1

5.1.2..2. SetSettintings gs ...25.25 5.

5.1.1.3.3. ExExamamplple: Mae: Maststerer/F/Folollolowewer r

with LON communication ...26 with LON communication ...26 5.2.

5.2. Minimizing Minimizing Circulating Circulating Current Current (MCC) (MCC) mode ...28mode ...28 5.2

5.2.2..2. SetSettintings gs ...29.29 5.2

5.2.3..3. LON coLON confinfigurguratiation on ...30...30 5.2

5.2.4..4. ExaExamplmple: e: MinMinimiimizinzing g CirCirculculatiating ng CurCurrenrentt

mode of operation ...31 mode of operation ...31 5.3.

5.3. Negative Negative Reactance Reactance Principle Principle (NRP) (NRP) mode ...mode ... ... 3232 5.3

5.3.2..2. SetSettintings gs ...33.33 5.3

5.3.3..3. ExaExamplmple: Ne: Negaegativtive Re Reaceactantance Pce Prinrincipciple ...le ...34..34 5.4.

5.4. CommissionCommissioning ing and and troubleshootroubleshooting ...ting ... ...35...35

6. 6. Refe

Referenc

rences

es ...

...

...38

....38

7.

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Copyrights

The information in this document is subject to change without notice and should not The information in this document is subject to change without notice and should not be construed as a commitment by ABB Oy. ABB Oy a

be construed as a commitment by ABB Oy. ABB Oy a ssumes no responsibility for ssumes no responsibility for any errors that may appear in this document.

any errors that may appear in this document.

In no event shall ABB Oy be liable for direct, indirect, special, incidental or In no event shall ABB Oy be liable for direct, indirect, special, incidental or consequential damages of any nature or kind arising from the use of this

consequential damages of any nature or kind arising from the use of this document,document, nor shall ABB Oy be liable for incidental or consequential damages arising from use nor shall ABB Oy be liable for incidental or consequential damages arising from use of any software or hardware described in this document.

of any software or hardware described in this document.

This document and parts thereof must not be reproduced or copied without written This document and parts thereof must not be reproduced or copied without written permission from ABB Oy, and the contents thereof must not be imparted to a third permission from ABB Oy, and the contents thereof must not be imparted to a third party nor used for any unauthorized purpose.

party nor used for any unauthorized purpose.

The software or hardware described in this document is furnished under a license The software or hardware described in this document is furnished under a license and may be used, copied, or disclosed only in accordance with the terms of such and may be used, copied, or disclosed only in accordance with the terms of such license.

license.

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1. Scope

This document refers to the transformer terminal RET 54_ when the terminal is used This document refers to the transformer terminal RET 54_ when the terminal is used as an automatic voltage regulator for

as an automatic voltage regulator for power transformers with on-load tap-changer.power transformers with on-load tap-changer. The operation mode of automatic and

The operation mode of automatic and manual voltage control of the tmanual voltage control of the transformer ransformer function block (COLTC) is described. The settings required for the different function block (COLTC) is described. The settings required for the different operation principles are explained in application examples.

operation principles are explained in application examples.

Single and parallel use of power transformers are described. The COLTC function Single and parallel use of power transformers are described. The COLTC function block supports three different parallel operation principles, i.e. the Master/Follower block supports three different parallel operation principles, i.e. the Master/Follower principle (M/F), the Minimizing Circulating

principle (M/F), the Minimizing Circulating Current principle (MCC) and theCurrent principle (MCC) and the Negative Reactance principle (NRP).

Negative Reactance principle (NRP). KEYWORDS:

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2. Introduction

Automatic voltage regulators (AVR) are used to maintain a stable voltage on the Automatic voltage regulators (AVR) are used to maintain a stable voltage on the load side of the

load side of the power transformer under varying network load conditions.power transformer under varying network load conditions.

The on-load tap-changer of a power transformer can be controlled with an AVR, The on-load tap-changer of a power transformer can be controlled with an AVR, which measures the voltage on the side of the power transformer where the voltage which measures the voltage on the side of the power transformer where the voltage is to be controlled, normally the LV side.

is to be controlled, normally the LV side.

Provided with the function block COLTC, the transformer terminal RET 54_ is able Provided with the function block COLTC, the transformer terminal RET 54_ is able to control the tap

to control the tap changer of the power transformer. The function block changer of the power transformer. The function block COLTC canCOLTC can be used to control the tap changer of a single transformer or it

be used to control the tap changer of a single transformer or it can operate in parallelcan operate in parallel with AVRs of other transformers feeding the same busbar.

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3.

3. Operation

Operation principle

principle

3 3..1

1..

G

Ge

en

ne

erra

all

The COLTC function block is used to control the voltage on the load side of the The COLTC function block is used to control the voltage on the load side of the power transformer. Based on the voltage (and current) measured, the function block power transformer. Based on the voltage (and current) measured, the function block determines whether the voltage needs to be increased or decreased. The voltage is determines whether the voltage needs to be increased or decreased. The voltage is regulated by Raise or Lower commands sent to the tap changer.

regulated by Raise or Lower commands sent to the tap changer.

M

U12b U12b Ch_ VT_ Ch_ VT_ Ch_ CT_ Ch_ CT_

+

-LO

LOWER WER RAIRAISESE

TCO TCO

RET 54_

sing_trafo sing_trafo

IL1b, IL2b, IL3b

Fig.

Fig. 3.1.-3.1.-11 Basic cBasic conneconnection dtion diagraiagram for thm for the voltae voltage rge regulaegulatortor..

The basic principle for voltage regulation is that no regulation will take place as long The basic principle for voltage regulation is that no regulation will take place as long as the voltage stays within the bandwidth setting. The measured voltage is

as the voltage stays within the bandwidth setting. The measured voltage is alwaysalways compared with the

compared with the Control voltageControl voltage (Up), which is calculated using equation(Up), which is calculated using equation (1)(1).. Once the measured voltage deviates from the bandwidth, the delay time T1 starts. Once the measured voltage deviates from the bandwidth, the delay time T1 starts. When the set delay time elapses, a raise or lower control pulse is sent to the tap When the set delay time elapses, a raise or lower control pulse is sent to the tap changer. Should, after one tap change, the measured voltage still be outside the changer. Should, after one tap change, the measured voltage still be outside the bandwidth, the delay time T2 starts. T2

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T

T1 1 ssttaarrt t TT1 1 rreesseet t TT1 1 ssttaarrt t _T1_T1 LLoowweer r

Up, control voltage

hysteresis limit

Um, measured voltage

bandwidth limit bandwidth limit D DUU_s_s h h y y s s t t__ d d i i a a g g

r r a a m m U U t t hysteresis limit hysteresis limit bandwidth limit bandwidth limit D DUU_s_s Fig.

Fig. 3.1.3.1.-2-2 PrinciPrinciple ple of of the the voltagvoltage re regulaegulating ting functifunction.on.

Under certain circumstances, the automatic voltage regulator needs to be enhanced Under certain circumstances, the automatic voltage regulator needs to be enhanced with additional functions such as Line Drop Compensation (LDC) and Reduce Set with additional functions such as Line Drop Compensation (LDC) and Reduce Set Voltage (RSV). Also, various parallel operation modes are available to fit

Voltage (RSV). Also, various parallel operation modes are available to fit applications where two or more power transformers are connected to the same applications where two or more power transformers are connected to the same busbar at the same time. The parallel operation modes i.e. the Master/Follower (M/ busbar at the same time. The parallel operation modes i.e. the Master/Follower (M/

F), Minimizing Circulating Current (MCC) and Negative Reactance Principle F), Minimizing Circulating Current (MCC) and Negative Reactance Principle (NRP) will be explained later in this document.

(NRP) will be explained later in this document.

All these features mentioned affect the control voltage, i.e. the requested voltage All these features mentioned affect the control voltage, i.e. the requested voltage calculated, towards which the COLTC function block regulates the measured calculated, towards which the COLTC function block regulates the measured voltage.

voltage.

U

_p_p

=

U

_s_s

+

U

_z_z

+

U

_ci_ci

–

U

_{rs vv}_rs

(1) (1) where:

where:

U

U_p_p == ccoonnttrrool l vvoollttaaggee U

U_ss == rreeffeerreenncce e vvoollttaagge e sseettttiinngg U

U_zz == lliinne de drroop p ccoommppeennssaattiioon n tteerrmm U

U_ci_ci == cciirrccuullaattiinng cg cuurrrreennt tt teerrmm U

U_rsv_rsv == vvololtatage ge rereduducctition on bby ty the he RSRSV fV fununctctioionn

3 3..2

2..

T

Ta

ap

p--c

ch

ha

an

ng

ge

er

r p

po

os

siittiio

on

n iin

nd

diic

ca

attiio

on

n

The tap-changer position can be measured by the RET 54_ terminal. Besides tap The tap-changer position can be measured by the RET 54_ terminal. Besides tap position indication, an out-of-step function and alarms can

position indication, an out-of-step function and alarms can be obtained by measuringbe obtained by measuring the position of the tap changer.

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Tap-changer position information can be brought to the

Tap-changer position information can be brought to the RET 54_ terminal in threeRET 54_ terminal in three different ways: as a mA signal, a resistance value or a binary coded decimal value different ways: as a mA signal, a resistance value or a binary coded decimal value (BCD).

(BCD).

When tap-changer position information is connected to the RET 54_ terminal in the When tap-changer position information is connected to the RET 54_ terminal in the form of a mA signal or a res

form of a mA signal or a resistance value, the signal is istance value, the signal is connected to the input of anconnected to the input of an optional RTD card for the RET 54_ terminal.

optional RTD card for the RET 54_ terminal. Fig. 3.2.-1

Fig. 3.2.-1 andand Fig. 3.2.-2Fig. 3.2.-2 show an example of how the mA signal and resistanceshow an example of how the mA signal and resistance value is connected to the RTD input, and how it is configured.

value is connected to the RTD input, and how it is configured.

DIFF DIFF + + -X6.1 X6.1 1 1 2 2 3 3 4 4 SHUNT SHUNT REAL_TO_SINT REAL_TO_SINT RTD1_6_AI1 RTD1_6_AI1 + + -GND GND TC_pos_mA TC_pos_mA COLTC COLTC TAP_POS_ TAP_POS_ Relay configuration Relay configuration mA signal mA signal Fig. 3

Fig. 3.2.-1.2.-1 TTap-chap-changer panger positioosition informn information ation wirwired as a mA sied as a mA signal to Rgnal to RTD inpuTD input t 1. 1. DIFF DIFF + + -X6.1 X6.1 1 1 2 2 3 3 4 4 SHUNT SHUNT REAL_TO_SINT REAL_TO_SINT RTD1_6_AI1 RTD1_6_AI1 GND GND COLTC COLTC TAP_POS_ TAP_POS_ Resistor Resistor sensor sensor Relay configuration Relay configuration TC_pos_res TC_pos_res Fig. 3

Fig. 3.2.-2.2.-2 TTap-chap-changeanger positior position inforn informatiomation suppln supplied as a ried as a resistanesistance signace signal l using a two-wire connection from the tap changer to

using a two-wire connection from the tap changer to the RTD input 1.the RTD input 1. The mA or resistance signal also has to be calibrated to match the different The mA or resistance signal also has to be calibrated to match the different tap-changer positions. The mA signal or resistance value can be easily calibrated with changer positions. The mA signal or resistance value can be easily calibrated with the Transducer Linearization Tool (TLT) of CAP 505. This tool allows the input the Transducer Linearization Tool (TLT) of CAP 505. This tool allows the input signal to be accurately calibrated, also in the event of a non-linear signal.

signal to be accurately calibrated, also in the event of a non-linear signal. The mA signal should be calibrated before

The mA signal should be calibrated before the power transformer is put into the power transformer is put into service.service. For the calibration the Transducer Linearization Tool needs at least two positions, For the calibration the Transducer Linearization Tool needs at least two positions, but with additional positions available, the calibration result w

but with additional positions available, the calibration result w ill be more accurate,ill be more accurate, if the mA signal is not absolutely linear.

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Before starting the TLT tool, set the following parameters in the CAP 505 Relay Before starting the TLT tool, set the following parameters in the CAP 505 Relay Setting Tool under

Setting Tool under Configuration/RTD1/Input _Configuration/RTD1/Input _according to the tapaccording to the tap position signal used.

position signal used.

•• Input Input mode (mode (currencurrent or ret or resistancsistance)e) •• CurreCurrent rannt range (if ge (if a mA siga mA signal is unal is used)sed)

•• ResistaResistance rangnce range (if a resiste (if a resistance signance signal is used)al is used) •• LinLinear cear curvurve = Dise = Disablableded

When calibrating the tap-changer position

When calibrating the tap-changer position Input values Input values from the tap changer, thefrom the tap changer, the signal can be read from the relay setting tool under

signal can be read from the relay setting tool under Status/RTD1/InputStatus/RTD1/Input. The. The input values are first read for different tap positi

input values are first read for different tap positi ons, one at a time, and then enteredons, one at a time, and then entered into the TLT accordingly. The tool has a capacity of maximum 10 values. The into the TLT accordingly. The tool has a capacity of maximum 10 values. The linearization curve is uploaded to the relay with the Relay download tool. To linearization curve is uploaded to the relay with the Relay download tool. To activate the linearization curve, set the parameter

activate the linearization curve, set the parameter Linear curve Linear curve = Enabled.= Enabled.

Note!

Note!_{The settings will not take effect until they are stored and the relay is reset.}_{The settings will not take effect until they are stored and the relay is reset.}

Fig. 3

Fig. 3.2.-3.2.-3 CalibraCalibration otion of mA sigf mA signal frnal from tap om tap changchanger with er with steps frsteps from 1 to om 1 to 1919 using Transducer Linearization

using Transducer Linearization TTool.ool.

If the tap changer uses a binary coded decimal signal (BCD) for tap-changer position If the tap changer uses a binary coded decimal signal (BCD) for tap-changer position indication, the BCD signals are connected to the dedicated binary inputs of the indication, the BCD signals are connected to the dedicated binary inputs of the RET 54_ terminal. For this purpose a special function block, BCD2INT (BCD to RET 54_ terminal. For this purpose a special function block, BCD2INT (BCD to integer) which converts the BCD signal into tap-position information is available. integer) which converts the BCD signal into tap-position information is available. Fig. 3.2.-4

Fig. 3.2.-4 shows a configuration example for tap positions from 1 shows a configuration example for tap positions from 1 to 19. If negativeto 19. If negative tap-changer positions are needed, a separate input is connected to the SIGN_BIT tap-changer positions are needed, a separate input is connected to the SIGN_BIT input of the configuration.

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X7.1 X7.1 1 1 2 2 3 3 4 4 SINT_TO_REAL SINT_TO_REAL BIO1_7_BI1 BIO1_7_BI1 COLTC COLTC TAP_POS_ TAP_POS_ 5 5 6 6 7 7 8 8 BIO1_7_BI2 BIO1_7_BI2 BIO1_7_BI3 BIO1_7_BI3 BIO1_7_BI4 BIO1_7_BI4 BIO1_7_BI5 BIO1_7_BI5 FALSE FALSE BCD2INT BCD2INT B0 B0 B1 B1 B2 B2 B3 B3 B4 B4 B5 B5 B6 B6 B7 B7 SIGN_BIT SIGN_BIT TC_pos_BCD TC_pos_BCD -MMIDATA_ MMIDATA_ ON ON DATA DATA TRUE TRUE 1 1 2 2 3 3 4 4 5 5 Relay

Relay configuratioconfigurationn

Fig.

Fig. 3.2.-3.2.-44 ConneConnection action and cond configurnfiguration ation when fwhen five BCive BCD signaD signals frls from the om the taptap changer are connected to the binary

changer are connected to the binary inputs X7.1.inputs X7.1. Table 3.2.-1

Table 3.2.-1 shows the tap positions corresponding with different combinations of shows the tap positions corresponding with different combinations of BCD signals.

BCD signals.

Ta

Table 3.ble 3.2.-2.-11 BCDBCD2IN2INT funcT function btion bloclock inpuk inputs and tts and tap posap positioitionsns

S Siiggnn.. BB77 BB66 BB55 BB44 BB33 BB22 BB11 BB00 PPooss.. F Faaccttoorr 8800 4400 2200 1100 88 44 22 11 ... ... 1 1 00 00 00 00 11 00 00 11 --99 1 1 00 00 00 00 11 00 00 00 --88 1 1 00 00 00 00 00 11 11 11 --77 1 1 00 00 00 00 00 11 11 00 --66 1 1 00 00 00 00 00 11 00 11 --55 1 1 00 00 00 00 00 11 00 00 --44 1 1 00 00 00 00 00 00 11 11 --33 1 1 00 00 00 00 00 00 11 00 --22 1 1 00 00 00 00 00 00 00 11 --11 0 0 00 00 00 00 00 00 00 00 00 0 0 00 00 00 00 00 00 00 11 11 0 0 00 00 00 00 00 00 11 00 22 0 0 00 00 00 00 00 00 11 11 33 0 0 00 00 00 00 00 11 00 00 44 0 0 00 00 00 00 00 11 00 11 55 0 0 00 00 00 00 00 11 11 00 66 0 0 00 00 00 00 00 11 11 11 77 0 0 00 00 00 00 11 00 00 00 88 0 0 00 00 00 00 11 00 00 11 99 0 0 00 00 00 11 00 00 00 00 1100 0 0 00 00 00 11 00 00 00 11 1111 0 0 00 00 00 11 00 00 11 00 1122

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T

Tap-changer operating (TCO)

ap-changer operating (TCO) signal

signal

If an operating signal is available when the tap

If an operating signal is available when the tap changing process is active, it shouldchanging process is active, it should be connected to the TCO input of the COLTC function block. Since

be connected to the TCO input of the COLTC function block. Since the TCO signalthe TCO signal is used only for alarm purposes, it will not affect the operation if left unconnected. is used only for alarm purposes, it will not affect the operation if left unconnected. If the TCO signal has been

If the TCO signal has been active for more than 15 seconds after active for more than 15 seconds after a control pulse froma control pulse from RET 54_ has been deactivated, an alarm will be generated. An active TCO signal RET 54_ has been deactivated, an alarm will be generated. An active TCO signal will not prevent new operation commands to the tap changer. If new operation will not prevent new operation commands to the tap changer. If new operation commands must be prevented during the tap-changing process, the TCO signal is commands must be prevented during the tap-changing process, the TCO signal is connected to the BLOCK input as well.

connected to the BLOCK input as well.

3 3..3

3..

L

Liin

ne

e D

Drro

op

p C

Co

om

mp

pe

en

ns

sa

attiio

on

n ((L

LD

DC

C))

When a long line is loaded, it is obvious that the voltage at the load end of the line When a long line is loaded, it is obvious that the voltage at the load end of the line is lower than the voltage at the transformer end. Because the impedance of a line is lower than the voltage at the transformer end. Because the impedance of a line consists of both a resistive and a reactive component, compensation must be consists of both a resistive and a reactive component, compensation must be considered for both components. The LDC function allows

considered for both components. The LDC function allows voltage drops caused byvoltage drops caused by both the resistive and the reactive component to be effectively compensated.

both the resistive and the reactive component to be effectively compensated. In a network with lines of varying lengths the voltage of a shorter line with less In a network with lines of varying lengths the voltage of a shorter line with less voltage drop is not allowed to rise

voltage drop is not allowed to rise too high. In such a network, a compromise musttoo high. In such a network, a compromise must be made when the line drop compensation parameters are calculated.

be made when the line drop compensation parameters are calculated. 0 0 00 00 00 11 00 00 11 11 1133 0 0 00 00 00 11 00 11 00 00 1144 0 0 00 00 00 11 00 11 00 11 1155 0 0 00 00 00 11 00 11 11 00 1166 0 0 00 00 00 11 00 11 11 11 1177 0 0 00 00 00 11 11 00 00 00 1188 0 0 00 00 00 11 11 00 00 11 1199 0 0 00 00 11 00 00 00 00 00 2200 0 0 00 00 11 00 00 00 00 11 2211 0 0 00 00 11 00 00 00 11 00 2222 0 0 00 00 11 00 00 00 11 11 2233 0 0 00 00 11 00 00 11 00 00 2244 0 0 00 00 11 00 00 11 00 11 2255 0 0 00 00 11 00 00 11 11 00 2266 0 0 00 00 11 00 00 11 11 11 2277 0 0 00 00 11 00 11 00 00 00 2288 0 0 00 00 11 00 11 00 00 11 2299 0 0 00 00 11 11 00 00 00 00 3300 0 0 00 00 11 11 00 00 00 11 3311 0 0 00 00 11 11 00 00 11 00 3322 0 0 00 00 11 11 00 00 11 11 3333 0 0 00 00 11 11 00 11 00 00 3344 0 0 00 00 11 11 00 11 00 11 3355 0 0 00 00 11 11 00 11 11 00 3366 ... ... Tabl

Table e 3.2.-13.2.-1 BCD2IBCD2INT NT function function block block inputs inputs and and tap tap positions positions (Contin(Continued)ued)

S

Siiggnn.. BB77 BB66 BB55 BB44 BB33 BB22 BB11 BB00 PPooss.. F

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Because the voltage drop of a line increases with the load current, it

Because the voltage drop of a line increases with the load current, it is important tois important to set a limit to the

set a limit to the voltage compensation to prevent overvoltage for consumers locatedvoltage compensation to prevent overvoltage for consumers located closer to the transformer.

closer to the transformer. Fig. 3.3.-1Fig. 3.3.-1 shows a voltage compensation curve atshows a voltage compensation curve at

different load currents. In this example the maximum voltage compensation is 900 different load currents. In this example the maximum voltage compensation is 900 V, which is set using the

V, which is set using the LDC limit LDC limit parameter. The total voltage compensationparameter. The total voltage compensation consists of both resistive and reactive voltage compensation. Reactive voltage consists of both resistive and reactive voltage compensation. Reactive voltage compensation is relevant only when there is a reactive load.

compensation is relevant only when there is a reactive load.

Fig. 3

Fig. 3.3.-1.3.-1 VVoltagoltage compene compensation asation at diffet differenrent load cut load currerrents usinnts using the LDC g the LDC function.

function.

The calculation of the line drop compensation parameters

The calculation of the line drop compensation parameters U U _r_randand U U _x_xwill bewill be explained more in detail in section 4.4 and in the COLTC manual.

explained more in detail in section 4.4 and in the COLTC manual.

Note!

Note!_{It should be noted that if embedded generation is employed on the load side}_{It should be noted that if embedded generation is employed on the load side}

of the transformer, line drop compensation cannot be used. of the transformer, line drop compensation cannot be used.

3 3..4

4..

R

Re

ed

du

uc

ce

e S

Se

et

t V

Vo

olltta

ag

ge

e ((R

RS

SV

V))

The Reduce Set Voltage function is used to temporarily decrease the load in the The Reduce Set Voltage function is used to temporarily decrease the load in the network. By setting an integer to the RSV input of the COLTC function block, the network. By setting an integer to the RSV input of the COLTC function block, the control voltage can be lowered. The reduced voltage depends on

control voltage can be lowered. The reduced voltage depends on the integer and thethe integer and the RSV step

RSV step setting. If thesetting. If the RSV step RSV step is set to 2.00% Un and the RSV input to 1, theis set to 2.00% Un and the RSV input to 1, the reference voltage will be decreased by 1 x 2.00%. When the RSV input is set to 2, reference voltage will be decreased by 1 x 2.00%. When the RSV input is set to 2, the reference voltage will be decreased by 2 x 2.00%, etc.

the reference voltage will be decreased by 2 x 2.00%, etc.

It should be noted that the reduced power depends on the characteristic of the load It should be noted that the reduced power depends on the characteristic of the load when the voltage is decreased. A purely resistive load is decreased by about the when the voltage is decreased. A purely resistive load is decreased by about the square of the voltage, whereas inductive load is decreased less.

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Fig. 3.4.-1

Fig. 3.4.-1 shows the decrease of the target voltage when the RSV function is used.shows the decrease of the target voltage when the RSV function is used.

RSV activated RSV activated T T1 1 ssttaarrtt LLoowweer r T1 T1 R R S S V V__ d d i

i a a g g

r r a a m m

U

t

Fig.

Fig. 3.4.3.4.-1-1 VVoltagoltage re reductieduction uon using sing the Rthe RSV fSV functiounction.n.

Configuration example with the RSV function available in the COLTC function Configuration example with the RSV function available in the COLTC function block manual.

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4.

4. Regulation

Regulation of

of a

a single

single transformer

transformer

4 4..1

1..

P

Pu

urrp

po

os

se

e a

an

nd

d c

co

on

nn

ne

ec

cttiio

on

ns

s

Basically, the voltage regulation of a

Basically, the voltage regulation of a single transformer requires only one phase-to-single transformer requires only one phase-to- phase voltage from the transformer's LV side to be connected to the COLTC

phase voltage from the transformer's LV side to be connected to the COLTC function block. The phase-to-phase voltage may be

function block. The phase-to-phase voltage may be UU_12b_12b, U, U_23b_23bor or UU_31b_31b. Also, virtual. Also, virtual voltage measurement U

voltage measurement U_12bs_12bscan be used if phase voltages are connected to thecan be used if phase voltages are connected to the RET 54_ terminal. If line drop compensation is needed, at least

RET 54_ terminal. If line drop compensation is needed, at least one phase current isone phase current is required from the LV side

required from the LV side of the power transformer. By default the of the power transformer. By default the overcurrentovercurrent blocking function measurement is made on the HV side. If the load current is blocking function measurement is made on the HV side. If the load current is

measured only on the LV side, it will be used for overcurrent blocking instead. measured only on the LV side, it will be used for overcurrent blocking instead.

4 4..2

2..

S

Se

ettttiin

ng

gs

s

Table 4.2.-1

Table 4.2.-1 andand Table 4.2.-2Table 4.2.-2 show the settings for the voltage regulation of a singleshow the settings for the voltage regulation of a single transformer. A rule of thumb is that settings not used are set to 0, e.g.

transformer. A rule of thumb is that settings not used are set to 0, e.g. Ur Ur ,, UxUx andand RSV step

RSV step..

Ta

Table 4.2ble 4.2.-1.-1 SettSettings foings found undeund under Contror Control/Cl/COLOLTC/TC/SettSetting grouing group1/ p1/

P

Paarraammeetteerr SSeettttiinng g rraannggee CCoommmmeenntt R

Reeffeerreenncce e vvoolltt. . UUss 00..000000...22..00000 0 x x UUnn TTaarrggeet t vvoollttaaggee D

Deellaay y ttiimme e 1 1 TT11 11..0 0 ... . 330000..0 0 ss DDeellaay y ttiimme e ffoor r ffiirrsst t RRaaiissee// Lower pulse

Lower pulse D

Deellaay y ttiimme e 2 2 TT22 11..0 0 ... . 330000..0 0 ss DDeellaay y ttiimme e ffoor r sseeccoonnd d RRaaiissee// Lower pulse

Lower pulse U

Ur r [[%%]] 00..0 0 ... . 2255..0 0 % % UnUn RReessiissttiivve e lliinne e ddrroopp compensation compensation U

Ux x [[%%]] 00..0 0 ... . 2255..0 0 % % UnUn RReeaaccttiivve e lliinne e ddrroopp compensation compensation

Ta

Table 4.2.ble 4.2.-2-2 SettSettings fouings found under Connd under Controltrol/CO/COLLTC/TC/ConControl settrol settinting/ g/

P

Paarraammeetteerr SSeettttiinng g rraannggee CCoommmmeenntt O

Oppeerraattiioon n mmooddee AAuuttoomm. . SSiinngglle e oor r OOpp. . mmooddee inputs

inputs

When Op. mode input is used When Op. mode input is used the operation mode is

the operation mode is selected via the

selected via the AUTO_MAUTO_MANAN input of the

input of the COLCOLTC functionTC function block

block D

Deellaay y mmooddee DDeeffiinniitte e oor r iinnvveerrssee DDeellaay y ttiimme e cchhaarraacctteerriissttiicc O

Ouuttppuut t ppuullssee 00..5 5 ... . 1100..0 0 ss PPuullsse e lleennggtth h oof f RRaaiisse e aanndd Lower commands

Lower commands B

Baannddwwiiddtth h DDUUss 00..660 0 ... . 99..000 0 % % UUnn TThhe e rreeccoommmmeennddeed d sseettttiinng g iiss the same as the tap-changer the same as the tap-changer step voltage.

step voltage. O

Ovveerrccuurrrr. . LLiimmiitt 00..110 0 ... . 55..000 0 x x IInn SSeettttiinng g ffoor r oovveerrccuurrrreenntt blocking

blocking U

Unnddeerrvvoolltt. . LLiimmiitt 00..1 1 ... . 11..220 0 x x UUnn SSeettttiinng g ffoor r uunnddeerrvvoollttaaggee blocking

blocking O

Ovveerrvvoolltt. . LLiimmiitt 0..8080 0 ... . 11..660 0 x x UUnn SSeettttiinng g ffoor r ffaasst t lloowweer r ccoonnttrrooll M

Miinn. . vvoolltt. . TTaapp --336 6 ... . 3366 TTaap p ppoossiittiioon n aat t lloowweesst t vvoollttaaggee M

Maaxx. . vvoolltt. . TTaapp --336 6 ... . 3366 TTaap p ppoossiittiioon n aat t hhiigghheesstt voltage

(16)

Further, it is important that the

Further, it is important that the voltagevoltage andand current transformer current transformer settings and thesettings and the Protected unit

Protected unit scaling are set according to the VT and CT used. These settings canscaling are set according to the VT and CT used. These settings can be found under

be found under ConfigurationConfigurationin CAP 505.in CAP 505.

4 4..3

3..

E

Ex

xa

am

mp

plle

e 1

1:

: B

Ba

as

siic

c p

pa

arra

am

me

ette

errs

s

Fig. 4.3.-1

Fig. 4.3.-1 illustrates a single transformer feeding a busbar. In addition to a stabileillustrates a single transformer feeding a busbar. In addition to a stabile busbar voltage the following requirements have to be fulfilled:

busbar voltage the following requirements have to be fulfilled: •• targetarget busbt busbar voar voltage ltage 20.5 20.5 kVkV

•• maximumaximum througm through-curh-current for tap charent for tap changer 15nger 150 A (HV side)0 A (HV side) •• overvovervoltage doltage detectioetection activatn activated at 22.5 kVed at 22.5 kV

•• undundervervoltoltage blocage blockinkingg

•• tap-chtap-changer panger position iosition indicandication frotion from 1 to 19.m 1 to 19.

20 000 / 100V 20 000 / 100V 100 / 1 A 100 / 1 A 25 MVA 25 MVA 110 ± 9x1,67 / 21kV 110 ± 9x1,67 / 21kV I123 I123 U12 U12 RET 54_ RET 54_ single_trafo_example single_trafo_example Fi

Fig. 4.g. 4.3.-3.-11 AAVR coVR connennected tcted to a sino a single trgle transansforformer mer L

LDDC C lliimmiitt 00..000 0 ... . 22..000 0 x x UUnn MaMaxxiimmuum m ppeerrmmiitttteed d lliinne e ddrroopp compensation

compensation L

LDDC C sseelleeccttiioonn OONN//OOFFFF EnEnaabblle e oor r ddiissaabblle e LLDDCC function

function R

RSSV V sstteepp 00..000 0 ... . 99..000 0 % % UUnn SStteep p ssiizze e ffoor r RReedduucceed d SSeett Voltage

Voltage

Ta

(17)

I

_nT_nT

S

nn

3

××

U

_n_n

---=

=

(2) (2) where: where:

II_nT_nT == rarateted d cucurrrrenent t of of ppowoweer r trtranansfsfoormrmer er S

S_n_n == rraatteed pd poowweer or of pf poowewer tr trraannssffoorrmmeer r U

U_n_n == rraatteed d pphhaassee--ttoo--pphhaasse e vvoollttaaggee

The rated primary current is calculated on the side where the CT is located, in this The rated primary current is calculated on the side where the CT is located, in this example the HV side.

example the HV side.

I

_nT_nT

25

25 MVA

MVA

3

××

1

11

10

0 kV

kV

---

131

131 A

A

=

The rated values of the CT and VT do not match the ratings of the power The rated values of the CT and VT do not match the ratings of the power

transformer. Therefore the scaling factors for the protected unit are calculated for the transformer. Therefore the scaling factors for the protected unit are calculated for the channels to which the CTs and the VTs

channels to which the CTs and the VTs are connected. The channel scaling settingsare connected. The channel scaling settings are found in CAP 50_ under

are found in CAP 50_ under Configuration/Protected unit/Configuration/Protected unit/

Current measurement

scalingfactor

I

nmnm d d

I

_nT_nT

---=

=

II_nmd_nmd == rraatteed d pprriimmaarry y ccuurrrreennt t oof f CCTT

II_nT_nT == rarateted d cucurrrrenent t of of ppowoweer r trtranansfsfoormrmer er

scalingfactor

100

100 A

A

131

131 A

A

---

0.763

0.763 =

=

Voltage measurement

The scaling factor of the protected unit is calculated as follows for the voltage The scaling factor of the protected unit is calculated as follows for the voltage measurement:

measurement:

scalingfactor

U

nmnmd d

U

_nT_nT

---=

=

(4) (4) where: where: U

U_nmd_nmd == rraatteed d pprriimmaarry y ccuurrrreennt t oof f VVTT U

(18)

scalingfactor

20 000

V

21 000

V

---

0.952

0.952 =

=

It should be noted that the settings of the protected unit are part of the relay setting It should be noted that the settings of the protected unit are part of the relay setting and thus affecting all protection function blocks.

and thus affecting all protection function blocks.

Voltage regulator settings

The

The Reference voltage U Reference voltage U _s_sis calculated from the target voltage level of the busbar.is calculated from the target voltage level of the busbar.

U

_s_s

U

ttargarget et

U

_n_n

---

20 500

V

20 000

20 000V

V

---

1.025

××

U

_n_n

=

The

The Bandwidth Bandwidth∆∆_U_U s

scan be set according to the tap-changer step voltage. Too smallcan be set according to the tap-changer step voltage. Too small a value may result in unstable or too sensitive regulation. The bandwidth setting a value may result in unstable or too sensitive regulation. The bandwidth setting should not be less than half the

should not be less than half the tap-changer step voltage. The recommended settingtap-changer step voltage. The recommended setting is equal to the tap step voltage.

is equal to the tap step voltage.

U

_s_s ∆ ∆

_1.67%

_1.67%U

_U

n n

=

To avoid damage to the tap changer at overload, the

To avoid damage to the tap changer at overload, the Overcurrent limit Overcurrent limit blocks theblocks the operation of the voltage regulator.

operation of the voltage regulator.

Overcurr.limit

I

mamaxx

I

_nT_nT

---

150

150 A

A

131

131 A

A

---

1.15

××

I

_n_n

=

When the

When the Overvoltage limit Overvoltage limit setting is reached, the voltage regulator starts giving fastsetting is reached, the voltage regulator starts giving fast lower commands, continuing until the voltage is within the bandwidth.

lower commands, continuing until the voltage is within the bandwidth.

Overvolt.limit

U

mama xx

U

_nT_nT

---

22 500

V

20 000

V

---

1.13

××

U

_n_n

=

Once the measured voltage drops below the set

Once the measured voltage drops below the set Undervoltage limit Undervoltage limit , the undervoltage, the undervoltage limit function blocks the operation of the voltage regulator. Therefore, the

limit function blocks the operation of the voltage regulator. Therefore, the undervoltage limit should be given a value that will not be reached when the undervoltage limit should be given a value that will not be reached when the

transformer is in normal service. The default value of 0.70 x Un can be used in most transformer is in normal service. The default value of 0.70 x Un can be used in most situations.

situations.

The tap-changer position will be displayed in the range from

The tap-changer position will be displayed in the range from 1 to 19, where position1 to 19, where position 1 represents the lowest voltage and 19 the highest voltage. Consequently,

1 represents the lowest voltage and 19 the highest voltage. Consequently, Min.volt.tap

Min.volt.tap is set to 1 andis set to 1 and Max.volt.tap Max.volt.tap to 19. Please refer toto 19. Please refer to Section 3.2. Tap-Section 3.2. Tap-changer position indication

changer position indication for more details.for more details.

4 4..4

4..

E

Ex

xa

am

mp

plle

e 2

2:

: L

Liin

ne

e d

drro

op

p c

co

om

mp

pe

en

ns

sa

attiio

on

n

In this example a transformer is feeding three lines of different length and voltage In this example a transformer is feeding three lines of different length and voltage drop. Suitable line drop compensation parameters, which do not

drop. Suitable line drop compensation parameters, which do not lead to overvoltagelead to overvoltage on the shortest line or undervoltage on the

on the shortest line or undervoltage on the longest line, are to be found. The voltagelongest line, are to be found. The voltage in the load end of the lines (A, B and C) should be kept close to 20 kV.

(19)

50 MVA 50 MVA 110 ± 9x1,67 / 20kV 110 ± 9x1,67 / 20kV LL o o a a d d L L o o a a d d L L o o a a d d Line 1 = 21km Line 1 = 21km Line 2 = 14km Line 2 = 14km Line 3 = 28km Line 3 = 28km R R R R R R X X X X X X A A B B C C LDC_exampl LDC_exampl

AVR

Fig.

Fig. 4.4.-4.4.-11 A tranA transformesformer feedr feeding seing several veral lines lines of difof differferent leent length.ngth. The resistance and reactance for the line type used are R = 0.164

The resistance and reactance for the line type used are R = 0.164 Ω/Ω/_{km and X =}_{km and X =} 0.120

0.120ΩΩ_/km_/km

First, the total resistance and reactance of the lines are calculated. First, the total resistance and reactance of the lines are calculated. Line 1: 21 km Line 1: 21 km

R

_Line1_Line₁

₌

0.164

ΩΩ

_//

_km

××

₂₁

_km

₌

_3.444

ΩΩ

X

_Line1_Line₁

₌

0.120

ΩΩ

_//

_km

××

₂₁

_km

₌

_2.520

ΩΩ Line 2: 14 km Line 2: 14 km Line Line22

=

0.164

ΩΩ

//

km

××

14

14 km

km

=

2.296

ΩΩ

X

_Line2_Line₂

₌

0.120

ΩΩ

_//

_km

××

₁₄

_km

₌

_1.680

ΩΩ Line 3: 28 km Line 3: 28 km Line Line33

=

0.164

ΩΩ

//km

km

××

28

28 km

km

=

4.592

ΩΩ

X

_Line3_Line₃

₌

0.120

ΩΩ

_//

_km

××

₂₈

_km

₌

_3.360

ΩΩ Since there are three separate l

Since there are three separate lines with different voltage drops, a compromise mustines with different voltage drops, a compromise must be made. In general, the most convenient way is to calculate the average of the line be made. In general, the most convenient way is to calculate the average of the line

with the biggest and the smallest voltage drop. In this example, this is Line 2 and with the biggest and the smallest voltage drop. In this example, this is Line 2 and Line 3.

(20)

R

_average_average

2.296

ΩΩ

+

4.592

ΩΩ

2

2 ---

3.444

ΩΩ

=

X

_average_average

1.680

ΩΩ

+

3.360

ΩΩ

2

2 ---

2.520

ΩΩ

=

The R and X values used when calculating the line drop compensation parameters The R and X values used when calculating the line drop compensation parameters must also be divided by the number of lines fed by the power transformer.

must also be divided by the number of lines fed by the power transformer.

R

₌

3.444

ΩΩ ⁄ ⁄

₃

₌

_1.148

ΩΩ

X

₌

2.520

ΩΩ ⁄ ⁄

₃

₌

_0.840

ΩΩ It is now possible to calculate the s

It is now possible to calculate the setting parametersetting parameters U U _r_randand U U _x_xusing the followingusing the following formulas:

formulas:

U

_r_r

%

3 3 I

I

nT nT

× × ××

_R

U

_n_n

---

××

100%

=

(5) (5)

U

_x_x

%

3

3 I

I

nT nT

× × ××

_X

U

_n_n

---

××

100%

=

IInnTT == rraatteed d ccuurrrreennt t oof f ppoowweer r ttrraannssffoorrmmeer r R

R == lliinne e rreessiissttaannccee,, ΩΩ_/phase_/phase X

X == lliinne e rreeaaccttaannccee,,ΩΩ_/phase_/phase U

Unn == rraatteed d vvoollttaagge oe of pf poowweer tr trraannssffoorrmmeer r Rated current of LV side power transformer

Rated current of LV side power transformer

I

_nT_nT

50

50 MVA

MVA

3

××

20 20kV

kV

---

1443

A

=

U

_r_r

%

3

××

1

14

44

43

3 A

A

××

1.148

ΩΩ

20 000

V

--- 100%

××

100%

_14.35%

_U

n n

=

U

_x_x

%

3

××

1

14

44

43

3 A

A

××

0.840

ΩΩ

20 000

V

--- 100%

××

100%

_10.50%

_U

n n

=

Line drop compensation has to be activated by means of the LDC parameter Line drop compensation has to be activated by means of the LDC parameter ((Control/COLTC/Control settingControl/COLTC/Control setting).).

(21)

4 4..5

5..

C

Co

om

mm

miis

ss

siio

on

niin

ng

g a

an

nd

d ttrro

ou

ub

blle

es

sh

ho

oo

ottiin

ng

g

Before commissioning a transformer provided with voltage

Before commissioning a transformer provided with voltage regulation check theregulation check the following:

following:

First, select manual mode for the voltage regulator. First, select manual mode for the voltage regulator.

•• Check that the CCheck that the COLOLTC function block TC function block measures the correct vmeasures the correct voltage and currentoltage and current ((Control/COLTC/Input data/Control/COLTC/Input data/))

Voltage U12 Voltage U12

Primary and/or Second. Current Primary and/or Second. Current

•• If LDC is used, chIf LDC is used, check that the phase angeck that the phase angle measured by thle measured by the COLe COLTC functionTC function block is correct (

block is correct (Control/COLTC/Input data/Angle U1-IL1Control/COLTC/Input data/Angle U1-IL1). It). It should be equal to the phase angle of the load.

should be equal to the phase angle of the load.

•• Check Check that nthat no bloco blockings kings are actare active (ive (Control/COLTC/Output data/Control/COLTC/Output data/)) •• Raise the tap changer Raise the tap changer manuallymanually, verifying that th, verifying that the voltage and tap e voltage and tap position doposition do

rise. Then, lower the tap changer manually and verify the changes. rise. Then, lower the tap changer manually and verify the changes.

•• Select Automatic mode for thSelect Automatic mode for the voltage regulatore voltage regulator, either via the , either via the binary inputs or binary inputs or the MIMIC.

the MIMIC.

•• Check thCheck that the presat the present opeent operation mration mode is corrode is correct (ect (Control/COLTC/OutputControl/COLTC/Output data/Output OPER_MODE

data/Output OPER_MODE == Automatic Automatic))

•• Check Check that nthat no alaro alarms are ams are active (ctive (CControl/COLTC/Output data/Alarmontrol/COLTC/Output data/Alarm reason

reason == 000000))

In the event of abnormal operation or

In the event of abnormal operation or incorrect measurement, check incorrect measurement, check Table 4.5.-1Table 4.5.-1 for for a solution.

a solution.

T

Tabable le 4.4.5.-5.-11 TrTrououblebleshshooootinting g

P

Prroobblleemm SSoolluuttiioonn Wr

Wrong ong phaphase ase anglngle mee measuasured red in Cin COLOLTCTC • Check • Check the the polpolariarity oty of thf the voe voltaltage age and/nd/or or current connection.

current connection.

• Check that the phase currents are • Check that the phase currents are connected to the correct terminal. connected to the correct terminal. T

Taap cp chahannggeer mr moovvees is in wn wrroonng dg diirreeccttiioonn • C• Chheecck tk thheeMin. volt. TapMin. volt. TapandandMax. volt. TapMax. volt. Tap

settings. settings.

• Check the Raise and Lower wiring. • Check the Raise and Lower wiring. • Check the polarity of the voltage and

• Check the polarity of the voltage and currentcurrent connection.

connection.

• Check that the phase currents are • Check that the phase currents are connected to the correct terminals connected to the correct terminals Wr

Wronong tg tapap-c-chahangnger er poposisitition on inindidicacatitionon • Cal• Calibibrarate te ththe te tapap-c-chahangnger er poposisitition on sisigngnalal with the Transducer Linearization Tool. with the Transducer Linearization Tool. • Check that

• Check thatLinear curveLinear curveis “Enabled” in CAPis “Enabled” in CAP under

under Configuration/RTD1/Configuration/RTD1/ Input _

Input _

• Make sure that the

• Make sure that the settings are stored andsettings are stored and the relay restarted.

(22)

To reset an alarm manually, press the

To reset an alarm manually, press the CC_{button for two seconds.}_{button for two seconds.}

Delay times T1 and T2 are

Delay times T1 and T2 are not according tonot according to setting

setting

• Alarm activated. The

• Alarm activated. The Alarm reason Alarm reason

parameter should be 000, otherwise T1 and parameter should be 000, otherwise T1 and T2 are doubled. Check which alarm is T2 are doubled. Check which alarm is activeactive from

fromControl/COLTC/OutputControl/COLTC/Output data/Alarm reason

data/Alarm reason

• Check that the correct setting group is • Check that the correct setting group is

active. active. The voltage regulator does not increase the

The voltage regulator does not increase the voltage even if the dU value

voltage even if the dU value is greater thanis greater than the bandwidth setting.

the bandwidth setting.

• If the line drop compensation function is • If the line drop compensation function is

used, the

used, theLDC limit LDC limit may have been reachedmay have been reached and therefore the regulator is prevented and therefore the regulator is prevented from increasing the voltage

from increasing the voltage • External blocking activated • External blocking activated

• The extreme tap changer position has been • The extreme tap changer position has been

reached reached “Command error” alarm

“Command error” alarm (Alarm reason = 001)(Alarm reason = 001) • The tap-changer pos• The tap-changer position did not respond toition did not respond to a Raise or Lower command within 20

a Raise or Lower command within 20 seconds.

seconds.

• The position did not change at all, or • The position did not change at all, or

changed more than one step. Re-calibrate changed more than one step. Re-calibrate the tap-changer position signal.

the tap-changer position signal. • The tap changer moved in

• The tap changer moved in the wrongthe wrong direction. The Raise and Lower

direction. The Raise and Lower wiring mightwiring might be swapped.

be swapped. “TCO signal does not fall" alarm (Alarm

“TCO signal does not fall" alarm (Alarm reason = 010)

reason = 010)

• The TCO signal stays active for more than • The TCO signal stays active for more than

15 seconds after a Raise or Lower 15 seconds after a Raise or Lower command.

command.

• Possible tap-changer control failure • Possible tap-changer control failure "Regulator pumping" alarm (Alarm reason =

"Regulator pumping" alarm (Alarm reason = 100)

100)

• Too many Raise and Lower commands • Too many Raise and Lower commands

during one hour. during one hour.

• Unstable regulation. The reason may be too • Unstable regulation. The reason may be too

small

smallBandwidthBandwidthand/or T1, T2 settingand/or T1, T2 setting values.

values.

• Check if Controls per 1h

• Check if Controls per 1h is set according tois set according to the permitted limit. (

the permitted limit. (Control/COLTC/Control/COLTC/ Control setting/

Control setting/))

Ta

Table ble 4.54.5.-1.-1 TroTroublublesheshootiooting (Cong (Continntinued)ued)

P

(23)

5.

5. Parallel

Parallel operation

operation

Parallel operation means that two or several power transformers are feeding the Parallel operation means that two or several power transformers are feeding the same busbar. Further, the parallel power transformers must all be fed from the same same busbar. Further, the parallel power transformers must all be fed from the same source. Since single-operation mode of the voltage regulator cannot be used with source. Since single-operation mode of the voltage regulator cannot be used with parallel transformers, a suitable parallel mode must be used.

parallel transformers, a suitable parallel mode must be used. The COLTC function block supports three

The COLTC function block supports three different parallel operation modes, i.e.different parallel operation modes, i.e. the Master/Follower mode (M/F), Minimizing Circulating Current mode (MCC) and the Master/Follower mode (M/F), Minimizing Circulating Current mode (MCC) and Negative Reactance principle (NRP).

Negative Reactance principle (NRP).

To avoid incorrect operation, the settings of all parallel AVRs have to be identical. To avoid incorrect operation, the settings of all parallel AVRs have to be identical. However, the setting of the stability parameter used i

However, the setting of the stability parameter used i n the MCC and NRP mode, isn the MCC and NRP mode, is proportional to the rated currents of

proportional to the rated currents of the power transformers.the power transformers. The operation mode is selected with the

The operation mode is selected with the Operation modeOperation mode parameter. The actualparameter. The actual operation mode can be set to be fixed or selectable via the inputs of the function operation mode can be set to be fixed or selectable via the inputs of the function block. With the parameter setting

block. With the parameter setting Op. mode inputsOp. mode inputs, the operation depends on the, the operation depends on the states of the PARAL_MODE, AUTO_MAN and PARALLEL inputs of the function states of the PARAL_MODE, AUTO_MAN and PARALLEL inputs of the function block.

block. Table 5.-1

Table 5.-1 shows the operation mode at different values of the inputs of the COLTCshows the operation mode at different values of the inputs of the COLTC function block.

function block.

T

Tabable le 5.5.-1-1 OpOpereratatioion mn modode oe of vf vololtatage ge reregugulalatotor r

Operation mode Operation mode parameter parameter PPAARRAALL__MMOODDEE AAUUTTOO__MMAANN PAPARRAALLLLEELL Actual operation Actual operation mode mode O

Opp. . mmoodde e iinnppuutt 0 0 oor r 1 1 oor r 22 00 00 MMaannuuaall O

Opp. . mmoodde e iinnppuutt 00 00 11 AAuuttoommaattiic c ffoolllloowweer r O

Opp. . mmoodde e iinnppuutt 0 0 oor r 1 1 or or 22 11 00 AAuuttoommaattiic c ssiinnggllee O

Opp. . mmoodde e iinnppuutt 00 11 11 AAuuttoommaattiic c mamasstteer r O

Opp..mmooddeeiinnppuutt 11 00oorr11 11 MMCCCC O

Opp..mmooddeeiinnppuutt 22 00oorr11 11 NNRRPP O

Otthheer r sseettttiinngg NNAA NNAA NNAA AAccccoorrddiinng g tto o OOpp.. mode parameter mode parameter Fig. 5.-1

Fig. 5.-1 shows an example of a configuration used for switching between differentshows an example of a configuration used for switching between different operation modes with external switches connected to the binary inputs BI9 and operation modes with external switches connected to the binary inputs BI9 and BI10. Binary input BI9 is used for switching to

BI10. Binary input BI9 is used for switching to parallel mode, whereas BI10, whenparallel mode, whereas BI10, when active, switches the COLTC function block to automatic mode.

active, switches the COLTC function block to automatic mode.

The OPER_MODE output is used to indicate the operation mode of the voltage The OPER_MODE output is used to indicate the operation mode of the voltage regulator. In this example, the operation mode is shown on the MIMIC display and regulator. In this example, the operation mode is shown on the MIMIC display and also by two state output relays.

(24)

COLTC COLTC PARAL_MODE PARAL_MODE AUTO_MAN AUTO_MAN PARALLEL PARALLEL USINT#0 USINT#0 BIO1_5_BI9 BIO1_5_BI9 BIO1_5_BI10 BIO1_5_BI10 Single / Parallel Single / Parallel mode selection mode selection Auto / Man Auto / Man mode selection mode selection GE GE OPER_MODE OPER_MODE GE GE USINT#2 USINT#2 USINT#3 USINT#3 COIND_ COIND_ BINOPEN BINOPEN BINCLOSE BINCLOSE IV IV NOT NOT COIND_ COIND_ BINOPEN BINOPEN BINCLOSE BINCLOSE IV IV NOT NOT Auto / Man Auto / Man mode indication mode indication Single / parallel Single / parallel mode indication mode indication BIO1_5_SO5 BIO1_5_SO5 BIO1_5_SO6 BIO1_5_SO6 opermode_conf_general opermode_conf_general Fig. 5.-1

Fig. 5.-1 Configuration for Configuration for switching between switching between manual, automamanual, automatic and tic and parallel parallel mode

mode

The OPER_MODE output provides an integer between 0 and 6 representing the The OPER_MODE output provides an integer between 0 and 6 representing the actual operation mode of the COLTC function block:

actual operation mode of the COLTC function block: 0 = Not in use 0 = Not in use 1 = Manual 1 = Manual 2 = Autom. Single 2 = Autom. Single 3 = Autom. Master 3 = Autom. Master 4 = Autom. Follower 4 = Autom. Follower 5 = NRP 5 = NRP 6 = MCC 6 = MCC

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The Master/Follower mode can be used exclusively in cases where all parallel power The Master/Follower mode can be used exclusively in cases where all parallel power transformers have the same ratings and the tap changers have

transformers have the same ratings and the tap changers have the same step voltages.the same step voltages. The Master/Follower mode means that all parallel transformers operate as one unit. The Master/Follower mode means that all parallel transformers operate as one unit. The Master regulates all the Followers simultaneously with Raise and Lower The Master regulates all the Followers simultaneously with Raise and Lower commands. Basically, an unlimited number of followers can be used with this commands. Basically, an unlimited number of followers can be used with this operation mode. For a simple Master/Follower voltage regulation only voltage operation mode. For a simple Master/Follower voltage regulation only voltage measurement is required.

measurement is required.

When the M/F mode is used, it is recommended to transfer tap-changer position When the M/F mode is used, it is recommended to transfer tap-changer position information from the Followers to the Master,

information from the Followers to the Master, either via an analogue signal, or over either via an analogue signal, or over LON communication. This will automatically enable the

LON communication. This will automatically enable the out-of-stepout-of-step function, whichfunction, which means that the Master can regulate a separate Follower, if its tap position is different means that the Master can regulate a separate Follower, if its tap position is different from that of the Master. The out-of-step function also requires that the Raise and from that of the Master. The out-of-step function also requires that the Raise and Lower commands sent to Followers are

Lower commands sent to Followers are obtained from the FLLW_CTRL output of obtained from the FLLW_CTRL output of the Master's COLTC function block. The out-of-step function enables a maximum the Master's COLTC function block. The out-of-step function enables a maximum of four parallel transformers to be used.

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Fig. 5.1.1.-1

Fig. 5.1.1.-1 shows an example of a configuration that can be used for both Master shows an example of a configuration that can be used for both Master and Follower. The tap changer position information of the own transformer is and Follower. The tap changer position information of the own transformer is connected to RTD1_6_AI1 and transmitted via the RTD1_6_AO1 output as a mA connected to RTD1_6_AI1 and transmitted via the RTD1_6_AO1 output as a mA signal. The same signal is connected to the RTD1_6_AI2 input of parallel units. In signal. The same signal is connected to the RTD1_6_AI2 input of parallel units. In this configuration it makes no difference which one is the Master and which one is this configuration it makes no difference which one is the Master and which one is a Follower. a Follower. MF_CONF MF_CONF INT2BOOL INT2BOOL B0 B0 B1 B1 B2 B2 B3 B3 COLTC COLTC LOWER_FOLLOWER LOWER_FOLLOWER FLLW_CTRL FLLW_CTRL RAISE_FOLLOWER RAISE_FOLLOWER TAP_POS1 TAP_POS1 TAP_POS2 TAP_POS2 LOWER_OWN LOWER_OWN RAISE_OWN RAISE_OWN PS1_4_HSPO4 PS1_4_HSPO4 PS1_4_HSPO5 PS1_4_HSPO5 BIO1_5_SO1 BIO1_5_SO1 BIO1_5_SO2 BIO1_5_SO2 BIO1_5_BI1 BIO1_5_BI1 BIO1_5_BI2 BIO1_5_BI2 REAL_TO_SINT REAL_TO_SINT RTD1_6_AI2 RTD1_6_AI2 RTD1_6_AO1 RTD1_6_AO1 RTD1_6_AI1 RTD1_6_AI1 REAL_TO_SINT REAL_TO_SINT (Lower to follower) (Lower to follower) (Raise to follower) (Raise to follower)

(Lower to own tap changer)

(Raise to own tap changer)

(Ta

(Tap pos. to p pos. to master)master)

(Raise from Master)

(Lower from Master)

Fi

Fig. 5.g. 5.1.11.1.-1.-1 ExamplExample of Mae of Masterster/Fo/Follollower cwer confonfiguiguratration wion with oith out-ut-of-of-stepstep function

function

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The same principle of setting the AVR parameters as

The same principle of setting the AVR parameters as for a single transformer can befor a single transformer can be used in the Master/Follower mode (refer to

used in the Master/Follower mode (refer to Section 4.2. SettingsSection 4.2. Settings).).

The operation mode can either be set to be fixed for the Master and Follower, or The operation mode can either be set to be fixed for the Master and Follower, or selectable via binary inputs.

selectable via binary inputs. Table 5.1.2-1Table 5.1.2-1 shows the operation mode at differentshows the operation mode at different input values of the COLTC function block. See the configuration example in input values of the COLTC function block. See the configuration example in Fig. 5.-1.

Fig. 5.-1.

Ta

Table 5.ble 5.1.2-1.2-1 1 OpeOperatiration modon mode of the Ae of the AVR at diVR at diffefferenrent settt settingsings

Operation mode Operation mode parameter parameter PPAARRAALL__MMOODDEE AAUUTTOO__MMAANN PAPARRAALLLLEELL Actual operation Actual operation mode mode O

Opp. . mmoodde e iinnppuutt 0 0 oor r 1 1 oor r 22 00 00 MMaannuuaall O

Opp. . mmoodde e iinnppuutt 0 0 oor r 1 1 or or 22 11 00 AAuuttoommaattiic c ssiinnggllee O

Opp. . mmoodde e iinnppuutt 00 11 11 AAuuttoommaattiic c mamasstteer r O

Opp. . mmoodde e iinnppuutt 00 00 11 AAuuttoommaattiic c ffoolllloowweer r A

Auuttoomm. . SSiinnggllee NNAA NNAA NNAA AAuuttoommaattiic c ssiinnggllee A

Auuttoomm. . MMaasstteerr NNAA NNAA NNAA AAuuttoommaattiic c mmaasstteer r A

Auuttoomm. . FFoolllloowweerr NNAA NNAA NNAA AAuuttoommaattiic c ffoolllloowweer r O

Otthheer r sseettttiinngg NNAA NNAA NNAA AAccccoorrddiinng g ttoo Operation mode Operation mode parameter parameter It should be noted that there can be only one Master in the Master/Follower It should be noted that there can be only one Master in the Master/Follower operation mode.

operation mode.

Functions such as LDC and RSV can also be used in the Master/Follower mode. In Functions such as LDC and RSV can also be used in the Master/Follower mode. In M/F mode only the regulation settings of the Master are effective. A

M/F mode only the regulation settings of the Master are effective. A Follower(s) willFollower(s) will operate according to the Raise and Lower commands given by the Master.

AVR

RET 54_

RET 54_

Application and Setting Guide

Contents:

Contents:

Copyrights ...4

Copyrights ...4

1.

1. Scope

Scope ...

...

...

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...5

...5

2.

2. Intro

Introducti

duction

on ...

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3.

3. Oper

Operation

ation princ

principle

iple ...

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...7

.7

4.

4. Regulation

Regulation of

of a

a single

single transformer

transformer ...

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... 15

15

5.

5. Para

Parallel

llel oper

operation

ation ...

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...23

..23

6.

6. Refe

Referenc